heart disease

Is Red Meat As Healthy As White Meat?

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The Lies of the Beef Industry

Eating Red MeatLast week I wrote about a recent review claiming that the evidence for the health risks of red meat consumption was so weak that the best advice for the American public was to eat as much of it as they like. I pointed out the many flaws in that study.

  • One of the flaws was that the review discounted dozens of association studies showing a link between red meat consumption and disease and relied instead on randomized controlled trials. Normally, that would be a good thing, but…
  • The association studies looked at health outcomes and had hundreds of thousands of participants. They found clear links between red meat consumption and increased risk of heart disease and cancer.
  • The randomized controlled trials looked at blood parameters like LDL cholesterol and averaged less than 500 participants. These studies were too small to provide meaningful results, and, not surprisingly, the results were conflicting. Some linked red meat consumption to increased risk, while others did not.

Because they had discounted evidence from association studies, the authors of the review concluded that the overall evidence was weak.

This week I want to address why the evidence from randomized controlled trials for health risks of red meat is so weak. More importantly, I want to highlight the role of the beef industry in making sure the evidence on the health risks of red meat consumption is weak.

I will also point out the role of the media in this process because they are equally complicit in spreading misleading information about the health risks of red meat consumption.

You might be asking: “How does the beef industry influence clinical trials to produce outcomes supporting their message that red meat is perfectly healthy?” “Surely they can’t convince reputable scientists to falsify their results.”

  • The answer is they don’t need to convince scientists to falsify their results. They just need to influence the design of the experiments so the results will be to their liking.” I will give two examples of that in this article.

Next you might be wondering: “What is the role of the media in this? Surely they just report what the scientific publication says.” Don’t be deceived. The media isn’t interested in accuracy. They are interested in generating the largest possible audience. They know controversy attracts an audience. They are looking for “man bites dog” headlines even if it isn’t true.

  • If you actually read the studies, you discover that reputable scientists always discuss the weaknesses and flaws in their study. The media either doesn’t read the publication or ignores the weaknesses. Instead they focus on the most controversial headline they can craft. I will give some examples of that as well.

Is Red Meat As Healthy As White Meat?

Red Meat Vs White MeatFor years we have been told that red meat increases our risk of heart disease because it is high in saturated fats. We’ve been told that white meat and plant proteins are better alternatives.

But the latest headlines claim that red meat is just as heart healthy as white meat. You are probably wondering what to believe. Let’s examine the study behind the headline and ask two important questions?

  1. Did the beef industry influence the study?
  2. Did the media distort the study in their reporting?

I will start by reporting the study design and the results of the studies without comment. Then I will discuss how the beef industry influenced the design of the study to produce misleading results.

The Headlines Said: “Red Meat and White Meat Are Equally Heart Healthy.” The study behind the headlines was a 4-week study (N Bergeron et al, American Journal of Clinical Nutrition, 110: 24-33, 2019) comparing equivalent amounts of red meat, white meat, and non-meat protein on LDL levels. It did report that red meat and white meat raised LDL cholesterol levels to the same extent, but here is what the headlines didn’t tell you:

  • The authors of this study are heavily funded by the dairy and beef industries. I will point out the implications of this funding below.
  • 4 weeks is a very short time. This study provides no information on the long-term effects of red meat versus white meat consumption.
  • The study only measured LDL and related lipoproteins. It did not measure heart disease outcomes. LDL and lipoprotein levels are only one indicator of heart disease risk. Thus, they are imperfect predictors of heart disease risk. I will point out why that is important below as well.
  • The study was performed at two levels of saturated fat – low (7% of calories) and high (14% of calories).

At the low level of saturated fat, only the leanest cuts of red meat (top round and top sirloin) were used to keep saturated fat low in the red meat group. High fat dairy foods were added to the non-meat protein group to increase saturated fat content. Thus, all 3 groups consumed the same amount of saturated fat.

At the high level of saturated fat, butter and high-fat dairy foods were added to the white meat and non-meat protein groups to increase saturated fat content. Once again, saturated fat content was identical in all 3 groups.

Here were the results:High Cholesterol

  • LDL and related lipoproteins were higher for the high saturated fat group than the low saturated fat group. Nothing new here. This is consistent with dozens of previous studies. We know that saturated fat increases LDL cholesterol levels when other aspects of the diet are kept constant.
  • In both the low and high saturated fat groups, red and white meat raised LDL cholesterol to the same extent. In other words, when saturated fat levels are held constant, red meat and white meat raise cholesterol levels to the same extent.

In interpreting that statement, you need to remember the study design.

    • In the low saturated fat group, only two cuts of red meat were low enough in saturated fat for a direct comparison to white meat.
    • In the high saturated fat group, butter and high fat dairy had to be added to white meat so it could be compared to red meat.

Obviously, this is not the real world. 95% of the red meat the average American consumes is higher in saturated fat than most white meat.

The authors concluded “The findings…based on lipid and lipoprotein effects, do not provide evidence for choosing white over red meat for reducing heart disease risk”. That conclusion is clearly inaccurate.

  • The study did not measure heart disease outcomes. It measured only LDL cholesterol and related lipoprotein levels. That is just one factor in determining heart disease risk. The significance of that statement will be explained below.
  • Red meat and white meat raised LDL cholesterol levels to the same extent only when saturated fat is held constant. We know that most red meat is higher in saturated fat than white meat and saturated fat raises LDL cholesterol levels. In fact, the study confirmed that the high-fat red meats most people consume raised LDL cholesterol more than white meats.
  • The accurate conclusion to this study would have been: “Most red meat raises LDL cholesterol more than white meat, which suggests red meat may increase heart disease risk compared to white meat.”
  • Did I mention that the authors are heavily funded by the beef industry?

What About TMAO And Heart Disease Risk?

heart diseaseInterestingly, the authors also looked at another risk factor for heart disease in the same study, something called TMAO. I have discussed the relationship between red meat, TMAO, and heart disease risk in a previous issue of “Health Tips From the Professor”).

Let me summarize briefly here:

  • Red meat has 10-50-fold higher concentrations of a compound called L-carnitine than white meat.
  • Meat eaters have a very different population of gut bacteria than people who eat a primarily plant-based diet. It is not clear whether that is due to the meat or the loss of plant foods that meat displaces from the diet.
  • The gut bacteria of meat eaters convert L-carnitine to trimethylamine (TMA), which the liver then converts to trimethylamine N-oxide (TMAO).
  • The gut bacteria of people consuming a primarily plant-based do not convert L-carnitine to TMA, so no TMAO is formed. For example, in one study investigators fed an 8-ounce sirloin steak to meat eaters and to vegetarians. The meat eaters ended up with high levels of TMAO in their blood. The vegetarians had little or no TMAO in their blood.
  • High levels of TMAO are associated with atherosclerosis, increased risk of heart attacks, and death. Therefore, TMAO is considered an independent risk factor for heart disease.

The authors of the study comparing red meat and white meat also found that blood TMAO levels were two-fold higher in the red meat group than in the other two groups and this was independent of dietary saturated fat. However, rather than publishing this in the same paper where it might have interfered with their message that red and white meat affect heart disease risk to the same extent, the authors chose to publish these data in a separate paper (Z.Wang, European Heart Journal, 40: 7: 583-594, 2018).

Did I mention the authors are heavily funded by the beef industry?

Is Red Meat Healthy As Part Of A Mediterranean Diet?

Mediterranean Diet FoodsLet me briefly touch on one other study funded by the beef industry. The headlines said: “You may not have to give up red meat. It is healthy as part of a Mediterranean diet.”

The study (LE O’Connor et al, American Journal of Clinical Nutrition, 108: 33-40, 2018) behind the headlines did report that lean beef and pork did not raise LDL cholesterol levels when they were included in a Mediterranean diet. However, it is important to look at what the headlines didn’t tell you.

  • The red meat group consumed only 2.4 ounces of red meat a day. We aren’t talking about 8-ounce steaks or a rack of pork ribs here.
  • The red meat group ate only the very leanest (tenderloin) cuts of beef or pork.
  • On a positive note, while it wasn’t measured in this study, it is likely that TMAO levels would be relatively low because the subjects were consuming a primarily plant-based diet. They were consuming 7 servings of vegetables, 4 servings of fruit, and 4 servings of whole grains each day.
  • Similarly, red meat has several components that appear to increase cancer risk. However, they can be largely neutralized by various plant foods. This is something I have discussed in more detail in my book “Slaying The Food Myths”.

In summary, it would have been more accurate to conclude that very small, very lean servings of red meat may be healthy as part of a primarily plant-based diet like the Mediterranean diet.

The Lies Of The Beef Industry

LiesBoth these studies utilized the very leanest cuts of red meat so they could conclude that red meat is healthy. This is a common design of studies funded by the beef industry. Rather than looking at the health effects of the high fat red meats most people consume, the studies focus only on the leanest cuts of meat.

The studies appear to be designed to purposely mislead the American public. Let’s look at how that happens. When studies like these are incorporated into larger meta-analyses or reviews, investigators often look at the conclusions, not at the experimental design.

Meta-analyses and reviews are only as good as the studies they include, a concept referred to as “Garbage in – Garbage Out”. That is what happened with the review and recommendations I discussed last week. The review relied heavily on short-term randomized controlled trials.

