Mediterranean Diet Archives - Health Tips From The Professor

The Low Carb Myth

April 8, 2025 by Dr. Steve Chaney

The “Goldilocks Effect”

Author: Dr. Stephen Chaney

The low carb wars rage on. Low carb enthusiasts claim that low-carb diets are healthy. And they claim the lower you go, the healthier you will be. Let me start with some definitions:

The typical American diet is high carb. It gets about 55% of its calories from carbohydrates. [Note: The Mediterranean and DASH diets also get about 55% of their calories from carbohydrates. I’ll talk more about that later.]

Moderate carb diets get 26-46% of their calories from carbohydrates. Examples include the low carb Mediterranean diet and the Paleo, South Beach, and Zone diets.

Low carb diets get <26% of their calories from carbohydrates. The Atkins diet is the classic example of a low carb diet.

Very low carb diets get <10% of their calories from carbohydrates. Examples are the Keto and Carnivore diets.

And I don’t need to tell you that the Keto and Carnivore diets are receiving a lot of favorable press lately.

But some health experts warn that low carb and very low carb diets may be dangerous. Several studies have reported that low carb diets increase the risk of mortality (shorten lifespan).

As a consumer you are probably confused by the conflicting claims. Are low carb diets healthy, or is this another myth? In this issue of “Health Tips From the Professor” I am going to discuss two very large studies that came to opposite conclusions.

Both were what we call meta-analysis studies. Simply put, that means they combine the data from several smaller studies to obtain more statistically reliable data. But as Mark Twain said, “There are lies. There are damn lies. And then there are statistics.”

The first study, called the Prospective Urban Rural Epidemiology (PURE) study, was published a few years ago. It included data from 135,335 participants from 18 countries across 5 continents. That’s a very large study, and normally we expect very large studies to be accurate.

It showed a linear relationship between carbohydrate intake and mortality. Simply put, the more carbohydrate people consumed, the greater their risk of premature death. The results from the PURE study had low carb enthusiasts doing a victory lap and claiming it was time to rewrite nutritional guidelines to favor low carb diets.

Whenever controversies like this arise, reputable scientists are motivated to take another look at the question. They understand that all studies have their weaknesses and biases. So, they look at previous studies very carefully and try to design a study that eliminates the weaknesses and biases of those studies. Their goal is to design a stronger study that reconciles the differences between the previous studies.

And this study had two glaring weaknesses.

The percent carbohydrate intake ranged from 40% to 80%. It showed that a moderate carbohydrate intake might be healthier than a high carbohydrate intake, but it provided no information about low carb or very low carb diets.

The data was primarily from Asian countries. It was not clear whether it was relevant to the kind of diets consumed in North America and Europe.

A second study published a year later (SB Seidelmann et al, The Lancet, doi.org/10.1016/S2468-2667(18)30135-X eliminated these weaknesses and resolved the conflicting data.

How Was The Second Study Done?

This study was performed in two parts. This first part drew on data from the Atherosclerosis Risk in Communities (ARIC) study. That study enrolled 15,428 men and women, aged 45-64, from four US communities between 1987 and 1989. This group was followed for an average of 25 years, during which time 6283 people died.

Carbohydrate intake was calculated based on food frequency questionnaires administered when participants enrolled in the study and again 6 years later. The study evaluated the association between carbohydrate intake and mortality.

The second part was a meta-analysis that combined the data from the ARIC study with all major clinical studies since 2007 that measured carbohydrate intake and mortality and lasted 5 years or more. The total number of participants included in this meta-analysis was 432,179, and it included data from previous studies that claimed low carbohydrate intake was associated with decreased mortality.

The Low Carb Myth

The results from the ARIC study were:

The relationship between mortality and carbohydrate intake was a U-shaped curve.

- The lowest risk of death was observed with a moderate carbohydrate intake (50-55%). This is the intake recommended by current nutrition guidelines.

- The highest risk of death was observed with a low carbohydrate intake (<20%).

- The risk of death also increased with very high carbohydrate intake (>70%).

When the investigators used the mortality data to estimate life expectancy, they predicted a 50-year-old participant would have a projected life expectancy of:

- 33.1 years if they had a moderate intake of carbohydrates.

- 4 years less if they had a very low carbohydrate intake.

- 1 year less if they had a very high carbohydrate intake.

The risk associated with low carbohydrate intake was affected by what the carbohydrate was replaced with.

- When carbohydrates were replaced with animal protein and animal fat there was an increased risk of mortality on a low-carb diet.

The animal-based low-carb diet contained more beef, pork, lamb, chicken, and fish. It was also higher in saturated fat.

- When carbohydrates were replaced with plant protein and plant fats, there was a decreased risk of mortality on a low-carb diet. The plant-based low-carb diet contained more nuts, peanut butter, dark or whole grain breads, chocolate, and white bread. It was also higher in polyunsaturated fats.

The effect of carbohydrate intake on mortality was virtually the same for all-cause mortality, cardiovascular mortality, and non-cardiovascular mortality.

There was no significant effect of carbohydrate intake on long-term weight gain (another myth busted).

The results from the dueling meta-analyses were actually very similar in some respects. When the data from all studies were combined:

Very high carbohydrate diets were associated with increased mortality.

Meat-based low-carb diets increased mortality, and plant-based low-carb diets decreased mortality.

The results were the same for total mortality, cardiovascular mortality, and non-cardiovascular mortality.

The authors concluded: “Our findings suggest a negative long-term association between life-expectancy and both low carbohydrate and high carbohydrate diets…These data also provide further evidence that animal-based low carbohydrate diets should be discouraged.

Alternatively, when restricting carbohydrate intake, replacement of carbohydrates with predominantly plant-based fats and proteins could be considered as a long-term approach to healthy aging.”

Simply put, that means if a low carb diet works best for you, it is healthier to replace the carbs with plant-based fats and protein rather than animal-based fats and protein.

The “Goldilocks Effect”

This study also resolved the discrepancies between previous studies. The authors pointed out that the PURE study relied heavily on data from Asian and developing countries, and the average carbohydrate intake is very different in Europe and the US than in Asian and developing countries.

In the US and Europe mean carbohydrate intake is about 50% of calories and it ranges from 25% to 70% of calories. With that range of carbohydrate intake, it is possible to observe the increase in mortality associated with both very low and very high carbohydrate intakes.

The US and European countries are affluent, which means that low carb enthusiasts can also afford diets high in animal protein.

In contrast, white rice is a staple in Asian countries, and protein is a garnish rather than a main course. Consequently, overall carbohydrate intake is greater in Asian countries and very few Asians eat a truly low carbohydrate diet.

High protein foods tend to be more expensive than high carbohydrate foods. Thus, very few people in developing countries can afford to follow a very low carbohydrate diet, and overall carbohydrate intake also tends to be higher in those countries.

Therefore, in Asian and developing countries the average carbohydrate intake is greater (~61%) than in the US and Europe (~50%), and the range of carbohydrate intake is from 45% to 80% of calories instead of 25% to 70%. With this range of intake, it is only possible to see the increase in mortality associated with very high carbohydrate intake.

In fact, when the authors of the current study overlaid the data from the PURE study with their ARIC data, there was an almost perfect fit. The only difference was that their ARIC data covered both low and high carbohydrate intake while the PURE study touted by low carb enthusiasts only covered moderate to high carbohydrate intake.

[I have given you my rendition of the graph on the right. If you would like to see the data yourself, look at the paper.]

Basically, low carb advocates are telling you that diets with carbohydrate intakes of 26% or less are healthy based on studies that did not include carbohydrate intakes below 40%. That is misleading. The studies they quote are incapable of detecting the risks of low carbohydrate diets.

In short, the ARIC study finally answered the question, “How much carbohydrate should we be eating if we desire a long and healthy life?” The answer is “Enough”.

I call this “The Goldilocks Effect”. You may remember “Goldilocks And The Three Bears”. One bed was too hard. One bed was too soft. But one bed was “just right”. One bowl of porridge was too hot. One was two cold. But one was “just right”.

According to this study, the same is true for carbohydrate intake. High carbohydrate intake is unhealthy. Low carbohydrate intake is unhealthy. But moderate carbohydrate intake is “just right”.

What Does This Study Mean For You?

There are several important take-home lessons from this study:

1) All major studies agree that very high carbohydrate intake is unhealthy. In part, that reflects the fact that diets with high carbohydrate intake are likely to be high in sodas and sugary junk foods. It may also reflect the fact that diets which are high in carbohydrates are often low in plant protein or healthy fats or both.

2) All studies that cover the full range of carbohydrate intake agree that low and very low carbohydrate diets are also unhealthy. They shorten the life expectancy of a 50-year-old by about 4 years.

3) The studies quoted by low carb enthusiasts to support their claim that low-carb diets are healthy don’t include carbohydrate intakes below 40%. That means their claims are misleading. The studies they quote are incapable of detecting the risks of low carbohydrate diets. Their claims are a myth.

4) Not all high carb diets are created equally. As I noted above, the Mediterranean and DASH diets are just as high in carbohydrates as the typical American diet, but their carbohydrates come from whole fruits and vegetables, whole grains, beans, nuts, and seeds. And multiple studies show that both diets are much healthier than the typical American diet.

5) Not all low carb diets are created equally. Meat-based low-carb diets decrease life expectancy compared to the typical American diets while plant-based low carb diets increase life expectancy.

6) The health risks of meat-based low-carb diets may be due to the saturated fat content or the heavy reliance on red meat. However, the risks are just as likely to be due to the foods these diets leave out – typically fruits, whole grains, legumes, and some vegetables.

7) Proponents of low-carb diets assume that you can make up for the missing nutrients by just taking multivitamins. However, each food group also provides a unique combination of phytonutrients and fibers. The fibers, in turn, influence your microbiome. Simply put, whenever you leave out whole food groups, you put your health at risk.

The Bottom Line

The low-carb wars are raging. Several studies have reported that low carb diets increase risk of mortality (shorten lifespan). However, a study published a few years ago came to the opposite conclusion. That study had low carb enthusiasts doing a victory lap and claiming it is time to rewrite nutritional guidelines to favor low-carb diets.

However, a study published a year later resolves the conflicting data and finally answers the question: “How much carbohydrate should we be eating if we desire a long and healthy life?” The answer is “Enough”.

I call this “The Goldilocks Effect”. According to this study, high carbohydrate intake is unhealthy. Low carbohydrate intake is unhealthy. But moderate carbohydrate intake is “just right”.

Specifically, this study reported:

Moderate carbohydrate intake (50-55%) is healthiest. This is the carbohydrate intake found in healthy diets like the Mediterranean and DASH diets, and is the intake recommended by current nutritional guidelines.

2) All major studies agree that very high carbohydrate intake (60-70%) is unhealthy. It shortens the life expectancy of a 50-year-old by about a year.

