Do Diet Sodas Hurt Your Heart?

Love Your Heart

Author: Dr. Stephen Chaney

confusionHeart healthy diets are confusing.

  • First, we were told that fats, especially saturated fats, were the problem. Then it was carbohydrates.
  • Then, we were told not all carbohydrates were equally bad for us. Sugars were the culprit.
  • Next, we were told not all sugars were bad for us. It was added sugars, especially the sugars added to sodas and other sugary drinks.
  • In fact, most of the clinical studies on the bad effects of sugar have been done with sugar-sweetened sodas.
  • If sugar-sweetened sodas are the problem, then surely diet sodas must be the answer.

Maybe not. In a previous issue of “Health Tips From The Professor” I summarized studies showing that consuming diet sodas was just as likely to be associated with obesity and diabetes as consuming sugar-sweetened sodas.

But what about heart health? Are diet sodas better for your heart than sugar-sweetened sodas? A recent study (E. Chazelas et al, Journal of the American College of Cardiology, 76: 2175-2180, 2020) suggests the answer is no.

How Was The Study Done?

Clinical StudyThis study is part of a much larger French study on the effect of diet on health outcomes called the NutriNet-Sante cohort. The NutriNet-Sante cohort study was started in 2009 and, as the name suggests, makes extensive use of online questionnaires. For example:

  • Participants are asked to fill out online questionnaires on physical activity, socioeconomic status, anthropometric data (height, weight, etc.), and major health events on a regular basis.
  • Every 6 months participants are asked to fill out 3 web-based 24-h dietary records (2 on weekdays and 1 on a weekend).
  • Major health events were validated based on their medical records and France’s national health insurance system (Yes, Big Brother is definitely watching in France).
  • Deaths were validated using France’s national mortality registry.

The study included a total of 104,760 participants with an average age of 42.9 and an average BMI of 23.7 (towards the upper end of the normal range) and followed them for 10 years. [Note: The average BMI for Americans at age 40 is 28.6, which is towards the upper end of the overweight category.]

The study compared consumption of diet drinks and sugary drinks with first-time cases of heart disease events (stroke, heart attack, angina, and angioplasty) during a 10-year period.

  • All first-time cases of heart disease events were combined into a single category for this publication. They will be considered separately in a subsequent publication.
  • Artificially sweetened beverages (diet drinks) were defined as beverages containing non-nutritive sweeteners. Sugary drinks consisted of all beverages containing ≥ 5% sugar (sodas, syrups, 100% juice, and fruit drinks).
  • For both categories of beverages, the participants were divided into non-consumers, low consumers, and high consumers.

Do Diet Sodas Hurt Your Heart?

Fast Food DangersThe results were clear. When high consumers were compared with non-consumers:

  • High consumers of sugary drinks had a 20% increased risk of first-time heart disease events.
  • High consumers of diet drinks had a 32% increased risk of first-time heart disease events.

The authors concluded, “In this cohort, higher intakes of [both] sugary drinks and diet drinks were associated with a higher risk of heart disease, suggesting that artificially sweetened beverages might not be a healthy substitute for sugary drinks.”

I also might point out that if this study had been done in the United States the increased risk of heart disease might have been greater.

That is because the French drink less sugary drinks and diet drinks than Americans.

  • High consumers of both sugary drinks and diet drinks in this study averaged 6 ounces per day.
  • In contrast, the average consumption sugary drinks in the United States is around 17 ounces per day.

Since consumption of sugary drinks is associated with increased incidence of heart disease and we drink more sugary drinks, the increased risk of heart disease in Americans might be greater than the 20% reported in this study.

What Are The Pros And Cons Of This Study?

pros and consOn the plus side, this was a very large and well-designed study.

For example, many studies of this type take a single assessment of the participant’s diet, either at the beginning or end of the study. They have no idea whether the participants changed their diet during the study. This study did a diet assessment every 6 months.

On the minus side, this was an association study. It measured the association of sugary drink and diet drink consumption with heart disease. Association studies have several limitations. Here are the top three:

#1: Confounding variables. Here are a couple of examples:

  • People who are overweight tend to drink more diet drinks than people who are normal weight. Obesity increases the risk of heart disease. Therefore, obesity is a confounding variable. You don’t know whether heart disease increased because the participants drank more diet drinks or because they were obese.
  • People who consume more diet drinks tend also to eat less healthy diets. Unhealthy diets increase the risk of heart disease. Thus, unhealthy diets are also a confounding variable.