However, this is problematic. Because of the way they are designed, industry funded studies tend to find no adverse effects of consuming red meat. Independently funded studies tend to find adverse health effects from red meat. If you throw them all together without considering how the experiments were designed, the studies cancel each other out.

On that basis the authors of the review concluded that the evidence for red meat adversely affecting health outcomes was weak and recommended that everyone could continue consuming red meat. (That is a recommendation that virtually every health organization and top expert in the field have rejected for the reasons I summarized last week).

The beef industry doesn’t have to influence the design of every study, just enough studies to confuse the science and confuse the media.

The Complicity Of The Media

newspaper heallinesUnfortunately, the media is equally guilty of misleading the public. As I said above, the media is interested in attracting an audience, not in accuracy. For example:

  • The headlines describing the first study should have said: “Saturated fat raises LDL cholesterol levels”. But everyone knows that. Headlines like that are non-controversial. They don’t attract readers.
  • The headlines describing that study could have said: “Very lean cuts of red meat don’t raise LDL levels any more than white meat”. That would have been accurate, but that wouldn’t attract readers either. Most Americans prefer high fat cuts of red meat. They aren’t interested in reading articles suggesting they should change what they are eating.
  • Similarly, the headlines describing the second study should have said: “Very small amounts of very lean red meat may be healthy as part of a Mediterranean diet.”
  • In fact, the authors of both studies admitted in their discussions that they could not extrapolate their findings to the effects of higher-fat red meats. The media ignored those statements. Presumably, they decided the American public didn’t want to hear that message.
  • The first study also found that LDL and related lipoprotein levels were lower for the non-meat protein group than the red and white meat groups at both saturated fat levels. In fact, the main conclusion of the authors was: “The findings are in keeping with recommendations promoting diets with a high proportion of plant foods.” Somehow the media completely ignored that finding.

When the media consistently misleads the public about what constitutes a healthy diet, it leads to confusion. Confusion leads to inaction. At a time when so many Americans are suffering from preventable diseases, this is inexcusable.

Is Red Meat Healthy?

red meat heart healthyLet’s return to the question I posed last week: “Is red meat healthy?” Most of what I say below is identical to what I said last week. However, with the information I provided in the article above it may be easier to understand.

  • The saturated fat in red meat is associated with increased heart disease risk.
  • Red meat increases blood levels of TMAO, which is associated with increased heart disease risk.
  • The heme iron in red meat can be converted in the gut to N-nitroso compounds, which are associated with increased risk of cancer.
  • Benzopyrene and heterocyclic amines are formed when red meat is cooked. And they are associated with increased risk of cancer.

As I said last week, “There are too many studies that show a strong association between red meat consumption and disease risk to give red meat a clean bill of health. We can’t say red meat is healthy with any confidence.”

However, that doesn’t mean we need to eliminate red meat from our diet. As described above, the health risks of red meat are determined by the type of red meat consumed, the amount of red meat consumed, and the overall composition of our diet. For example:

  • Very lean cuts of red meat contain no more saturated fat than white meat.
  • Primarily plant-based diets alter our gut bacteria in such a way that production of TMAO and N-nitroso compounds are decreased.
  • Diets high in plant fiber sweep benzopyrene and heterocyclic amines out of our intestine before they can cause much damage.

So, what does that mean to you?

  • If you are thinking in terms of a juicy 8-ounce steak with a baked potato and sour cream, red meat may increase your risk of disease.
  • However, if you are thinking of 2-3 ounces of very lean steak in a vegetable stir fry or a green salad, red meat is probably OK.
  • If you are thinking about the very leanest cuts of red meat, they are probably just as healthy as white meat.

What About Grass Fed Beef?

Of course, one question I am frequently asked is: “What about grass fed beef? Is it healthier than conventionally raised beef?” Grass fed beef does have a slightly healthier fat profile. It is modestly lower in saturated fat and modestly higher in omega-3 fats. However, grass feeding doesn’t affect TMAO, N-Nitroso, benzopyrene, and heterocyclic amine formation.

  • That means the 8-ounce steak is only slightly less unhealthy and the 2-3 ounces of steak in a green salad only slightly healthier when you substitute grass-fed for conventionally raised beef. It’s probably not worth the extra cost.

Next week I will return with the answer to another question I get a lot. “If plant protein is good for me, what about all those meatless burgers that are popping up in my favorite fast food restaurants. Are they healthy?”

The Bottom Line

Last week I wrote about a recent review claiming that the evidence for the health risks of red meat consumption was so weak that the best advice for the American public was to eat as much of it as they like. I pointed out the many flaws in that study.

This week I provided two examples of how the beef industry influences the design of clinical trials to minimize the health risks of red meat and the media misleads the public about what the studies showed.

The bottom line is that red meat likely has no adverse health effects only if you are consuming very small amounts of very lean red meat in the context of a primarily plant-based diet. Unfortunately, this is not the message you are getting from the media and from Dr. Strangelove’s health blog.

As for grass-fed beef, it is only modestly healthier than conventionally raised beef for reasons I have given in the article above. It’s probably not worth the extra cost.

Next week I will return with the answer to another question I get a lot. “If plant protein is good for me, what about all those plant-based burgers that are popping up in my favorite fast food restaurants. Are they healthy?” Stay tuned.

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.

 

 

Is Red Meat Healthy For You?

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Why Is Red Meat So Controversial?

fatty steakThe American Heart Association, the American Cancer Society, the World Health Organization and other organizations have been telling us for years that diets high in red meat are likely to increase our risk of chronic diseases. If you are like most Americans, you have been trying to cut back on red meat.

However, the latest headlines are saying things like: “Red meat is actually good for you” and “Most adults don’t need to cut back on red meat for their health”. Where did those headlines come from?

A group calling itself the Nutritional Recommendations Consortium (NutriRECS) has reviewed the scientific literature and said: “The evidence is too weak to justify telling individuals to eat less beef and pork.” They have issued guidelines (BC Johnston et al, Annals of Internal Medicine, 171: 756-764, 2019) saying that adults really don’t need to change the amounts of red meat they are eating.

As you can imagine, that has proven to be a controversial recommendation. Many of the top experts in the field have questioned the validity of the study and have condemned the guidelines as misleading.

However, most of you don’t care about arguments between the experts. Your questions are: “What does this study mean to me?” Is everything I have been told about red meat wrong?” “Is red meat healthy after all? Can I really eat as much as I want?”

Why Is Red Meat So Controversial?

ArgumentIf you are confused by the latest headlines, it’s not your fault. Over the past few decades you have been bombarded by conflicting headlines about red meat. One month it is bad for you. The next month it is good for you. It is fair to ask: “Why is red meat so controversial? Why is it so confusing?”

Perhaps the best way to answer those questions is to review the scientific critique of the latest guidelines saying we can eat as much red meat as we want and then look at the authors’ rebuttal.

The best summary of the scientific critique of these guidelines is a WebMD Health News report. Let me cover a few of the most important criticisms:

#1: The NutriRECS group was not backed by any major health, government, or scientific organizations. The members of this group self-nominated themselves as gurus of nutritional recommendations. In an earlier publication they concluded that the evidence was too weak to justify telling individuals to eat less sugar. But in that review they stopped short of recommending that adults could eat as much sugar as they wanted.

#2: The review left out 15 important studies showing that diets high in red meat are associated with increased disease risk. If those studies had been included in the analysis, the link between meat consumption and disease would have been much stronger. Even worse, the omitted studies met the author’s stated criteria for inclusion in their analysis. No reason was given for omitting those studies. This suggests author bias.

#3: The authors used an assessment method that prioritizes evidence from randomized controlled trials and downgrades evidence from association studies. As a result, multiple association studies showing red and processed meat consumption increases disease risk were discounted, and a few randomized controlled clinical trials giving inconsistent results dominated their analysis.

Let me state for the record that my research career was devoted to cancer drug development. I am a big proponent of the value of randomized controlled trials when they are appropriate.

·       Randomized controlled trial are perfect for determining the effectiveness of new drugs. In this context it is appropriate. In a drug trial it is easy to design a randomized, placebo-controlled clinical trial. In addition, every participant already has the disease. If a drug has a benefit, it is apparent in a very short time.

·       However, randomized controlled trials are not optimal for dietary studies. In the first place, it is impossible to design a placebo or have a “blinded study”. People know what they are eating. In addition, diseases like heart disease, cancer, and diabetes take decades to develop. You can’t keep people on specific diets for decades.

·       In addition, because randomized controlled trials are short, they can only measure the effect of diet on disease markers like LDL cholesterol. These disease markers are imperfect predictors of disease outcomes. I will discuss this in more detail next week.

·       Consequently, most of the major studies in nutrition research are “association studies” where the investigators ask people what they customarily eat and look at the association of those dietary practices with disease outcomes. These studies aren’t perfect, but they represent the best tool we have for determining the influence of diet on disease outcomes.

confusion#4: The authors included people’s attitudes about eating meat in their analysis. Because many meat eaters stated they would be unwilling to give up meat, the authors downgraded the association between meat consumption and disease risk.

·       That really had the outside experts scratching their heads. They agreed that people’s attitudes should be considered in discussions about how to implement health guidelines. However, they were unanimously opposed to the idea that people’s opinions should be a factor in crafting health guidelines.

#5: The authors ignored the environmental impact of meat consumption. As I indicated in a previous issue of “Health Tips From the Professor”, this should be a major consideration when choosing your diet.