3) All studies that cover the full range of carbohydrate intake agree that low carbohydrate intake (<26%) is also unhealthy. It shortens the life expectancy of a 50-year-old by about 4 years.

4) The studies quoted by low carb enthusiasts to support their claim that low-carb diets are healthy don’t include carbohydrate intakes below 40%. That means their claims are misleading. The studies they quote are incapable of detecting the risks of low carbohydrate diets.

5) Meat-based low-carb diets decrease life expectancy compared to the typical American diet while plant-based low carb diets increase life expectancy. This is consistent with the results of previous studies.

Simply put, the latest study means that the supposed benefits of low carb diets are a myth.

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.

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My posts and “Health Tips From the Professor” articles carefully avoid claims about any brand of supplement or manufacturer of supplements. However, I am often asked by representatives of supplement companies if they can share them with their customers.

My answer is, “Yes, as long as you share only the article without any additions or alterations. In particular, you should avoid adding any mention of your company or your company’s products. If you were to do that, you could be making what the FTC and FDA consider a “misleading health claim” that could result in legal action against you and the company you represent.

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

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About The Author

Dr. Chaney has a BS in Chemistry from Duke University and a PhD in Biochemistry from UCLA. He is Professor Emeritus from the University of North Carolina where he taught biochemistry and nutrition to medical and dental students for 40 years. Dr. Chaney won numerous teaching awards at UNC, including the Academy of Educators “Excellence in Teaching Lifetime Achievement Award”. Dr Chaney also ran an active cancer research program at UNC and published over 100 scientific articles and reviews in peer-reviewed scientific journals. In addition, he authored two chapters on nutrition in one of the leading biochemistry textbooks for medical students.

Since retiring from the University of North Carolina, he has been writing a weekly health blog called “Health Tips From the Professor”. He has also written two best-selling books, “Slaying the Food Myths” and “Slaying the Supplement Myths”. And most recently he has created an online lifestyle change course, “Create Your Personal Health Zone”. For more information visit https://chaneyhealth.com.

For the past 53 years Dr. Chaney and his wife Suzanne have been helping people improve their health holistically through a combination of good diet, exercise, weight control and appropriate supplementation.

The Good Cholesterol Myth

April 1, 2025 by Dr. Steve Chaney

Is Everything You Knew About HDL Wrong?

Author: Dr. Stephen Chaney

Over the past couple of weeks” I have talked about one of the greatest strengths of the scientific method – namely that investigators constantly challenge, and occasionally disprove, existing paradigms. That allows us to discard old models of how things work and replace them with better ones.

Two weeks ago, I shared a study that disproved the myth that low to moderate alcohol consumption is healthier than total abstinence.

Last week I shared a study that disproved the myth about chocolate helping you lose weight weight.

This week I tackle the “good” cholesterol myth. I will share several studies that challenge the belief that HDL cholesterol is good for your heart.

The belief that HDL is good for your heart has all the hallmarks of a classic paradigm.

It is supported by multiple clinical studies.

Elaborate metabolic explanations have been proposed to support the paradigm.

It is the official position of most medical societies, scientific organizations, and health information sites on the web.

It is the recommendation of most health professionals.

It has been repeated so often by so many trusted sources that everyone assumes it must be true.

Once we accept the HDL/heart health paradigm as true, we can construct other hypotheses on that foundation. For example:

Raising your HDL levels naturally takes effort. Pharmaceutical companies have been pursuing the “magic pill” that raises HDL levels without any effort on your part.

Low carb diets like the Keto and Paleo diets are high in saturated fat. The low carb enthusiasts claim this is a good thing because saturated fat raises HDL levels, and HDL is good for your heart.

But what if the paradigm that HDL is good for your heart isn’t true? What if it is a myth? These hypotheses would be like the parable of a house built on a foundation of sand. They will be washed away as soon as the paradigm is critically tested.

Do Drugs That Increase HDL Levels Work?

The first hint that the HDL/heart health paradigm might be faulty happened when a pharmaceutical company developed a drug that selectively increased HDL levels.

The drug company thought they had found the goose that laid golden eggs. Just imagine. People wouldn’t have to lose weight, exercise, or change their diet. They could simply take a pill and dramatically decrease their heart disease risk. A drug like that would be worth billions of dollars.

The problem was that when they tested their drug (torcetrapib) in clinical trials, it had absolutely no effect on heart disease outcomes (AR Tall et al, Atherosclerosis, Thrombosis, and Vascular Biology 27:257-260, 2007).

The pharmaceutical company couldn’t believe it. Raising HDL levels just had to reduce heart disease risk. They concluded they didn’t have the right drug, and they continued to work on developing new drugs.

That was 18 years ago, and no HDL-increasing drug has made it to market. Have they just not found the right drug, or does this mean the HDL/heart health paradigm is incorrect?

Does Saturated Fat Decrease Heart Disease Risk?

Now let’s turn to two claims of low carb enthusiasts.

#1: Saturated fats decrease your risk of heart disease in the context of a low carb diet. I have debunked that claim in several previous issues of “Health Tips From The Professor”. But let me refer you to two articles here – one on saturated fat and heart disease risk and one on low-carb diets.

#2: Saturated fats decrease heart disease risk because they raise HDL levels. This is the one I will address today.

The idea that saturated fats decrease heart disease risk because they raise HDL levels is based on a simplistic concept of HDL particles. The reality is more complex. Several clinical studies have shown:

The type of fat determines the property of the HDL particles.

- When polyunsaturated fats predominate, the HDL particles have an anti-inflammatory effect. When saturated fats predominate, the HDL particles have a pro-inflammatory effect.

Anti-inflammatory HDL particles relax the endothelial cells lining our blood vessels. That makes the lining of our blood vessels more pliable, which improves blood flow and reduces blood pressure.

- Anti-inflammatory HDL particles also help reduce inflammation of the endothelial lining. This is important because an inflamed endothelial lining is more likely to accumulate fatty plaques and to trigger blood clot formation that can lead to heart attacks and strokes.

So, the question becomes, “What good is it to raise HDL levels if you are producing an unhealthy, pro-inflammatory HDL particle that may increase the risk of high blood pressure, heart attacks, and strokes?”

In short, these studies suggest it isn’t enough to just focus on HDL levels. You need to ask what kind of HDL particles you are creating.

So, let’s look at experiments that have challenged the HDL/heart health paradigm.

Is HDL Good For Your Heart?

Once the studies were published showing that…

Drug-induced increase of HDL levels without any change in health habits is not sufficient to decrease heart attack risk, and…

Not all HDL particles are healthy. There are anti-inflammatory or pro-inflammatory HDL particles, which are likely to have opposite effects on heart attack risk…

…some people started to question the HDL/heart health paradigm. And one group came up with the perfect study to test the paradigm.

But before I describe the study, I need to review the term “confounding variables”. Here is a brief synopsis:

The studies supporting the HDL/heart health paradigm are association studies. Association studies measure the association between a single variable (in this case, increase in HDL levels) and an outcome (in this case, heart disease events, heart disease deaths, and total deaths).

Associations need to be corrected for other variables known to affect the same outcome (things like age, gender, smoking, and diabetes would be examples in this case).

Confounding variables are variables that also affect the outcome but are unknown or ignored. Thus, they are not used to correct the associations, which can bias the results.

The Good Cholesterol Myth

The authors of this study (M Briel et al, BMJ 2009:338.b92) observed that most interventions that increase HDL levels also lower LDL levels. Lowering LDL is known to decrease the risk of heart disease deaths. But this effect had been ignored in most studies looking at the association between HDL and heart disease deaths.

They hypothesized that the change in LDL levels was a confounding variable that had been ignored in previous studies and may have biased the results.

To test this hypothesis the authors searched the literature and identified 108 studies with 299,310 participants that:

Compared the effect of drugs, omega-3 fatty acids, or diet with either a placebo or usual care.
Measured both HDL and LDL levels.
Measured reduction in cardiovascular risk.
Had a randomized control design.
Lasted at least 6 months.

They found that every 10 mg/dl decrease in LDL levels in these studies was responsible for a:

1% reduction in heart disease events (both heart disease deaths and non-fatal heart attacks).

2% reduction in heart disease deaths.

4% reduction in total deaths.

After correcting for the effect of decreased LDL levels on these heart disease outcomes, the increase in HDL levels had no statistically significant effect on any of the outcomes.

The authors concluded, “Available data suggest that simply increasing the amount of circulating HDL cholesterol does not reduce the risk of coronary heart disease events, coronary heart disease deaths, or total deaths. The results support reduction in LDL cholesterol as the primary goal for lipid modifying interventions.”

In other words, this study:

Supports the author’s hypothesis that LDL levels were a confounding variable that biased the studies supporting the HDL/heart health paradigm.

Concludes that increasing HDL levels has no effect on heart disease outcomes, thus invalidating the HDL/heart health paradigm.

In short, this study destroyed the “good” cholesterol myth.

Is Everything You Knew About HDL Wrong?

Does that mean that everything you knew about HDL is wrong? Not exactly. It just means that you may need to change your perspective.

Don’t focus on HDL levels. Peek behind the curtain and focus on what’s behind the HDL levels. For example:

Losing weight when overweight increases HDL levels. But the decrease in heart disease outcomes is more likely due to weight loss than to the increase in HDL levels.

Exercise increases HDL levels. But the decrease in heart disease outcomes is more likely due to exercise than to the increase in HDL levels.

Reversing pre-diabetes or type 2 diabetes increases HDL levels. But the decrease in heart disease outcomes is more likely due to the reversal of diabetes than to the increase in HDL levels.

High-dose omega-3 fatty acids increase HDL levels. But the decrease in heart disease outcomes is more likely due to the omega-3 fatty acids than to the increase in HDL levels.

The Mediterranean diet increases HDL levels. But the decrease in heart disease outcomes is more likely due to the diet than to the increase in HDL levels.

And if you want to go the drug route:

Statins and some other heart drugs increase HDL levels, but the reduction in heart disease outcomes is probably due to their effect on LDL levels rather than their effect on HDL levels.

On the other hand:

Saturated fats increase HDL levels. But saturated fats increase heart disease risk and create pro-inflammatory HDL particles. So, in this case the increase in HDL levels is not a good omen for your heart.

Drugs have been discovered that selectively increase HDL levels. However, there is nothing of value behind this increase in HDL levels, so the drugs have no effect on heart disease outcomes.

The Bottom Line

In this article I discuss several studies that have challenged the good cholesterol myth – the belief that HDL is good for your heart.

For example, one group of investigators analyzed the studies underlying the HDL/heart health paradigm. They hypothesized that these studies were inaccurate because they failed to account for the effects of LDL levels on heart disease outcomes.

After correcting for the effect of decreased LDL levels on heart disease outcomes in the previous studies, the authors showed that increases in HDL levels had no significant effect on any heart disease outcome.

In other words, this study:

Supports the author’s hypothesis that LDL levels were a confounding variable that biased the studies supporting the HDL/heart health paradigm.