The study authors adjusted for confounding variables by statistically correcting the data for:

  • Age, sex, BMI, sugar intake from other dietary sources, smoking status, physical activity, and family history of heart disease.
  • Intakes of alcohol, total calories, fruits & vegetables, red & processed meats, nuts, whole grains, legumes, saturated fat, sodium, and proportion of highly processed food in the diet.
  • Presence of type 2 diabetes, elevated cholesterol or triglycerides, or high blood pressure upon entry into the study.

In short, they did an excellent job of controlling for confounding variables that also affect the risk of heart disease.

#2: Reverse Causation: This is the chicken and egg question. This study measured the association between sugary and diet drink consumption and heart disease. None of the participants in the study had diagnosed heart disease when the 10-year study began.

However, both obesity and sugar consumption have been linked to increased risk of heart disease. What if some participants in the study had been diagnosed with heart disease early in the study and switched to diet drinks to lose weight or reduce sugar intake?

In that case, the diagnosis of heart disease would have caused increased diet drink consumption rather than the other way around. That would be reverse causation.

The study authors took reverse causation into account by excluding participants who experienced a first-time heart disease event in the first 3 years of this 10-year study. In other words, participants had to have been consuming sugary or diet drinks for at least 3 years before their heart disease event for their data to be included in the analysis.

This is considered the gold standard for reducing the influence of reverse causation on the outcome of the study.

#3: Uncertainty About Causation:

Association studies do not provide information on the possible mechanism(s) of the association.

For example, multiple previous studies have shown that people are just as likely to gain weight and develop type 2 diabetes when they consume diet drinks or sugary drinks. However, after years of study, the mechanism(s) of that effect are uncertain.

  • The mechanism may be physiological. However, many physiological mechanisms have been proposed. None have been proven.
  • The mechanism may be psychological. We may feel so virtuous for drinking diet drinks that we think it gives us license to eat more junk food. As a former University of North Carolina colleague once put it, “The problem is that we are using our diet drinks to wash down a Big Mac and fries.”

Association studies also do not prove causation. We cannot say with confidence that diet drink consumption increases our risk of heart disease. Nor can we speculate on the mechanism by which this might occur.

However, as the authors of this study concluded, we can say with confidence that there is no evidence that diet drink consumption decreases the risk of obesity, diabetes, or heart disease.

Love Your Heart

Love Your Heart – Drink Water Rather Than Sugar-Sweetened Or Artificially Sweetened Beverages. 

strong heartIf drinking diet drinks does not decrease your risk of heart disease, what can you do to decrease your risk?

The short answer is to fall in love with water. Water has no calories, no sugar, and no artificial sweeteners. In the study described above, it was the non-consumers of sugary beverages and diet beverages that had the lowest risk of heart disease.

Pure water is, of course, the best alternative. However, if plain water is too boring, try herbal teas. If you crave the fizz of sodas, try unsweetened sparkling water, perhaps infused with a little of your favorite fresh fruit. If you crave the caffeine of sodas, coffee or tea might suit you best, preferably without the sugar and cream. There are just two caveats:

  • Tea and coffee should not be your only source of liquid.
  • It goes without saying that you want to avoid the 500 calorie Starbucks extravaganzas.

Love Your Heart – What About Artificially Sweetened Foods?

If artificially sweetened drinks have no benefit for preventing obesity, diabetes, or heart disease, what about artificially sweetened foods? Do they also have no benefit?

The short answer is that we don’t know. Most of the studies to date have been with artificially sweetened beverages. However, these studies should make us cautious. We should not automatically assume that artificially sweetened foods are beneficial because they contain fewer calories. They may be just as useless as artificially sweetened beverages.

