diabetes

Does An Apple A Day Keep Diabetes Away?

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A Holistic Approach To Preventing Diabetes 

Author: Dr. Stephen Chaney

VillainLow carb enthusiasts will tell you that carbohydrates are the villain. They tell you that cutting carbohydrates out of your diet will reduce your risk of obesity, diabetes, heart disease, and cancer.

If they limited their list of villainous foods to foods with white flour and/or added sugars, many nutrition experts would agree with them. There is widespread agreement in the nutrition community that we eat far too much of these foods.

However, I don’t have to tell you that many low carb diets also eliminate fruits, whole grains, and beans from their diets based solely on the carbohydrate content of these foods. Is this good advice? Is there any data to back up this claim?

The short answer is no. In fact, most studies suggest the opposite is true. I have covered these studies in previous issues of “Health Tips From The Professor”. For example:

  • In one issue I covered studies showing the people consuming primarily plant-based diets weigh less, have less inflammation, and have a lower risk of diabetes, heart disease, and high blood pressure than people consuming the typical American diet.
  • In another issue I shared studies showing that women consuming a plant-based low carb diet weigh less, and have reduced risk of diabetes and heart disease than women consuming a meat-based low carb diet.

However, these studies looked at the effect of the whole diet, not individual components of the diet.

This week I will review a study (NP Bondonno et al, The Journal of Clinical Endocrinology & Metabolism, 2021, doi:10.1210/clinem/dgab335) looking at the effect of fruit consumption on the risk of developing type 2 diabetes.

Next week I will review a study looking at the effect of whole grain consumption on the risk of developing type 2 diabetes.

How Was This Study Done?

Clinical StudyThis study made use of data from the Australian Diabetes Obesity And Lifestyle Study. This study recruited 7675 Australians 25 years or older from 7 states and territories in Australia in 1999 and 2000 and followed them for 5 years. The characteristics of the study population were:

  • Gender = 45% male, 55% female
  • Average age = 54 years
  • Average BMI = 26.8 (slightly overweight)
  • Did not have diabetes at time of entry into the study.

The participants filled out a food frequency questionnaire at the time of entry into the study. This questionnaire was used to analyze:

  • the amount of fruit consumed.
  • the amounts of vegetables, red meat, and processed meat consumed.
  • how many calories were consumed.

At the time of entry into the study several measurements were taken that assessed whether the participants had an increased risk of developing diabetes (otherwise known as pre-diabetes). These included:

  • Fasting plasma glucose and insulin levels.
  • A 2-hour glucose tolerance test. The results of this test were used to calculate insulin resistance and insulin sensitivity.

The study also recorded any participants who were diagnose with diabetes over the next 5 years.

Does An Apple A Day Keep Diabetes Away?

AppleThe data from this study were statistically adjusted for confounding variables (Other variables that might affect the risk of diabetes). Many confounding variables were included in the adjustment, but the ones of interest to us are age, sex, physical activity, obesity, caloric intake, and intakes of alcohol, vegetables, red meat, and processed meat.

After adjustment for all these variables the results were:

At the beginning of the study:

  • Fruit intake was inversely associated with insulin levels and insulin resistance.
  • Fruit intake was directly associated with insulin sensitivity.

In other words, the more fruit people ate, the less likely they were to have prediabetes at the time they entered the study.

At 5 years:

  • Fruit intake was inversely associated with diabetes.
  • Fruit juice had no effect on diabetes risk.

In other words, the more fruit people ate, the less likely they were to develop diabetes 5 years later. Fruit juice, on the other hand, had no beneficial effect on diabetes risk.

  • The benefit of fruit intake plateaued at 2-3 servings a day.

In other words, you don’t need to become a fruitarian. A modest intake of fruit (2-3 servings a day) is all you need.

In case you haven’t noticed, 2-3 servings of fruit a day matches USDA recommendations – and the recommendations of almost every other governmental and medical organization. What do they know that you didn’t know?

The most commonly eaten fruits in this study were apples (23%), bananas (20%), and oranges and other citrus fruits (18%). Enough people ate these three fruits that their effects on the risk of developing diabetes could be analyzed separately.

  • The beneficial effect of each of these fruits plateaued at about one serving a day.

In other words, an apple a day does keep diabetes away. However, apples can’t do it alone. You need a variety of fruits for optimal benefit.

The authors concluded, “A healthy diet including whole fruits, but not fruit juice, may play a role in mitigating type 2 diabetes risk.”

A Holistic Approach To Preventing Diabetes

Myth Versus FactsThis study explodes the myth that you should avoid fruits if you want to prevent diabetes. Yes, fruits do contain sugar, but:

  • They also contain fiber, which slows the absorption of that sugar.
  • The sugar is trapped in a cellular matrix, which must be digested before that sugar can be released. That also slows the absorption of sugar.

This is why fruit consumption reduces the risk of diabetes while fruit juice consumption does not.

However, I don’t want to give you the impression that you can reduce your risk of diabetes just by consuming more fruit. You need a holistic approach. Here are diabetes prevention tips from the American Diabetes Association.

  1. Get more physical activity.
    • The greatest benefit comes from a fitness program that includes both aerobic exercise and resistance training.

2) Get plenty of fiber.

    • Include fruits, vegetables, whole grains, beans, and nuts in your diet.

3) Lose extra weight.

    • One recent study showed that losing as little as 7% of your body weight and exercising regularly could reduce your risk of developing diabetes by almost 60%.

4) Skip fad diets and simply make healthier food choices.

    • “Low-carb diets, the glycemic index diet, and other fad diets may help you lose weight initially. But their effectiveness at preventing diabetes and their long-term effects aren’t known. And by excluding or strictly limiting a particular food group, you may be giving up essential nutrients.”

5) See your doctor on a regular basis and have your blood sugar tested, especially if you are overweight, have a family history of diabetes, or are over 45.

The Bottom Line

Low carb enthusiasts tell you to eliminate fruits from your diet if you want to reduce your risk of developing diabetes. Is this true? Is it good advice?

A recent study put this advice to the test. The study recruited 7675 Australians 25 years or older and followed them for 5 years. It correlated fruit intake with measures of prediabetes at the beginning of the study and correlated fruit intake with the onset of diabetes over the next 5 years. Here is what the study found.

  • The more fruit people ate, the less likely they were to have prediabetes at the time they entered the study.
  • The more fruit people ate, the less likely they were to develop diabetes 5 years later.
  • The benefit of fruit intake plateaued at 2-3 servings a day. In other words, you don’t need to become a fruitarian. A modest intake of fruit (2-3 servings a day) is all you need.

The most commonly eaten fruits in this study were apples (23%), bananas (20%), and oranges and other citrus fruits (18%). Enough people ate these three fruits that their effects on the risk of developing diabetes could be analyzed separately.

  • The beneficial effect of each of these fruits plateaued at about one serving a day.

In other words, an apple a day keeps diabetes away. However, apples can’t do it alone. You need a variety of fruits for optimal benefit.

The authors concluded, “A healthy diet including whole fruits, but not fruit juice, may play a role in mitigating type 2 diabetes risk.”

For more details about this study and a holistic approach to reducing your risk of diabetes recommended by the American Diabetes Association, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

Do Low Fat Diets Reduce The Risk Of Diabetes?

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Why Is Nutrition So Confusing?

Author: Dr. Stephen Chaney

EpigeneticsSometimes the professor likes to introduce you to the frontiers of nutrition. Epigenetics is such a frontier. In recent years, the hype has centered on DNA sequencing. It seems like everyone is offering to sequence your genome and tell you what kind of diet is best for you, what foods to eat, and what supplements to take. But can DNA sequencing fulfill those promises?

The problem is that DNA sequencing only tells you what genes you have. It doesn’t tell you whether those genes are active. Simply put, it doesn’t tell you whether those genes are turned on or turned off.

This is where epigenetics comes in. Epigenetics is the science of modifications that alter gene expression. In simple terms, both DNA and the proteins that bind to DNA can be modified. This does not change the DNA sequence. But these modifications can determine whether a gene is active (turned on) or inactive (turned off).

This sounds simple enough, but here is where it really gets interesting. These modifications are affected by our diet, our lifestyle (BMI and exercise), our microbiome (gut bacteria), and our environment.

In today’s “Health Tips From The Professor” I am going to share a study (CQ Lai et al, American Journal of Clinical Nutrition, 112: 1200-1211, 2020) that looks at the effect of diet (low-fat versus low-carb diets) on a particular kind of DNA modification (methylation) that affects a gene (CPT) which influences our risk for metabolic diseases (obesity, high triglycerides, low HDL, insulin resistance, pre-diabetes, and type 2 diabetes).

[Note: For simplicity I will just refer to type 2 diabetes in the rest of this article. Just be aware that whatever I say about type 2 diabetes applies to other metabolic diseases as well.]

Previous studies have shown that:

  • Methylation of the CPT gene is the only epigenetic change in the entire genome that is associated with decreased risk of type 2 diabetes.
  • CPT gene activity regulates multiple metabolic pathways that influence the risk of type 2 diabetes.
  • High fructose and sucrose consumption increases CPT gene methylation in rats, and high fat diets suppress that methylation.

Based on those data, the authors hypothesized that carbohydrate and fat intake affect the methylation of CPT gene, which:

  • Alters the activity of the CPT gene and…
  • Affects the risk of developing type 2 diabetes.

Since we are talking about our diet making alterations to our DNA, we could consider this as an example of, “We are what we eat”.

Biochemistry 101: Why Is Nutrition So Confusing?

ConfusionNow it is time for my favorite topic, Biochemistry 101. Along the way you will discover why nutrition is so complicated – and so confusing.

The CPT gene codes for a protein called carnitine palmitoyltransferase or CPT. CPT transports fats into the mitochondria where they can be oxidized to generate energy. Simply put, without CPT we would be unable to utilize most of the fats we eat. And, as you might expect, CPT is not required for carbohydrate metabolism.

  • In a simple world where our DNA sequence determines our destiny, we would either have an active CPT gene or an inactive mutant version of the gene. If we had the mutant version of the CPT gene, we would be unable to use fat as an energy source.

However, we don’t live in a simple world. Epigenetic modifications alter the activity of the CPT gene. When the CPT gene is unmethylated it is fully active. Methylation inactivates the gene.

  • In a simple world, a high fat diet would activate the CPT gene so our body would be able to utilize the fat in our diet. It would do that by decreasing methylation of the gene. Conversely, a high carbohydrate, low fat diet would decrease CPT gene activity by increasing methylation of the gene.

This is the one simple prediction that works exactly as expected. 

  • In a simple world, CPT would be involved in transport of fat into our mitochondria and nothing else. In that world, the activity of the CPT gene would only affect fat metabolism.

However, we don’t live in a simple world. By mechanisms that are not completely understood, carnitine palmitoyltransferase (CPT) also influences both insulin resistance and release of insulin by our pancreas. That means the activity of the CPT gene also affects our risk of developing type 2 diabetes. 

  • In the simplest terms, we can think of diabetes as an inability to properly regulate blood sugar levels. In a simple world, that would mean that carbohydrates are the problem, and we could reduce our risk of developing diabetes by restricting our intake of carbohydrates.

However, we don’t live in a simple world. There are short-term studies supporting the effectiveness of both low carb and low fat diets at helping to control blood sugar levels. However, longer term studies generally show that only whole food, low fat diets are associated with reduced risk of developing type 2 diabetes.

