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

Does An Apple A Day Keep Statins Away?

February 4, 2014 by Dr. Steve Chaney

The Latest On Diet And Heart Health

Author: Dr. Stephen Chaney

In a previous “Health Tips From the Professor” I talked about how difficult it has been to prove that statins significantly reduce the risk of heart attack or cardiovascular deaths in a low risk population group. Now let’s look at the other side of the coin – lifestyle change –and ask how effective lifestyle change is at reducing the risk of cardiovascular disease.

You’ve all heard the saying “An apple a day keeps the doctor away”. It dates back to Victorian England. It was the public health message of the day – much simpler and more concise than our current food guide plate.

A prominent British doctor and his research team recently decided to see how accurate that saying really was. But they took their study one step further. They compared the effectiveness of an apple a day versus a statin a day at reducing the risk of cardiovascular deaths (Briggs et al, British Medical Journal, 3013;347:f7267 doi: 10.1136/bmj.f7267).

The results of that comparison may surprise you.

Does An Apple A Day Keep Statins Away?

They used the data from the Cholesterol Treatment Trialist meta-analysis to estimate the effectiveness of statin drugs at reducing cardiovascular deaths. They used the data from the PRIME comparative risk assessment model to estimate the effectiveness of apple a day at reducing cardiovascular deaths.

They asked what would happen if each of them were the primary intervention for the entire British population over 50 who were not currently taking statin drugs (17.6 million people).

They assumed a 70% compliance rate for both interventions. In simple terms that means they assumed that 70% of the population would actually do what their doctors told them. (Patients must be more compliant in England than in the US).

The results were interesting. They estimated that:

Giving a statin drug each day to 17.6 million people would reduce the number of cardiovascular deaths by 9,400.

Giving an apple each day to the same 17.6 million people would reduce the number of cardiovascular deaths by 8,500 (not significantly different).

But when they looked at side effects and cost the two interventions were significantly different.

Giving a statin drug each day to 17.6 million people would also cause some significant side effects. The authors estimated that it would lead to:

1,200 excess cases of severe muscle pain and weakness
200 excess cases of rhabdomyolysis (muscle breakdown, which can lead to irreversible kidney failure)
12,300 excess cases of diabetes

On the other hand, there are no known side effects to an apple a day.

The statin intervention would cost an estimated $295 million. In the case of apples, you would presumably be substituting a more healthy food for a less healthy food so there would be little or no net cost.

And the 70% compliance rate is probably wildly optimistic. Some experts have estimated that up to 50% of patients discontinue their statin medications within the first year because of side effects or cost.

Is There A Scientific Basis For Those Estimates?

Of course, we all know that the “apple a day…” saying was never meant to be taken literally. It was just a simple way of saying that a good diet will reduce the risk of disease.

It turns out that there was another major study on the effect of dietary fiber on reducing the risk of cardiovascular disease in the very same issue (Threapleton et al, British Medical Journal, 2013;347:f6879 doi: 10.1136/bmj.f6879). It was a meta-analysis that combined the data from 22 previously published studies.

This study showed:

For every 7 g/day increase in dietary fiber the risk of both heart attacks and cardiovascular disease decreases by 9% (7 grams of dietary fiber could come from one serving of whole grains plus one serving of beans or lentils or from two servings of fruits or vegetables).

For every 4g/day of fruit fiber (equivalent to one apple) the risk of heart attacks decreases by 8% and the risk of cardiovascular disease decreases by 4%.

The numbers are similar for every 4 g/day of vegetable fiber.

Another recent study showed that consumption of 75 g/day of dried apple (equivalent to two apples a day) lowered total cholesterol by 13% and LDL-cholesterol by 24% in post-menopausal women (Chai et al, J. Acad Nutr Diet, 112: 1158-1168, 2012). That’s comparable to the cholesterol reduction achieved with statin drugs.

The Bottom Line

If you have not previously had a heart attack and are at relatively low risk, something as simple as adding an apple a day (in place of less healthy foods) may just as effective as statin drugs at reducing your risk of cardiovascular death without the side effects and cost of the drugs.

This is not really new information. For years both the American Heart Association and the National Institutes of Health have recommended that Therapeutic Lifestyle Changes (weight loss, healthy diet and exercise) should be tried BEFORE drug treatment to reduce the risk of heart disease.

So if you want to avoid statins, tell your doctor that you are willing to make the needed lifestyle changes to reduce your risk of heart disease and stick with it. Lifestyle changes are hard, but clinical studies clearly show they can often be just as effective as drug therapy, without the cost and side effects.