Love Your Heart – A Holistic Approach

With that in mind, here is what the American Heart Association recommends for reducing your risk of heart disease:

  • If you smoke, stop.
  • Choose good nutrition.
    • Choose a diet that emphasizes vegetables, fruits, whole grains, low-fat dairy products, poultry, fish, legumes, nuts, and nontropical vegetable oils (ie, avoid coconut and palm oil).
    • Choose a diet that limits sweets, sugar-sweetened beverages, and red meats.
    • [Note: Don’t substitute artificially sweetened beverages for sugar-sweetened beverages. That doesn’t appear to offer any advantage. Drink water instead.]
  • Reduce high blood cholesterol and triglycerides.
    • Reduce your intake of saturated fat, trans fat and cholesterol and get moving.
    • If diet and physical activity don’t get your cholesterol and triglyceride numbers under control, then medication may be the next step.
    • [Note: The American Heart Association recommends changing your diet and physical activity first and only resorting to medications if lifestyle changes don’t work. Diet and exercise do not have side effects. Medications do.]
  • Lower High Blood Pressure.
  • Be physically active every day.
  • Aim for at least 150 minutes per week of moderate-intensity physical activity per week.
  • Aim for a healthy weight.
  • Manage diabetes.
  • Reduce stress.
  • Limit alcohol.

The Bottom Line 

Previous studies have shown that people are just as likely to gain weight and develop type 2 diabetes when they consume artificially sweetened and sugar-sweetened drinks. In this issue of “Health Tips From the Professor” I shared a study showing that artificially sweetened drinks are just as bad for your heart as sugar-sweetened drinks.

These are all association studies. Association studies do not provide information on the possible mechanism(s) of the association.

That means we don’t know why artificially sweetened drinks are bad for your heart.

  • The mechanism may be physiological. However, many physiological mechanisms have been proposed. None have been proven.
  • The mechanism may be psychological. We may feel so virtuous for drinking diet drinks that we think it gives us license to eat more junk food. As a former UNC colleague once put it, “The problem is that we are using our diet drinks to wash down a Big Mac and fries.”

Association studies also do not prove causation. We cannot say with confidence that diet drink consumption increases our risk of heart disease. Nor can we speculate on the mechanism by which this might occur.

However, we can say with confidence that there is no evidence that diet drink consumption decreases the risk of obesity, diabetes, or heart disease.

The authors of this study concluded, “…higher intakes of [both] sugary drinks and diet drinks were associated with a higher risk of heart disease, suggesting that artificially sweetened beverages might not be a healthy substitute for sugary drinks.”

For more details on the study and information on a holistic approach for reducing heart disease risk read the article above.

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

 

Which Foods Should I Avoid?

What Is Nutritionism?

In Defense Of FoodRecently, I have been reading Michael Pollan’s book “In Defense of Food”. Yes, I know the book has been around for a long time. Normally I read the scientific literature rather than popular health books. However, in the past few weeks I have had a lot more time to read books, so I decided to read this one.

Some of the things he says are “off the wall”. As he readily admits, he isn’t a scientist or a medical doctor. However, a lot of what he says is “right on”. He echoes many of the things I have been talking about for years. But he does a masterful job of pulling everything together into a framework he calls “nutritionism”.

If you have a chance, I highly recommend that you read his book.

I will briefly summarize his discussion of nutritionism below. I will also share some scientific support for what he is saying. Finally, I will close by sharing what the Bible says on the subject.

What Is Nutritionism?

Low Fat LabelSimply put, nutritionism is the belief that we can understand food solely in terms of its nutritional and chemical constituents and our requirements for them. I use the term “belief” purposely. As Michael Pollan puts it: “As the ‘-ism’ suggests, nutritionism is not a scientific subject, but an ideology.”

What Michael Pollan is referring to is taking food constituents like saturated fats, cholesterol, sugar, carbohydrates, polyunsaturated fats, monounsaturated fats, fiber, antioxidants, and probiotics and labeling them as either “good” or “bad”.

As he points out, that leads to debacles like the creation of margarine as a substitute for butter. Of course, everyone reading this article knows that we subsequently found out that the trans fat in margarine was worse for us than the saturated fat in butter. He offers many other examples like this.

He also points out that the nutritionism concept has given free rein to the food industry to replace whole foods with processed foods that are cholesterol-free, sugar-free, low-fat, low-carb, or high in fiber, omega-3s, etc. He says that these foods are seldom healthier than the foods they replace. I agree.