Concludes that increasing HDL levels has no effect on heart disease outcomes, thus invalidating the HDL/heart health paradigm.

Does that mean that everything you knew about HDL is wrong? Not exactly. It just means that you need to change your perspective. Don’t focus on HDL levels. Focus on what’s behind the HDL levels. For more information on that, read the article above.

For more information on this study, and what it means 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.

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For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

________________________________________________________________________________________

About The Author

Dr. Chaney won numerous teaching awards at UNC, including the Academy of Educators “Excellence in Teaching Lifetime Achievement Award”.

Dr Chaney also ran an active cancer research program at UNC and published over 100 scientific articles and reviews in peer-reviewed scientific journals. In addition, he authored two chapters on nutrition in one of the leading biochemistry text books for medical students.

Do Bad Genes Doom You To Bad Health?

October 1, 2024 by Dr. Steve Chaney

The Influence Of Genetics And Diet On Type 2 Diabetes

Author: Dr. Stephen Chaney

Does it ever feel like you have drawn the short straw?

Everyone in your family has succumbed to heart disease, diabetes, or cancer at a young age. Are you doomed to the same fate?

You ordered a DNA test. It sounded like fun. But when the gene report came back it said you had a “bad” genetic profile. You were told you are at high risk of diabetes, heart attack, stroke, cancer, or dementia. Are you doomed to a short and sickly life?

In both cases, you are probably wondering, “Is there anything I can do to improve my odds of a healthy life? What if I lost some of those extra pounds, exercised more, and ate a healthier diet? Would that make a difference?”

The study (J Merino et al, PLoS Medicine 19(4): e1003972, April 26, 2022) I will describe today was designed to answer these questions.

But before I describe the study, I should probably cover what I call Genetics 101: “How Genes Affect Your Health”.

Genetics 101: How Genes Affect Your Health

If you studied genetics in school, you probably learned about diseases like sickle cell anemia, which is caused by a single mutation in a single gene. If you get two copies of the “bad” gene, you will have sickle cell anemia. If you get one copy of the “bad” gene and one copy of the normal gene, you have sickle cell trait, which is much less severe.

Simply put, you either have the disease or you don’t. It’s dependent on your genetics, and you can’t do much about it.

If you know someone who has been treated for breast cancer, you are probably familiar with a more complex relationship between genetics and health. There are several “bad” genes that increase the risk of breast cancer. And knowing which gene is involved is important for selecting the best treatment regimen.

But most of the diseases that shorten our lives (like diabetes, heart disease, most cancers, and dementia) are what we call polygenetic diseases. Simply put, that means that there are dozens of genes that increase the risk of these diseases. Each gene makes a small contribution to the increased risk. So, we can only measure the genetic contribution to these diseases by measuring hundreds of mutations in dozens of genes, something called a polygenetic risk score.

The study I will be describing today looked at the relative effect of genetics (measured as the type 2 diabetes polygenic risk score) and diet quality (measured as the Alternative Healthy Eating Index (AHEI)) on the risk of developing type 2 diabetes.

How Was This Study Done?

The data for this study were obtained from 3 long-term clinical studies conducted in the United States – the Nurses’ Health Study (121,700 participants), the Nurses’ Health Study II (116,340 participants), and the Health Professionals Follow-Up Study (51,529 participants).

These studies measured lifestyle factors (including diet) every 4 years and correlated them with disease outcomes over 20+ years.

The study I will be discussing today was performed with 35,759 participants in these 3 studies for whom DNA sequencing data was available.

The DNA sequence data were used to generate a type 2 diabetes polygenic risk score for each participant in this study.

Food frequency questionnaires obtained every 4 years in these studies were used to calculate the Alternative Healthy Eating Index (AHEI) score for each participant.

- The AHEI is based on higher intake of fruits, whole grains, vegetables, nuts and legumes, polyunsaturated fatty acids, long-chain omega-3 fatty acids, moderate intake of alcohol, and lower intake of red and processed meats, sugar sweetened drinks and fruit juice, sodium, and trans-fat).

The investigators used these measurements to estimate the relative effect of genetics and diet quality on the risk of developing type 2 diabetes.

The Influence Of Genetics And Diet On Type 2 Diabetes

The participants were divided into low, intermediate, and high genetic risk based on their type 2 diabetes polygenic risk score.

Compared with low genetic risk:

Intermediate genetic risk increased the risk of developing type 2 diabetes by 26%.

High genetic risk increased the risk of developing type 2 diabetes by 75%.

Put another way, each 1 standard deviation increase in the polygenetic risk score:

Increased the risk of developing type 2 diabetes by 42%.

Simply put, bad genes can significantly increase your risk of developing type 2 diabetes. That’s the bad news. But that doesn’t mean you should think, “Diabetes is in my genes. There is nothing I can do.”

The investigators also divided the participants into those who had a high-quality diet, those who had an intermediate quality diet, and those who had a low-quality diet based on their AHEI (Alternative Healthy Eating Index) score.

Finally, they divided the participants into groups depending on their BMI, a measure of obesity.

Compared to an obese person consuming a low-quality diet, a lean person consuming a high-quality diet:

Reduced their risk of developing type 2 diabetes by around 43% for each category of genetic risk.

More specifically, a lean person consuming a high-quality diet reduced their risk of developing type 2 diabetes:

- By 41% if they were at low genetic risk.

- By 50% if they were at intermediate genetic risk.

- By 38% if they were at high genetic risk.

The investigators then made a statistical adjustment to remove BMI from their calculations, so they could focus on the effect of diet alone on the risk of developing type 2 diabetes.

Compared to a low-quality diet, a high-quality diet:

Reduced the risk of developing type 2 diabetes by around 33% for each category of genetic risk.

More specifically, a high-quality diet reduced the risk of developing type 2 diabetes:

- By 31% for those at low genetic risk.

- By 39% for those at intermediate genetic risk.

- By 29% for those at high genetic risk.

Looking at it another way:

When people at high genetic risk consumed a high-quality diet, their risk of developing type 2 diabetes was only 13% higher than people at intermediate genetic risk who consumed a low-quality diet (such as the typical American diet).

When people at intermediate genetic risk consumed a high-quality diet, their risk of developing type 2 diabetes was 5% less than people at low genetic risk who consumed a low-quality diet.

Simply put:

If you are at intermediate genetic risk, a high-quality diet may completely reverse your risk of developing type 2 diabetes.

If you are at high genetic risk, a high-quality diet can partially reverse your risk of developing type 2 diabetes.

In short, the good news is that bad genes do not doom you to type 2 diabetes.

The investigators did not provide similar information for the effect of an ideal weight on the risk of developing type 2 diabetes, but it is likely that the combination of diet plus weight management would result in an even more significant reduction in risk of developing type 2 diabetes for individuals in the even the highest risk category.

The authors concluded, “These data provide evidence for the independent associations of genetic risk and diet quality with incident type 2 diabetes and suggest that a healthy diet is associated with lower diabetes risk across all levels of genetic risk.”

Do Bad Genes Doom You To Bad Health?

At the beginning of this article I posed the question, “Do bad genes doom you to bad health?”

Based on this study, the good news is that bad genes don’t doom you type 2 diabetes. And just because most of your relatives are diabetic doesn’t mean that must be your fate.

This study shows that a healthy diet significantly reduces your risk of developing type 2 diabetes at every genetic risk level.

And the study suggests that a healthy diet plus a healthy weight is even more beneficial at reducing your risk of type 2 diabetes.

While not included in this study, other studies have shown that exercise also plays a role in reducing type 2 diabetes risk.

None of this information is new. What is new is that a healthy diet is equally beneficial at reducing type 2 diabetes risk even in individuals with a high genetic risk of developing the disease. Simply put, you can reverse the effects of bad genes.

“And what is this magic diet?”, you might ask. In this study, it was based on AHEI score. Someone with a high AHEI score consumes:

Lots of fruits, whole grains, vegetables, nuts and legumes, polyunsaturated fatty acids, and long-chain omega-3 fatty acids.

Moderate or no amounts of alcohol.

Little or no red and processed meats, sugar sweetened drinks, fruit juices, sodium, and foods with trans-fat.

Any whole food, primarily plant-based diet from vegan to Mediterranean or DASH fits the bill.

Finally, while this study focused just on type 2 diabetes, other studies have come to similar conclusions for other diseases.

Should You Get Your DNA Tested?

If you are looking for guidance on how to reduce your risks, the answer is, “No”. In this study, the same diet and lifestyle changes lowered the risk of type diabetes at every genetic risk level. Despite what some charlatans may tell you, there is no special diet or magic potion for people with a high genetic risk for developing type 2 diabetes.

If you are looking for motivation, the answer may be, “Yes”. If knowing you are at high risk makes it more likely that you will make the diet and lifestyle changes needed to lower your risk of type 2 diabetes, a DNA test may be just what you need

The Bottom Line

If a serious disease runs in your family or if you have had your DNA tested and found out you are at high risk for some disease, you are probably wondering whether there is anything you can do or whether your bad genes have doomed you to a short and sickly life.

A recent study answered that question for type 2 diabetes. It showed a healthy diet significantly reduces the risk of type 2 diabetes even in people at high genetic risk of developing the disease.

Other studies have come to similar conclusions for other diseases. In short, bad genes don’t doom you to bad health.

For more details about the study and what it means 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.

_____________________________________________________________________________

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

_______________________________________________________________________

About The Author

For the past 45 years Dr. Chaney and his wife Suzanne have been helping people improve their health holistically through a combination of good diet, exercise, weight control and appropriate supplementation.

Is Olive Oil Overrated?

September 24, 2024 by Dr. Steve Chaney

What Is The Truth About Olive Oil And You?

Author: Dr. Stephen Chaney

You may have seen headlines claiming that olive oil doesn’t deserve its “health halo”. It isn’t as healthy as many experts have claimed. It is overrated.

These headlines aren’t referring to the scandalous practice of selling “extra virgin” olive oil that contains cheaper oils. That is another topic for another day.

The headlines are claiming that, while the Mediterranean diet is healthy, it is fruits, vegetables, whole grains, legumes, and fish that make the Mediterranean diet healthy. Their claim is that olive oil has little to do with it.

To evaluate these claims I have reviewed the study (AK Krenek et al, Journal of the American Heart Association, Volume 13, Number 15:e035034, July 24, 2024) behind the headlines.

And to provide context, I have also reviewed another recent study (M Guasch-Ferre et al, Journal of the American College of Cardiology, Volume 79, Number 2, 2022).

How Were These Studies Done?

The two studies were very different:

The First Study used a randomized cross-over design to compare high and low olive oil diets.

In the randomized cross-over design participants were randomly assigned to one of the two diets at the beginning of the study. They followed that diet plan for 4 weeks. And after a one week “washout” they followed the other diet plan for 4 weeks. In this type of study each participant serves as their own control.