#6: The authors may have been influenced by the beef industry. The NutriRECS group stated that the Agriculture and Life Sciences (AgriLife) program at Texas A&M provided generous support for their study. While that sound innocuous, the AgriLife program receives financial support from the “Texas Beef Checkoff Program”, which is a meat industry marketing program paid for by cattle ranchers.

#7: The beef industry influenced the studies the authors relied on in their review. The beef industry supports randomized controlled clinical trials on red meat and influences the outcome of those studies in ways that minimize the health effects of red meat consumption. I will give some examples of this next week. Unfortunately, these are the studies the NutriRECS group relied on for their recommendations.

What Did The Authors Say About Their Guidelines?

balance scaleBecause I like to provide a balanced evaluation of nutrition controversies, it is only fair that I summarize the authors argument for their recommendations. However, I will add my commentary. Here is a summary of their arguments.

#1: Nutritional recommendations should be based on sound science. In principle, this is something that everyone agrees on. However, as I noted above randomized controlled trials are not always the best scientific approach for studying the health effects of diet.

My comment: In matters of public health it is better to be safe than sorry. Simply put, it is better to warn people about probable dangers to their health rather than waiting decades for certainty. Smoking is a perfect example. The Surgeon General warned the US public about the dangers of smoking long before the evidence was conclusive.

Smoking is also an example of how industry tries to influence scientific opinion. The tobacco industry supported and influenced research on smoking. Industry funded research tended to minimize the dangers of smoking. Next week I will show how the meat industry is doing the same concerning the dangers of red meat.

#2: It is difficult to get good dietary information in association studies. That is because most association studies ask people what they have eaten over the past few decades. There are two problems with that.

1)    Most people have enough trouble remembering what they ate yesterday. Remembering what they ate 10 or 20 years ago is problematic.

2)    People listen to the news and often change their diets based on what they hear. What they are eating today may not resemble what they ate 10 years ago.

My comment: That is a legitimate point. However, in recent years the best association studies have started collection dietary information at the start, the mid-point, and the end of the study. I agree we need more of those studies.

#3: The authors claim they found no statistically significant link between meat consumption and risk of heart disease, diabetes, or cancer in a dozen randomized controlled trials that had enrolled about 54 000 participants.

label deceptionMy comment: That statement is highly misleading. One of those studies had 48,835 participants. That study wasn’t even designed to measure the effect of red meat consumption. It was designed to measure the health effects of low fat versus high fat diets. The difference in red meat consumption between the two groups was only 1.4 servings per day, a 20% difference. Even with that small difference in red meat consumption, there was about a 2% reduction in some heart disease outcomes, which the authors considered insignificant.

That leaves 11 studies with only 5,165 participants, which averages out to 470 participants per study. Those studies had too few participants to provide any meaningful estimate of the effect of red meat on health outcomes.

In addition, the meat industry influenced the design of some of those studies to further minimize the effect of red meat on health outcomes, something I will discuss next week.

#4: The authors found a slight effect of red meat consumption on heart disease and cancer deaths in association studies, but said the decrease was too small to recommend that people change their diet.

My comment: This represents the folly of looking at any single food or single nutrient rather than the whole diet. We need to take a holistic approach and ask questions like: “What are they replacing red meat with? What does their overall diet look like?

For example, let’s look at what happens when you reduce saturated fats, something I discussed in a previous issue (https://www.chaneyhealth.com/healthtips/are-saturated-fats-bad-for-you/) of “Health Tips From the Professor”. When you replace saturated fats with:

·       Trans fats, your heart disease risk increases by 5%.

·       Refined carbohydrates and sugars (the kind of carbohydrates in the typical American diet), your heart disease risk increases slightly.

·       Complex carbohydrates (whole grains, fruits and vegetables), your heart disease risk decreases by 9%.

·       Monounsaturated fats (olive oil & peanut oil), your heart disease risk decreases by 15%.

·       Polyunsaturated fats (vegetable oil & fish oil), your heart disease risk decreases by 25%.

·       Unsaturated fats in the context of a primarily plant-based diet like the Mediterranean diet, your heart disease risk decreases by 47%.

While we don’t have such precise numbers for red meat, we do have enough evidence to know that the situation with red meat is similar.

·       Replacing high-fat red meat with low-fat red meat or white meat in the context of a typical American diet will probably have only a modest effect on disease risk.

·       Replacing red meat with plant protein in the context of a typical American diet (think Impossible Burgers or the equivalent at your local Fast Food restaurant) will also probably have only a modest effect on disease risk.

·       Replacing red meat with white meat or plant protein in the context of a primarily plant-based diet is likely to significantly reduce disease risk.

Is Red Meat Healthy For You?

Steak and PotatoesLet’s return to the question I posed at the beginning of this article: “Is red meat healthy for you?” In the context of headlines saying: “Red meat is actually good for you”, the answer is a clear No!

·       The saturated fat in red meat is associated with increased heart disease risk.

·       However, it’s not just saturated fat. Other components of red meat are associated with increased risk of heart disease and cancer. I will discuss those next week.

There are simply too many studies that show an association between red meat consumption and disease risk to give red meat a clean bill of health. We can’t say red meat is healthy with any confidence.

However, that doesn’t mean we need to eliminate red meat from our diet. The health risks of red meat are determined by the type of red meat consumed, the amount of red meat consumed, and the overall composition of our diet. So:Steak Salad

·       If you are thinking in terms of a juicy 8-ounce steak with a baked potato and sour cream, red meat is probably not healthy.

·       However, if you are thinking of 2-3 ounces of lean steak in a vegetable stir fry or a green salad, red meat may be healthy.

Of course, one question I am frequently asked is “What about grass fed beef? Is it healthier than conventionally raised beef?” I will answer that question next week.

The Bottom Line

A group calling itself the Nutritional Recommendations Consortium (NutriRECS) recently reviewed the scientific literature and said: “The evidence is too weak to justify telling individuals to eat less beef and pork.” They then issued guidelines saying that adults really don’t need to change the amounts of red meat they are eating.

As you can imagine, that has proven to be a controversial recommendation. Many of the top experts in the field have questioned the validity of the study and have condemned the guidelines as misleading.

When you examine the pros and cons carefully, it becomes clear that the NutriRECS group:

1)    Put too little emphasis on association studies with hundreds of thousands of participants showing a link between red meat consumption and increased risk of heart disease and cancer.

2)    Put too much emphasis on very small randomized controlled trials that had no possibility of evaluating the effect of red meat consumption on disease risk. In part, that is because many of the randomized controlled trials were funded and influenced by the meat industry, something I will discuss next week.

3)    Did not ask what the red meat was replaced with or look at red meat consumption in the context of the overall diet.

Based on what we currently know:

1)    Replacing high-fat red meat with low-fat red meat or white meat in the context of a typical American diet will probably have only a modest effect on disease risk.

2)    Replacing red meat with plant protein in the context of a typical American diet (think Impossible Burgers or the equivalent at your local Fast Food restaurant) will also probably have only a minor effect on disease risk.

3)    Replacing red meat with white meat or plant protein in the context of a primarily plant-based diet is likely to significantly reduce disease risk.

That means:

1)    If you are thinking in terms of a juicy 8-ounce steak with a baked potato and sour cream, red meat is probably not healthy.

2)   However, if you are thinking of 2-3 ounces of lean steak in a vegetable stir fry or a green salad, red meat may be healthy.

Of course, one question I am frequently asked is “What about grass fed beef? Is it healthier than conventionally raised beef?” I will answer that question next week. Stay tuned.

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.

Is The Paleo Diet Bad For Your Heart?

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Is The Paleo Diet Bad For Your Gut?

the paleo dietThere is a lot to like about the Paleo diet:

·       It is a whole food diet. Any diet that eliminates sodas, junk foods, and highly processed foods is an improvement over the American diet.

·       It includes lots of vegetables and some fruits.

·       It helps you lose weight, and any diet that results in weight loss improves your blood work – things like cholesterol, triglycerides, blood sugar control and more.

However, there are concerns the Paleo diet may not be healthy long term.

·       In part, that is because the diet is high in meat, red meat, and saturated fat.

·       Equally important, however, is what the diet eliminates – namely whole grains, legumes (beans), and dairy.

Those of you who have read my book, “Slaying The Food Myths”, know that I say: “We have 5 food groups for a reason”. This is particularly true for the plant food groups. That’s because each plant food group provides a unique blend of:

·       Vitamins and minerals. Those can be replaced with good multivitamin/multimineral supplement.

·       Phytonutrients. You can only get the full complement of health-promoting phytonutrients from a variety of foods from all 5 food groups.

·       Fiber. There are many kinds of fiber and they each play different roles in our intestine. You can only get all the health-promoting varieties of fiber by consuming fruits, vegetables, whole grains and legumes.

·       Gut bacteria. What we call fiber, our gut bacteria call food. Each of the plant food groups supports different populations of friendly gut bacteria.

Based on this reasoning, one might suspect that the Paleo diet might alter our gut bacteria in ways that could be bad for our health. Until recently, this sort of reasoning was just a theoretical concern. That’s because:

1)    We knew far too little about the health effects of different populations of bacteria. This is rapidly changing. Several recent studies have systematically investigated the connection between gut bacteria and health outcomes.