Finally, he points out that the scientific support for the classification of individual ingredients or foods as “good” or “bad” is weak. That’s because when scientists design a study that removes a chemical constituent or a food from the diet, they have to replace it with something. And what they replace it with determines the outcome of the study. I give some examples of this in the next section.

The essence of Michael Pollan’s message is:

  • The effect of an individual nutrient or chemical constituent on your health depends on the food it is found in. Forget the fancy nutrition labels. Whole foods are almost always healthier than processed foods.
  • The effect of a food or food constituent on your health also depends on your overall diet. We should be thinking about healthy diets rather than the latest “magical” or “forbidden” food.

I will discuss these points below.

Which Foods Should I Avoid?

Question MarkNow, let’s get to the question, “Which Foods Should I Avoid?” If we are talking about whole foods, the short answer is “None”. As I said in my book, “Slaying The Food Myths”, “We have 5 food groups for a reason”.

For example, if we are talking about plant foods, each plant food group:

  • Has a unique blend of vitamins and minerals.
  • Has a unique blend of phytonutrients.
  • Has a unique blend of fiber.
  • Supports the growth of a unique combination of beneficial gut bacteria.
  • Dr Strangelove and his friends are telling you to eliminate whole grains, fruits, and legumes (beans) from your diet. Recent studies suggest that might not be a good idea. Here is one example.

If we are talking about animal foods, each animal food group:

  • Has a unique blend of vitamins and minerals.
  • May have unique components that are important for our health. [Note: This is an active area of research. Theories have been proposed for which components in animal foods may be important for our health, but they have not been confirmed.]
  • Vegan purists will tell you that you have no need for meat and dairy foods. Recent studies suggest otherwise. Here is one example.

With that as background, let’s turn our attention to nutritionism and look at some of science behind claims that certain food components are either good for us or bad for us.

Saturated Fat. Saturated fat is the poster child for nutritionism.lowfat

First, we were told by the American Heart Association and other health organizations that saturated fat was bad for us. Recently Dr. Strangelove and his friends are telling us that saturated fat is good for us. Instead of limiting saturated fat, we should be limiting carbs by cutting out fruits, whole grains, and legumes. Both cite clinical studies to support their claims. How can this be?

Perhaps a little history is in order. When the American Heart Association recommended that we decrease intake of saturated fat, they were envisioning that we would replace it with monounsaturated and polyunsaturated fat in the context of a healthy diet of fruits, vegetables, whole grains, and legumes. That never happened.

Big Food quickly realized that if the American public were to follow the AHA guidelines, it would be disastrous for their bottom line. So, they sprang into action. They mixed sugar, white flour, and a witch’s brew of chemicals to create highly processed, low fat “foods”. Then they told the American public, “Don’t worry. You don’t have to give up your favorite foods. We have created low fat alternatives.”

This is the essence of what Michael Pollan refers to as nutritionism. By marketing their fake foods as low fat Big Food created the halo of health. In fact, Big Food’s fake foods were less healthy than the foods they replaced. Americans got fatter and sicker.

Now let’s look at the conflicting claims that saturated fat is bad for us or good for us. How can clinical studies disagree on such an important question? The answer is simple. It depends on what you replace it with. You need to consider saturated fat intake in the context of the overall diet.

I discussed this in a previous issue of “Health Tips From the Professor”, but let me summarize it briefly here. The American Heart Association tells us that replacing half of the saturated fat in a typical American diet with:

  • Trans fats, increases heart disease risk by 5%.
  • Refined carbohydrates and sugars (the kind of carbohydrates in the typical American Diet), slightly increases heart disease risk.
  • Complex carbohydrates (whole grains, fruits & vegetables), decreases heart disease risk by 9%.
  • Monounsaturated fats (olive oil & peanut oil), decreases heart disease risk by 15%.
  • Polyunsaturated fats (vegetable oils and fish oil), decreases heart disease risk by 25%.
  • Unsaturated fats in the context of a Mediterranean diet, decreases heart disease risk by 45%.

My advice: Saturated fat is neither good for you nor bad for you. A little bit of saturated fat in the context of a healthy diet is fine. A lot of saturated fat in the context of an unhealthy diet is problematic.

fatty steakRed Meat. Is red meat bad for you? Like saturated fat, it depends on the amount of red meat and the overall diet. I covered this in detail in “Slaying The Food Myths”, but let me summarize briefly here:

According to the World Health Organization, red meat is a probable carcinogen. If we look at the postulated mechanisms by which it causes cancer, they can be mostly neutralized by components of various plant foods.