Study participants (50 obese participants, average age = 64, 75% women, 72% white, ≥ 5% risk of heart disease) were all eating a typical American diet.

Each of the experimental diets was a whole food plant-based diet, with comparable amounts of fruits, vegetables, whole grains, legumes, nuts, and seeds. Both diets were high in fiber, low in added sugar, and contained less than an ounce of animal products a day. In other words, the base diet was a healthy plant-based diet.

Participants in the high olive oil group were asked to add 4 tablespoons/day of extra virgin olive oil to their diet while participants in the low olive oil group were asked to restrict their olive oil intake to < 1 teaspoon/day.

No effort was made to control portion sizes or caloric intake. As we will see below, this was a major weakness of the study. As you might expect, fat intake was significantly greater for those on the high olive oil diet (49% of calories) compared to the low olive oil diet (32% of calories). Consequently, caloric intake was also significantly greater on the high olive oil diet.

All participants met with a dietitian/chef at the beginning of the study and were given access to online training programs and a dietitian hotline for questions. Dietary intake was measured by a 24-hour dietary recall 4-7 times prior to the study and 4 times during each diet period.

Fasting blood and urine samples were collected prior to the study and at the end of each 4-week diet period to measure biomarkers with possible predictive value for heart disease, such as LDL cholesterol.

The Second Study was a prospective cohort study using data obtained from 60,582 women in the Nurses Health Study and 31,801 men in the Health Professionals Follow-Up Study.

In a prospective cohort study a cohort or group of people (in this case, the 60,582 women and 31,801 men in the two studies) are followed over time (in this case for 28 years from1990 to 2018). The study then measures the association between some aspect of their diet and lifestyle (in this case the kind of fat in their diet) and health outcomes at the end of the study (in this case all-cause mortality, cardiovascular mortality, cancer mortality, neurodegenerative disease mortality, and respiratory disease mortality).

A strength of this study was that the diet of all participants was assessed every 4 years, which allowed the investigators to track changes in their diet over time. The intake of most fats was remarkably stable over the entire 28-year duration of the study.

However, as the bad news about margarine and the good news about olive oil entered the popular media, margarine consumption declined, and olive oil consumption increased. Because the investigators were able to track these changes over time, they were able to correct for them in their data analysis.

Is Olive Oil Overrated?

Results From The First Study: If we restrict ourselves to statistically significant observations, the results were as follows:

Switching from the baseline diet (typical American diet) to either the high olive oil or low olive oil diets for 4 weeks resulted in a significant decrease in total cholesterol, LDL cholesterol, HDL cholesterol, and blood glucose levels.

In this case, there was no statistically significant difference between the two diets.

However, when transitioning from the low olive oil diet to the high olive oil diet and from the high olive oil diet to the low olive oil diet, some statistically significant differences were observed.

For example, transitioning from the high olive oil diet to the low olive oil diet resulted in:

A 7% decrease in total cholesterol.

An 11% decrease in LDL-cholesterol.

A 2.2% decrease in HDL-cholesterol.

A 2% decrease in blood glucose levels.

And transitioning from the low olive oil diet to the high olive oil diet resulted in:

A 14% increase in total cholesterol.

A 14% increase in LDL-cholesterol.

A 15% increase in HDL-cholesterol.

A 17% decrease in blood glucose levels.

The authors of this study said, “Although both [whole food, primarily plant-based] diets improved [risk factors for heart disease], a low olive oil intervention may provide superior LDL-cholesterol lowering in individuals at highest risk [of heart disease]. Future studies are needed to determine if these short-term effects are sustainable and translate to improvements in cardiac outcomes…Nevertheless, a whole food primarily plant-based diet with relatively lower olive oil may be a useful tool for clinicians for improving cardiovascular risk compared with greater olive oil intake.”

The authors also went on to say, “…olive oil may not be the beneficial additive of a Mediterranean diet.”

Results From The Second Study:

Higher intake of olive oil (>0.5 tablespoons/day compared to ≤1 teaspoon/day) resulted in:

A 19% decrease in the risk of all-cause mortality. And when that was broken down by cause it amounted to:

- A 19% decrease in the risk of cardiovascular mortality.

- A 17% decrease in the risk of cancer mortality.

- A 29% decrease in the risk of neurodegenerative disease mortality.

- An 18% decrease in the risk of respiratory disease mortality.

In a substitution analysis calculating the effect of consuming 10 g/day of olive oil instead of 10 g/day of:

Butter resulted in a 14% decrease in the risk of all-cause mortality.

Margarine or dairy fat resulted in a 13% decrease in the risk of all-cause mortality.

Mayonnaise resulted in a 9% decrease in the risk of all-cause mortality.

Other vegetable oils had no effect on all-cause mortality.

Results were similar when the investigators looked at the effect of replacing fats with olive oil on mortality due to cardiovascular disease, cancer, neurodegenerative disease, and respiratory disease.

The authors of the second study concluded, “Higher olive oil intake was associated with lower risk of total and cause-specific mortality. Replacing margarine, butter, mayonnaise, and dairy fat with olive oil was associated with lower risk of mortality.”

How can we reconcile these conflicting viewpoints? Let me start by looking at the flaws in the first study. Then I will summarize the “truth” about olive oil based on what these two studies tell us.

Is The Study Behind The Headlines Misleading?

First let me summarize why I consider the study to be misleading. Then I will discuss why the headlines about the study are misleading.

Why The Study Is Misleading: The main conclusion of this study was that adding olive oil to a primarily plant-based diet increased the risk of heart disease. While this study is well-designed in some respects, it is flawed in others. I will summarize the flaws here:

Flaw Number 1: The authors rely on the relative effects of the high and low olive oil diets on LDL-cholesterol levels in predicting the effect of the two diets on heart disease risk. However, there is a major problem with this argument:

HDL-cholesterol levels move in the same direction. Both are decreased in the transition from the high olive oil to the low olive oil diet. Both are increased in the transition from the low olive oil to high olive oil diet. The ratio of HDL to LDL cholesterol changes very little, so it is almost impossible to predict what effect these changes will have on heart disease outcomes.

Flaw Number 2: This is related to the flaw I mentioned earlier. No effort was made to control portion size or caloric intake of participants on these diets. The high olive oil diet added 4 tablespoons of olive oil to the low olive oil diet. This significantly increased the fat and caloric intake of participants on the high olive oil diet.

Participants lost weight on both diets, but weight loss was significantly greater on the low olive oil diet. In their discussion, the authors admitted that the greater reduction in LDL-cholesterol on the low olive oil diet could have been due to the greater reduction in weight on that diet.

Flaw Number 3: I call this the “straw man” flaw. By adding 4 tablespoons of olive oil to the high olive oil diet the authors created the equivalent of a straw man that was easy knock over. Even if their conclusions were correct, nobody has recommended the addition of 4 tablespoons of olive oil to any diet as a heart-healthy approach.

Mediterraneans don’t add 4 tablespoons of olive oil to their diet. Olive oil is part of the foods they eat and the way they prepare their food.

Why The Headlines Are Misleading: Of course, the headlines were misleading because they ignored the many flaws of the study.

However, I find it amusing that some of the headlines came from “Forks Over Knives” an organization that advocates for a very low-fat plant-based diet. They were using this study to question the value of olive oil as part of a whole-food plant-based diet.

However, when you look at the study, 32% of calories came from fat in the low olive oil diet, and 49% of calories came from fat in the high olive oil diet.

For perspective:

The low-fat whole-food plant-based diet recommended by “Forks Over Knives” has <10-15% of calories from fat.

The Mediterranean diet typically contains 35-40% of calories from fat.

- Around 18-19% of that is monounsaturated fat.

- Around 8% of that is saturated fat.

The typical American diet also contains 35-40% of calories from fat.

- Around 12-14% of that is monounsaturated fat.

- Around 12% of that is saturated fat.

In other words, the low olive oil diet in this study resembles the fat content of the Mediterranean and typical American diets, not the low-fat whole food plant-based diet recommended by “Forks Over Knives”.

And the high olive oil diet contains fat levels not seen in any natural diet. Except for a few keto enthusiasts, I don’t know of any experts who think getting almost 50% of your calories from any kind of fat is a good thing.

What Is The Truth About Olive Oil And You?

As described above, the study behind the headlines is a very small, very short study with multiple flaws. So, you can ignore headlines like “Olive oil is overrated” or “Olive oil doesn’t deserve its health halo.”

The second study I discussed is much larger (92,383 participants) and of much longer duration (28 years). More importantly, it measures health outcomes, not blood biomarkers that might predict health outcomes.

Finally, the second study was not measuring the health benefits of the Mediterranean diet, as many other studies have done. It was looking at the effect of varying olive oil intakes in the American diet. The high olive oil intakes in this study were less than those seen in the Mediterranean diet. This is good news for the average American who may feel overwhelmed trying to adopt to a Mediterranean diet.

This study reinforces previous studies showing that olive oil is healthy. But let me put this into context.

Olive oil is not a superfood. This study showed that it is no healthier than other plant oils. It is, however, considered one of the best vegetable oils for sauteing. It is also less susceptible to oxidation than seed oils, although I still recommend you store it in the refrigerator.

It is not something you add to your diet. It is something you incorporate into your diet. People who live in Mediterranean regions:

- Cook with olive oil.

- Use olive oil in their salad dressings and drizzle a little olive oil on cooked vegetable and pasta dishes instead of adding butter.

- Dip their bread in olive oil rather than using butter or mayonnaise.

- Use it in spreads like tapenade or hummus.

- Use olives in cooking.

Finally, look for extra virgin olive oil. That doesn’t mean you need to spend “an arm and a leg”. But I would do a little online research before I bought the cheapest brand at the discount store.

The Bottom Line

You may have seen recent headlines claiming that olive oil is overrated and that it doesn’t deserve its “health halo”. So, I looked at the study behind the headlines.

It was a very small, very short study with multiple flaws. You can forget the headlines.

For context I also reviewed another recent study. It was a much larger (92,383 participants) and longer duration (28 years) study. More importantly, it measured actual health outcomes, not just blood biomarkers that might predict health outcomes.

It concluded that olive oil is good for us. It is healthier than most fats commonly found in the American diet, but it is no healthier than other plant oils.

For more details on these studies, what they mean for you, and how to incorporate more olive oil into your diet 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.

______________________________________________________________________________

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

_____________________________________________________________________

About The Author

Dr. Chaney won numerous teaching awards at UNC, including the Academy of Educators “Excellence in Teaching Lifetime Achievement Award”.

Are All Plant-Based Diets Healthy?

September 10, 2024 by Dr. Steve Chaney

Why Are Plant-Based Diets Healthy?

Author: Dr. Stephen Chaney

Unless you are like Rip van Winkle and have been asleep for the past 30 years, you have probably heard that plant-based diets are good for you. In fact, that advice is sound. It is based on multiple long-term studies.