2)    We knew our diet influenced the bacteria populations found in our gut, but we had no understanding of how these changes might influence our health. This too is changing. The study (A Genoni et al, European Journal of Nutrition, https://doi.org/10.1007/s00394-019-02036-y) I discuss this week is an excellent example of recent studies linking diet, gut bacteria, and risk factors for disease.

How Was The Study Done?

can you believe clinical studies doctorThis study recruited 91 participants from Australia and New Zealand. It was a very well designed study in that:

·       The Paleo diet group (44 participants) was recruited based on self-proclaimed adherence to the Paleo diet (< 1 serving/day of grains and dairy products) for one year or more. This is important because short term effects of switching to a new diet are confounded by weight loss and other factors.

o   After analyzing the diets of the Paleo group, the investigators found it necessary to subdivide the group into Strict Paleo (< 1 serving/day of grains and dairy products) and Pseudo-Paleo (> 1 serving/day of grains and dairy).

·       The control group (47 participants) was recruited based on self-proclaimed adherence to a “healthy diet” for 1 year or more with no change in body weight (A healthy diet was defined as a whole food diet containing a variety of foods from all 5 food groups). This is important because far too many studies compare the diet they are promoting to an unhealthy diet with a lot of sugar and highly processed junk foods. These studies provide little useful information because almost anything is better than an unhealthy diet.

·       The participants completed a diet survey based on the frequency of consumption of various foods during the previous year. However, because diet surveys based on the recollection of participants can be inaccurate, the investigators used two rigorous tests to validate the accuracy of those diet surveys.

o   The first was a 3-day weighed dietary record (WDR). Simply put, this means that participants weighed and recorded all foods and beverages before they were eaten for 3 days. Two of those days were weekdays, and one was a weekend day.

o   Secondly, the investigators used blood, urine, and metabolic measures to independently determine protein and energy intake of each participant. Participants who were identified by these means as under reporting both protein and energy were considered unreliable dietary reporters and were excluded from the analysis.

o   It is very rare to find a study that goes to this length to validate the accuracy of the dietary data used in their analysis.

The participants also provided blood, urine and stool samples and completed a physical activity assessment.

What Were The Differences Between The Paleo Diet And The Healthy Control Diet?

Paleo FoodsOnly the Strict Paleo Diet group was faithfully following the Paleo diet. In addition, most of the results with the Pseudo Paleo Diet Group were intermediate between the other two diets. Therefore, to simplify my discussion of this study I will only compare the Strict Paleo Diet group, which I refer to as the Paleo Diet group, with the Healthy Diet control group.

The Paleo diet emphasizes fresh vegetables, especially green leafy vegetables, and discourages grains. Thus, it is no surprise that:

·       The Paleo Diet group ate 74% more vegetables and 3 times more leafy green vegetables than the Healthy Diet group.

·       The Paleo Diet group ate only 3% of the grains and 3% of the whole grains compared to the Healthy Diet group.

The Paleo diet encourages consumption of meat and eggs and discourages consumption of dairy and plant proteins. Thus, it is not surprising that:

·       The Paleo Diet group ate 3 times more red meat and 5 times more eggs than the Healthy Diet group.

·       The Paleo Diet group ate 10% of dairy foods compared to the Healthy Diet group.

·       The Paleo Diet group consumed two times more saturated fat and cholesterol than the Healthy Diet group.

The most interesting comparison between the two diets was the following:

·       Intake of total fiber, insoluble fiber, and soluble fiber was comparable on the two diets.

·       However, intake of resistant starch was 50% lower in the Paleo Diet group. This is significant because:

o   Resistant starch is a type of fiber found primarily in whole grains, legumes, potatoes, and yams (Potatoes and yams are also dietary “no nos” on most low-carb diets).

o   Resistant starch is an especially good food for certain species of healthy gut bacteria.

Is The Paleo Diet Bad For Your Gut?

Bas BacteriaBecause resistant starch affects gut bacteria, the study next looked at the effect of the two diets on the populations of gut bacteria. This is where the story starts to get interesting. When they looked at different groups of gut bacteria, they discovered that:

·       Bifidobacteria were much more abundant in the Healthy Diet group than in the Paleo Diet group, and the amount of Bifidobacteria in the gut was directly proportional to the amount of whole grains in the diet.

o   This is important because previous studies have suggested Bifidobacteria help maintain intestinal barrier integrity and protect against irritable bowel syndrome and obesity.

·       Roseburia were also much more abundant in the Healthy Diet group and proportional to the amount of whole grains in the diet.

o   This is important because previous studies have suggested Roseburia protect against inflammatory bowel diseases like Crohn’s disease and ulcerative colitis.

·       Hungatella were much more abundant in the Paleo Diet group and were inversely proportional to the amount of whole grains in the diet.

o   This is important because Hungatella metabolize carnitine and choline, which are found in meats (especially red meats), egg yolks, and high fat dairy, into a compound called trimethylamine or TMA. TMA is then further metabolized in the liver to trimethylamine-N-oxide, or TMAO.

o   TMAO is a bad player. It is positively associated with heart disease, stroke, kidney disease, diabetes, and Alzheimer’s disease. However, the evidence is strongest for heart disease. TMAO has been called an independent risk factor for cardiovascular death.

Because of this, the study looked at TMAO levels in the blood of the two diet groups. These results were concerning:

·       TMAO levels were 2.5-fold higher in the Paleo Diet group than in the Healthy Diet group.

·       As might be expected, TMAO levels were positively correlated with red meat intake and inversely proportional to whole grain intake.

Is The Paleo Diet Bad For Your Heart?

heart diseaseWhen you put all the evidence together you have a compelling argument that the Paleo diet is likely to increase the risk of heart disease. Let me summarize the data briefly:

1)    The Paleo diet discourages the consumption of whole grains.

2)    Whole grains are a major source of a dietary fiber called resistant starch.

3)    Because the Paleo diet is low in resistant starch, it causes a decrease in two healthy types of gut bacteria and an increase in a type of gut bacteria called Hungatella.

4)    Hungatella metabolize compounds found in meat, eggs, and dairy to a precursor of a chemical called TMAO. This study showed that TMAO levels were 2.4-fold higher in people consuming a Paleo diet.

5)    TMAO is associated with coronary artery disease and is considered an independent risk factor for cardiovascular death.

The authors of the study concluded: “Although the Paleo diet is promoted for improved gut health, results indicate long-term adherence is associated with different gut microbiota and increased TMAO. A variety of fiber components, including whole grain sources, may be required to maintain gut and cardiovascular health.”

Of course, studies like this are looking at associations. They are not definitive. What we need are long term studies looking at the effect of the Paleo diet on heart disease outcomes like heart attack and stroke. Until we have these studies my advice is:

·       Don’t accept claims that the Paleo diet is heart healthy. There are no long-term clinical studies to back up that claim.

·       Be aware that the Paleo diet affects your gut bacteria in ways that may be bad for your heart.

The more we learn about our gut bacteria, the more we appreciate the importance of including all 5 food groups in our diet, especially all the plant food groups.

Are Low Carb Diets Healthy?

low carb dietThe Paleo diet is not the only diet that is high in red meat and low in whole grains. The same is true for virtually all the popular low-carb diets. There are studies showing other low-carb diets also alter gut bacteria and raise TMAO levels, so there is a similar concern that they may also increase the risk of heart disease.

This is in addition to concerns about the high saturated fat consumption which increases the risk of heart disease and red meat consumption, which may increase the risk of certain cancers.

Finally, there are no studies showing that any low-carb diet is healthy long term, even the Atkins diet, which has been around for more than 50 years. Until we have long-term studies about the health consequences of low-carb diets, my advice is similar to that for the Paleo diet.

·       Don’t accept claims that low-carb diets are healthy. There are no long-term clinical studies to back up that claim.

·       Be aware that low-carb diets affect your gut bacteria in ways that may be bad for your health.

The Bottom Line

A recent study looked at the effect of the Paleo diet on an important risk factor for heart disease. Here is a brief summary of the data:

1)    The Paleo diet discourages the consumption of whole grains.

2)    Whole grains are a major source of a dietary fiber called resistant starch.

3)    Because the Paleo diet is low in resistant starch, it causes a decrease in two healthy types of gut bacteria and an increase in a type of gut bacteria called Hungatella.

4)    Hungatella metabolize compounds found in meat, eggs, and dairy to a precursor of a chemical called TMAO. This study showed that TMAO levels were 2.4-fold higher in people consuming a Paleo diet.

5)    TMAO is associated with coronary artery disease and is considered an independent risk factor for cardiovascular death.

Of course, studies like this are looking at associations. They are not definitive. What we need are long term studies looking at the effect of the Paleo diet on heart disease outcomes – like heart attack and stroke. Until we have these studies my advice is:

·       Don’t accept claims that the Paleo diet is heart healthy. There are no long-term clinical studies to back up that claim.

·       Be aware that the Paleo diet affects your gut bacteria in ways that may be bad for your heart.

·       Virtually all the popular low-carb diets discourage consumption of whole grains, so my advice for them is the same as for the Paleo diet.

The more we learn about our gut bacteria, the more we appreciate the importance of including all 5 food groups in our diet, especially all the plant food groups.

For more details on 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

Does Sugar Cause Heart Disease?

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Is Sugar No Longer Your Best Friend?