My advice: An 8-ounce steak with fries and a soda is probably bad for you. Three ounces of that same steak in a green salad or stir fry may be good for you.

I should make one other point while I am on the topic. Dr. Strangelove and his friends have been telling you that grass-fed beef is better for you than conventionally raised beef. Once again, that is nutritionism.  Grass-fed beef is lower in saturated fat and high in omega-3s than conventionally raised beef. That may be better for your heart, but it has no effect on the cancer-causing potential of red meat. It doesn’t give the license to eat 8-ounce steaks on a regular basis. You still want to aim for 3-ounces of that grass-fed beef in a green salad or stir fry. 

High-Fructose Corn Syrup. This one seems to be on everyone’s “naughty list”. You are being told to read labels, and if the food has high-fructose corn syrup on the label, put it back on the shelf. But is that good advice?

It turns out that all the studies on the bad effects of high-fructose corn syrup have been done with sodas and highly processed foods. This should be your first clue.

Of course, as soon as high-fructose corn syrup gained its “bad” reputation, Big Food started replacing it with Sugar Comparisons“heathier” sugars. Does that make those foods healthier?

The answer is a clear “No”. Both chemically and biologically, high-fructose corn syrup is identical to sucrose (table sugar), honey, molasses, maple syrup, coconut sugar, date sugar, or grape juice concentrate. Agave sugar is even higher in fructose than high-fructose corn syrup. This is your second clue.

Substituting these sugars for high-fructose corn syrup doesn’t turn sodas and processed foods into health foods. This is nutritionism at its worst.

My advice: Forget reading the label. Forget trying to avoid foods with high-fructose corn syrup. Avoid sodas and processed foods instead.

Sugar. Once the public started to realize that natural sugars in processed foods were just as bad for us as high-fructose corn syrup, sugars became “bad”. We were told to avoid all foods containing sugar in any form. In fact, we were told we needed to become “label detectives” and recognize all the deceptive ways that sugar could be hidden on the label.

Apple With Nutrition LabelI have discussed this in detail in a previous issue of “Health Tips From The Professor”.

Let me just summarize that article with one quote, “It’s not the sugar. It’s the food. There is the same amount and same types of sugar in an 8-ounce soda and a medium apple. Sodas are bad for you, and apples are good for you.” If you are wondering why that is, I have covered it in another issue of “Health Tips From the Professor”.

Before leaving this subject, I should mention that nutritionism has risen its ugly head here as well. Big Food has struck again. They have replaced sugar with a variety of artificial sweeteners.

Once again, nutritionism has failed. Those artificially sweetened sodas and processed foods are no healthier and no more likely to help you keep the weight off than the sugar-sweetened foods they replace. I have covered the science behind that statement in several previous issues of “Health Tips From the Professor”. Here is one example.

My advice: Forget about sugar phobia. You don’t need to become a label detective. Just avoid sodas, sugar-sweetened beverages, and sweet processed foods. Get your sugar in its natural form in fruits and other whole foods.

low carb dietCarbs. Dr. Strangelove and his friends are now telling you that you need to avoid all carbs. That is pure nutritionism. Carbs are neither good nor bad. It depends on the type of carb and what you replace it with.

Once again, clinical studies have given conflicting outcomes. Each side of the carbohydrate debate can provide clinical studies to support their position. How can that be? The answer is simple. It depends on what assumptions went into the design of the clinical studies. I have written several articles on this topic in “Health Tips From the Professor”, but let me give you one example here.

In this example, I looked at two major studies. The PURE (Prospective Urban Rural Epidemiology) study included data from 135,000 participants in 18 countries. In this study, the death rate decreased as the % carbohydrate in the diet decreased. The low-carb enthusiasts were doing a victory dance.

However, it was followed by a second, even larger study. The ARIC (Atherosclerosis Risk In Communities) study included 432,000 participants from even more countries. In this study, the death rate decreased as the % carbohydrate decreased to about 40%. Then a curious thing happened. As the % carbohydrate in the diet decreased further, the death rate increased.