Don’t misunderstand me. I’m not advocating avoiding statin drugs if they are absolutely necessary. If you have had a heart attack or are at high risk of heart disease, it is clear that statins can save lives. Even here I would recommend talking with your physician about incorporating therapeutic lifestyle change into your regimen. It may allow them to minimize the dose, and therefore the side effects, of the statin drugs.

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.

Omega-3 Fatty Acids And Brain Health

December 3, 2013 by Dr. Steve Chaney

Is it How Much You Eat, or How Much You Keep?

Author: Dr. Stephen Chaney

Why do some studies conclude that omega-3 fatty acids are essential for a strong mind, a strong heart and will wipe out inflammation – while other studies suggest that they are ineffective? The simple answer is that nobody really knows.

However, in the process of reviewing two recent studies on omega-3 fatty acids and brain health I made an interesting observation that offers a possible explanation for the discrepancies between studies. And if my hypothesis is correct, it suggests that the design of many of the previous studies with omega-3 fatty acids is faulty.

Omega-3 Fatty Acids And Brain Health

The first study (J.K. Virtanen et al, J Am Heart Assoc, 2013, 2:e000305 doi: 10.1161/JAHA.113.000305) looked at the effect of omega-3 fatty acids on brain function in older adults (>65 years old). It concluded that high omega-3 levels were associated with better white matter grade and a 40% reduction in subclinical infarcts (Sorry for the technical jargon – but both of those are good things in terms of brain function for those of us who are getting a bit older).

The second study (C. M. Milte et al, J of Attention Disorders, 2013, doi: 10.1177/1087054713510562) looked at the effect of omega-3 fatty acids on children (ages 6-13) with ADHD. It concluded that high omega-3 levels were associated with improved spelling and attention and reduced oppositional behavior, hyperactivity, cognitive problems and inattention.

What Is The Common Thread In These Studies?

Why, you might ask, am I comparing a study in the elderly, where the concern is retention of cognitive skills, with a study on ADHD in children?

That’s because there is a very important common thread in those two studies. It wasn’t the amount of omega-3 fatty acids in their diet that counted. It was the levels of omega-3 fatty acids in their blood that made the difference.

The first study included a detailed dietary history to estimate the habitual intake of omega-3 fatty acids in the participants.

There was no correlation between estimated dietary intake of omega-3 fatty acids and any measure of brain function in those older adults.

However, there was a strong correlation between blood levels of omega-3s and brain health in that population group.

The second study was actually a placebo controlled intervention study in which the children were given 1 gm/day of either omega-3 fatty acids or omega-6 fatty acids.

Once again, there was no correlation between dietary intake of omega-3 or omega-6 fatty acids and any outcome related to ADHD.

However, there was a strong correlation between blood levels of omega-3 fatty acids or omega-3/omega-6 ratio and improvement in multiple measures of ADHD.

How Could The Effect of Dietary Intake And Blood Levels Of Omega-3s Be So Different?

Both studies were relatively small and suffered from some technical limitations, but the most likely explanations are:

Inaccurate recall of the participants as to what they eat on a habitual basis. (study 1)

Individual differences in the ability of participants to convert short chain omega-3 fatty acids (found in foods such as canola oil, flaxseed oil and walnuts) to the beneficial long chain fatty acids (found in cold water fish). (study 1)

Poor compliance in taking the supplements. (study 2)

Why Are These Studies Important?

The most important insight to come out of both of these studies is that it is essential to actually measure blood levels of omega-3 fatty acids and not just rely on dietary intake or supplementation for a valid clinical trial.

That’s a concern because blood measurements of omega-3 fatty acids are expensive and have not been a part of many of the clinical studies that have been performed to date. Even the largest, best designed clinical study is worthless if the dietary recalls aren’t accurate or people don’t take their capsules.

We need to go back and reevaluate many of the clinical studies that have been published.

We need to ask:

Are their conclusions valid?

Did some studies fail to show that omega-3s were effective simply because they only measured dietary intake and not how much of the omega-3s actually accumulated in the blood?

The Bottom Line

High blood levels of omega-3s in the blood correlated with improved brain health in the elderly and reduced ADHD symptoms in children

These studies were small, but they are consistent with a number of other studies that have come to similar conclusions.

Blood levels of omega-3s are better predictors than dietary intake for evaluating the health benefits of omega-3 fatty acids.

Many previous studies that failed to find an effect of omega-3 fatty acids on brain health, heart health or inflammation did not actually measure blood levels of the omega-3 fatty acids. These studies should be reevaluated.

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.