Author: Dr. Stephen Chaney

SugarSugar has gotten a lot of bad press in recent years. You’ve probably already heard that high sugar intake is associated with inflammation, obesity and diabetes. As if that weren’t bad enough, the latest headlines proclaim that added sugar may also increase our risk of fatal heart disease. Are those headlines true? And if they are true, what should you do about it?

Sugar Basics – The Truth About Sugar

There are three facts about sugar that almost every expert agrees with:

  • The sugars that occur naturally in foods like fruits and vegetables are generally not a problem unless you are a diabetic. It is the added sugars in our diet that we should be concerned with.
  • The amount of added sugars in the American diet has increased dramatically since the founding of this country. Based on data from the US Department of Commerce and the USDA, the amount of added sugar in the American diet has gone from 6.3 pounds/year in 1822 to over 100 pounds/year in 2000. Put another way, we have gone from consuming the amount of sugar in a 12 oz soda every 5 days in 1822 to every 7 hours in 2000.
  • The lion’s share of that added sugar is coming from sodas and similar sugary beverages. The amounts are: sodas and other sugar-sweetened beverages (37.1%), grain-based desserts (13.7%), fruit drinks (8.9%), dairy desserts (6.1%) and candy (5.8%).

Beyond that there is little agreement among experts. When I was a young man the sugar “villains” were glucose and sucrose. Then it was sugar alcohols. Today it is high-fructose corn syrup and maltodextrin. Tomorrow it will be something else.

In reality there are no sugar heroes and no sugar villains. The harmful effects of added sugars are based almost entirely on:

  • The amount of added sugars in the diet…and…
  • The type of foods those added sugars are found in.

For more information, watch my video “The Truth About Sugar”.

Does Sugar Cause Heart Disease?

The study behind the headlines (Yang et al, JAMA Internal Medicine, 174: 516-524, 2014) followed 11,733 participants in the 3rd National Health And Nutrition Examination Survey (NHANES III) for an average of 14.6 years. (NHANES studies are designed to represent a cross section of the adult US population). Sugar intake was based on the average of two dietary surveys for most of the participants, and cardiovascular deaths were determined from the NHANES III Linked Mortality Files.

The average intake of added sugar in the American population was around 16% of total calories (compared to around 1% of total calories in 1822). For comparison purposes, the authors divided the population into three groups based on added sugar consumption:

  • Those consuming less than 10% of calories from added sugar (28.6% of the population).
  • Those consuming between 10% and 25% of calories from added sugars (46.4% of the population).
  • Those consuming more than 25% of calories from added sugars (25.0% of the population).

When the groups with the 10-25% and >25% of calories from added sugars were compared to the <10% group with respect to cardiovascular deaths, the results were pretty striking.

  • The group consuming 10-25% of calories from added sugars had a 30% increased risk of dying from heart disease
  • And the group consuming >25% of calories from added sugars had a 275% increased risk of dying from heart disease!

This association between added sugar consumption and risk of cardiovascular death was independent of age, sex, race/ethnicity, educational attainment, physical activity, HEI score (a measure of overall diet quality and BMI (a measure of obesity).

The Strengths And Weaknesses of This Study

Strengths:

  • This was a particularly large, well designed study.
  • This study is consistent with a number of early studies suggesting that added sugar intake increases the risk of cardiovascular death. See, for example “Can Soft Drinks Cause Heart Disease?”

Weaknesses:

  • The main weakness of this study is that it measures associations only. It does not prove cause and effect.

Should You Switch To Diet Sodas?

Diet SodaYou may be thinking that you should switch to diet sodas – and perhaps artificially sweetened snacks and desserts as well. It only makes sense that if sugar is the problem, artificial sweeteners must be the answer. Wrong! The latest research suggests that diet sodas may be just as bad as the sugar-sweetened sodas.

I have already shared one study with you that linked consumption of diet sodas with increased risk of heart disease (see “Can Soft Drinks Cause Heart Disease?”). The link between diet sodas and heart disease has now been supported by another major clinical study reported by Dr. Ankur Vyas from University of Iowa, March 30, 2014 at the American College of Cardiology’s 63rd Annual Scientific Session.

This study followed 60,000 women with an average age of 62.8 years who were enrolled in the Woman’s Health Initiative Observational Study for 9 years. They reported that compared to women who never or rarely drank diet sodas, those who consumed two or more diet sodas/day were:

  • 30% more likely to suffer heart attacks and strokes…and…
  • 50% more likely to die from cardiovascular disease.

What Can You Drink?

By now you are probably asking yourself: “If regular sodas, diet sodas, other sugary and diet beverages, and even most fruit juices are out, what else can I drink? Is there anything left?”

It’s not quite as daunting as it seems at first. It may take some time to re-educate your taste buds, but your health is worth it. Here are some healthy alternatives:

  • My #1 recommendation is always water. If you crave some flavor, add lemon, mint, or your favorite fruits. Herbal teas are another flavorful, healthy choice.
  • If you crave caffeine, go for green tea, regular tea or coffee – without sweeteners, of course.
  • If you crave the carbonation, start with unsweetened mineral water or seltzer and add you favorite flavorings.

The Bottom Line:

1)    The evidence is getting stronger every day that too much added sugar in our diet is linked to increased risk of death from cardiovascular disease. If you are consuming >25% of calories from added sugars the increased risk is almost 3-fold!

2)    The evidence from this study suggests that it would be prudent to keep added sugars below 10% of calories. For most Americans this represents around 200 calories/day from added sugars. That compares with the World Health Organization’s recommendation that added sugars be <10% of calories, the Institute of Medicine’s recommendation that added sugars be <25% of calories, and the American Heart Association’s recommendation that added sugars be <100 calories for women and <150 calories for men.

3)    There are no sugar heroes and villains. The amount of added sugar in the diet is much more important than the kind of sugar. The food that the sugar is found in is also very important, with sodas and similar sugar-sweetened beverages being the worst offenders (See my video “The Truth About Sugar” for more information).

4)    Artificial sweeteners are not the solution. A recent study with postmenopausal women suggests that consumption of as few as two diet sodas a day increases the risk of heart attacks and strokes by 30% and cardiovascular death by 50%.

5)    Don’t despair. You won’t have to go thirsty. There are lots of healthy alternatives available (see 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.

Are The Benefits Of Resveratrol A Myth?

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Is Resveratrol Dead?

Author: Dr. Stephen Chaney

Red WineIt seems like just a few years ago that the headlines were proclaiming that resveratrol, a polyphenol found in red wines, grapes and chocolate, was the latest “super nutrient”. It was going to make you younger, smarter and healthier. You probably knew that all of the claims being made at the time could not be true.

But the latest headlines are claiming that resveratrol health benefits are all a myth. Has the resveratrol bubble burst? Was it all just hype?

Before you decide that resveratrol supplements are just a waste of money, let me take you behind the scenes and evaluate the latest study objectively. Let’s talk about what it showed, and didn’t show. But, before we look at the study, let’s review the history of resveratrol.

How Did The Resveratrol Story Get Started?

The resveratrol story started in the 1990’s when Dr. Serge Renaud at Bordeaux University coined the term “French Paradox” to describe the fact that cardiovascular disease incidence was relatively low in the French population despite the fact that they consumed diets high in saturated fat and cholesterol.

People immediately started asking what could possibly explain this discrepancy between the US and French populations? In other words, what could be protecting the French population from their high fat diet? One obviously difference between the French and Americans is that the French consume a lot more red wine – or at least they did before the “French Paradox” publicity turned red wine into a health food. Based on that difference, Dr. Renaud proposed that the French Paradox was due to the high red wine consumption in France.

But, red wine is an alcoholic beverage and overconsumption of alcoholic beverages is a major health problem for many people. And, while alcohol does have some cardiovascular benefits, alcohol consumption was pretty constant across countries.

So the next logical question was what other ingredients in red wine might explain their supposed health benefits. Polyphenols appear to have numerous health benefits, and resveratrol is the major polyphenol in red wine. So resveratrol became the “poster child” for the health benefits of red wine.

Even so, for years resveratrol was a “niche” supplement. It had a loyal following, but it wasn’t a big player in the nutritional supplement market. All that changed in 2009. Dr. David Sinclair at Harvard University had been studying genes that slow the aging process. He had screened thousands of naturally occurring small molecules in hopes of finding some that could turn on those anti-aging genes.

He announced that resveratrol and a few related polyphenols were the most potent activators of those anti-aging genes, and he went on to publish studies showing that resveratrol could help obese mice live longer and lean mice be healthier. All of a sudden resveratrol became a superstar.

But, does resveratrol also work in humans? There are many clinical studies that suggest it does. That’s why I was surprised by the recent headlines proclaiming that the supposed health benefits of resveratrol were myths. So once again, let’s look at the study behind the headlines.

Are The Benefits Of Resveratrol a Myth?

The study behind the headlines (Semba et al, JAMA Internal Medicine, doi: 10.1001/jamainternalmed.2014.1582) followed 783 men and women aged 65 years or older from the Chianti region of Italy for 9 years. None of the participants were taking resveratrol supplements. The investigators estimated resveratrol intake by measuring the concentrations of resveratrol metabolites in the urine.

The investigators measured all cause mortality and the prevalence of heart disease and cancer over the 9 year period and found no correlation between those outcomes and urinary resveratrol metabolites. From those data the authors concluded that “Resveratrol levels achieved with a Western diet did not have a substantial influence on health status or mortality risk of the population in this study.”