How can you explain this discrepancy? When you examine the PURE study:

  • The % carbohydrate only ranged from 70% to 40%.
  • The data for the PURE study was obtained primarily with third world countries. That is an important distinction because:
    • In those countries, it is primarily the well to do that can afford sodas, processed foods, and meat.
    • The poor subsist on what they can grow and inexpensive staples like beans and rice.
  • Simply put, in the PURE study, the type of carbohydrate changed as well as the amount of carbohydrate.
    • At the highest carbohydrate intakes, a significant percentage of the carbohydrate came from sugar and refined grains.
    • At the lowest carbohydrate intakes, most of the carbohydrate intake came from beans, whole grains, and whatever fruits and vegetables they could grow.

When you examine the ARIC study:how much carbohydrates should we eat aric

  • The % carbohydrate ranged from 70% to 20%.
  • The ARIC study added in data from the US and European countries. That is an important distinction because:
    • Low carb diets like Atkins and Keto are popular in these countries. And those are the diets that fall into the 20-40% carbohydrate range.
    • Most people can afford diets that contain a lot of meat in those countries.
  • Simply put, at the lower end of the scale in the ARIC study, people were eating diets rich in meats and saturated fats and eliminating healthy carbohydrate-containing foods like fruits, whole grains and legumes.

My advice: The lesson here is to avoid simplistic nutritionism thinking and focus on diets rather than on foods. When you do that it is clear that carbs aren’t bad for you, it’s unhealthy carbs that are bad for you.

Which Foods Should I Avoid? By now the answer to the question, “Which Foods Should I Avoid?” is clear. Avoid sodas, sugar-sweetened beverages and processed foods (The term processed foods includes convenience foods, junk foods, and most sweets).

What Does This Mean To You?

Questioning ManNow that we are clear on which foods you should avoid, let’s look at the flip side of the coin. Let’s ask, “Which foods should you include in your diet?

As I said at the beginning of this article, “We have 5 food groups for a reason”. We should consider whole foods from all 5 food groups as healthy.

Of course, each of us is different. We all have foods in some food groups that don’t treat us well. Some of us do better with saturated fats or carbs than others. We need to explore and find the foods and diets that work best for us.

However, whenever we assume one diet is best for everyone, we have crossed the line into nutritionism.

What Does The Bible Say?

Let me start this section by saying that I rely on the Bible for spiritual guidance rather than nutritional guidance. However, as part of our church’s Bible reading plan, I was reading 1 Timothy. A passage from 1 Timothy 4:1-5 leapt out at me. It reinforces the theme of Michael Pollan’s book and seems uniquely applicable to the times we live in.

“The Spirit clearly says that in later times some will abandon the faith and follow deceiving spirits and things taught by demons. Such teachings come through hypocritical liars, whose consciences have been seared as with a hot iron. They…order people to abstain from certain foods, which God created to be received with thanksgiving by those who believe and who know the truth. For everything God created is good, and nothing is to be rejected if it is received with thanksgiving, because it is consecrated by the word of God and prayer.”

Interesting.

The Bottom Line

In this article, I have discussed the concept of “nutritionism” introduced in Michael Pollan’s book “In Defense Of Food”. He defines nutritionism as the belief that we can understand food solely in terms of its nutritional and chemical constituents and our requirements for them.

What Michael Pollan is referring to is taking food constituents like saturated fats, cholesterol, sugar, carbohydrates, polyunsaturated fats, monounsaturated fats, fiber, antioxidants, and probiotics and labeling them as either “good” or “bad”. He points out that when we accept these simplistic labels, we often end up creating foods and diets that are less healthy than the ones we were trying to replace.

At the beginning of the article, I asked the question, “Which Foods Should I Avoid?” I then looked at several foods or food groups we have told to avoid, including saturated fats, red meat, high-fructose corn syrup, sugar, and carbs. When you look at the science behind these recommendations from the lens of nutritionism, you come to two conclusions:

  • We should avoid sodas, sugar-sweetened beverages and processed foods (The term processed foods includes convenience foods, junk foods, and most sweets).
  • Whole foods from all 5 food groups should be considered as healthy.

Of course, each of us is different. We all have foods in some food groups that don’t treat us well. Some of us do better with saturated fats or carbs than others. We need to explore and find the foods and diets that work best for us.