But you may still be hesitant to make the switch. You are probably wondering if you have to be a vegan purist to benefit from a plant-based diet. If so, you are wondering whether you can make that drastic a change in your diet. Or, you may have already decided “that is a bridge too far” and don’t want to even consider it.

So, one important question is, “Do you have to go vegan to benefit from a plant-based diet?”

On the other hand, “Big Food, Inc” has made it easier than ever to switch to more “plant-based” eating. After all, sugar comes from plants. And highly processed grains come from plants. Add a few chemicals and you can come up with an endless supply of highly processed plant-based foods.

So, another important question is, “Can a diet of highly processed plant-based foods be as healthy as a diet of whole, unprocessed plant-foods?”

The study (Y. Wang et al., Nutrition Journal, 22: 46, 2023) I am reviewing today was designed to answer these two questions. It also represents the first meta-analysis to combine data from studies on the effects of plant-based diets on diabetes, heart disease, cancer, and mortality into a single study.

How Was The Study Done?

The investigators performed a meta-analysis of 76 studies with 2,230,443 participants that looked at the associations of plant-based dietary patterns and the incidence of type 2 diabetes, cardiovascular disease, cancer, and mortality among adults 18 years or older.

The characteristics of study participants ranged from:

25 to 87 years old.
BMI of 20 to 30.

And the duration of the studies within the meta-analysis ranged from 2 to 36 years.

The adherence to plant-based diets was defined as higher consumption of plant-based foods and lower consumption or exclusion of animal-based foods.

The meta-analysis also included studies looking at the effect of changing from a more animal-based to a more plant-based dietary pattern.

The meta-analysis included studies looking at the benefit of vegan and vegetarian diets. In terms of participants these studies represented just over 50% of the data in the meta-analysis. So, this meta-analysis was ideally positioned to determine whether vegan and vegetarian diets were more beneficial than other primarily plant-based dietary patterns that included some animal foods.

The methodology used to classify diets as primarily plant-based varied from study to study. But in each case the study participants were divided into quartiles ranging from consuming the most plant-based diet to consuming the least plant-based diet.

The study then compared study participants with the highest adherence to plant-based diets to those with the lowest adherence to plant-based diets with respect to type 2 diabetes, cardiovascular disease, cancer, and mortality.

Finally, the study also compared adherence to healthy plant-based dietary patterns (whole or minimally processed fruits, vegetables, whole grains, beans, nuts, and seeds) to unhealthy plant-based dietary patterns (foods and drinks with added sugar, highly processed plant foods, and starchy vegetables).

Are Plant-Based Diets Healthy?

When comparing highest to lowest adherence to plant-based dietary patterns the risk of:

Type-2 diabetes was reduced by 18%.

Cardiovascular disease was reduced by 10%.

Cancer was reduced by 12%.

Mortality was reduced by 16%.

In short, all the news was good for primarily plant-based dietary patterns.

Are All Plant-Based Diets Healthy?

Increased adherence to a healthy plant-based dietary pattern (That term is defined in the methods section above) was associated with an even better reduction in disease risk. For example:

Type-2 diabetes was reduced by 21%.

Cardiovascular disease was reduced by 15%.

Cancer was reduced by 13%.

Mortality was reduced by 14%, which was statistically indistinguishable from the reduction in mortality associated with all plant-based dietary patterns above.

In contrast, increased adherence to an unhealthy plant-based dietary pattern was associated with increased risks of disease. For example:

The risk of type 2 diabetes increased by 8%.

The risk of cardiovascular disease increased by 14%.

The risk of cancer increased by 7%.

The risk of mortality increased by 16%.

In short, plant-based dietary patterns consisting of whole or minimally processed plant foods are good for you. Plant-based dietary patterns consisting of highly processed plant foods are not.

Are Vegan and Vegetarian Diets More Beneficial Than Other Plant-Based Dietary Patterns?

Twenty seven of the studies within this meta-analysis compared vegetarian or vegan dietary patterns with animal-based dietary patterns. These studies had 1,343,967 participants, which amounts to 57% of the participants in the meta-analysis.

Thus, this meta-analysis was well positioned to determine relative benefits of vegan and vegetarian diets compared to other primarily plant-based dietary patterns that include some animal foods. The investigators reported that:

The risk reduction for type 2 diabetes was greater in studies with vegan and vegetarian diets than in studies with other primarily plant-based diets.

No other statistically significant benefits were observed for vegan and vegetarian diets compared to other primarily plant-based diets.

In short, you don’t need to become a vegan to experience the health benefits of a plant-based diet.

In contrast, increased adherence to an unhealthy plant-based dietary pattern was associated with increased risks of disease. For example:

The risk of type 2 diabetes increased by 8%.

The risk of cardiovascular disease increased by 14%.

The risk of cancer increased by 7%.

The risk of mortality increased by 16%.

In short, plant-based dietary patterns consisting of whole or minimally processed plant foods are good for you. Plant-based dietary patterns consisting of highly processed plant foods are not.

What If You Change From An Animal-Based To A Plant-Based Diet?

If you have been consuming an animal-based diet for years, you may be wondering whether it is too late to change. Has the damage already been done?

Six studies within this meta-analysis examined the effect of changing from an animal-based diet to a plant-based diet on type 2 diabetes and mortality. Changing to a more plant-based dietary pattern:

Reduced diabetes by 17% and mortality by 5%.

In short, it’s never too late to switch to a more plant-based dietary pattern.

Why Are Plant-Based Diets Healthy?

The short answer is that we don’t know for sure, but the authors mentioned several popular hypotheses.

Obesity is a risk factor for type 2 diabetes, cardiovascular disease, and certain types of cancer. And studies have shown that people consuming plant-based diets tend to weigh less.

The increased fiber content and higher ratio of polyunsaturated fats to saturated fats lower cholesterol levels and improve blood lipid profiles, which are associated with a lower risk of cardiovascular disease.

Plant-based diets are anti-inflammatory, which reduces the risk of all three diseases.

Plant foods are rich in polyphenols and other phytonutrients that are associated with reduced risk of cardiovascular disease, lower blood pressure, and improvements in insulin sensitivity.

Plant foods are metabolized by gut bacteria to metabolites that are associated with reduced risk of type 2 diabetes and cardiovascular disease.

Plant foods support healthy gut bacteria associated with a reduced risk of several diseases.

Finally, plant-based dietary patterns are associated with no or reduced consumption of red and processed meats, which increase the risk of type 2 diabetes, cardiovascular disease, and certain types of cancer.

For a more detailed discussion read the article).

What Does This Study Mean For You?

The authors of this study concluded, “Higher adherence to plant-based dietary patterns, especially from healthy sources, may be universally beneficial for the primary prevention of type 2 diabetes, cardiovascular disease, cancer, and mortality. The current study provides further evidence in support of current recommendations that emphasize consuming high-quality plant-based foods for achieving optimal health.”

“Future studies are needed to elucidate…mechanistic pathways linking plant-based diets with multiple disease outcomes.”

I would just like to emphasize a few points:

These are all association studies. It takes decades for diseases like diabetes, heart disease, and cancer to develop. So, it is impossible to confirm these findings with double blind, placebo-controlled studies. However, when you have 76 studies with over 2 million participants all pointing to the same conclusion, it is hard to ignore the findings.

The good news is that you don’t have to become a vegan to experience these benefits. There are many healthy primarily plant-based diets available. Choose the one that best fits your food preferences and lifestyle.

Be aware that whatever diet you choose, Big Food Inc is only too happy to provide you with highly processed foods that fit that dietary pattern. Don’t fall for that trap. Stick with whole or minimally processed plant foods.

If your current diet isn’t the best, it is never too late to switch to a healthier primarily plant-based diet.

The Bottom Line

A recent meta-analysis of 76 studies with 2,230,443 participants looked at the associations of plant-based dietary patterns and the incidence of type 2 diabetes, cardiovascular disease, cancer, and mortality among adults 18 years or older.

The authors of the study concluded, “Higher adherence to plant-based dietary patterns, especially from healthy sources, may be universally beneficial for the primary prevention of type 2 diabetes, cardiovascular disease, cancer, and mortality. The current study provides further evidence in support of current recommendations that emphasize consuminh high-quality plant-based foods for achieving optimal health.”

Other key points from the study are:

These are all association studies. It takes decades for diseases like diabetes, heart disease, and cancer to develop. So, it is impossible to confirm these findings with double blind, placebo-controlled studies. However, when you have 76 studies with over 2 million participants all pointing to the same conclusion, it is hard to ignore the findings.

The good news is that you don’t have to become a vegan to experience these benefits. There are many healthy primarily plant-based diets available. Choose the one that best fits your food preferences and lifestyle.

Be aware that whatever diet you choose, Big Food Inc is only too happy to provide you with highly processed foods that fit that dietary pattern. Don’t fall for that trap. Stick with whole or minimally processed plant foods.

If your current diet isn’t the best, it is never too late to switch to a healthier primarily plant-based diet.

For more details about how the authors came to these conclusions and what they mean 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.

_______________________________________________________________________________

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

______________________________________________________________________

About The Author

Which Diets Are Best For The Planet?

August 13, 2024 by Dr. Steve Chaney

Which Diets Are Best For Your Health?

Author: Dr. Stephen Chaney

Is it hot enough yet? I’m not going to take a stand in the global warming debate. But I will say this summer has been extraordinarily hot – even for North Carolina.

So, what can we do about it? I will list some options below. But with “tongue in cheek” I will give voice to both sides of each option.

We can elect politicians of our choice and hope they have the wisdom to balance reductions in global warming with the energy needs of our country – but there has been little evidence of that wisdom from either end of the political spectrum.

We can purchase electric cars – despite their cost, limited range, and long refueling times.

We can recycle – even though most of what we recycle ends up in regular trash.

We can turn up our thermostats in summer and down in winter – and choose to swelter in summer and shiver in winter.

We can change our diet – but wait. Could this be a win no matter what our views are on climate change? Could the same diets that are better for the planet also be better for our health?

That is the hypothesis today’s study (K. O’Malley et al, The American Journal of Clinical Nutrition, 117: 701-708, 2023) set out to test.

How Was The Study Done?

The investigators analyzed 24-hour dietary recall data from 16,412 participants from the 2005 – 2010 NHANES survey. NHANES (National Health and Nutrition Examination Survey) is an ongoing, nationally representative, survey to measure the health and nutrition status of the US population. This investigation used data collected between 2005 and 2010.

The dietary data were used to categorize the intake of individual participants into different diets as follows:

Vegan – plant foods only.
Vegetarian – includes eggs and dairy but excludes meat.
Pescatarian – includes fish as the major source of meat.
Paleo – excludes grains, legumes, and dairy.
Keto – excludes grains, legumes, fruits, and starchy vegetables.
Omnivore – Any diet not included in the categories above.

The omnivore diet was further divided to identify people following the DASH and Mediterranean diets.