The Strengths And Weaknesses of The Study

There are really two important questions – what are the strengths and weaknesses of the study and what does the study actually show?

What are the strengths and weaknesses of the study?

  • A major strength of the study was the measurement of urinary resveratrol metabolites rather than relying on the less accurate dietary recall – although it should be noted that the assays used are relatively new and could benefit from further validation.
  • The main weakness is that it was a relatively small study in a relatively homogeneous population. Most of the resveratrol consumed by this population came from red wine and even the group with the lowest resveratrol intake was drinking 2-3 glasses of red wine per week (You don’t find many teetotalers in the wine growing regions of Italy).

What does the study actually show?

  • The level of resveratrol metabolites in this population directly correlated with alcohol consumption. And, the authors of the study concluded that since the study was done in the Chianti region of Italy, most of the resveratrol came from red wine. So the study actually suggests that red wine consumption has no effect on heart disease, cancer or longevity – in direct contradiction to Renaud’s French Hypothesis.
  • The conclusion that the amount of resveratrol one can obtain from diet alone is unlikely to provide health benefits needs to be replicated in a much larger population group with a wider range of resveratrol intakes from a wider variety of foods before it can be considered definitive.
  • Even if the amount of resveratrol in food does offer no significant health benefits, that information provides little or no guidance when we consider resveratrol supplements, which generally provide much higher levels of resveratrol.

The Bottom Line:

1)    Don’t pay too much attention to the headlines saying that the health benefits of resveratrol are a myth. The study behind the headlines was a small study in a relatively homogeneous population. If anything, it debunked the hypothesis that red wine consumption is responsible for the French Paradox.

2)    The study did suggest that the amount of resveratrol one can obtain from diet alone is unlikely to provide significant health benefits. While that may be true, it is irrelevant when considering resveratrol supplements because they provide much higher amounts of resveratrol.

3)    The clinical studies on resveratrol supplements are very encouraging, but not yet definitive (see, for example, my “Health Tips From the Professor” article on resveratrol and blood sugar control. That’s to be expected at this stage. It generally takes decades of studies before the scientific community reaches consensus on anything. In the meantime you will continue to see alternating headlines proclaiming the miracles and the myths of resveratrol.

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.

Our Gut Bacteria Are What We Eat

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We Grow What We Eat

Author: Dr. Stephen Chaney

BacteriaThe subtitle of this week’s “Health Tips From the Professor” is “We Grow What We Eat”.

No, this is not about each of us starting a backyard garden and literally growing what we eat – although that would probably be a good idea for most of us. I’m actually talking about the bacteria that we “grow” in our intestine.

Most of you probably already know about the concept of “good” and “bad” intestinal bacteria.

Evidence suggests that the “bad” bacteria and yeast in our intestine can cause all sorts of adverse health effects:

  • There is mounting evidence that they can compromise our immune system.
  • There is also evidence that they can create a “leaky gut” (you can think of this as knocking holes in our intestinal wall that allow partially digested foods to enter the circulation where they can trigger inflammation and auto-immune responses).
  • There is some evidence that they can affect brain function and our moods.
  • They appear to convert the foods that we eat into cancer causing chemicals which can be absorbed into the bloodstream.
  • Studies in mice even suggest that they can make us fat.

The list goes on and on…

The “good bacteria” are thought to crowd out the “bad” bacteria and prevent many of the health problems they cause.

In case you’re thinking that it seems a bit far-fetched to think that our intestinal bacteria could affect our health, let me remind you that we have about 100 trillion bacteria in our intestine compared to about 10 trillion cells in our body. They outnumber us 10 to 1.

For years we have thought of “bad” bacteria and yeast as originating from undercooked, spoiled or poorly washed foods that we eat and the “good” bacteria as originating from foods like yogurt and probiotic supplements.

But most of us have not thought that the kinds of foods we choose to eat on a daily basis can affect the kinds of bacteria we “grow” in our intestine – until now. You’ve heard for years that “We are what we eat”. Well it now appears that we also “grow what we eat”. I’m referring to a recent study by G. D. Wu et al (Science, 334: 105-108, 2011).

Our Gut Bacteria Are What We Eat

I’m going to get a bit technical here (Don’t worry. There won’t be a quiz). Scientists refer to the population of bacteria in our intestines as our “microbiome”. Previous studies have shown that people from all over the world tend to have one of two distinct microbiomes (populations of bacteria) in their intestines – Bacteroides or Prevotella. [Again, don’t let the specialized scientific terminology scare you. These are just the names scientists have given to these two distinctive populations of intestinal bacteria].

What this study showed was that people who habitually consumed high-fat/low-fiber diets (diets containing predominantly animal protein and saturated fats) tended to have the Bacteroides bacteria in their intestine, while people who habitually consumed low-fat/high-fiber diets (diets that are primarily plant based and are high in carbohydrate and low in meat and dairy) tended to have the Prevotella bacteria in their intestine. And surprisingly this appears to be independent of sex, weight and nationality.

Is This Important?

The research defining these two distinct microbiomes (populations of intestinal bacteria) and showing that they are influenced by what we eat is very new. At this point in time we know relatively little about the health benefits and risks associated with the Bacteroides and Prevotella microbiomes.

For example:

  • Most of the studies on the health effects of “bad intestinal bacteria” were based on the identification of one or two “bad bacteria” in the gut – not on the hundreds of bacterial species found in the Bacteroides microbiome. So we can’t say for sure that the Bacteriodes microbiome found in people with diets high in animal protein and saturated fats will cause the same health problems as the “bad bacteria”. Nor do we know for sure how important a role the Bacteriodes microbiome plays in the health consequences of consuming that kind of diet.
  • Similarly, many of studies on the health benefits of “good intestinal bacteria” have been based on probiotic supplements containing one or two bacterial species – not the hundreds of bacterial species found in the Prevotella microbiome. So we can’t really say if probiotics or even the Prevotella microbiome will convey the same health benefits seen in populations who consume vegetarian diets.

However, now that do we know that we “grow what we eat” there are numerous studies ongoing to define the benefits and risks associated with each type of bacterial population.

For example, I shared a study with you recently which shows that the intestinal bacteria in people who eat a lot of animal protein convert carnitine (which is also found in meat) to a compound called TMAO, which may increase the risk of heart attacks, and that the conversion of carnitine to TMAO does not occur in people who consume a vegetarian diet ( see “Does Carnitine Increase Heart Disease Risk”)

Stay tuned! I’ll keep you updated as more information becomes available.

The Bottom Line:

Most of the studies I report on are ones that you can act on right away. This one is different. This study introduces a whole new concept – one that raises as many questions as it answers. This makes us ask those “what if” questions.

1)     Previous studies have shown that most people have one of two different kinds of microbiomes (populations of bacteria) in their intestines. This study showed that diets high in animal protein and fat favored one kind of intestinal microbiome, while diets low in fat and high in fiber from fruits & vegetables favored another type of intestinal microbiome.

2)     With a few exceptions we don’t know yet how important a role these intestinal microbiomes play in determining the health consequences of different diets. However, because our intestinal bacteria outnumber the cells in our body by 10:1, it is tempting to ask “What if?”

3)     We also don’t yet know the extent to which probiotics (either from foods or supplements) can overcome the effects of a bad diet on our intestinal microbiome, but it is tempting to ask “What if?”

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

Is Vitamin D Overhyped?

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Are Clouds Gathering For the Sunshine Vitamin?

Author: Dr. Stephen Chaney

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

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

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

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

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

Is Vitamin D Overhyped?

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

The authors of the study reported that:

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

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

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

The Study Is Flawed

My specific criticisms of the study are:

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

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

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

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

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

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

Is Vitamin D Beneficial After All?

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

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

The Bottom Line:

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

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

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

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

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

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

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

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

Does Carnitine Increase Heart Disease Risk?

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Carnitine: Dr. Jekyl or Mr. Hyde?

Author: Dr. Stephen Chaney

Heart HealthIt’s both interesting and confusing when one Journal article appears talking about the dangers of a particular supplement and just a couple of weeks later another article appears talking about the benefits of that same supplement – especially when the conclusions of both articles are misrepresented in the media.

But that’s exactly what has just occurred with the supplement L-carnitine. Media reports of the first article trumpeted the headline “Cleveland Clinic study links L-carnitine to increased risk of heart disease”. Media reports of the second article featured the headline “Mayo Clinic review links L-carnitine to multiple health heart benefits”. As you might suspect, neither headline was completely accurate. So let me help you sort out the confusion about L-carnitine and heart health

What is Carnitine?

But first let me give you a little bit of background about L-carnitine. L-Carnitine is an essential part of the transport system that allows fatty acids to enter the mitochondria where they can be oxidized and generate energy. So it is an essential nutrient for any cell that has mitochondria and utilizes fatty acids as an energy source.

L-carnitine is particularly important for muscle cells, and the hardest working muscle cells in our body are those that pump blood through our hearts. So when we think of L-carnitine we should think of heart health first.

But that doesn’t mean that L-carnitine is an essential nutrient. In fact, our bodies generally make all of the L-carnitine that we need. There are some metabolic diseases that can prevent us from making L-carnitine or utilizing L-carnitine efficiently. People with those diseases benefit from L-carnitine supplementation, but those diseases are exceedingly rare.