However, whenever we assume one diet is best for everyone, we have crossed the line into nutritionism.

For more details and a bible verse that supports the theme of Michael Pollan’s book and seems uniquely applicable to the times we live in, 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.

Diet And Cancer Risk

What Can You Do To Reduce Your Risk Of Cancer?

Magic WandIt seems like everyone has a magic pill, essential oil, food, or diet that prevents cancer. It doesn’t take a genius to figure out that all the claims can’t be true. No wonder you are confused. You want to know:

  • Which of these claims are true?
  • What can you do to reduce your risk of cancer?

These aren’t trivial questions.

  • Cancer is the second leading cause of death in this country, and some experts predict it will surpass heart disease as the leading cause of death in the near future.
  • While cancer treatments have become much more effective in the past few decades, these treatment successes are often associated with severe side-effects, enormous expense, or both.

That is why I was intrigued by a recent study (FF Zhang et al, JNCI Cancer Spectrum (2019) 3(2): pkz034) on diet and cancer that came from the prestigious Friedman School of Nutrition and Public Policy at Tufts University. This study asked two important questions:

  • How many newly diagnosed cancer cases could have been prevented by changes in the American diet? This is something the authors referred to as the “preventable cancer burden associated with poor diet”.
  • Which foods increased or decreased the risk of cancer? This, of course, is the most useful information for you and me.

Diet And Cancer Risk

Diet And CancerThis study estimated that 80,110 new cancer cases among US adults 20 and older could be primarily attributed to poor diet. While poor diet contributes to many more cancers, the authors of this study felt 80,110 represented the number of cancer cases that were clearly preventable by some simple dietary changes.

While all cancers were affected by diet to some degree, the cancers most affected by poor diet were:

  • Colon cancer (65% of cases)
  • Mouth and throat cancer (18% of cases)
  • Endometrial cancer (4.0% of cases)
  • Breast cancer (3.8% of cases)

When the diet was broken down into individual food groups:

  • Low intake of whole grains was associated with the largest number of preventable cancer cases (35% of cases). This was followed by.
  • Low intake of dairy foods (22% of cases).
  • High intake of processed meats (18% of cases).
  • Low intake of vegetables (16% of cases).
  • Low intake of fruits (10% of cases).
  • High intake of red meat (7.1% of cases).
  • High intake of sugar sweetened beverages (4.0% of cases).

Of the diet-associated cancer cases, the scientists who lead the study estimated that 84% of them represented a direct effect of diet on cancer risk. The dietary factors most likely to directly increase the risk of cancer were:

  • Low intake of whole grains.
  • Low intake of dairy foods.
  • High intake of processed meats.

The scientists estimated that 16% of diet-associated cancer cases were “mediated by obesity”. In layman’s terms, this means that diet increased the risk of obesity and obesity increased the risk of cancer. The dietary factors most likely to increase the risk of obesity-mediated cancers were:

  • High intake of sugar sweetened beverages.
  • Low intake of fruits.

The authors concluded: “More than 80,000 new cancer cases [per year] are estimated to be associated with suboptimal diet among US adults…Our findings underscore the need for reducing cancer burden in the United States by improving the intake of key food groups and nutrients of Americans.”

What Does This Mean For You?

Questioning ManThese findings aren’t novel. Many previous studies have come to the same conclusions. However, many people find these recommendations to be confusing. Should they increase their intake of certain foods? Should they follow some sort of magic diet?

Perhaps we need to get away from the magic food concept. We need to understand that every time we increase one food in our diet, we exclude other foods. We need to step back and look at the overall diet.

Let me break down the recommendations from this study into three categories: foods we should eliminate from our diet, foods we should include in our diet, and foods we should balance in our diet.