In other words, healthy carbohydrates aren’t the problem. They are the solution for reducing your risk of type 2 diabetes. This isn’t intuitive. It isn’t simple. But the weight of evidence points in this direction.

[I should add the emphasis is on “healthy” carbohydrates. I am talking about diets that emphasize whole food sources of carbohydrates (fruits, vegetables, whole grains, and legumes), not diets loaded with sugar, refined carbohydrates, and highly processed foods.]

Confused yet? Don’t worry. The authors of this study combined all this information into a single, unifying hypothesis.

They proposed that the fat and carbohydrate content of the diet influence methylation of the CPT gene, which influences the activity of the CPT gene, which influences both fat metabolism and the risk of developing type 2 diabetes. Specifically, they proposed that:

  • High fat diets reduce methylation of the CPT gene. This activates the CPT gene which results in more carnitine palmitoyltransferase (CPT) being produced. This improves fat metabolism, but also increases the risk of developing type 2 diabetes.
  • High carbohydrate, low fat diets increase methylation of the CPT gene. This inactivates the CPT gene which results in less CPT being produced. This is OK because there is little fat to be metabolized. However, it also has the advantage of reducing the risk of developing type 2 diabetes.

This can be visually represented as:Diet And CPT

How Was This Study Done?

Clinical StudyThis study combined the results from 3,954 selected participants in three previous clinical trials:

  • The Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study.
  • The Framingham Heart Study.
  • The REGICORE study. This study is similar in design to the Framingham Heart Study except the participants were drawn from a region of Spain.

The participants were selected based on 4 criteria:

  • The study they were in measured metabolic disease outcome.
  • The study they were in included a detailed diet analysis.
  • A DNA methylation analysis was performed on blood taken from these participants so that the methylation status of the CPT gene could be determined.
  • mRNA levels were measured for the CPT gene (This is a measure of how active the gene is. Active genes will produce lots of mRNA. Inactive genes will produce very little mRNA).

The study then analyzed the data and looked at the associations between carbohydrate and fat intake with:

  • Methylation of the CPT gene.
  • Activity of the CPT gene (measured as the amount of CPT mRNA produced by the gene).
  • Type 2 diabetes and other metabolic diseases.

Do Low Fat Diets Reduce The Risk Of Diabetes?

The authors systematically tested the predictions of their unifying hypothesis (To help you understand the significance of their findings, I am repeating the visual representation of their unifying hypothesis below):

Diet And CPT

  1. Methylation of the CPT gene was negatively associated with type 2 diabetes. Simply put, when the methylation of the of the CPT gene was high, the risk of type 2 diabetes was low. This confirmed the results of previous studies.

2) Carbohydrate and fat intake influenced methylation of the CPT gene. Specifically:

    • Carbohydrate intake and the ratio of carbohydrate to fat intake were positively associated with CPT methylation. Simply put, a high carbohydrate, low fat diet resulted in increased methylation of the CPT gene.
    • Fat intake was negatively associated with CPT methylation. Simply put, a high fat, low carbohydrate diet resulted in decreased methylation of the CPT gene.

3) Carbohydrate and fat intake influenced the activity of the CPT gene. Specifically:Diabetes and healthy die

    • Carbohydrate intake and the ratio of carbohydrate to fat intake was negatively associated with CPT mRNA levels (a measure of CPT gene activity). Simply put, a high carbohydrate, low fat diet resulted in lower CPT gene activity. This means the CPT gene produced less CPT. And, combined with the previous data, it also means that methylation of the CPT gene decreases its activity.
    • Fat intake was positively associated with CPT mRNA levels. Simply put, a high fat, low carbohydrate diet resulted in greater CPT gene activity. This means the CPT gene produces more CPT. And, combined with the previous data, it also means that reducing methylation of the CPT gene increases its activity.

4) CPT gene activity influenced the prevalence of type 2 diabetes. Specifically:

    • High CPT gene activity was positively associated with the risk of type 2 diabetes.
    • Low CPT gene activity was negatively associated with the risk of type 2 diabetes.

Putting this all together, as the authors had predicted,

  1. High fat, low carbohydrate diets reduce methylation of the CPT gene. This activates the CPT gene which results in more CPT being produced. This improves fat metabolism, but also increases the risk of developing type 2 diabetes.

2) High carbohydrate, low fat diets increase methylation of the CPT gene. This results in less CPT being produced. This is OK because there is little fat to be metabolized. However, it also has the advantage of reducing the risk of developing type 2 diabetes.

In short, the results of the study confirmed all the predictions of the author’s unifying hypothesis.

Putting it all together, the authors concluded, “Our results suggest that the proportion of total energy supplied by carbohydrate and fat can have a causal effect on metabolic diseases [like type 2 diabetes] via the epigenetic status (DNA methylation) of the CPT gene.” Simply put, their data suggested that high carbohydrate, low fat diets reduced the risk developing type 2 diabetes.

What Does This Study Mean For You?

Peek Behind The CurtainLet me start by saying that occasionally I like to give you a peak behind the curtain and talk about emerging areas of research. We should think of this article as the beginning of an exciting new area of research rather than as a definitive study.

I should start with the disclaimer that this study looks at associations between diet, methylation of the CPT gene, and risk of developing type 2 diabetes.

Associations do not prove cause and effect. This study does not prove that epigenetic changes to the CPT gene caused the reduction in type 2 diabetes risk.

High carbohydrate and high fat diets likely influence the risk of developing type 2 diabetes in other ways as well. For example, the fiber in healthy high carbohydrate diets may support friendly gut bacteria that reduce the risk of developing type 2 diabetes.

I also don’t view this study as one that settles the debate as to whether low carb or low fat diets are better for reducing the risk of type 2 diabetes. It does not clinch the argument for low fat diets. Rather, this study suggests a mechanism by which low fat diets may reduce the risk of metabolic diseases.

In summary, this study does not end the debate as to whether low carb or low fat diets are best. However, it does remind us just how complex the human body is. It reminds us that simple assumptions about how foods affect our bodies may not be the correct assumptions. It also helps us understand why nutrition can be so confusing.

The Bottom Line 

In recent years, DNA sequencing has become all the rage. It seems like everyone is offering to sequence your genome and tell you what kind of diet is best for you.

The problem is that DNA sequencing only tells you what genes you have. It doesn’t tell you whether those genes are active. Simply put, it doesn’t tell you whether those genes are turned on or off.

That is where epigenetics comes in. Epigenetics is the science of modifications that alter gene expression. In simple terms, both DNA and the proteins that bind to DNA can be modified. This does not change the DNA sequence. But these modifications can determine whether a gene is active (turned on) or inactive (turned off).

Epigenetics makes nutrition more complicated, and more confusing. For example, diabetes is characterized an inability to control blood sugar levels properly. Accordingly, it seems only logical that carbohydrates, especially sugars and simple carbohydrates, are the problem.

This study showed that high carbohydrate, low fat diets cause epigenetic modifications to a gene that reduces the risk of developing type 2 diabetes and other metabolic diseases. Conversely, high fat, low carb diets have the opposite effect.

This mechanism is consistent with multiple long-term studies showing that whole food, low fat diets reduce the risk of developing type 2 diabetes.

This study does not end the debate as to whether low carb or low fat diets are best. However, it does remind us just how complex the human body is. It reminds us that simple assumptions about how foods affect our bodies may not be the correct assumptions. It also helps us understand why nutrition can be so confusing.

For more details read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

 

Which Diets Are Best In 2021?

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Which Diet Should You Choose?

Emoticon-BadMany of you started 2021 with goals of losing weight and/or improving your health. In many cases, that involved choosing a new diet. That was only 2 months ago, but it probably feels like an eternity.

For many of you the “bloom” has gone off the new diet you started so enthusiastically in January.

  • Perhaps the diet isn’t working as well as advertised…
  • Perhaps the diet is too restrictive. You are finding it hard to stick with…
  • Perhaps you are always hungry or constantly fighting food cravings…
  • Perhaps you are starting to wonder whether there is a better diet than the one you chose in January…
  • Perhaps you are wondering whether the diet you chose is the wrong one for you…

If you are rethinking your diet, you might want to know which diets the experts recommend. Unfortunately, that’s not as easy as it sounds. The diet world has become just as divided as the political world.

Fortunately, you have an impartial resource. Each year US News & World Report invites a panel of experts with different points of view to evaluate popular diets. They then combine the input from all the experts into rankings of the diets in various categories.

If you are still searching for your ideal diet, I will summarize the US News & World Report’s “Best Diets In 2021”. For the full report, click on this link.

How Was This Report Created?

Expert PanelUS News & World Report recruited panel of 25 nationally recognized experts in diet, nutrition, obesity, food psychology, diabetes, and heart disease to review the 39 most popular diets.  They rated each diet in seven categories:

  • How easy it is to follow.
  • Its ability to produce short-term weight loss.
  • Its ability to produce long-term weight loss.
  • its nutritional completeness.
  • Its safety.
  • Its potential for preventing and managing diabetes.
  • Its potential for preventing and managing heart disease.

They converted the experts’ ratings to scores 5 (highest) to 1 (lowest). They then used these scores to construct nine sets of Best Diets rankings:

  • Best Diets Overall combines panelists’ ratings in all seven categories. However, all categories were not equally weighted. Short-term and long-term weight loss were combined, with long-term ratings getting twice the weight. Why? A diet’s true test is whether it can be sustained for years. And safety was double counted because no diet should be dangerous.
  • Best Commercial Diets uses the same approach to rank 15 structured diet programs that require a participation fee or promote the use of branded food or nutritional products.
  • Best Weight-Loss Diets was generated by combining short-term and long-term weight-loss ratings, weighting both equally. Some dieters want to drop pounds fast, while others, looking years ahead, are aiming for slow and steady. Equal weighting accepts both goals as worthy.
  • Best Diabetes Diets is based on averaged diabetes ratings.
  • Best Heart-Healthy Diets uses averaged heart-health ratings.
  • Best Diets for Healthy Eating combines nutritional completeness and safety ratings, giving twice the weight to safety. A healthy diet should provide sufficient calories and not fall seriously short on important nutrients or entire food groups.
  • Easiest Diets to Follow represents panelists’ averaged judgments about each diet’s taste appeal, ease of initial adjustment, ability to keep dieters from feeling hungry and imposition of special requirements.
  • Best Plant-Based Diets uses the same approach as Best Diets Overall to rank 12 plans that emphasize minimally processed foods from plants.
  • Best Fast Weight-Loss Diets is based on short-term weight-loss ratings.

Which Diets Are Best In 2021?

The word WInner in white letters surrounded by a burst of colorful stars in 3d

Are you ready? If this were an awards program I would be saying “Envelop please” and would open the envelop slowly to build suspense.

However, I am not going to do that. Here are the top 5 and bottom 5 diets in each category (If you would like to see where your favorite diet ranked, click on this link). [Note: I excluded commercial diets from this review.]

Best Diets Overall 

The Top 5: 

#1: Mediterranean Diet

#2: DASH Diet (This diet was designed to keep blood pressure under control, but you can also think of it as an Americanized version of the Mediterranean diet.)

#3: Flexitarian Diet (A flexible semi-vegetarian diet).

#4: Mayo Clinic Diet

#5: MIND Diet (This diet is a combination of Mediterranean and DASH but is specifically designed to reduce cognitive decline as we age.)