The environmental impact of each diet was calculated based on the amount of CO₂ and methane produced in the production of the foods included in the diet.

The impact on our health of each diet was calculated based on the Alternative Healthy Eating Index.

The Healthy Eating Index was first developed in 1995 as tool to gauge how well a diet followed the Dietary Guidelines for Americans established by the Department of Health & Human Services and the USDA.

The Alternative Healthy Eating Index was first developed in 2002 to include a wider range of foods and to better predict the effect of diet on chronic diseases based on clinical studies of health outcomes.

Each of these indices are regularly updated as more data become available.

Which Diets Are Best For the Planet?

I have put the data in a graphical format, so it is easier to visualize.The vertical axis is greenhouse gas emissions expressed as kg of CO₂ equivalents per 1,000 calories (The term CO₂ equivalents is used because cows and sheep produce methane which is a much more potent greenhouse gas than CO₂). Lower is better.

On the horizontal axis the diets from left to right are vegan, vegetarian, pescatarian, paleo, keto, omnivore, DASH, and Mediterranean. The diets with the least greenhouse gas emissions are shown in green (the greener the better), and the diets with the most greenhouse gas emissions are shown in orange and red.

Which Diets Are Best For Your Health?

Once again, I have chosen a graphical representation.

The vertical axis is the Alternative Healthy Eating Index. In this case, higher is better.

The color score is the same as above. However, I would note that:

Fish is the main animal protein source in the pescatarian diet. I suspect that the vegan and vegetarian diets would score just as high as the pescatarian diet in the Alternative Healthy Eating Index if an omega-3 supplement was taken along with the diets.

The Alternative Healthy Eating Index is weighted heavily on clinical studies showing that a particular diet reduces the risk of heart disease, diabetes, and/or cancer. That is likely why the DASH diet ranks so high. It was designed to decrease the risk of hypertension. Because of that there have been dozens of studies showing it reduces the risk of strokes and heart attacks.

The available evidence suggests that the Mediterranean diet is just as effective as the DASH diet at reducing the risk of strokes, heart attacks, and diabetes. But we do not yet have as many studies looking at the effect of the Mediterranean diet on those diseases. Based on the currently available evidence, I consider the Mediterranean diet to be just as healthy as the DASH diet.

Finally, I would like to point out the obvious. This and other studies show that the same diets that are good for the planet are good for our health.

For example, the authors estimated:

For any given day, if a third of omnivores in the United States switched to a vegetarian diet, it would be equivalent to eliminating 340 million passenger miles in gas-powered vehicles.

If this change were implemented year-round, it would amount to almost 5% of the reductions in greenhouse gas emissions needed to meet the original US targets in the Paris accords.

For those omnivores who made the switch to a vegetarian diet, it would improve diet quality by 6%.

Of course, if all omnivores in the United States switched to a vegetarian diet, these percentages would be tripled, but that is wildly unrealistic.

What Does This Study Mean For You?

The take home lesson from this study is clear.

If your primary concern is climate change, choose the planet-healthy diet that best fits your food preferences and lifestyle. [The ones with the lowest greenhouse gas emissions are shown in green in the first graph above – the greener, the better.] Any of these diets will also be good for your health.

If your primary concern is health, choose the healthy diet that best fits your food preferences and lifestyle. [The ones with the highest Alternate Healthy Eating Index are shown in green in the second graph above – the greener, the better.] Any of these diets will also be good for the planet.

The Bottom Line

A recent study compared 8 popular diets (vegan, vegetarian, pescatarian, paleo, keto, omnivore, DASH, and Mediterranean) with respect to their impact on the environment and on your health.

The results were clear-cut. The diets that were best for the planet were best for your health and vice-versa.

For example, the authors estimated:

For any given day, if a third of omnivores in the United States switched to a vegetarian diet, it would be equivalent to eliminating 340 million passenger miles in gas-powered vehicles.

If this change were implemented year-round, it would amount to almost 5% of the reductions in greenhouse gas emissions needed to meet the original US targets in the Paris accords.

For those omnivores who made the switch to a vegetarian diet, it would improve diet quality by 6%.

For more details about this study and what it means 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.

______________________________________________________________________________

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

About The Author

Is The Mediterranean Diet Healthy For Women?

May 28, 2024 by Dr. Steve Chaney

What Does This Study Mean For You?

Author: Dr. Stephen Chaney

There is a well-known health disparity in clinical studies related to health. For years most of the studies have been done by men for men. Women have been assumed to experience the same benefits and risks from diet choices as men. But that hasn’t always proven to be true.

The Mediterranean diet is no exception. For example, it has garnered a reputation of reducing heart disease risk for both men and women.

However, most studies on the Mediterranean diet have included primarily male participants or did not report sex specific differences in outcomes.

And the few studies that reported sex specific outcomes have been inconsistent.

Some studies have found that men and women benefitted equally from the Mediterranean diet.

Other studies have reported that men benefitted more than women.

However, these were all small studies. No meta-analyses have been reported that focused on the heart benefits of the Mediterranean diet for women.

The study (A Pant et al., Heart; 109: 1208-1215, 2023) I will describe today was designed to fill that gap.

How Was The Study Done?

The investigators started by screening the literature to find studies that:

Measured adherence to the Mediterranean diet using the original MDS (Mediterranean Diet Score) or more recent modifications of the MDS.

Included women ≥18 years without previous diagnosis of clinical or subclinical heart disease.

Performed the study with only women participants or organized their data so that the data pertaining to women could be extracted from the study.

The investigators then performed a meta-analysis on data from 722,495 women in 16 studies published between 2006 and 2021 that met these criteria. These studies followed the women for an average of 12.5 years. The studies were primarily conducted in the United States and Europe.

The individual studies divided participants into either quintiles or quartiles and compared participants with the highest adherence to the Mediterranean diet to those with the lowest adherence.

The primary outcomes measured were total mortality and the incidence of CVD, cardiovascular disease (defined as including CHD (coronary heart disease), myocardial infarction (heart attack), stroke, heart failure, and cardiovascular death).

The secondary outcomes measured were stroke and CHD, coronary heart disease (heart disease caused by atherosclerotic plaque build up in the coronary arteries).

Is The Mediterranean Diet Healthy For Women?

When comparing the highest to the lowest adherence to the Mediterranean diet:

The incidence of CVD (cardiovascular disease) was reduced by 24%.

Total mortality during the ~12.5-year follow-up was reduced by 23%.

The incidence of CHD (coronary heart disease) was reduced by 25%.

The risk of stroke was reduced by 13%, but that risk reduction was not statistically significant.

- The risk reduction for both CVD and total mortality was similar to that previously reported for men.

- Risk reduction for CVD was slightly higher for women of European descent (24%) than for women of non-European descent (21%). The later category included women of Asian, Native-Hawaiian, and African – American descent.

The authors concluded, “This study supports a beneficial effect of the Mediterranean diet on the primary prevention of CVD and death in women and is an important step in enabling sex-specific guidelines.”

I would add that the data from women of non-European decent suggests that genetic background and/or ethnicity may influence the effectiveness of the Mediterranean diet at reducing heart disease risk, but this effect appears to be small.

What Does This Mean For You?

The results of this study are not unexpected. But that doesn’t mean that studies with women are not valuable. There have been several examples in recent years where health or medical advice based on studies with men needed to be modified for females once the studies were repeated with women.

Before covering what this study means for you, I should point out that while women often fear breast cancer most, heart disease is their number one killer, as the graph on the left shows. In fact, a woman’s risk of dying from coronary heart disease is 6 times greater than her risk of dying from breast cancer.

This study shows that following a Mediterranean–style diet lowers their risk of developing and dying from heart disease. But the Mediterranean diet is not alone in providing these health benefits. It is simply a whole food, primarily plant-based diet that reflects the food preferences of the Mediterranean region.

The DASH diet, which reflects the food preferences of Americans, and the Nordic diet, which reflects the food preferences of the Scandinavian countries, are equally heart healthy. In fact, any whole food, primarily plant-based diet will reduce the risk of heart disease. You should choose the one that best fits your food preferences and lifestyle.

Of course, diet is just part of a holistic approach for reducing heart disease risk. Other important risk reduction strategies include:

Don’t smoke.

Exercise and maintain a healthy weight.

Manage stress.

Avoid or limit alcohol.

Know your numbers (cholesterol, triglycerides, and blood pressure, for example).

Manage other health conditions that increase the risk of heart disease (high blood pressure, diabetes, and high cholesterol, for example).

The Bottom Line

Most studies on the heart health benefits of the Mediterranean diet have been done with men or have not analyzed the data from men and women separately. A recent meta-analysis combining data from 16 studies with 722,495 women showed that the Mediterranean diet was just as heart healthy for women as it was for men.

For more details on this study and information on other diets that are heart healthy, 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.

_____________________________________________________________________________My My posts and “Health Tips From the Professor” articles carefully avoid claims about any brand of supplement or manufacturer of supplements. However, I am often asked by representatives of supplement companies if they can share them with their customers.

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

_____________________________________________________________________

About The Author

Dr. Chaney won numerous teaching awards at UNC, including the Academy of Educators “Excellence in Teaching Lifetime Achievement Award”.

Which Diets Are Heart Healthy?

November 7, 2023 by Dr. Steve Chaney

Which Diet Is Best For You?

Author: Dr. Stephen Chaney

The top 3 claims the advocates of every popular diet make are:

It will help you lose weight.

It reduces your risk of diabetes.

It reduces your risk of heart disease.

The truth is any restrictive diet helps you lose weight. And when you lose weight, you improve blood sugar control. Which, of course, reduces your risk of developing diabetes.

But what about heart disease? Which diets are heart healthy? When it comes to heart disease the claims of diet advocates are often misleading. That’s because the studies these advocates use to support their claims are often poor quality studies. Many of these studies:

Look at markers of heart disease risk rather than heart disease outcomes. Markers like LDL cholesterol, triglycerides, c-reactive protein, etc. are only able to predict possible heart disease outcomes. To really know which diets are heart healthy you have to measure actual heart disease outcomes such as heart attacks, stroke, and cardiovascular deaths.

Are too short to provide meaningful results. Many of these studies last only a few weeks. You need much longer to measure heart disease outcomes.

Are too small to provide statistically significant results. You need thousands of subjects to be sure the results you are seeing are statistically significant.

Have not been confirmed by other studies. The Dr. Strangeloves of the world like to “cherry pick” the studies that support the effectiveness of their favorite diet. Objective scientists know that any individual study can be wrong. So, they look for consensus conclusions from multiple studies.

A recent study (G Karam et al, British Medical Journal, 380: e072003, 2023) avoided all those pitfalls. The investigators conducted a meta-analysis of 40 high-quality clinical studies with 35,548 participants to answer the question, “Which diets are heart healthy?”

How Was The Study Done?

The authors started by searching all major databases of clinical studies for studies published on the effect of diets on heart disease outcomes through September 2021.