Foods we should eliminate from our diet:

  • Sugar Sweetened Beverages. They provide no nutritional benefit, and the sugar in most beverages rushes into our bloodstream and overwhelms our body’s ability to utilize it in a healthy way. This leads to obesity, diabetes, and a host of other health issues.
    • Public enemy number one is sodas. However, this category also includes fruit juices, sweetened teas and energy drinks, and sugary processed foods.
    • This category also includes diet sodas. For reasons we don’t completely understand, diet sodas appear to be just as likely to lead to obesity, diabetes, and heart disease as sugar sweetened sodas. I have discussed the proposed explanations of this phenomenon in a recent issue of “Health Tips From the Professor”.
    • Sugar, however, is not the enemy. Sugar found naturally in fruits and other whole foods enters the bloodstream slowly and is metabolized in healthy ways by the body. I have discussed this in another issue  of “Health Tips From the Professor”. This is what I mean by restoring balance in our diet. Decreasing the sugar intake from sugar sweetened beverages and increasing sugar intake from fruits is associated with a decreased risk of obesity and obesity-related cancers.
  • Processed Meats. The evidence is overwhelming at this point that processed meats directly increase the risk of cancer.
    • If you have trouble completely eliminating processed meats from your diet, my advice is to minimize them and consume them only in the context of an overall healthy diet. Personally, I still consume bacon occasionally as flavoring for a healthy green salad.

Whole GrainsFoods we should include in our diet. I put these in a separate category because Dr. Strangelove and his colleagues have been telling us to eliminate them from our diet, and many Americans are following those recommendations:

  • Whole grains. We can think of whole grains as the underserving victim of the low-carb craze. The low-carb craze is on the mark when it comes to eliminating added sugars and refined grains from the diet. However, eliminating whole grains from the diet may be doing more harm than good. In fact, this and other studies suggest that whole grains are the most effective foods for reducing cancer risk. Why is that?
    • If we assume whole grains are just a good source of fiber and a few vitamins and minerals, it is hard to grasp their importance. We could easily get those nutrients elsewhere.
    • However, we are beginning to realize that whole grains play a unique role in supporting certain species of gut bacteria that are very beneficial to our health. In short, whole grains may be essential for a healthy gut.
  • Dairy Foods. This is another food that has been treated as a villain by Dr. Strangelove and his many colleagues. However, for reasons we don’t completely understand, dairy foods appear to decrease the risk of heart disease and cancer.

Foods we should balance in our diet.

  • Red Meat. Diets high in red meat are consistently associated with a slight increase in cancer risk. The World Health Organization lists red meat as a probable carcinogen, but that has proven to be controversial.
    • Much of the research has centered on why red meat causes cancer. Several mechanisms have been proposed, but none of them have been proven.
    • In contrast, very little consideration has been given to what red meat is displacing from the diet. Diets high in red meat are often low in whole grains, fruits and/or vegetables.
    • Perhaps instead of eliminating red meat from our diets we should be talking about balancing red meat in our diets by consuming less red meat and more whole grains, fruits, and vegetables.

What Can You Do To Reduce Cancer Risk?

American Cancer SocietyYou may have been thinking that 80,110 cases/year represents a small percentage of new cancer cases. That’s because diet is only one component of a holistic cancer prevention strategy. Here is what the American Cancer Society recommends for reducing cancer risk:

  • Avoid tobacco.
  • Limit sun exposure.
  • Achieve and maintain a healthy weight.
  • Eat a healthy diet, with an emphasis on plant foods (Their recommendations are in line with this study).
  • Be physically active.
  • Limit alcohol use.
  • Get vaccinated against HPV.
  • Get regular medical checkups.

Doing any of these things will reduce your cancer risk. But the more of these you can incorporate into your lifestyle, the lower your risk.

The Bottom Line

A recent study looked at diet and cancer risk. The authors reported that 80,110 new cancer cases among US adults 20 and older could be primarily attributed to poor diet.

When the diet was broken down into individual food groups:

  • Low intake of whole grains was associated with the largest number of preventable cancer cases. This was followed in descending order by.
  • Low intake of dairy foods.
  • High intake of processed meats.
  • Low intake of vegetables.
  • Low intake of fruits.
  • High intake of red meat.
  • High intake of sugar sweetened beverages.

The authors concluded: “More than 80,000 new cancer cases [per year] are estimated to be associated with suboptimal diet among US adults…Our findings underscore the need for reducing cancer burden in the United States by improving the intake of key food groups and nutrients of Americans.”

For more details, read the article above. For example, I discuss which foods we should eliminate, which foods we should eat more of, and which foods we should balance in our diet. To add a more holistic perspective, I also discuss the American Cancer Society’s recommendations for reducing cancer risk.

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

Health Tips From The Professor