The Bottom 5: 

#35: Modified Keto Diet

#36: Whole 30 Diet

#37: GAPS Diet (A diet designed to improve gut health).

#38: Keto Diet

#39: Dukan Diet

Best Weight-Loss DietsWeight Loss

The Top 5: 

#1: Flexitarian Diet

#2: Vegan Diet

#3: Volumetrics Diet (A diet based on the caloric density of foods).

#4: Mayo Clinic Diet

#5: Ornish Diet

The Bottom 5: 

#35: Fertility Diet

#36: Whole 30 Diet

#37: Alkaline Diet

#38: AIP Diet (A diet designed for people with autoimmune diseases)

#39: GAPS Diet

Best Diabetes Diets

The Top 5: 

#1: Flexitarian Diet

#2: Mediterranean Diet

#3: DASH Diet

#4: Mayo Clinic Diet

#5: Vegan Diet

The Bottom 5: 

#35: The Fast Diet

#36: AIP Diet

#37: GAPS Diet

#38: Whole 30 Diet (A diet designed for people with autoimmune diseases)

#39: Dukan Diet

strong heartBest Heart-Healthy Diets 

The Top 5: 

#1: DASH Diet

#2: Mediterranean Diet

#3: Ornish Diet (A diet based on the caloric density of foods).

#4: Flexitarian Diet

#5: Vegan Diet

The Bottom 5: 

#35: Keto Diet

#36: AIP Diet

#37: Whole 30 Diet

#38: Modified Keto Diet

#39: GAPS Diet

Best Diets for Healthy Eating

The Top 5: 

#1: DASH Diet

#2: Mediterranean Diet

#3: Flexitarian Diet

#4: TLC Diet (A diet designed to promote heart health)

#5: MIND Diet

The Bottom 5: 

#35: Atkins Diet

#36: Raw Food Diet

#37: Modified Keto Diet

#38: Dukan Diet

#39: Keto Diet 

Easiest Diets to FollowEasy

The Top 5: 

#1: Mediterranean Diet

#2: Flexitarian Diet

#3: MIND Diet

#4: DASH Diet

#5: Fertility Diet

The Bottom 5: 

#35: Keto Diet and Modified Keto Diet (tie)

#36: Whole 30 Diet

#37: Dukan Diet

#38: GAPS Diet

#39: Raw Foods Diet 

Best Fast Weight-Loss Diets

The Top 5 (Excluding Commercial Diets): 

#1: Atkins Diet

#2: Biggest Loser Diet

#3: Keto Diet

#4: Raw Food Diet

#5: Volumetrics Diet

Which Diets Are Best For Rapid Weight Loss?

Happy woman on scaleLet me start with some general principles:

#1: If you are looking for rapid weight loss, any whole food restrictive diet will do.

  • The Atkins and keto diets are meat heavy, low carb diets. They restrict fruits, some vegetables, grains, and most legumes.
  • The Biggest Loser diet relies on restrictive meal plan and exercise programs.
  • The restrictions of the raw food diet are obvious.
  • The volumetrics diet restricts foods with high caloric density.
  • The vegan diet, which ranks #7 on this list, is a very low fat diet that eliminates meat, dairy, eggs, and animal fats.
  • I did not include commercial diets that rated high on this list, but they are all restrictive in one way or another.

#2: Restrictive diets ultimately fail.

  • The truth is 90-95% of people who lose weight quickly on a restrictive diet regain most of that weight in the next two years. The pounds come back and often bring their friends along as well. Many people regain more weight than they lost. This is the famous “Yo-Yo Effect”.
  • If dieters paid for one of the commercial diets, they may as well have burned their money.
  • When I talk with people about weight loss, many of them tell me the Atkins diet is the only one they can lose weight on. That would be impressive if they were at a healthy weight, but most are not. They are overweight. I am starting to see the same thing from overweight people who have used the keto diet to lose weight and have regained their weight.

#3: We should ask what happens when we get tired of restrictive diets and add back some of your favorite foods.

  • If you lose weight on a vegan diet and add back some of your favorite foods, you might end up with a semi-vegetarian diet. This is a healthy diet that can help you maintain your weight loss.
  • If you lose weight on the Atkins or keto diets and add back some of your favorite foods, you end up with the typical American diet – one that is high in both fat and carbs. This is not a recipe for long-term success.
  • Long term weight loss is possible if you transition to a healthy diet after you have lost the weight. In a recent article in “Health Tips From The Professor” I wrote about an organization called the National Weight Control Registry. These are people who have been successful at keeping the weight off. For purposes of this discussion, two points are important.
  • They lost weight on every possible diet.
  • They kept the weight off by following a healthy reduced calorie, low fat diet. (For what else they did, click here).

Which Diet Should You Choose?

Which Diet Is BestWith rapid weight loss out of the way, let’s get back to the question, “Which Diet Should You Choose?” My recommendations are:

  • Choose a diet that fits your needs. That is one of the things I like best about the US News & World Report ratings. The diets are categorized. If your main concern is diabetes, choose one of the top diets in that category. If your main concern is heart health… You get the point.
  • Choose diets that are healthy and associated with long term weight loss. If that is your goal, you will notice that primarily plant-based diets top these lists. Meat-based, low carb diets like Atkins and keto are near the bottom of the lists.
  • Choose diets that are easy to follow. The less-restrictive primarily plant-based diets top this list – diets like Mediterranean, DASH, MIND, and flexitarian.
  • Choose diets that fit your lifestyle and dietary preferences. For example, if you don’t like fish and olive oil, you will probably do much better with the DASH or flexitarian diet than with the Mediterranean diet.
  • Finally, focus on what you have to gain, rather than on foods you have to give up.
    • On the minus side, none of the diets include sodas, junk foods, and highly processed foods. Teose foods should go on your “No-No” list. Sweets should be occasional treats and only as part of a healthy meal. Meat, especially red meat, should become a garnish rather than a main course.
    • On the plus side, primarily plant-based diets offer a cornucopia of delicious plant foods you probably didn’t even know existed. Plus, for any of the top-rated plant-based diets, there are websites and books full of mouth-watering recipes. Be adventurous.

The Bottom Line 

For many of you the “bloom” has gone off the new diet you started so enthusiastically in January. If you are rethinking your diet, you might want to know which diets the experts recommend. Unfortunately, that’s not as easy as it sounds. The diet world has become just as divided as the political world.

Fortunately, you have an impartial resource. Each year US News & World Report invites a panel of experts with different points of view to evaluate popular diets. They then combine the input from all the experts into rankings of the diets in various categories. In the article above I summarize the US News & World Report’s “Best Diets In 2021”.

There are probably two questions at the top of your list.

#1: Which diets are best for rapid weight loss? Here are some general principles:

  • If you are looking for rapid weight loss, any whole food restrictive diet will do.
  • Restrictive diets ultimately fail.
  • We should ask what happens when we get tired of restrictive diets and add back some of our favorite foods.
  • Long term weight loss is possible if you transition to a healthy diet after you have lost the weight.

#2: Which diet should you choose? Here the principles are:

  • Choose a diet that fits your needs.
  • Choose diets that are healthy and associated with long term weight loss.
  • Choose diets that are easy to follow.
  • Choose diets that fit your lifestyle and dietary preferences.
  • Finally, focus on what you have to gain, rather than on foods you have to give up.

For more details on the diet that is best for you, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

Is Fructose Good For You Or Bad For You?

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Is It The Fructose Or Is It The Food?

Author: Dr. Stephen Chaney

VillainFructose is the villain of the day. It is #1 on everyone’s “No-No” list. Almost every website, blog, and diet book demonize it. Even authors I highly respect say we should absolutely avoid it.

We are told it causes obesity, diabetes, heart disease, and non-alcoholic fatty liver disease – a disease that was unheard of only a few decades ago. We are told to read labels and avoid any foods with fructose or high-fructose corn syrup listed on their label.

But wait. Isn’t fructose a natural sugar? The answer is, “Yes”. It is the main sugar in fruit and many other naturally sweet whole foods. In fact, there is the same amount of fructose in an 8-ounce soda and a medium apple.

Does that mean that fruits are also bad for us? What is the truth?

Is It The Fructose Or Is It The Food?

AppleLet me put this into perspective for you. I have covered this in detail in a previous issue of Health Tips From The Professor. Here is a brief summary.

  • There are no sugar villains. There are no sugar heroes. Most of your favorite “natural” sugars are chemically and biologically indistinguishable from high-fructose corn syrup. Other natural sugars, like agave sugar, contain more fructose than high-fructose corn syrup.
  • All the studies showing the bad effects of fructose have been done with sodas and/or highly processed foods with added sugar. Let’s be clear. Those foods are bad for you.
  • Fruits, on the other hand, are good for you. You’ve heard the old adage, “An apple a day keeps the doctor away”. A recent study showed that isn’t just an “old wives’ tale”. It is true.

Why is that? Why is fructose in sodas and junk foods bad for us and fructose in fruits good for us?

Part of the answer is that fruits are high in fiber, which slows the release of fructose into the intestine as fruits are digested. In addition, the fructose in fruits is trapped in a cellular matrix, which also slows the release of fructose during digestion.

Sodas and highly processed foods, on the other hand, have nothing to slow the release of fructose. It is immediately available as soon as the food reaches the intestine.

A recent study sheds light on why the rate of fructose release in our intestine may be important. The study showed:

  • When fructose is released slowly our bodies know exactly what to do with it.
    • Most of it is metabolized by the cells that line our intestine, and the rest is metabolized by the liver.
    • In both cases fructose is converted to glucose and slowly released into the bloodstream.
    • This stabilizes blood sugar levels.
  • When fructose is released quickly our bodies are overwhelmed and bad things happen.
    • The intestine passes the excess on to the liver, and the liver converts it to fat rather than glucose.
    • The fat is stored in the liver.
    • This leads to insulin resistance, diabetes, heart disease, and fatty liver disease.

But could the fiber in fruits have other beneficial effects such as supporting populations of beneficial gut bacteria? The study ( J Beisner et al, Nutrients, 12: 3444, 2020) I will focus on today suggests the answer is yes.

How Was The Study Done?

Clinical StudyInvestigators from the University of Hohenheim, Germany recruited 12 healthy female volunteers, ages 20 – 40 (average age = 28).

Each of the subjects was given a series of diets to follow for one week each.

  • Week one was a low fructose diet (10 g of fructose/day). For this diet phase subjects had to avoid sweets, highly processed foods, sodas, and fruits and vegetables containing more than 1 g of fructose per serving.
  • Week two was a high fructose fruit diet (100 g of fructose/day). This diet phase emphasized fructose-rich fruits and vegetables. Sweets, highly processed foods, and sodas had to be avoided.
  • Week three was a repeat of the low fructose diet (10 g of fructose/day).
  • Week four was a high-fructose corn syrup diet (100 g of fructose/day). For this diet phase subjects had to sweeten the food they were eating with a measured amount of high-fructose corn syrup. They also had to avoid fructose-rich fruits and vegetables.

The diets were designed to have around 2,000 calories/day and to have the same amounts of fat (30% of calories), protein (15% of calories), and carbohydrate (55% of calories). However, the fiber content of the diets was very different (around 17 g/day on the low fructose and high-fructose corn syrup diets and around 38 g/day on the high fructose fruit diet).

The subjects were given detailed instructions and training before starting on the 4-week program. They also kept a daily dietary record of everything they ate and drank so the investigators would know how closely they stuck to their dietary instructions.

This experimental design was based on previous studies showing that populations of gut bacteria change within 24-48 hours when you go on a new diet. Stool samples were collected at the end of each week and analyzed for gut bacteria.

Is Fructose Good For You Or Bad For You?

MicrobiomeThe study showed:

  • Consumption of a high-fructose, fruit-rich diet resulted in:
    • An increase in beneficial butyrate-producing bacteria (more about that below).
    • A decrease in bacteria associated with elevated total and LDL cholesterol.
    • Decreased blood levels of total and LDL cholesterol.
  • Consumption of a high-fructose corn syrup diet had the opposite effect. It resulted in:
    • A decrease in beneficial butyrate-producing bacteria.
    • An increase in bacteria associated with elevated total and LDL cholesterol.
    • Increased blood levels of total and LDL cholesterol.

The authors concluded: “We provide evidence that the high-fructose corn syrup diet induces an imbalanced microbiota [gut bacteria] profile characterized by a significantly reduced abundance of beneficial butyrate-producing bacteria and of bacteria known for anti-obesity effects…Despite the high fructose content, the fruit-rich diet shifts the intestinal microbiota composition in a protective manner…”

The authors said that there were probably two mechanisms for the different effects of fructose in high-fructose corn syrup and in fruits.

  • The fiber found in fruit supports the growth of beneficial bacteria in our intestine.
  • When high-fructose corn syrup is present in foods with low fiber content, it is released rapidly in the intestine. As I noted above, the cells that line our intestine become overwhelmed and pass some of that excess fructose on to our liver. However, the authors cited previous studies showing that some of that excess fructose remains in our intestine and supports the growth of unhealthy bacteria.

What Does Butyrate Do?

Question MarkYou are probably wondering what is special about butyrate-producing bacteria. Here is a brief synopsis.

  • Butyrate is a short chain fatty acid. As you might expect from its name, it was originally identified as a constituent of butter.
  • Some species of gut bacteria convert the fats in our diet to butyrate.
    • It is used as a preferred energy source for the cells that line our intestine. Consequently, butyrate production in our intestines has been linked to:
      • Reduced inflammation of the cells lining our intestine, which reduces the risk for diseases like inflammatory bowel disease (IBS) and Crohn’s Disease.
      • Reduced risk of “leaky gut syndrome”.
      • Reduced risk of colon cancer.
    • It is also absorbed into the bloodstream and appears to affect several metabolic pathways. For example, butyrate production in the intestine is associated with:
      • Decreased cholesterol levels.
      • Improved blood sugar control.
      • A healthy body weight.

What Does This Mean For You?

Questioning ManThis was a small study. As the authors noted, larger studies of longer duration are needed to confirm that the effects of fructose on our gut bacteria depend on the food the fructose is in. However, several other studies have come to similar conclusions.

More importantly, this study merely shows that the effect of fructose-containing foods on our gut bacteria is a potential mechanism for explaining why the effect of fructose depends on the food it is in.

There is already overwhelming evidence that fructose in fruits is good for us, while high-fructose corn syrup in sodas and highly processed foods is bad for us.

Does that mean high-fructose corn syrup is villainous? Should we read labels and avoid any food containing high-fructose corn syrup?

I would remind you that the amount of fructose and the relative abundance of fructose and glucose are virtually identical in fruits and high-fructose corn syrup. It is not high-fructose corn syrup that is the problem, it is the foods it is found in.

We don’t need to become compulsive label readers. We just need to eat more foods without labels.

The Bottom Line 

High-fructose corn syrup has been vilified in recent years. However, there is increasing evidence that it is not fructose that is the problem. It is the foods it is found in.

A recent study was designed to test that hypothesis. The investigators fed subjects high fructose diets in which the fructose came either from fruits or high-fructose corn syrup. The amount of fructose was identical in the two diets. The investigators then asked what effect the two diets had on gut bacteria. In short:

  • Consumption of the high-fruit diet increased healthy levels of beneficial gut bacteria and suppressed levels of unhealthy gut bacteria.
  • Consumption of the high-fructose corn syrup diet had the opposite effect. It increased unhealthy bacteria and suppressed beneficial bacteria.

The authors concluded: “We provide evidence that the high-fructose corn syrup diet induces an imbalanced microbiota [gut bacteria] profile characterized by a significantly reduced abundance of beneficial…bacteria and of bacteria known for anti-obesity effects…Despite the high fructose content, the fruit-rich diet shifts the intestinal microbiota composition in a protective manner…”

My take is as follows: This study shows that the effect of fructose-containing foods on our gut bacteria is a potential mechanism for explaining why the effect of fructose depends on the food it is in.

There is already overwhelming evidence that fructose in fruits is good for us, and high-fructose corn syrup in sodas and highly processed foods is bad for us.

Does that mean that high-fructose corn syrup is villainous? Should we read labels and avoid any food containing high-fructose corn syrup?

I would remind you that the amount of fructose and the relative abundance of fructose and glucose is virtually identical in fruits and high-fructose corn syrup. It is not high-fructose corn syrup that is the problem, it is the foods it is found in.

We don’t need to become compulsive label readers. We just need to eat more foods without labels.

For more details read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Do Processed Foods Increase Your Risk Of Diabetes?

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Why Do We Keep Eating Processed Foods?

Fast Food DangersUnless you are Rip Van Winkle and have been asleep for the past 20 years you probably know that the highly processed foods in the typical American diet are bad for your health. But perhaps you didn’t realize just how bad they were.

But first, let’s start with a bit of perspective. Scientists like to be precise. Even healthy foods go through some processing.

  • The oatmeal you ate this morning was either steel-cut or ground. That is processing.
  • The almond butter you put on your whole grain toast this morning was made by roasting and grinding. That is processing.

So, scientists have developed the term “ultra-processed food” to describe the worst of the worse. In short, ultra-processed foods:

  • Usually go through several physical and chemical processes, such as extruding, molding, prefrying, and hydrogenation that can lead to the formation of toxic contaminants. One example you may have heard about recently would be acrylamide in French fries.
  • Typically contain ingredients of no or little nutritive value, such as refined sugar, hydrogenated oils, emulsifiers, artificial sweeteners, thickening agents, and artificial colors. Some of these ingredients have been linked to cancer, heart disease, and premature death.
  • Have long shelf-lives because of added preservatives. This allows migration of chemicals such as bisphenol A from the packaging materials into the food.

Examples of ultra-processed foods include:

  • Sodas
  • Chips
  • Candy and packages of cookies or crackers
  • Most breakfast cereals
  • Boxed cake, cookie, and pancake mix
  • Chicken nuggets and fish sticks
  • Fast food burgers
  • Hot dogs and other processed meats
  • Infant formula
  • Instant noodles
  • Most store-bought ice cream
  • Flavored yogurt

In short, ultra-processed foods include sodas and the junk and convenience foods Americans hold so dear. Even things like infant formula and flavored yogurt make the list.

Evidence of the ill effects of ultra-processed foods on our health is becoming overwhelming. In previous issues of “Health Tips From the Professor” I have shared recent studies that have shown that heavy consumption of ultra-processed foods is linked to increased risk of obesity and cancer. Other studies have linked ultra-processed food consumption with increased risk of depression, heart disease, and premature death.

In this issue of “Health Tips From the Professor” I:

  • Ask the important question, “If we know these foods are so bad for us, why do we still keep eating them?”

How Was The Study Done?

Clinical StudyThe data from this study were taken from an ongoing study in France (the NutriNet-Sante study) looking at associations between nutrition and health. This study began enrolling French adults 18 and older in 2009.

This is a web-based study. Participants are prompted to go to a dedicated website and fill out questionnaires related to things like sex, age, height, weight, smoking status, physical activity, health status, and diet.

With respect to diet, participants filled out a series of 3 nonconsecutive 24-hour dietary records at the time of enrollment and every 6 months. This is a particularly strong feature of this study. Many studies of this type only analyze participant’s diets at the beginning of the study. Those studies have no way of knowing how the participant’s diets may have changed during the study.

Diagnosis of type 2 diabetes for study participants was obtained from the French centralized health records.

The study enrolled 104,708 participants, 20% men and 80% women, and followed them for an average of 6 years. The average age of the participants was 43 years.

Do Processed Foods Increase Your Risk Of Diabetes?

High Blood SugarIn this study the range of ultra-processed foods in the French diet ranged from 7% to 27% (average = 17%). High intake of ultra-processed foods was associated with:

  • Younger participants. Simply put, young people were more likely to drink sodas and eat junk food than older adults.
  • Increased caloric intake. Ultra-processed foods have a higher caloric density than whole, unprocessed foods.
  • No surprise here. Previous studies have shown that ultra-processed food consumption increases the risk of obesity.
  • Poorer diet quality. Again, no surprise. Junk foods tend to crowd healthier foods out of the dirt. Specifically, ultra-processed food consumption was associated with:
    • Higher intake of sugar and salt.
    • Lower intake of fiber.
    • Higher intake of sugary drinks, red and processed meats.
    • Lower intake of whole grains, yogurt, nuts, fruits, and vegetables.

However, even after statistically correcting for all these factors, there was a significant association between ultra-processed food consumption and the onset of type 2 diabetes in the 6-year follow-up period.

  • There was a linear relation between ultra-processed food consumption and the development of type 2 diabetes. Simply put, the more ultra-processed food the participants consumed the more likely they were to be diagnosed with type 2 diabetes.
  • There was a 15% increased risk of developing type 2 diabetes for every 10% increase in ultra-processed food consumption.

The authors concluded:

“In this large observational prospective study, a higher proportion of ultra-processed food in the diet was associated with a higher risk of type 2 diabetes. Even though these results need to be confirmed in other populations and settings, they provide evidence to support efforts by public health authorities to recommend limiting ultra-processed food consumption.”

What Does This Study Mean For You?

Questioning WomanYou might be tempted to say that a 15% increase in the risk of developing diabetes is a small price to pay for continuing to eat the foods you enjoy. However, you should be alarmed by this study. Here is why.

The French diet is much healthier than the American. Remember that ultra-processed foods only comprised 17% of the French Diet. In contrast, a recent survey found that:

  • Ultra-processed foods make up 58% of the average American’s diet.
  • Ultra-processed foods account for 90% of the added sugar in our diet.

It is no wonder that obesity and diabetes are reaching epidemic proportions in our country.

You might also be tempted to think that you can just take some medications and live with type 2 diabetes. However, you should think of type 2 diabetes as a gateway disease. It increases your risk of heart disease, high blood pressure, Alzheimer’s disease, kidney damage, and neuropathy, just to name a few. These are diseases that make your life miserable and ultimately kill you.

More importantly, type 2 diabetes is completely reversible if you catch it early enough. Just lose some weight, exercise more, give up the ultra-processed foods, and eat a healthy diet. I recommend a whole food, primarily plant-based diet.

Why Do We Keep Eating Processed Foods?

Fast FoodsWe all know that ultra-processed foods are bad for us. Study after study show that they make us sick. They kill us prematurely. And, unlike most topics in the field of nutrition, this is not controversial.

For example, there have been lots of bizarre diets that have come and gone over the years. There have been books written on “The Steak Lover’s Diet” and “The Drinking Man’s Diet”. But nobody has written a book on “The Junk Food Lover’s Diet”. It simply would not be believable.

So why do we Americans keep eating such unhealthy foods. Part of the answer is physiological. A preference for sweet, salty, and fatty foods is hardwired into our brain. That’s because they had great survival value in prehistoric times.

If we think back to the time when we were hunters and gatherers:

  • Fruits are healthy foods. They are a great source of antioxidants, phytonutrients, and fiber, but there were no orchards or grocery stores back then. We had to search for fruits in the wild. Our desire for sweet tasting foods provided the motivation to seek them out.
  • Game was seasonal and sometimes scarce. We had to be prepared to go for days or weeks without eating except for the leaves and roots we could gather. Our bodies are designed to store fat as the primary energy source to get us through the lean times. Our preference for fatty foods encouraged us to store as much fat as possible in times of plenty so we would be prepared for times of scarcity.
  • If we fast forward to our early recorded history, salt was scarce. It was worth its weight in gold. Yet some salt is essential for life. Our preference for salty foods encouraged us to search out supplies of salt.

Unfortunately, the food industry has weaponized these food preferences to create the ultra-processed foods we know today. Their ads entice us by associating these foods with youth and good times. And ultra-processed foods have become ubiquitous. There are fast food restaurants on almost every street corner and shopping mall in the country.

Fortunately, we do not have to let the food industry destroy our health. We can retrain our taste buds to appreciate the sweetness of fresh fruits and vegetables. We can substitute healthy fats for the kinds of fat found in most ultra-processed foods. We can also retrain our taste buds to appreciate herbs and spices with just a pinch of salt.

The Bottom Line

Ultra-processed foods, such as sodas, junk foods, and convenience foods have become the biggest food group in the American diet. A recent study found:

  • Ultra-processed foods make up 58% of the average American’s diet.
  • Ultra-processed foods account for 90% of the added sugar in our diet.

That is scary because ultra-processed foods are deadly. Previous studies have shown that consumption of ultra-processed foods is linked to obesity, heart disease, cancer, and Alzheimer’s disease.

The study discussed this week looked at the association between ultra-processed food consumption and type 2 diabetes. It showed:

  • There was a linear relation between ultra-processed food consumption and the development of type 2 diabetes. Simply put, the more ultra-processed food the participants consumed the more likely they were to be diagnosed with type 2 diabetes.
  • There was a 15% increased risk of developing type 2 diabetes for every 10% increase in ultra-processed food consumption.

You might be tempted to think that you can just take some medications and live with type 2 diabetes. However, you should think of type 2 diabetes as a gateway disease. It increases your risk of heart disease, high blood pressure, Alzheimer’s disease, kidney damage, and neuropathy, just to name a few. This are diseases that make your life miserable and ultimately kill you.

More importantly, type 2 diabetes is completely reversible if you catch it early enough. Just lose some weight, exercise more, give up the ultra-processed foods, and eat a healthy diet. I recommend a whole food, primarily plant-based diet.

For more details and a discussion of why Americans continue to eat ultra-processed food even though we know it is bad for us, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

Why Do Diet Sodas Make You Fat?

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Is Mixing Diet Sodas With Carbs Bad For You?

Why Do Sodas Cause Obesity?Many people, and many doctors, believe that diet sodas and artificially sweetened foods are a healthy choice. After all:

  • Cutting calories by drinking diet sodas and eating artificially sweetened foods should help you lose weight.
  • If sugar is the problem for diabetics, diet sodas and artificially sweetened foods should be a healthier choice.

On the surface, these ideas appear to be self-evident. They seem to be “no-brainers”. The truth, however, is more complicated.

When studies are tightly controlled by dietitians so that the people consuming diet sodas don’t add any extra calories to their diet, the results are exactly as expected. People consuming diet sodas lose weight compared to people drinking regular sodas.

However, as I have described in an earlier issue of “Health Tips From the Professor”, the results are different in the real world where you don’t have a dietitian looking over your shoulder. In those studies, diet sodas are just as likely to cause weight gain as regular sodas.

As Barry Popkin, a colleague at the University of North Carolina, put it” “The problem is that we [Americans] are using diet sodas to wash down our Big Macs and fries.” In short, people drinking diet sodas tend to increase their caloric intake by adding other foods to their diet. Even worse, the added foods aren’t usually fruits and vegetables. They are highly processed junk foods.

Why is that? The short answer is that nobody knows (more about that later). However, a recent study (JR Dalenberg et al, Cell Metabolism, 31: 493-502, 2020) suggests an unexpected mechanism for the weight gain associated with diet soda consumption. Let’s look at that study.

How Was The Study Done?

Clinical StudyThe study recruited 45 healthy young adults (ages 20-45) who habitually consumed less than 3 diet sodas a month. They were randomly assigned to three groups. The participants in each group came into the testing facility seven times over a span of 2 weeks. Each time they were given 12 ounces of one of three equally sweet tasting beverages in a randomized, double-blind fashion.

  • Group 1 received a sucralose-sweetened drink contained 0.06 grams of sucralose (equivalent to two packets of Splenda).
  • Group 2 received a sugar-sweetened drink contained 7 teaspoons of sucrose (table sugar).
  • Group 3 received a combo drink contained 0.06 grams of sucralose plus 7 teaspoons of maltodextrin. Maltodextrin is a water-soluble carbohydrate that does not have a sweet taste.

o   Maltodextrin was used because Splenda and most other commercial sucralose products contain it along with sucralose. You need something to fill up those little sucralose-containing packets.

o   This drink was included as a control. The expectation was that it would give the same results as the sucralose-sweetened drink.

Three measurements were performed prior to and following the 2-week testing period:

  • An oral glucose tolerance test in which participants drink a beverage containing a fixed amount of glucose. Then their blood sugar and blood insulin levels are measured over the next two hours.

o   This is a measure of how well they were able to control their blood sugar levels.

  • A test in which they were given samples that had either a sweet, sour, salty, or savory taste. Then:

o   They were asked to identify each taste and report how strong the taste was.

o   MRI scans of their brains were performed to determine how strongly their brains responded to each of the tastes.

Is Mixing Diet Soda With Carbs Bad For You?

The results were surprising. The first surprise came when the investigators unblinded the results of the oral glucose tolerance test:

  • Blood sugar and blood insulin responses were unaffected by the 2-week exposure to sugar-sweetened drinks.

o   This was expected.

  • Blood sugar and blood insulin were relatively unaffected by the 2-week exposure to sucralose-sweetened drinks. If anything, the control of blood sugar levels was slightly improved at the end of two weeks.

o   This was a disappointment for the investigators. One of the prevailing theories is that artificially sweetened beverages alter the blood sugar response. The investigators found no evidence for that idea.

  • Following the 2-week exposure to the combo drinks (sucralose plus maltodextrin), blood sugar levels were unaffected, but blood insulin levels were increased. This implies that more insulin was required to control blood sugar levels. In other words, these participants had developed insulin resistance.

o   This result was unexpected. Remember the investigators had included this drink as a control.

o   The investigators pointed out that the insulin resistance associated with the sucralose-maltodextrin combo could increase the risk of type 2 diabetes and obesity.

  • Because of this unexpected result, the investigators did a follow-up study in which participants were given a maltodextrin-only drink using the same study protocol. The oral glucose tolerance test was unchanged by the 2-week exposure to maltodextrin-only drinks.

When the investigators conducted taste tests, the ability of participants to taste all four flavors was unchanged by a 2-week exposure to any of the drinks.

However, when the investigators did MRI scans to measure the brain’s response to these flavors:

  • A two-week exposure to the sucralose plus maltodextrin drinks reduced the brain’s response to sweet but not to any of the other flavors.

o   In other words, the subjects could still taste sweet flavors, but their brains were not responding to the sweet taste. Since sweetness activates pleasure centers in the brain this could lead to an increased appetite for sweet-tasting foods.

o   This might explain the weight gain that has been observed in many previous studies of diet sodas.

  • Two-week exposures to the other drinks had no effect on the brain’s response to any of the flavors. Once again, this effect was only seen in the sucralose-maltodextrin combination.

The investigators concluded:

  • “Consumption of sucralose combined with carbohydrates impairs insulin sensitivity…and…neural responses to sugar.
  • Insulin sensitivity is not altered by sucralose or carbohydrate consumption alone.
  • The results suggest that consumption of sucralose in the presence of a carbohydrate dysregulates gut-brain regulation of glucose metabolism.”

The investigators pointed out that this could have several adverse consequences. Again, in the words of the authors:

“Similar exposure combinations (artificial sweeteners plus carbohydrates) almost certainly occur in free-living humans, especially if one considers the consumption of a diet drink along with a meal. This raises the possibility that the combination effect may be a major contributor to the rise in incidence of type 2 diabetes and obesity. If so, addition of artificial sweeteners to increase the sweetness of carbohydrate-containing food and beverages should be discouraged and consumption of diet drinks with meals should be counseled against.”

Why Do Diet Sodas Make You Fat?

As I mentioned at the start of this article, there are a lot of hypotheses as to why diet sodas make us fat. These hypotheses break down into two classifications: psychological and physiological.

The psychological hypothesis is easiest to explain. Essentially, it goes like this: We feel virtuous for choosing a zero-calorie sweetener, so we allow ourselves to eat more of our favorite foods. It is unlikely that this hypothesis holds for all diet soda drinkers. However, it is also hard to exclude it as at least part of the explanation for the food overconsumption associated with diet soda use.

There are multiple physiological hypotheses. Most of them are complicated, but here are simplified explanations of the three most popular hypotheses:

  • The sweet taste of artificial sweeteners tricks the brain into triggering insulin release by the pancreas. This causes blood sugar levels to plummet, which increases appetite.
  • The sweet taste of artificial sweeteners is not appropriately recognized by the brain. This diminishes release of hormones that suppress appetite.
  • Artificial sweeteners interfere with insulin signaling pathways, which leads to insulin resistance.

There is some evidence for and against each of these hypotheses.

However, this study introduces a new physiological hypothesis – namely that it is the combination of artificial sweeteners and carbohydrates that results in a dysregulation of the normal mechanisms controlling appetite and blood sugar.

What Does This Study Mean For You?

Diet Soda DangersLet’s start with the obvious. This is just a hypothesis.

  • This was a very small study. Until it is confirmed by other, larger studies, we don’t know whether it is true.
  • This study only tested sucralose. We don’t know whether this applies to other artificial sweeteners.
  • The study only tested maltodextrin in combination with sucralose. We don’t know whether it applies to other carbohydrates.

Therefore, in discussing how this study applies to you, let’s consider two possibilities – if it is true, and if it is false.

If this hypothesis is true, it is concerning because:

  • We often consume diet sodas with meals. If, for example, we take the earlier example of a diet soda with a Big Mac and fries, both the hamburger bun and the fries are high carbohydrate foods.

 

  • Sucralose and other artificial sweeteners are used in low calorie versions of many carbohydrate rich processed foods.

If this hypothesis is false, it does not change the underlying association of diet soda consumption with weight gain and type 2 diabetes. It is merely an attempt to explain that association. We should still try to eliminate diet sodas and reduce our consumption of artificially sweetened, low calorie foods.

My recommendation is to substitute water and other unsweetened beverages for the diet drinks or sugar sweetened beverages you are currently consuming. If you crave the fizz of sodas, drink carbonated water. If you need more taste, try herbal teas or infuse water with slices of lemon, lime, or your favorite fruit. If you buy commercial brands of flavored water, check the labels carefully. They may contain sugars or artificial sweeteners. Those you want to avoid.

The Bottom Line

Many studies have called into question the assumption that diet sodas and diet foods help us lose weight. In fact, most of these studies show that diet soda consumption is associated with weight gain rather than weight loss.

There are many hypotheses to explain this association, but none of them have been proven at present.

This study introduces a new hypothesis – namely that the combination of artificial sweeteners and carbohydrates results in a dysregulation of the normal mechanisms controlling appetite and blood sugar. In particular, this study suggested that combining sucralose with carbohydrates caused insulin resistance and reduce the ability of the brain to respond appropriately to sweet tastes.

The authors concluded: “Similar exposure combinations (artificial sweeteners plus carbohydrates) almost certainly occur in free-living humans, especially if one considers the consumption of a diet drink along with a meal. This raises the possibility that the combination effect may be a major contributor to the rise in incidence of type 2 diabetes and obesity. If so, addition of artificial sweeteners to increase the sweetness of carbohydrate-containing food and beverages should be discouraged and consumption of diet drinks with meals should be counseled against.”

If this hypothesis is true, it is concerning because:

  • We often consume diet sodas with meals. If, for example, we take the example of a diet soda with a Big Mac and fries, both the hamburger bun and the fries are high carbohydrate foods.
  • Artificial sweeteners are used in low calorie versions of many carbohydrate rich processed foods.

If this hypothesis is false, it does not change the underlying association of diet soda consumption with weight gain and type 2 diabetes. It is merely an attempt to explain that association. We should still try to eliminate diet sodas and reduce our consumption of artificially sweetened, low calorie foods.

My recommendation is to substitute water and other unsweetened beverages for the diet drinks or sugar sweetened beverages you are currently consuming. If you crave the fizz of sodas, drink carbonated water. If you need more taste, try herbal teas or infuse water with slices of lemon, lime, or your favorite fruit. If you buy commercial brands of flavored water, check the labels carefully. They may contain sugars or artificial sweeteners. Those you want to avoid.

For more details, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Could A Probiotic Supplement Make You Healthier?

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What Is The Truth About Our Microbiome?

Myth BusterOur gut bacteria, often referred to as our microbiome, are a “hot” topic in today’s world. They have been in the news a lot in recent years. If you believe the headlines, the right gut bacteria can make you smarter, healthier, and cure what ails you. They appear to have almost mystical powers. Could a probiotic supplement make you healthier?

How much of this is true and how much is pure speculation? It’s hard to say. Our microbiome is incredibly complex. To make matters more confusing, the terminology used to classify our gut bacteria into groups is not consistent. It varies from study to study.

Perhaps it is time to take an unbiased look at the data and separate fact from speculation.

Could A Probiotic Supplement Make You Healthier?

Probiotic SupplementTo answer the question of whether a probiotic supplement could make you healthier, we need to differentiate between what we know is true and what we think might be true. Let’s start with what we know for certain:

  • Our gut bacteria are affected by diet. People consuming a primarily plant-based diet have different populations of gut bacteria than people consuming a primarily meat-based diet.
    • The populations of gut bacteria found in people consuming a plant-based diet are associated with better health outcomes, but associations have their limitations as discussed below.
  • Our gut bacteria are affected by exercise.
    • It’s not clear whether it is the exercise or the fitness (increased muscle mass, decreased fat mass, improved metabolism) associated with exercise that is responsible for this effect.

Most of the other claims for the effects of gut bacteria on our health are based on associations. However, associations do not prove cause and effect. For example:

  • Certain populations of gut bacteria are associated with obesity.
    • Do our gut bacteria make us obese, or does obesity affect our gut bacteria? There is evidence to support both viewpoints.
  • Certain populations of gut bacteria are associated with better mental health.
    • Do gut bacteria influence mental health, or does the stress associated with poor mental health influence our gut bacteria? Again, there is evidence to support both viewpoints.
  • Certain populations of gut bacteria are associated with better health outcomes (reduction in diseases like heart disease, diabetes, and high blood pressure).
    • Here the question is a little different. In general, the populations of gut bacteria associated with disease reduction are produced by a healthy diet, exercise, and weight control. In this case, the question becomes: Is it the gut bacteria that caused disease reduction, or is it diet, exercise, and weight control that caused disease reduction?

To better understand these points, let’s look at four recently published studies. After reviewing those studies, I will come back to the question of whether a probiotic supplement might decrease our disease risk.

Is Our Microbiome Better Than Our Genes For Predicting Disease?

Predict DiseaseThis study (T. Tierney et al, bioRxiv, 2020) reviewed 47 studies that analyzed people’s microbiome (their gut bacteria) and their genes and asked which was better at predicting their risk of various diseases. The study focused on 13 diseases that are considered “complex” because they are caused by both genetic and environmental factors such as diet and exercise. Examples include diabetes, high blood pressure, digestive disorders, asthma, Parkinson’s disease, and schizophrenia.

The study found that our microbiome was a better predictor of these diseases than our genes. This finding is not surprising. Our microbiome is heavily influenced by diet and other environmental factors. Our DNA sequence is not.

This study supports previous studies in suggesting that our microbiome is a better predictor of most diseases than our DNA sequence. The exception would be diseases that are clearly caused by gene mutations, such as sickle cell disease.

Does this mean our microbiome is directly influencing these diseases, or is it merely serving as a marker for diet and other environmental factors that are influencing these diseases? Nobody knows.

Does The Mediterranean Diet Support Gut Bacteria Linked To Healthy Aging?

Mediterranean dietThis study ( TS Ghosh et al, Gut, 17 February 2020) divided people aged 65-79 into two groups. One group consumed a Mediterranean diet rich in fruits, vegetables, nuts, legumes, olive oil, and fish and low in red meat and saturated fat. The other group consumed a typical western diet. After a year on the diets the gut bacteria in the microbiomes of the two groups was analyzed.

The study found that the group consuming the Mediterranean diet had an increase in gut bacteria associated with healthy aging, reduced inflammation, and reduced frailty.

The title of the paper describing this study was “Mediterranean diet intervention alters the gut microbiome in older people, reducing frailty and improving health status”. But is that true?

There is already good evidence that the Mediterranean diet improves health status. Is it the gut bacteria supported by the Mediterranean diet that were responsible for healthy aging, or were other aspects of the Mediterranean diet responsible for healthy aging? Nobody knows.

Are Low Fat Diets Healthy Because Of Their Effect On Our Microbiome?

Heart Healthy DietThis study (Y Wang et al, Gut Microbes, 21 January 2020) put participants on a low fat diet (20% fat and 66% carbohydrates), a moderate fat diet (30% fat and 56% carbohydrate) or a high fat diet (40% fat, 46% carbohydrates). To assure the accuracy of the diets, participants were provided with all foods and beverages they consumed. After 6 months on the three diets, the gut bacteria of each group were analyzed.

Note: Because all food and beverages were provided, none of the diets included sodas, added sugar, refined flour, saturated fats, or highly processed food. In short, the diets were very different than the typical low fat or low carb diets consumed by the average American.

This study found that participants consuming the high fat, low carb diet had gut bacteria associated with increased risk of heart disease and diabetes. In contrast, the low fat, high carbohydrate diet group had gut bacteria associated with decreased risk of heart disease and diabetes.

To understand this study, you need to reevaluate what you may have learned from Dr. Strangelove’s health blog. It is true that low fat diets in which fat has been replaced with sugar, refined flour, and highly processed low-fat foods are unhealthy. But that’s not what happened in this study.

Remember that all the food and drink the participants consumed was selected by dietitians.

When you replace the fat with whole foods – fresh fruits and vegetables, whole grains, nuts, and legumes, as was done in this study, you end up with a very healthy diet.

The authors talked about the importance of the “diet-gut axis” for reducing the risk of heart disease and diabetes. However, is it the gut bacteria that influenced the risk of heart disease and diabetes, or is it the diets themselves that influenced disease risk? Nobody knows.

Can Gut Bacteria Reduce Heart Disease Risk?

MicrobiomeThis study (Y Heianza et al, Journal of The American College Of Cardiology, 75: 763-772, 2019) focused on the interactions between diet, gut bacteria, and a metabolite called TMAO (trimethylamine N-oxide).

Here is what we know for certain:

  • L-carnitine (found in high levels in red meat) can be converted to TMA (trimethylamine) by gut bacteria and then to TMAO in the liver.
  • The gut bacteria of meat eaters are very efficient at converting L-carnitine to TMA. Thus, meat eaters tend to have high levels of TMAO in their blood.
  • The gut bacteria of vegans and vegetarians are very inefficient at converting L-carnitine to TMA. Thus, people consuming a primarily plant-based diet tend to have low TMAO levels in their blood.

Here is what we are uncertain about:

  • High TMAO levels are associated with increased heart disease risk. However, there is no direct evidence that TMAO causes heart disease.

What made this study unique is that it measured TMAO levels in the study participants at their entrance into the study and again 10 years later. The study found:

  • Participants with the greatest increase in TMAO levels over the 10 years had a 67% increased risk of heart disease compared to participants whose TMAO levels remained constant.
  • Participants consuming a healthy, primarily plant-based diet had little or no increase in TMAO levels over 10 years. It was the participants consuming an unhealthy diet who had significant increases in their TMAO levels.

This study strengthens the association between TMAO levels and heart disease risk. Because gut bacteria are required to produce TMAO, it also strengthens the association between gut bacteria and heart disease risk. However, is it the high TMAO levels that increased heart disease risk or is it the unhealthy diet that increased heart disease risk? Nobody knows.

What Is The Truth About Our Microbiome?

MicrobiomeBy now you have probably noticed a common theme that runs through all four studies. This is also true of most published studies on our microbiome.

  • We have good evidence that whole food, primarily plant-based diets lead to improved long-term health outcomes.
  • We also have good evidence that whole food, primarily plant-based diets influence the populations of gut bacteria found in our microbiome.
  • We know the populations of gut bacteria supported by primarily plant-based diets are associated with improved health outcomes.
  • We don’t really know whether it is the gut bacteria or the diets that are responsible for the improved health outcomes.

Don’t misunderstand me. I am not a microbiome skeptic. I think we have enough evidence to say that our gut bacteria are likely to have an important effect on our health. However, to claim that gut bacteria play a primary role in influencing our health would be pure speculation at this point.

A Cautionary Tale

HDL CHolesterolWhy do I make this point? It’s because I suspect that some in the supplement industry will be tempted to make probiotic supplements and claim they contain bacteria “known” to reduce the risk of heart disease, diabetes, or cancer. You wouldn’t need to change your diet. All you would need to do to improve your health would be to take their probiotic supplement.

Lest you be taken in by such future claims, let me share a cautionary tale.

High HDL cholesterol levels are associated with a reduced risk of heart disease. Exercise and weight loss increase HDL levels. However, those require work. They aren’t easy. So, pharmaceutical companies were constantly looking for ways to raise HDL levels without the hard work.

A few years ago, a pharmaceutical company discovered a drug that increased HDL levels. They thought they had discovered a wonder drug that would bring in billions of dollars. People wouldn’t need to exercise. They wouldn’t need to lose weight. All they would need to do would be to take their drug. HDL levels would go up and heart disease risk would go down.

However, when they tested their drug in a major clinical trial, it didn’t move the needle. HDL levels went up, but heart disease risk stayed the same. It turns out it was the exercise and weight loss that decreased heart disease risk, not the increase in HDL levels.

My message is simple. Even if our gut bacteria are found to play a major role in mediating the effect of diet on health outcomes, don’t assume we can take a probiotic and forget about the role of diet and exercise. Good health starts with a whole food, primarily plant-based diet and a healthy lifestyle.

The Bottom Line

Our gut bacteria, often referred to as our microbiome, are “hot”. If you believe the headlines, the right gut bacteria can make you smarter, healthier, and cure what ails you. How much of this is true and how much is pure speculation? In this article I reviewed four recent studies on diet, gut bacteria, and health outcomes. I took an unbiased look at the data and separated fact from speculation.

There was a common theme that ran through all four studies. This is also true of most published studies on our microbiome.

  • We have good evidence that whole food, primarily plant-based diets lead to improved long-term health outcomes.
  • We also have good evidence that whole food, primarily plant-based diets influence the populations of bacteria found in our gut, also known as our microbiome.
  • We know the populations of gut bacteria supported by primarily plant-based diets are associated with improved health outcomes.
  • We don’t really know whether it is the gut bacteria or the diets that are responsible for the improved health outcomes.

Don’t misunderstand me. I am not a microbiome skeptic. I think we have enough evidence to say that our gut bacteria are likely to have an important effect on our health. However, to claim that gut bacteria play a primary role in influencing our health would be pure speculation at this point.

Why do I make this point? It’s because I suspect that some in the supplement industry will be tempted to make probiotic supplements and claim they contain bacteria “known” to reduce the risk of heart disease, diabetes, or cancer. You wouldn’t need to change your diet. All you would need to do to improve your health would be to take their probiotic supplement.

My message is simple. Even if our gut bacteria are found to play a major role in mediating the effect of diet on our health outcomes, don’t assume we can take a probiotic and forget about the role of diet and exercise. Good health starts with a whole food, primarily plant-based diet and a healthy lifestyle.

For more details, read the article above. You may be particularly interested in the cautionary tale I shared about HDL and heart disease risk.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease

Does Resveratrol Improve Blood Sugar Control?

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Is The Promise of Resveratrol True?

Author: Dr. Stephen Chaney

blood sugar testIt was just a few years ago that resveratrol was the latest “miracle nutrient”. It was featured on Dr. Oz and on 60 Minutes. It was hot! Today you see dueling headlines. The headlines one week proclaim the benefits of resveratrol. Next week’s headlines say that it’s all hype. What’s a person to believe?

Let me take you behind the headlines to look at the actual studies and answer some important questions.

1)    What do we actually know about the benefits of resveratrol?

2)    Is the evidence for beneficial effects of resveratrol where it should be considering the number of clinical studies that have been published?

3)    What additional studies need to be done before we can be sure that resveratrol is beneficial?

4)    Should you wait until we are absolutely certain resveratrol is beneficial, before you start using it? This is perhaps the most important question of all.

To answer those questions, let’s examine the study behind one of the latest headlines, namely: “Resveratrol Improves Blood Sugar Control in Diabetics”. One of the promises of resveratrol has been that it might help diabetics and pre-diabetics who struggle with blood sugar control. However, this promise was based on animal studies. The study that generated the headlines in question was a meta-analysis of recently published human clinical trials in this area (Liu et al, Am. J. Clin. Nut., 2014, doi: 10.3945/ajcn.113.082024).

Does Resveratrol Improve Blood Sugar Control?

The meta-analysis included 11 published placebo controlled double blind clinical studies looking at the effects of resveratrol supplementation on fasting blood sugar levels, insulin levels, hemoglobin A1c (a measure of blood sugar control) and insulin resistance (a measure closely associated with type 2 diabetes).

A strength of this meta-analysis is the fact that it included 11 clinical studies. However, a weakness of this analysis is that these studies utilized a wide variety of resveratrol doses (10 mg/day to 1 gram/day), a wide variety of end points and both diabetic and non-diabetic patients. That means that there were only a few studies with common population groups, resveratrol doses, and end points.

The conclusions of the study (and the headlines you may have seen) were that:

•    Resveratrol appeared to improve blood sugar control (based on improvements in fasting blood sugar levels, insulin levels, hemoglobin A1c and insulin resistance) in diabetics.

•    No consistent effect of resveratrol on blood sugar control was seen in non-diabetics.

How Good Are These Studies?

While these studies are very promising, they are bot definitive.  There were only 3 published clinical studies in diabetics. While all 3 of the studies showed a positive effect of resveratrol supplementation:

•    The doses used were different in each study (ranging from 10 mg/day to 1 gram/day)

•    Each study measured different end points (one measured blood glucose, insulin levels, hemoglobin A1c and insulin resistance, one measured blood glucose and hemoglobin A1c and the third measured insulin resistance).

As a research scientist I would like to see more studies done at comparable doses and measuring the same end points – we scientists always want more studies.

Similarly, there was not enough consistency in the studies with non-diabetics to draw a firm conclusion. (3 were with obese patients, 3 were with patients with cardiovascular disease, 1 was with patients with metabolic syndrome and 1 was with perfectly healthy subjects.)

If you really wanted to see if something like resveratrol helps non-diabetics with blood sugar control, you would want to start with people who are already experiencing some difficulties with blood sugar control (pre-diabetics or patients with metabolic syndrome) and follow them for a couple of years to see if resveratrol reduces the number of them who become diabetic.

Are The Headlines Just Hype?

Newspaper HeadlinesDoes that mean that the blood sugar benefits of resveratrol are just hype? The answer is no. There is a difference between “very promising, but not yet definitive” and “hype”. We shouldn’t be surprised that human studies on the health benefits of resveratrol are not yet definitive. Science moves slowly. It often takes decades of scientific research before promising concepts are widely accepted by the scientific community.

When a research area is as young as this one, we sometimes need to go beyond the clinical studies and look at the totality of evidence. In this case:

•    In mice resveratrol exerts its beneficial effects by turning on a specific anti-aging gene called SIRT1 (Cell Metabolism, 15: 675-690, 2012). In humans, resveratrol appears to activate the same genetic pathways as in mice (Journal of Clinical Endocrinology & Metabolism, 96: 1409-1414, 2011).

•    In obese mice resveratrol improves markers of blood sugar control (Nature, 444: 337-342, 2006). Published clinical studies in diabetic humans also show improvements in blood sugar control (Journal of Clinical Nutrition, 2014, doi: 10.3945/ajcn.113.082024).

So while more and better clinical studies are needed to be absolutely certain that resveratrol helps improve blood sugar control, the evidence supporting that effect is substantial.

What Should You Do?

The ONLY important question for each of you is probably: “Should I wait a decade or two until we are absolutely sure about the health benefits of resveratrol before I take a resveratrol supplement?” That question is ultimately yours to answer. It’s all about benefits and risk.

Benefits – In animal studies resveratrol clearly improves blood sugar control. The human clinical studies published to date are consistent with the animal studies.

Risk – Current data suggest that resveratrol appears to be safe, even at high doses. For example, one recent study indicated that up to 5 gm/day is safe (Cancer Epidemiology BioMarkers & Prevention, volume 16:1246-1262, 2007), but I wouldn’t personally recommend exceeding 100-200 mg/day.

The Bottom Line:

1)     Don’t get too excited about the headlines suggesting that resveratrol might help improve blood sugar control in diabetics. The few human clinical studies that have been published to date are consistent with previous animal studies. That is very promising, but more studies are needed before we can be absolutely confident that resveratrol supplementation is beneficial for diabetics.

2)     Similarly, don’t be discouraged by the headlines suggesting that resveratrol does not help with blood sugar control in non-diabetics. Those results are preliminary as well.

3)     That doesn’t mean that the headlines are just hype. It takes decades to accumulate definitive proof that any kind of food or nutrient offers proven benefits, and the bulk of human clinical research on reveratrol has occurred in the last couple of years. We are exactly where we should expect to be at this point in time.

4)     With something as promising as resveratrol, the real question becomes whether you can afford to wait a decade or two until you know whether the potential benefits have been definitely proven. That question is up to you. On the plus side, current data suggest that resveratrol is highly promising for blood sugar control. In addition, resveratrol appears to be safe, even at high doses, but I wouldn’t personally recommend exceeding 100-200 mg/day.

5)     We already know that weight control, exercise and a healthy diet improve blood sugar control. You should think of resveratrol as something you may wish to add to a healthy lifestyle, not as a substitute for a healthy lifestyle.

6)     If you are diabetic and decide to try a resveratrol supplement, be sure to work with your physician so they can modify your dose of insulin or blood sugar medication as necessary.

7)     Finally, you may be asking whether resveratrol supplements are even necessary. Can’t you just get all the resveratrol you need from a glass or two of red wine? Stay tuned. I’ll have the answer to that question in a couple of weeks.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Is Vitamin D Overhyped?

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Are Clouds Gathering For the Sunshine Vitamin?

Author: Dr. Stephen Chaney

Clouds Obscuring The SunWe’ve known for years that vitamin D plays an essential role in calcium metabolism and is important for bone health. In fact, the use of vitamin D to prevent and cure rickets is one of the greatest success stories in the field of nutrition.

However, in recent years a number of studies have suggested that adequate vitamin D status was also important in reducing the risk of cancer, heart disease, diabetes, infectious diseases and autoimmune diseases – as well as overall mortality. Suddenly it seemed as if vitamin D could leap over tall buildings in a single bound (I realize that I’m probably dating myself with that analogy).

So when I saw the headlines about a new study (Theodoratou et al, BMJ, 2014;348:g2035 doi: 10.1136/bmj.g2035)  that concluded all of those benefits of vitamin D were unconfirmed, I was not surprised. After all there have been many examples of periods in which individual vitamins were reported to have miraculous benefits – only to have most of those benefits debunked by subsequent studies. I fully expected that would be the theme of this issue of “Health Tips From the Professor”.

But when I read the article I found that the study had multiple flaws (more about that latter). I also discovered that the same issue of the British Medical Journal had another, much better designed, study that came to the exact opposite conclusion (Chowdhury et al, BMJ 2014;348:g1903 doi: 10.1136/bmj.g1903).

Funny how only the first study made it into the headlines. It’s only the negative news that sells.

Is Vitamin D Overhyped?

The first study was a very large meta-analysis that included 107 systematic reviews, 74 meta-analyses of observation studies (studies that compare population groups) and 87 meta-analyses of randomized, placebo controlled trials. In case you were wondering, the total number of patients enrolled in these studies must have numbered in the hundreds of thousands.

The authors of the study reported that:

  • There was no relationship between vitamin D intake and cancer, heart disease, autoimmune disease, infectious diseases, diabetes and other diseases. In other words, they concluded that most of the recent excitement about vitamin D was just hype.
  • There was also no evidence that vitamin D increased bone density or reduced the risk of fractures and falls in older people – in contrast to many previous studies.

Based on this evidence the authors said “universal conclusions about vitamin Ds benefits cannot be drawn [from current data]” and that vitamin D “might not be as essential as previously thought in maintaining bone mineral density”.

Both of those statements are pretty revolutionary, but a study this large has to be true – right? The answer is a definite maybe. The problem is that many of the studies included in this meta-analysis were poorly designed by today’s standards. Remember the old saying “garbage in, garbage out”.

