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Is The Paleo Diet Bad For Your Heart?

November 12, 2019 by Dr. Steve Chaney

Is The Paleo Diet Bad For Your Gut?

There 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?

This 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?

Only 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?

Because 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?

When 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?

The 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

Is The Paleo Diet Healthy?

August 8, 2017 by Dr. Steve Chaney

Did Cave Men Have The Secret For A Longer, Healthier Life?

Author: Dr. Stephen Chaney

It seems like everyone you talk to is following the Paleo diet or knows someone who is following the Paleo diet. It is the latest diet fad. But, is the Paleo diet healthy?

If you have been around for a few years, like me, you have seen lots of fad diets come and go. They are immensely popular for a few years. Then people discover their weight loss was temporary or they aren’t any healthier, and the diet slowly fades into obscurity.

Is the Paleo diet one of those fad diets that will fade into obscurity, or is it a healthy diet that will stand the test of time? A lot has been written about the Paleo diet, both pro and con. I have analyzed the science behind the claims and counter-claims so I can bring you the truth about the Paleo diet.

Unicorns And the Paleo Diet

I titled this section “Unicorns and the Paleo Diet” because both are myths. In fact, the Paleo Diet is based on several myths.

Myth #1: Our ancestors all had the same diet. What we currently know as the Paleo diet is based on the diets of a few primitive hunter-gatherer societies that still exist in some regions of the world. However, when you look at the data more carefully, you discover that the diet of primitive societies varies with their local ecosystems.

The “Paleo diet” is typical of ecosystems in which game is plentiful and fruits and vegetables are less abundant or are seasonal. In ecosystems where fruits and vegetables are abundant, primitive societies tend to be more gatherers than hunters. They eat more fruits and vegetables and less meat.

The assumption that starchy foods were absent in the paleolithic diet is also a myth. For some primitive societies, starchy fruits or starchy roots are a big part of their diet. In short, our paleolithic ancestors ate whatever nature provided.

Myth #2: Our genetic makeup is hardwired around the “paleolithic diet.” In fact, humans are very adaptable. We are designed to thrive in a wide variety of ecosystems. It is this adaptability that has allowed us to expand to every nook and cranny of the world.

For example, the enzymes needed to digest grains are all inducible, which means the body can turn them on when needed. Our paleolithic ancestors may not have eaten much grain, but we can very quickly adapt to the introduction of grains into our diet.

Myth #3: Our paleolithic ancestors were healthier than modern man: It many respects, the paleolithic diet is healthy, as I will discuss below. However, we need to remember that our paleolithic ancestors rarely lived past 30 or 40. They simply did not live long enough to experience degenerative diseases like heart disease and cancer. We have no idea whether a diet that served our paleolithic ancestors well will keep us healthy into our 70s, 80s and beyond.

However, just because the Paleo diet is based on mythology does not mean that it isn’t healthy. Let’s look at the pros and cons of the Paleo diet.

The Pros Of The Paleo Diet

There are lots of things to like about the Paleo diet. For example:

It eliminates sodas, fast foods, processed foods, sugar and salt. Any diet that does that is a vast improvement over the typical American diet.
It emphasizes fresh fruits and vegetables, another big improvement over the typical American diet.
It has a healthier profile of fats than the other low carb diets. It favors grass-fed beef, wild-caught fish, and free-range chicken, so it has less saturated fat and more omega-3s. It also emphasizes healthy oils such as olive, walnut, avocado, and flaxseed. In this regard, it is clearly healthier than the other low carb diets. It does include coconut oil, which is a concern. As I have pointed out in a previous article, Is Coconut Oil Bad For You, there is no convincing evidence that coconut oil is healthy.
It emphasizes use of unrefined or extra virgin oils rather than refined oils. That is a plus for most oils because the unrefined oils are more likely to contain antioxidants and beneficial phytonutrients. It is, however, a concern for coconut oil because the unrefined oil is more likely to contain cancer-causing aflatoxins.
Like most other restrictive diets that eliminate processed foods, it can give short term weight loss, although long term weight loss is less certain.

The Cons Of The Paleo Diet

There are, however, some concerns about the Paleo diet. Other experts have commented on the cost and difficulty in following the diet, especially if you eat out a lot, so I won’t comment on those aspects here. I will stick with nutritional concerns with the Paleo diet. For example:

It eliminates cereal grains, legumes, and dairy. I am always concerned with the nutritional adequacy of diets that eliminate whole food groups. For example:
- Dairy is a major source of calcium and vitamin D in the American diet. Eliminating dairy has the potential to increase the risk of osteoporosis.
- Whole grains, legumes and dairy are important sources of magnesium. Magnesium deficiency has the potential to increase the risk of heart disease, among other things.
- Most Americans are already not getting enough of these nutrients in their diet. We can scarcely afford to eliminate foods that are good sources of these nutrients.
- It is possible to carefully design a Paleo diet so these nutrients are provided by other foods, but most people don’t carefully design their daily diet.
It recommends increasing protein intake to 19 – 35% of calories. Because legumes have been eliminated, the increased protein intake is coming almost entirely from animal protein, primarily red meat and fish. I will discuss the health concerns with red meat below. However, there is a practical consideration as well. Grass-fed beef is not always available, especially if you eat out frequently. If you are not eating grass-fed beef, you will be taking in more saturated fats and the healthier fat profile of the Paleo diet will disappear.
It has been influenced by the recent hype about health benefits of coconut oil. Coconut oil is just one of several oils that are recommended. However, if you look on the internet today, coconut oil is featured in almost every Paleo diet recipe. Until we have definitive evidence whether or not coconut oil is healthy, I would emphasize the other oils recommended for the Paleo diet, and use coconut oil sparingly.
There are no studies showing the Paleo diet is healthy long term. In contrast, there are long term studies showing that Vegan, Mediterranean, and DASH diets decrease the risk of heart disease, diabetes, some cancers and Alzheimer’s.