There is some evidence that supplemental L-carnitine may be of benefit in individuals suffering from congestive heart failure and other diseases characterized by weakened heart muscles. Other than that there is little evidence that supplemental L-carnitine is beneficial for healthy individuals.

Does Carnitine Increase Heart Disease Risk?

fatty steakLet’s look at the first study (Koeth et al, Nature Medicine, doi:10.1038/nm.3145, April 7, 2013) – the one that purportedly linked L-carnitine to increase risk of heart disease. The authors were trying to gain a better understanding of the well-established link between red meat consumption and cardiovascular disease risk. The classical explanation of this link has been the saturated fat and cholesterol content of the red meat.

However, several recent studies have questioned whether saturated fat and cholesterol actually increase the risk of cardiovascular disease (see last week’s article “Are Saturated Fats Good For You?”)

Since red meat is also high in L-carnitine, the authors hypothesized that it might be the L-carnitine or a metabolite of the L-carnitine that was associated with increased risk of heart disease in people consuming red meat.

The authors honed in on a metabolite of L-carnitine called trimethylamine-N-oxide or TMAO that is produced by bacteria in the intestine and had been previously shown to accelerate atherosclerosis in mice. They developed what they called an L-carnitine challenge. Basically, they gave their subjects an 8 ounce sirloin steak, which contains about 180 mg of L-carnitine, and measured levels of L-carnitine and TMAO in the blood one hour later and the urine 24 hours later. [I’m guessing they didn’t have much trouble finding volunteers for that study.]

When the subjects were omnivores (meaning meat eaters) they found a significant increase in both L-carnitine and TMAO in their blood and urine following the L-carnitine challenge. When they put the same subjects on broad-spectrum antibiotics for a week to wipe out their intestinal bacteria and repeated the L-carnitine challenge, they found an increase in L-carnitine but no increase in TMAO. This simply confirmed that the intestinal bacteria were required for the conversion of L-carnitine to TMAO.

Finally, because previous studies have shown that omnivores and vegetarians have very different populations of intestinal bacteria, they repeated their L-carnitine challenge in a group of vegans and found that consumption of the same 8 ounce sirloin steak by the vegans did not result in any significant increase in TMAO in either their blood or urine.

Armed with this information, the authors measured L-carnitine and TMAO concentrations in the fasting blood of 2595 patients undergoing cardiac evaluation in the Cleveland Clinic. They used an established protocol to assess the three-year risk for major adverse cardiac events in the patients they examined. They observed a significant association between L-carnitine levels and cardiovascular event risks, but only in subjects who also had high blood levels of TMAO.

Now it’s time to compare what the headlines said to what the study actually showed. The headlines said “L-carnitine linked to increased risk of heart disease”. What the study actually showed was that there were two things that were required to increase the risk of heart disease – L-carnitine and a population of intestinal bacteria that converted the L-carnitine to TMAO.

The major source of L-carnitine in the American diet is red meat, and habitual red meat consumption is required to support a population of intestinal bacteria that is capable of converting L-carnitine to TMAO. So the headlines should have read “red meat consumption linked to increased risk of heart disease”. But, of course, that’s old news. It doesn’t sell subscriptions.

Does Carnitine Decrease Heart Disease Risk?

Heart AttackThe second study (DiNicolantonio et al, Mayo Clinic Proceedings, dx.doi.org/10.1016/j.mayocp.2013.02.007) was a meta-analysis. It reviewed 13 clinical studies involving 3629 people who had already had heart attacks and were given L-carnitine or a placebo after the heart attack.

In evaluating the results of this study it is useful to remember that a heart attack generally kills some of the heart muscle and weakens some of the surviving heart muscle. When the data from all of the studies was combined the authors reported a 27% reduction in all cause mortality, a 65% reduction in arrhythmias, and a 40% reduction in angina. However, there was no reduction in a second heart attack or the development of heart failure.

So perhaps the headlines describing this study were a little closer to being on target, but they failed to mention that these effects were only seen in people who had already suffered a heart attack and had weakened heart muscles. They also failed to mention that there was no decreased risk of a second heart attack or congestive heart failure.

The Bottom Line:

1)     The first study should be considered preliminary. It needs to be confirmed by other studies. If it is true, it is not ground breaking. It merely gives us a fuller understanding of why red meat consumption may be linked to increased risk of heart disease and gives you yet another reason to minimize red meat consumption.

The study does raise the possibility that use of L-carnitine supplements may increase your risk of heart disease if you eat red meat on a regular basis, and that this same risk may not be associated with L-carnitine supplementation if you are a vegan. But the study did not directly test that hypothesis, and much more research is required before I would give it any weight.

2)     The second study suggests that if you have already had a heart attack, you may want to consult with your physician about whether L-carnitine supplementation might be of benefit. Once again, this study is not ground breaking. We already knew that L-carnitine supplementation was helpful for people with weakened heart muscle. This study merely confirmed that.

Contrary to what the headlines suggested, this study provides no guidance about whether L-carnitine supplementation has any heart health benefits in people without pre-existing heart disease – and the bulk of existing literature suggests that it does not.

3)     Finally, I realize that the major use of L-carnitine in the US market is in sports supplements purported to increase strength and endurance. The literature on that is decidedly mixed, but that’s another subject for another time.

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.

Are Saturated Fats Good For You?

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Is Everything We Thought We Knew About Fats Wrong?

Author: Dr. Stephen Chaney

fatty steakBring out the fatted calf! Headlines are proclaiming that saturated fats don’t increase your risk of heart disease – and that they may actually be good for you.

The study (Annals of Internal Medicine, 160: 398-406, 2014) that attracted all the attention in the press was what we scientists call a meta-analysis. Basically, that is a study that combines the data from many clinical trials to improve the statistical power of the effect being studied.

And it was a very large study. It included 81 clinical trials that looked at the effects of various types of fat on heart disease risk.

Are Saturated Fats Good For You?

The answer to this question is a simple No. The headlines suggesting that saturated fats might be good for you were clearly misleading. The study concluded that saturated fats might not increase the risk of heart disease, but it never said that saturated fats were good for you.

In short, the study concluded that:

  • Saturated fats, monounsaturated fats and long-chain omega-6 polyunsaturated fats did not affect heart disease risk.
  • Long chain omega-3 polyunsaturated fats decreased heart disease risk [Note: The original version of the paper said that the decrease was non-significant, which is what the headlines have reported. However, after several experts pointed out an error in their analysis of the omega-3 data, the authors corrected their analysis, and the corrected data show that the decrease in risk is significant.]
  • Trans fats increased heart disease risk

If those conclusions are correct, they would represent a major paradigm shift. We have been told for years that we should limit saturated fats and replace them with unsaturated fats. Has that advice been wrong?

Is Everything We Thought We Knew About Fats Wrong?

Before we bring out the fatted calf and start heaping butter on our12 ounce steaks, perhaps we should look at some of the limitations of this study.

We Eat Foods, Not Fats

When the authors broke the data down into the effects of individual saturated and unsaturated fatty acids on heart disease risk some interesting insights emerge.

For example, with respect to saturated fats:

  • Both palmitic acid and stearic acid – which are abundant in palm oil and animal fats – increased the risk of heart disease.
  • On the other hand, margic acid – which is more abundant in dairy products – decreased the risk of heart disease.

Whipped CreamSo while the net effect of saturated fats on heart disease risk may be zero, these data suggest:

  • It is still a good idea to avoid fatty meats, especially red meats, if you want to reduce your risk of heart disease. When you focus on foods, rather than fats this fundamental advice has not changed in over 40 years! In next week’s “Health Tips From the Professor” I will share some of the latest research on the dangers of red meat.
  • With fatty dairy foods the situation is a little more uncertain. I’m not ready to tell you to break out the butter and whipped cream just yet, but recent research does suggest that dairy foods have some beneficial effects that may outweigh their saturated fat content.

With respect to omega-3 fatty acids:

  • alpha-linolenic acid – which is found in vegetable oils and nuts and is the most abundant omega-3 fatty acids in our diets – had no effect on heart disease risk.
  • On the other hand, EPA and DHA – which are found primarily in oily fish and omega-3 supplements – decreased heart disease risk by 20-25%.

Once again, while the net effect of omega-3 fatty acids on heart disease risk was very small, that’s primarily because most Americans consume mostly alpha-linolenic acid and very little EPA and DHA. This study shows that fish oil significantly reduces heart disease risk, which is fully consistent with the heart healthy advice of the American Heart Association and National Institutes of Health over the past decade or more.

What We Replace the Fats With Is Important

A major weakness of the current study is that it did not ask what the individual clinical trials were replacing the fatty acids with. Many of them were simply replacing the saturated fats with carbohydrates. To understand why that is important, you have to go back to the research of Dr. Ancel Keys.

The whole concept of saturated fats increasing the risk of heart disease is based on the groundbreaking research of Dr. Ancel Keys in the 50’s and 60’s. But, it is important to understand what his research showed and didn’t show.

His research showed that when you replaced saturated fats with monounsaturated fats and/or polyunsaturated fats the risk of heart disease was significantly reduced. He was the very first advocate of what we now call the Mediterranean diet. (He lived to 101 and his wife lived to 97, so he must have been on to something.)