The Study Is Flawed

My specific criticisms of the study are:

1)     The conclusions about vitamin D and bone density were seriously flawed. The authors acknowledged that previous studies have shown that calcium and vitamin D together increased bone density, but they considered calcium to be a confounding variable and only included clinical trials using vitamin D supplementation alone. That shows a complete misunderstanding of the biochemical role of vitamin D.

The purpose of vitamin D is to maintain constant levels of blood calcium, not to build strong bones.

  • When blood levels of calcium are high, vitamin D lowers it by depositing the calcium in bones.
  • When blood levels of calcium are low, vitamin D raises it by leaching calcium from bone.

That’s why vitamin D and calcium work together. It is utter nonsense to expect vitamin D to increase bone density or prevent fractures unless you make sure that calcium intake is at least adequate.

2)     Most studies of vitamin D supplementation did not stratify the data based on low versus high levels of 25-hydroxy vitamin D at the beginning of the study. That’s important because you would only expect vitamin D supplementation to be of benefit in people with low levels of 25-hydroxy vitamin D to begin with. If their 25-hydroxy vitamin D levels are already optimal, vitamin D supplementation is unlikely to be of additional benefit.

3)     Finally, the authors did not separate the studies based on whether vitamin D2 or vitamin D3 was used. That’s important because some recent studies have suggested that D3 is more beneficial than D2.

Is Vitamin D Beneficial After All?

SunThe second study came to the exact opposite conclusions. It was also a very large study. It included 73 observational studies (849,412 participants) and 22 randomized, placebo controlled studies (30,716) participants. Here is what the authors of this study concluded.

  • High blood levels of 25-hydroxy vitamin D decreased the risk of heart disease by 35%, cancer by 14% and overall mortality by 35%.
  • Supplementation with vitamin D3 reduced overall mortality by 11%, while supplementation with vitamin D2 increased overall mortality by an insignificant 4%.
  • 65% of the US population can be classified as vitamin D insufficient (blood levels of 25-hydroxy vitamin D of below 30 ng/ml) and 4% as severely deficient in vitamin D (blood levels below 10 ng/ml)
  • Vitamin D deficiency contributes to 13% of the deaths in the United States. For comparison the corresponding numbers for other major risk factors are: smoking – 20%, physical inactivity – 11% and alcohol – 9%.
  • About the only point on which the two studies agreed was that there is a need for more, better designed studies to clarify the benefits of vitamin D.

The Bottom Line:

1)     Two studies were published in the April 2014 issue of the British Medical Journal. The first concluded that all of the supposed benefits of vitamin D – including increasing bone density – were not supported by the available data. The second study concluded that adequate intake of vitamin D significantly reduced deaths due to heart disease and cancer and also significantly reduced overall mortality. Somehow, only the first study made it into the headlines. Why does that not surprise me?

2)     The suggestion in the first study that vitamin D may not be essential for strong bones is based on a complete misunderstanding of the role of vitamin D in the body. There are ample clinical studies showing that vitamin D and calcium together are essential for strong bones. Nobody who understands biochemistry would expect vitamin D to increase bone density in the absence of calcium, but the authors only considered studies that excluded calcium in drawing their conclusion that vitamin D did not increase bone density.

3)     The only point of agreement between the two studies is that more and better studies are needed to sort out the benefits of vitamin D and what levels of vitamin D are optimal. I wholeheartedly agree.

4)     My advice is to ignore the headlines telling you that vitamin D is dead. On the other hand, don’t get caught up in the hype and buy megadoses of vitamin D supplements. While the evidence is rock solid that vitamin D and calcium together are essential for strong bones, the jury is still out on some of the other health benefits of vitamin D.

5)     If you are supplementing with vitamin D you should know that the RDAs for vitamin D are 600 IU for ages 1-70 and 800 IU over 70. The safe upper limit has been set at 4,000 IU. You should only go above that on a doctor’s advice.

6)     However, people metabolize vitamin D with different efficiencies, so I strongly recommend that you get your blood levels of 25-hydroxy vitamin D tested and let your doctor help you determine how much vitamin D you should be getting.

7)     Finally, a number of recent studies suggest that vitamin D3 may be more effective than vitamin D2, so I only recommend supplements that contain D3.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Do High Protein Diets Cause Cancer?

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How Much Protein Should We Eat?

Author: Dr. Stephen Chaney

Animal Protein FoodsThe recent headlines suggesting that high protein diets may cause cancer, diabetes and premature death in middle aged Americans are downright scary. You are probably asking yourself:

  • “Is this new information?”
  • “Does this apply to me?”
  • “Should I radically change what I eat?”

In this issue of “Health Tips From the Professor” I will address each of these questions.

Do High Protein Diets Cause Cancer?

The study in question (Levine et al., Cell Metabolism, 19: 407-417, 2014) suggested that high protein diets were associated with increased risk of cancer, diabetes and premature death in Americans in the 50-65 age range. I will touch on all three of these observations, but it is the increased risk of cancer that generated the most headlines – and the most concern (The consequences of diabetes take years to manifest, and death seem to be a more distant concern for most people. Cancer is immediate and personal).

The study looked at 6,381 adults aged 50 and older (average age 65) from the NHANES III data base. (NHANES is a comprehensive database collected by the Centers for Disease Control and Prevention that consists of surveys and physical examinations and is designed to be representative of the health and nutritional status of the US population.)

The data collected consisted of a single diet questionnaire conducted when the subjects were enrolled in the study. Based on the diet questionnaire the authors of the study divided the group into those with low protein intake (<10% of calories), those with moderate protein intake (10-19% of calories) and those with high protein intake (>20% of calories). Overall death and mortality from various diseases over the next 18 years was obtained by linking the NHANES data with the National Death Index.

Based on preliminary data suggesting that the age of the population might influence the results (I won’t go into details here) the authors of the study decided to subdivide the dataset into people aged 50-65 and people over 65. When they did that, they came to the following conclusions:

1)     In the 50-65 age group diets high in animal protein were associated with a:

  • 45% increase in overall mortality
  • 4-fold increase in cancer death risk
  • 4-fold increase in diabetes death risk.

Diets with moderate protein intake were associated with intermediate increases in risk. Surprisingly, there was no increase in cardiovascular disease risk.

Protein Shakes2)     When they looked at people in the 50-65 age group consuming diets high in vegetable protein:

  • the increased overall mortality and increased in cancer mortality disappeared
  • the increased diabetes mortality was still seen.

3)     In the 65+ age group high protein diets were associated with a:

  • 28% decrease in overall mortality
  • 60% decrease in cancer mortality.

The increased risk of diabetes related deaths was still observed. The authors did not distinguish between animal and vegetable protein in the over 65 age group.

All of that may seem to be a bit too complicated. At the risk of gross oversimplification I would summarize their message as follows:

  • Diets high in animal protein may be bad for you if you are in the 50-65 age range, but might actually be good for you if you are over 65.
  • Diets high in vegetable protein appear to be good for anyone over age 50 (The study didn’t look at younger age groups).

Is This New Information?

Let’s start by assuming that the conclusions of the authors are correct (more about that below).

When you boil their message down to its simplest components, the information isn’t particularly novel.

  • The idea that vegetable proteins may be better for you than animal proteins has been around for decades. There are a number of studies suggesting that diets high in animal protein increase the risk of cancer, heart disease, diabetes and overall death – although it is still not clear whether it is the animal protein itself or some other characteristic of populations consuming mostly animal protein that is the culprit.
  • Evidence has been accumulating over the past decade or so that protein needs increase as we age, so it is not surprising that this study found high protein diets to be beneficial for those of us over age 65.

What Do Other Experts Say?

ScientistSince this study has been released it has been roundly criticized by other experts in the field. Let me sum up their four main criticisms and add one of my own.

1)     The protein intake data were based on a single dietary survey taken at the beginning of an 18 year study. The authors stated that a single dietary survey has been shown to be a pretty accurate indicator of what an individual is eating at the time of the survey. However, it is problematic to assume that everyone’s diet remained the same over an 18 year period.

2)     The choice of less than 10% of calories from protein is also problematic. According to the Institute of Medicine standards anything below 10% is defined as inadequate protein intake, which can have long term health consequences of its own.

More importantly, only 7% of the population being studied (437 individuals) fell into this group. This is the baseline group (or put another way, the denominator for all of the comparisons). The conclusions of this study were based on comparing the other two groups to this baseline, and there were too few individuals in this group to be confident that the baseline is accurate.

This does not necessarily invalidate the study, but it does decrease confidence in the size of the reported effect – so forget the reported numbers like 45% increase in mortality and 4-fold increase in cancer deaths. They probably aren’t accurate.

3)     The number of people in this study who died from diabetes was exceedingly small (68 total) and most of them already had diabetes when the study began. The experts concluded that the numbers were simply too low to draw any conclusions about protein intake and diabetes related deaths, and I agree with them.

4)     While the study controlled for fat intake and carbohydrate intake, it did not control for weight. That is a huge omission. Overweight is associated with increased risk of cancer, diabetes and death, and vegetarians tend to weigh less than non-vegetarians.

5)     I would add that there are many other differences between vegetarians and non- vegetarians that could account for most of the differences reported between diets high in animal and vegetable protein. For example:

  • Vegetarians tend to be more health conscious and thus they tend to exercise more, consume more fiber, consume more fruits and vegetables, consume less fried food, and consume less processed and convenience foods – all of which are associated with decreased risk of cancer, diabetes and death.

The Bottom Line:

This is not a particularly strong study. Nor is it particularly novel. In fact, when you strip away the scary headlines and focus on what the data really show, the conclusions aren’t that different from what nutrition experts have been saying for years.

1)     This study suggests that if you are in the 50-65 age range, diets high in animal protein may not be good for you (this study focused on increased risk of cancer death and overall mortality. Other studies have suggested that diets high in animal protein may increase the risk of cardiovascular death).

This is not a new idea. These data are consistent with a number of other studies. However, none of these studies adequately assess whether the increased risk is from the animal protein alone or from other characteristics of populations that consume a lot of animal protein.

2)     This study also suggests that diets high in vegetable protein do not increase either cancer risk or all cause mortality. That’s also not new information. We’ve known for years that people who consume primarily vegetable protein appear to be healthier. Once again, it is not clear whether it is the vegetable protein itself that is beneficial or whether the benefit is due to other characteristics of populations who consume a lot of vegetable protein.

3)     Does that mean that you need to become a vegetarian? It probably reflects my personal bias, but I am reminded of a Woody Allen Quote: “Vegetarians don’t live longer. It just seems that way”. I am also encouraged by studies suggesting that most of the health benefits of vegetarianism can be achieved by diets that consist of around 50% vegetable protein.

I would never discourage anyone from becoming a vegetarian, but if you aren’t ready for that, I would highly recommend that you aim for at least 50% vegetable protein in your diet.

4)     Finally, this study suggests that a high protein diet is beneficial for people over 65. This is also not a completely novel idea. It is consistent with a lot of recent research.

My advice to those of you who, like me, are over 65 is to pay attention to high protein foods and make sure that they are an important part of your diet. I’m not suggesting that you go for the double bacon cheeseburger just because you are over 65. I would still aim for a significant percentage of vegetable protein as a part of a healthy diet at any age.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Health Tips From The Professor