They then performed a meta-analysis of the data from all studies that:

Compared the effect of a particular diet to minimal dietary intervention (defined as not receiving any advice or receiving dietary information such as brochures or brief advice from their clinician with little or no follow-up).

Looked at heart disease outcomes such as all cause mortality, cardiovascular mortality, non-fatal heart attacks, stroke, and others.

Lasted for at least 9 months (average duration = 3 years).

Were high-quality studies.

Using these criteria:

They identified 40 studies with 35,548 participants for inclusion in their meta-analysis.

- From those 40 studies, they identified 7 diet types that met their inclusion criteria (low fat (18 studies), Mediterranean (12 studies), very low fat (6 studies), modified fat (substituting healthy fats for unhealthy fats rather than decreasing fats, 4 studies), combined low fat and low sodium (3 studies), Ornish (3 studies), Pritikin (1 study).

One weakness of meta-analyses is that the design of the studies included in the meta-analysis is often different. Sometimes they don’t fit together well. So, while the individual studies are high-quality, a combination of all the studies can lead to a conclusion that is low quality or moderate quality.

Finally, the data were corrected for confounding factors such as obesity, exercise, smoking, and medication use.

Which Diets Are Heart Healthy?

Now that you understand the study design, we are ready to answer the question, “Which diets are heart healthy?” Here is what this study found:

Compared to minimal intervention,

The Mediterranean diet decreased all cause mortality by 28%, cardiovascular mortality by 45%, stroke by 35%, and non-fatal heart attacks by 52%.

Low fat diets decreased all cause mortality by 16% and non-fatal heart attacks by 23%. The effect of low fat diets on cardiovascular mortality and stroke was not statistically significant in this meta-analysis.

- For both the Mediterranean and low fat diets, the heart health benefits were significantly better for patients who were at high risk of heart disease upon entry into the study.

- The evidence supporting the heart health benefits for both diets was considered moderate quality evidence for this meta-analysis. [Remember that the quality of any conclusion in a meta-analysis is based on both the quality of evidence of the individual studies plus how well the studies fit together in the meta-analysis.]

While the percentage of risk reduction appears to be different for the Mediterranean and low fat diets, the effect of the two diets on heart health was not considered significantly different in this study.

The other 5 diets provided little, or no benefit, compared to the minimal intervention control based on low to moderate quality evidence.

The authors concluded, “This network meta-analysis found that Mediterranean and low fat dietary programs probably reduce the risk of mortality and non-fatal myocardial infarction [heart attacks] in people at increased cardiovascular risk. Mediterranean dietary programs are also likely to reduce the risk of stroke. Generally, other dietary programs were not superior to minimal intervention.”

Which Diet Is Best For You?

The fact that this study found both the Mediterranean diet and low fat diets to be heart healthy is not surprising. Numerous individual studies have found these diets to be heart healthy. So, it is not surprising when the individual studies were combined in a meta-analysis, the meta-analysis also concluded they were heart healthy. However, there are two important points I would like to make.

The diets used in these studies were designed by trained dietitians. That means the low fat studies did not use Big Food, Inc’s version of the low fat diet in which fatty foods are replaced with highly processed foods. In these studies, fatty foods were most likely replaced with whole or minimally processed foods from all 5 food groups.

The Mediterranean diet is probably the most studied of current popular diets. From these studies we know the Mediterranean diet improves brain health, gut health, and reduces cancer risk.

As for the other 5 diets (very low fat, modified fat, low fat and low sodium, Ornish, and Pritikin), I would say the jury is out. There is some evidence that these diets may be heart healthy. But very few of these studies were good enough to be included in this meta-analysis. Clearly, more high-quality studies are needed.

Finally, you might be wondering why other popular diets such as paleo, low carb, and very low carb (Atkins, keto, and others) were left out of this analysis. All I can say is that it wasn’t by design.

The authors did not select the 7 diets described in this study and then search for studies testing their effectiveness. They searched for all studies describing the effect of diets on heart health. Once they identified 40 high-quality studies, they grouped the diets into 7 diet categories.

I can only conclude there were no high-quality studies of paleo, low carb, or very low carb diets that met the criteria for inclusion in this meta-analysis. The criteria were:

The effect of diet on heart health must be compared to a control group that received no or minimal dietary advice.

The study must measure heart disease outcomes such as all cause mortality, cardiovascular mortality, non-fatal heart attacks, and stroke.

The study must last at least 9 months.

The study must be high-quality.

Until these kinds of studies are done, we have no idea whether these diets are heart healthy or not.

So, what’s the takeaway for you? Which diet is best for you? Both low fat diets and the Mediterranean diet are heart healthy provided the low fat diet consists of primarily whole or minimally processed foods. Which of these two diets is best for you depends on your food preferences.

The Bottom Line

Many of you may have been warned by your doctor that your heart health is not what it should be. Others may be concerned because you have a family history of heart disease. You want to know which diets are heart healthy.

Fortunately, a recent study answered that question. The authors performed a meta-analysis of 40 high-quality studies that compared the effect of various diets with the effect of minimal dietary intervention (doctors’ advice or diet brochure) on heart disease outcomes.

From this study they concluded that both low fat diets and the Mediterranean diet probably reduce mortality and the risk of non-fatal heart attacks, and that the Mediterranean diet likely reduces stroke risk.

Other diets studied had no significant effect on heart health in this study. That does not necessarily mean they are ineffective. But it does mean that more high-quality studies are needed before we can evaluate their effect on heart health.

So, what’s the bottom line for you? Both low fat diets and the Mediterranean diet are heart healthy provided the low fat diet consists of primarily whole or minimally processed foods Which of these two diets is best for you depends on your food preferences.

For more information on this study, 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.

___________________________________________________________________________

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

Is HDL Good For Your Heart?

June 13, 2023 by Dr. Steve Chaney

Is Everything You Knew About HDL Wrong?

Author: Dr. Stephen Chaney

In last week’s “Health Tips From the Professor” I talked about one of the greatest strengths of the scientific method – namely that investigators constantly challenge, and occasionally disprove, existing paradigms. That allows us to discard old models of how things work and replace them with better ones.

Last week I shared a study that disproved the paradigm that low to moderate alcohol consumption is healthier than total abstinence. This week I share several studies that challenge the belief that HDL cholesterol is good for your heart.

The belief that HDL is good for your heart has all the hallmarks of a classic paradigm.

It is supported by multiple clinical studies.

Elaborate metabolic explanations have been proposed to support the paradigm.

It is the official position of most medical societies, scientific organizations, and health information sites on the web.

It is the recommendation of most health professionals.

It has been repeated so often by so many trusted sources that everyone assumes it must be true.

Once we accept the HDL/heart health paradigm as true, we can construct other hypotheses on that foundation. For example:

Raising your HDL levels naturally takes effort. Pharmaceutical companies have been pursuing the “magic pill” that raises HDL levels without any effort on your part.

Low carb diets like the Keto and Paleo diets are high in saturated fat. The low carb enthusiasts claim this is a good thing because saturated fat raises HDL levels, and HDL is good for your heart.

But what if the underlying HDL/heart health paradigm weren’t true? These hypotheses would be like the parable of a house built on a foundation of sand. The paradigm will be washed away as soon as it is critically tested.

So, let’s look at experiments that have challenged the HDL/heart health paradigm.

Do Drugs That Increase HDL Levels Work?

The first hint that the HDL/heart health paradigm might be faulty happened when a pharmaceutical company developed a drug that selectively increased HDL levels.

That was 16 years ago, and no HDL-increasing drug has made it to market. Have they just not found the right drug, or does this mean the HDL/heart health paradigm is incorrect?

Does Saturated Fat Decrease Heart Disease Risk?

Now let’s turn to two claims of low carb enthusiasts.

#2: Saturated fats decrease heart disease risk because they raise HDL levels. This is the one I will address today.

The type of fat determines the property of the HDL particles.

- When polyunsaturated fats predominate, the HDL particles have an anti-inflammatory effect. When saturated fats predominate, the HDL particles have a pro-inflammatory effect.

Anti-inflammatory HDL particles relax the endothelial cells lining our blood vessels. That makes the lining of our blood vessels more pliable, which improves blood flow and reduces blood pressure.

- Anti-inflammatory HDL particles also help reduce inflammation of the endothelial lining. This is important because an inflamed endothelial lining is more likely to accumulate fatty plaques and to trigger blood clot formation that can lead to heart attacks and strokes.

In short, these studies suggest it isn’t enough to just focus on HDL levels. You need to ask what kind of HDL particles you are creating.

Is HDL Good For Your Heart?

Once the studies were published showing that…

Drug-induced increase of HDL levels without any change in health habits is not sufficient to decrease heart attack risk, and…

Not all HDL particles are healthy. There are anti-inflammatory or pro-inflammatory HDL particles, which likely have opposite effects on heart attack risk…

…some people started to question the HDL/heart health paradigm. And one group came up with the perfect study to test the paradigm.

But before I describe the study, I need to review the term “confounding variables”. I described the term and how it affects clinical studies in last week’s article. Here is a brief synopsis:

The studies supporting the HDL/heart health paradigm are association studies. Association studies measure the association between a single variable (in this case, increase in HDL levels) and an outcome (in this case, heart disease events, heart disease deaths, and total deaths).

Associations need to be corrected for other variables known to affect the same outcome (things like age, gender, smoking, and diabetes would be examples in this case).

Confounding variables are variables that also affect the outcome but are unknown or ignored. Thus, they are not used to correct the associations, which can bias the results.

They hypothesized that the change in LDL levels was a confounding variable that had been ignored in previous studies and may have biased the results.

To test this hypothesis the authors searched the literature and identified 108 studies with 299,310 participants that:

Compared the effect of drugs, omega-3 fatty acids, or diet with either a placebo or usual care.
Measured both HDL and LDL levels.
Measured reduction in cardiovascular risk.
Had a randomized control design.
Lasted at least 6 months.

They found that every 10 mg/dl decrease in LDL levels in these studies was responsible for a:

7.1% reduction in heart disease events (both heart disease deaths and non-fatal heart attacks).

7.2% reduction in heart disease deaths.

4.4% reduction in total deaths.

After correcting for the effect of decreased LDL levels on these heart disease outcomes, the increase in HDL levels had no statistically significant effect on any of the outcomes.

In other words, this study:

Supports the author’s hypothesis that LDL levels were a confounding variable that biased the studies supporting the HDL/heart health paradigm.

Concludes that increasing HDL levels has no effect on heart disease outcomes, thus invalidating the HDL/heart health paradigm.

Is Everything You Knew About HDL Wrong?

Does that mean that everything you knew about HDL is wrong? Not exactly. It just means that you need to change your perspective.

Don’t focus on HDL levels. Peek behind the curtain and focus on what’s behind the HDL levels. For example:

Losing weight when overweight increases HDL levels. But the decrease in heart disease outcomes is more likely due to weight loss than to the increase in HDL levels.