Unfortunately, his diet advice got corrupted. The mantra became low fat diets, where the saturated fat was replaced with carbohydrates – mostly simple sugars and refined flours. Since diets containing a lot of simple sugars and refined flours also increase the risk of heart disease you completely offset the benefits of getting rid of the saturated fats.

Just in case you think that is outdated dietary advice, Dr. Key’s recommendations were confirmed by a major meta-analysis published in 2009 (American Journal of Clinical Nutrition, 89: 1425-1432, 2009). That study showed once again that replacing saturated fats with carbohydrates had no effect on heart disease risk, while replacing them with polyunsaturated fats significantly reduced risk.

The Bottom Line:

You can put the fatted calf back out to pasture. The headlines telling you that saturated fats don’t increase the risk of heart disease were overstated and misleading. This study does not represent a paradigm shift. In fact, when you analyze the study in depth it simply reaffirms much of the current dietary advice about fats.

1)     When you simply replace saturated fats with carbohydrates, as did many of the studies in the meta-analysis that generated all of the headlines, there is little or no effect on heart disease risk. However, other studies have shown that when you replace the saturated fats with monounsaturated and polyunsaturated fats you significantly reduce heart disease risk.

In short, if you are interested in reducing your risk of heart disease, low fat diets may be of relatively little value while Mediterranean diets may be beneficial. No paradigm shift there. That sounds pretty familiar.

2)     Fatty meats, especially red meats, appear to increase the risk of heart disease. No surprises there.

3)     Alpha-linolenic acid, the short chain omega-3 fatty acid found in nuts, seeds and vegetable oils, does not decrease heart disease risk. However, EPA and DHA, the long chain omega-3 fatty acids found in fatty fish and fish oil supplements significantly decrease heart disease risk. That’s probably because the efficiency of conversion of alpha-linolenic acid to EPA & DHA in our bodies is only around 10%. No surprises there.

4)     The study did suggest that dairy foods may decrease heart disease risk. While there are a few other studies supporting that idea, I’m not ready to break out the butter and whipped cream yet. More research is needed.

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.

Can Diet Alter Your Genetic Destiny?

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Disease Is Not Inevitable

Author: Dr. Stephen Chaney

Bad GenesMany people seem to have the attitude that if obesity [or cancer, heart disease or diabetes] runs in their family, it is their destiny. They can’t really do anything about it, so why even try?

Most of us in the field of nutrition have felt for years that nothing could be further from the truth. But our belief was based on individual cases, not on solid science. That is no longer the case.

Recent scientific advances have given us solid proof that it is possible to alter our genetic destiny. A family predisposition to diabetes, for example, no longer dooms us to the same fate.

I’m not talking about something like the discredited Blood Type Diet. I’m talking about real science. Let me start by giving you an overview of the latest scientific advances.

Can Diet Alter Your Genetic Destiny?

The answer to this question is YES, and that answer lies in a relatively new scientific specialty called nutrigenomics – the interaction between nutrition and genetics. There are three ways in which nutrition and genetics interact:

1)     Your genetic makeup can influence your nutrient requirements.

The best characterized example of this is methylene tetrahydrofolate reductase (MTHFR) deficiency.  MTHFR deficiency increases the requirement for folic acid and is associated with neural tube defects and other neurological disorders, dementia, colon cancer & leukemia.

In spite of what some blogs and supplement manufacturers would have you believe, supplementation with around 400 IU of folic acid is usually sufficient to overcome the consequences of MTHFR deficiency. 5-methylene tetrahydrofolate (also sold as methyl folate or 5-methyl folate) offers no advantage in absorption, bioavailability or physiological activity (Clinical Pharmacokinetics, 49: 535-548, 2010; American Journal of Clinical Nutrition, 79: 473-478, 2004).

This is just one example. There are hundreds of other genetic variations that influence nutrient requirements – some known and some yet unknown.

2)     A healthy diet can reduce your genetic predisposition for disease.

This perhaps the one that is easiest to understand. For conceptual purposes let us suppose that your genetic makeup were associated with high levels of inflammation. That would predispose you to heart disease, cancer and many other diseases. However, a diet rich in anti-inflammatory nutrients could reduce your risk of those diseases.

This is just a hypothetical example. I’ll give some specific examples in the paragraphs below.

3)     Diet can actually alter your genes.

This is perhaps the most interesting scientific advance in recent years. We used to think that genes couldn’t be changed. What you inherited was what you got.

Now we know that both DNA and the proteins that coat the DNA can be modified, and those modifications alter how those genes are expressed. More importantly, we now know that those modifications can be inherited.

Perhaps the best characterized chemical modification of both DNA and proteins is something called methylation. Methylation influences gene expression and is, in turn, influenced by nutrients in the diet like folic acid, vitamin B12, vitamin B6, choline and the amino acid methionine.

Again this is just the “tip of the iceberg”. We are learning more about how diet can alter our genes every day.

Examples Of How Diet Can Alter Genetic Predisposition

Mature Man - Heart Attack Heart Disease

  • Perhaps the most impressive recent study is one that looked at the effect of diet on 20,000 people who had a genetic predisposition to heart disease (PLOS Medicine, October 2011, doi/10.1371/journal.pmed.1001106).

These people all had a genetic variant 9p21 that causes a 2 fold increased risk of heart attack. The study showed that a diet rich in fruits, vegetables and nuts reduced their risk of heart attack to that of the general population.

  • Another study, the Heart Outcomes Prevention Evaluation (HOPE) study (Diabetes Care, 27: 2767, 2004; Arteriosclerosis, Thrombosis and Vascular Biology, 24: 136, 2008), looked at genetic variations in the haptoglobin gene that influence cardiovascular risk. The haptoglobin 2-2 genotype increases oxidative damage to the arterial wall, which significantly increases the risk of cardiovascular disease.

When the authors of this study looked at the effect of vitamin E, they found that it significantly decreased heart attacks and cardiovascular deaths in people with the haptoglobin 2-2 genotype, but not in people with other haptoglobin geneotypes.

  • There was also a study called the ISOHEART study (American Journal of Clinical Nutrition, 82: 1260-1268, 2005; American Journal of Clinical Nutrition, 83: 592-600, 2006) that looked at a particular genetic variation in the estrogen receptor which increases inflammation and decreases levels of HDL. As you might expect, this genotype significantly increases cardiovascular risk.

Soy isoflavones significantly decreased inflammation and increased HDL levels in this population group. But they had no    effect on inflammation or HDL levels in people with other genotypes affecting the estrogen reception.

To put this in perspective, these studies are fundamentally different from other studies you have heard about regarding nutritional interventions and heart disease risks. Those studies were looking at the effect of diet or supplementation in the general population.

These studies are looking at the effect of diet or supplementation in people who were genetically predisposed to heart disease. These studies show that genetic predisposition [to heart disease] does not have to be your destiny. You can change the outcome!

Cancer

  • A healthy diet (characterized by high intakes of vegetables, fruits, whole grain products and low intakes of refined grain products) compared with the standard American diet (characterized by high intakes of refined grain products, desserts, sweets and processed meats) results in a pattern of gene expression that is associated with lower risk of cancer.  (Nutrition Journal, 2013 12:24).
  • A healthy lifestyle (low fat diet, stress management and exercise) in men with prostate cancer causes downregulation of genes associated with tumor growth (PNAS, 105: 8369-8374).
  • Sulforaphane, a nutrient found in broccoli, turns on genes that suppress cancer.

Diabetes

  • A study reported at the 2013 meeting of the European Association for the Study of Diabetes showed that regular exercise activated genes associated with a lower risk of type 2 diabetes

Cellular Stress Response

  • A diet rich in antioxidant fruits and vegetables activates the cellular stress response genes that protect us from DNA damage, inflammation and reactive oxygen species (BMC Medicine, 2010 8:54).
  • Resveratrol, a nutrient found in grape skins and red wine, activates genes associated with DNA repair and combating reactive oxygen species while it reduces the activity of genes associated with inflammation, increased blood pressure and cholesterol production.

To put these last three examples (cancer, diabetes and cellular stress response) in perspective, they show that diet and supplementation can alter gene expression – and that those alterations are likely to decrease disease risk.

Obesity

  • Finally, an animal study suggests that maternal obesity may increase the risk of obesity in the offspring by increasing their taste preference for foods with lots of sugar and fats (Endocrinology, 151: 475-464, 2010).

The Bottom Line:

The science of nutrigenomics tells us that diet and genetics interact in some important ways:

1)     Your genetic makeup can influence your requirement for certain nutrients.

    • For example, methylene tetrahydrofolate reductase (MTHFR) deficiency increases your requirement for folic acid.
    • Contrary to what many blogs would have you believe, folic acid is just as effective as 5-methylene tetrahydrofolate (also sold as methyl folate or 5-methyl folate) at correcting MTHFR deficiency.

2)     Healthy diet and lifestyle can overcome genetic predisposition to certain diseases. The best established example at present is for people genetically predisposed to heart disease, but preliminary evidence suggests that the risk of other diseases such as diabetes and cancer are altered by your diet.

3)     Diet can actually alter gene expression – for better or worse depending on your diet. Those alterations not only affect your health, but they may affect your children’s health as well.

4)     Nutrigenomics is a young science and many of the individual studies should be considered preliminary. However, the scientific backing is become stronger every day for what many experts in the field have believed for years.

“Your genes do not have to be your destiny. Healthy diet and lifestyle can overcome a genetic predisposition to many diseases.”

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