Concerns About Red Meat

The International Agency For Research On Cancer (IARC), the agency created by the WHO to set international standards for cancer risk, has designated red meat as a class 2a carcinogen. That designation means that there is probable cause to believe that it increases cancer risk in humans. The evidence is best for increased risk of colon cancer and breast cancer, although there is some evidence that it may increase risk of pancreatic and prostate cancer.

The increased cancer risk of red meat does not seem to be due to its fat content, so grass fed beef is just as likely to increase cancer risk as conventionally produced beef. There are multiple proposed mechanisms for this effect:

When fat and juices from the meat drip onto an open flame, carcinogenic polyaromatic hydrocarbons are formed that stick to the surface of the meat. This can be reduced, but not eliminated, by lower fat meat choices.
When red meats are cooked at high temperatures, amino acids in the meat combine with a compound called creatine, which is found in all red meats, to form carcinogenic heterocyclic amines. This can be reduced by cooking the meat at lower temperatures.
Heme iron, which is found in all red meats, combines with other component of our diet to form carcinogenic N-nitroso compounds in our intestines.
People who eat high meat diets have an entirely different population of intestinal bacteria than people who eat no meat. Several recent studies suggest that the intestinal bacteria of meat eaters are more likely to convert the foods we eat into chemicals that increase the risk of cancer and heart disease.

To be clear, red meat is a probable carcinogen and we aren’t sure of the exact mechanism(s) that cause this carcinogenicity. We do not yet have definitive evidence that red meat causes cancer. However, there is good reason to be cautious about how much red meat we consume.

The good news is that the antioxidants, fiber and phytonutrients found in fruits and vegetables can block most of these cancer-causing pathways. That means that small amounts of red meat in a largely plant-based diet may not be as concerning. Specifically, an ounce of red meat in a large green salad or stir fry is much less likely to increase your cancer risk than a 6 ounce steak.

Is The Paleo Diet Healthy?

As mentioned above, there is a lot to like about the Paleo diet. It is healthier than the typical American diet, and it is healthier than most of the low carb diets. I have concerns about the nutrition adequacy of any diet that eliminates whole food groups and the heavy emphasis on red meat. There is also no proof that the Paleo diet is healthy long term.

Since the restrictions of the Paleo diet are based on mythology rather than science, my recommendation would be to loosen the restrictions on whole grains, legumes & low-fat dairy, and rely less on red meat as a protein source. If you did that, the diet would more closely resemble the Mediterranean and DASH diets, which we know are healthy long term.

The Bottom Line

The Paleo diet is based on a myth.
- Our paleolithic ancestors did not eat a single diet. They followed a variety of diets depending on the foods most available where they lived.
- Our bodies are not genetically hardwired for a single diet, but are designed to adapt to a wide variety of foods. For example, all of us have the enzymes needed to digest grains, and those enzymes are inducible.
- We don’t know whether the paleolithic diet is healthy. The average lifespan of our paleolithic ancestors was in the range of 30 to 40 years. We have no idea whether a diet that served our paleolithic ancestors well will keep us healthy into our 70s, 80s and beyond.
However, the fact that the Paleo diet is based on a myth does not make it unhealthy. In fact, there is a lot to like about the Paleo diet.
- It eliminates sodas, fast foods, processed foods, sugar and salt which makes it much healthier than the standard American diet.
- It emphasizes fresh fruits and vegetables, which is also an improvement over the standard American diet.
- If features a relatively healthy profile of fats, which makes it healthier than most other low carb diets.
- It favors unrefined or extra virgin oils, which are generally healthier than highly processed oils. The exception is coconut oil because unrefined coconut oil may be contaminated with aflatoxins.
- It can give short term weight loss, although long term weight loss is uncertain.
However, there are concerns about the long-term safety of the Paleo diet. The minor concerns are:
- The elimination of whole grains, legumes, and dairy from the diet creates the potential for nutritional deficiencies that can have long-term health consequences. It is possible to carefully design a Paleo diet so these nutrients are provided by other foods, but most people don’t carefully design their daily diet.
- Most of the recipes you find on the internet for the Paleo diet use coconut oil. This is a concern because we don’t know whether coconut oil is healthy. My recommendation would be to substitute the healthier oils that are also part of the Paleo diet.
More serious concerns are:
- The heavy reliance on red meat. Red meat is classified as a probable carcinogen, potentially increasing the risk of colon cancer, breast cancer, pancreatic cancer and prostate cancer. The potential carcinogenicity of red meat is not reduced by substituting grass-fed beef for conventionally produced beef.
- There are no clinical studies showing the Paleo diet is healthy long term. In contrast, there are long term studies showing that Vegan, Mediterranean, and DASH diets decrease the risk of heart disease, diabetes, some cancers and Alzheimer’s.
Because the restrictions of the Paleo diet are based on myth rather than science, there are simple work arounds for the concerns. If one were to loosen the restrictions on whole grains, legumes and low-fat dairy & reduce the reliance on red meat, you would have a diet closer to the Mediterranean and DASH diets, which we know are healthy long term.
For 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.