Exercise increases HDL levels. But the decrease in heart disease outcomes is more likely due to exercise than to the increase in HDL levels.

Reversing pre-diabetes or type 2 diabetes increases HDL levels. But the decrease in heart disease outcomes is more likely due to the reversal of diabetes than to the increase in HDL levels.

High-dose omega-3 fatty acids increase HDL levels. But the decrease in heart disease outcomes is more likely due to the omega-3 fatty acids than to the increase in HDL levels.

The Mediterranean diet increases HDL levels. But the decrease in heart disease outcomes is more likely due to the diet than to the increase in HDL levels.

And if you want to go the drug route:

Statins and some other heart drugs increase HDL levels, but the reduction in heart disease outcomes is probably due to their effect on LDL levels rather than their effect on HDL levels.

On the other hand:

Saturated fats increase HDL levels. But saturated fats increase heart disease risk and create pro-inflammatory HDL particles. So, in this case the increase in HDL levels is not a good omen for your heart.

Drugs have been discovered that selectively increase HDL levels. However, there is nothing of value behind this increase in HDL levels, so the drugs have no effect on heart disease outcomes.

The Bottom Line

In this article I discuss several studies that have challenged the HDL/heart health paradigm – the belief that HDL is good for your heart.

In other words, this study:

Supports the author’s hypothesis that LDL levels were a confounding variable that biased the studies supporting the HDL/heart health paradigm.

Concludes that increasing HDL levels has no effect on heart disease outcomes, thus invalidating the HDL/heart health paradigm.

For more information on this study, and what it means 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.

____________________________________________________________________________

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

Does The Mediterranean Diet Improve Pregnancy Outcomes?

May 23, 2023 by Dr. Steve Chaney

Is The Mediterranean Diet Overrated?

Author: Dr. Stephen Chaney

You may have noticed that certain celebrities are singled out for fame and acclaim, while others of equal talent and accomplishment are virtually ignored.

The same thing occurs in the scientific realm. At present, the Mediterranean diet is the darling of the diet world. Study after study is designed to test the benefits of the Mediterranean diet while other excellent diets are ignored. I will discuss this phenomenon and ask whether the Mediterranean diet is overrated at the end of this article. But let’s start at the beginning.

Multiple studies have shown that the Mediterranean diet is associated with lower risk of heart disease, diabetes, and high blood pressure. Some studies suggest it is associated with lower risk of kidney disease and Alzheimer’s disease.

Studies also suggest that the Mediterranean diet is associated with an increase in lifespan (how long you live) and healthspan (how long you enjoy good health). In other words, these studies suggest that following a Mediterranean diet adds years to your life and life to your years.

Most of these studies have been done with men. However, there are enough studies with women to be confident that the beneficial effects of the Mediterranean diet on disease risk and lifespan apply to women as well as to men.

But what about pregnancy? Does the Mediterranean diet support a healthy pregnancy? Here the data are less clear. Three studies have been published showing that pregnant women who follow the Mediterranean diet are less likely to experience gestational diabetes (diabetes during pregnancy).

But what about other adverse pregnancy outcomes that can affect the health of both the mother and her baby such as:

Gestational hypertension (high blood pressure during pregnancy).
Preeclampsia (high blood pressure and protein in the urine that occurs late in pregnancy. It may be associated with liver and/or kidney damage).
Eclampsia (a severe form of preeclampsia where the mother also has seizures).
Preterm birth (birth prior to 37 weeks).
Low birth weight infant.

This study (N Makarem et al, JAMA Network Open. 5(12): e2248165, 2022) was designed to look at the effect of the Mediterranean diet on all seven of these adverse pregnancy outcomes.

How Was This Study Done?

The data for this analysis came from a large clinical trial called the Nulliparous Pregnancy (first time pregnancy) Outcomes Study. The study enrolled 7798 women in their first trimester of pregnancy from 8 medical centers across the country. The women were racially, ethnically, and geographically diverse.

Diet around the time of conception was assessed with a food frequency questionnaire administered at the mother’s first visit to the clinic (usually around 6-13 weeks after conception). The participants were asked to indicate their usual intake of 120 foods and beverages during the past 3 months. In other words, the participants were asked to indicate their diet prior to conception through early pregnancy.

Adherence to the Mediterranean diet was assessed using something called the aMed or Alternative Mediterranean Diet Score (a version of the Mediterranean diet that considers US food preferences). Each participant was assigned one point for:

Above average intake of vegetables, fruits, nuts, whole grains, legumes, fish, and the ratio of monounsaturated fat to saturated fat.

Below average intake of red meat and processed meats.

Alcohol intake was a bit more complicated:

Participants were given 1 point for one 12-ounce can of beer, 5 ounces of wine, or 1.5 ounces of liquor and 0 points for consumption above or below that amount.

The points for all these dietary components were added up to give an aMed score of 0-9, with 9 representing the best adherence to the Americanized version of the Mediterranean diet.

Does The Mediterranean Diet Improve Pregnancy Outcomes?

The authors started out by dividing the pregnant moms into thirds according to adherence to an Americanized Mediterranean diet based their aMed score. When they compared those in the top third (aMed scores of 6-9) with those in the lowest third (aMed scores of 0-3) the risk of developing:

Any adverse pregnancy outcome was reduced by 21%.

Preeclampsia or eclampsia were reduced by 28%.

Gestational diabetes was reduced by 37%.

Other adverse pregnancy outcomes were not statistically different.

Next, they asked whether stricter adherence to the Mediterranean diet would be even more beneficial. To do this they divided the pregnant moms into fifths. When they compared those in the top fifth (aMed scores of 7-9) with those in the lowest fifth (aMed scores of 0-2) the risk of developing:

Any adverse pregnancy outcome was still reduced by 20%, but…

- Preeclampsia and eclampsia were reduced by 35%.

- Gestational diabetes was reduced by 54%.

- Other adverse pregnancy outcomes were not statistically different.

When they broke the results down into participant subgroups:

The effect of the Mediterranean diet on any adverse pregnancy outcomes was not affected by prepregnancy BMI (a measure of obesity), race, or ethnicity.

However, it was significantly affected by age. Any adverse pregnancy outcome was reduced by:

- 48% in women over 35.

- 15% in women younger than 35.

The authors concluded, “We demonstrate that a Mediterranean diet pattern is associated with lower risk of developing any APO [adverse pregnancy outcome] and multiple individual APOs in US women…Our findings add to the growing body of evidence that the Mediterranean diet pattern may play an important role in preserving the health of women across the lifespan, including during pregnancy.”

Is The Mediterranean Diet Overrated?

At the beginning of this article, I posed the question, “Is the Mediterranean diet overrated?” When the authors broke the results down by food group, it suggested the answer may be, “Yes”.

The reduction in any adverse pregnancy outcome was associated with:

Above average consumption of vegetables, fruits, legumes, and fish.

The reduction in preeclampsia and eclampsia was associated with:

Above average consumption of vegetables, fruits, and fish.

The reduction in gestational diabetes was associated with:

Above average consumption of vegetables, and…

Below average consumption of red meat and processed meats.

If you are saying to yourself, “Wait a minute. Doesn’t this pattern of food consumption describe almost any whole food, primarily plant-based diet”, you would be correct. In theory, this pattern of food consumption is also consistent with the DASH diet, Mind diet, Scandinavian diet, flexitarian diet, pesco-vegetarian diet, and semi vegetarian diet, just to name a few.

In my opinion there is nothing about this study that restricts beneficial pregnancy outcomes to the Mediterranean diet. However, I do have a few caveats about that statement.

A good prenatal supplement is a good idea to make sure you are getting the vitamins and minerals required for a successful pregnancy. However, as I have described in a previous article finding a good prenatal supplement may not be as easy as it should be.

Choline is important for a healthy pregnancy, and it is missing in many prenatal supplements. While choline is found in many plant foods, the best sources of choline are fish, poultry, eggs, and dairy. You want to be sure to include some of these in your diet and/or look for a prenatal supplement containing at least 200 mg of choline.

The long chain omega-3s DHA and EPA are important for a healthy pregnancy and are also missing or present in inadequate amounts in many prenatal supplements.

The best dietary sources of DHA and EPA are cold water fish like salmon, tuna, sardines, and herring. That means:

- If you are following the DASH diet or something similar, you will want to substitute fish for red meat.

- A pesco-vegetarian diet is probably a better choice for you than a semi-vegetarian because it focuses on fish as the main protein source in place of poultry and red meat.

- If you are not a big fish lover, you should consider an omega-3 supplement supplying at least 250 mg of long chain omega-3s with most of it as DHA.

What Does This Study Mean For You?

Let me close by putting a few things into perspective.

1) When I said that the Mediterranean diet may be overrated, I did not mean it wasn’t an excellent diet. I simply mean it is probably not any better than other whole food, primarily plant-based diets (with the caveats I listed above).

2) The pregnancy benefits of the Mediterranean diet (and other healthy diets) are related to the overall health of the mother. A good prenatal supplement is still important to assure adequate amounts of all the nutrients essential for a healthy pregnancy.

For example, the authors pointed out that most women do not change their dietary habits when they become pregnant, and that their pregnancy is more likely to be successful if they are in good health at the time of conception.

3) Most diets of women of childbearing age do not provide adequate amounts of choline and omega-3s, so it is important to choose a prenatal supplement program that provides adequate amounts of choline and omega-3s.

4) Adequate calories and protein are also important for a healthy pregnancy.

Pregnancy is not the time to lose weight, even if you are overweight.

A vegan diet may not provide enough protein unless it has been designed by a dietitian.

You should discuss your current diet with your health care provider, and they may refer you to a dietitian if necessary.

The Bottom Line

The Mediterranean Diet is currently the darling of the nutrition world. Yes, numerous studies have shown that people consuming the Mediterranean diet are healthier and live longer. But we find ourselves in a situation where study after study is being designed to look for other benefits of the Mediterranean diet while equally healthy diets are being ignored.

The study discussed in this article is a perfect example. It was designed to determine whether adherence to the Mediterranean diet prior to and during pregnancy reduced the risk of experiencing adverse outcomes during pregnancy – outcomes that could affect the health of the mother and her baby.

The answer to that question was, “Yes”. Adherence to the Mediterranean diet reduced the risk of:

Any adverse outcome during pregnancy by 20%.

Preeclampsia and eclampsia by 35%.

Gestational diabetes by 54%.

And the risk reduction was even greater for women over 35.

However, when the investigators looked at the foods responsible for the reduction in adverse pregnancy outcomes, it appears likely that any whole food, primarily plant-based diet would provide the same results.

In short, this study showed that adherence to the Mediterranean diet improves pregnancy outcomes. The authors chose to focus on the Mediterranean diet because of its popularity. But their data show it is likely that other whole food, primarily plant-based diets would be equally beneficial.

For more information on this study and what it means 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.

___________________________________________________________________________

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance