Protein and Heart Disease: Meat vs Plant-Based

Written by Dr. Steve Chaney on . Posted in Protein and Heart Disease

Does Meat Protein Increase Heart Disease Risk?

Author: Dr. Stephen Chaney

 

Is a plant-based diet better than eating meat when it comes to protein and heart disease?

protein and heart disease plant-basedThere are a multitude of studies showing the long-term health benefits of plant-based diets. Among the best of these studies are the Seventh-Day Adventist Studies. That’s because the Adventist church advocates a vegan diet but allows personal choice. This means Seventh-Day Adventists eat a more plant-based diet than most Americans. However, there is also significant variation in the diet of Adventists.

 

Not all Adventists are vegans. Significant numbers of Adventists choose lacto-ovo-vegetarian (dairy, eggs & vegetarian), pesco-vegetarian (fish & vegetarian), and semi-vegetarian (meat & vegetarian).

Because of this variation, Adventists provide a rich database for clinical studies. You can compare health outcomes of a vegetarian diet to the standard American diet by comparing Adventists to the non-Adventist population living in the same area. You can also use the Adventist population to compare the health outcomes of the various types of vegetarian diets.

I have described the Adventist Health Studies in detail in my new book, Slaying The Food Myths. Let me briefly summarize the results with an emphasis on heart disease risk:

  • Compared to the standard American Diet, vegetarian diets decrease cardiovascular deaths by 41% in men and 51% in women.
  • The reduction in cardiovascular death is greater for vegans than for lacto-ovo-vegetarians.
  • If we look at the average of multiple studies, the risk of heart disease, diabetes, and cancer is less for vegans than for lacto-ovo-vegetarians, which is less than the risk for pesco-vegetarians, which is less than the risk for semi-vegetarians, which is much less than the risk for people consuming the standard American diet.

There are multiple reasons why vegetarian diets decrease the risk of heart disease compared to the standard American diet. These will be discussed below. The current study was designed to look at the proteins found in vegetarian and non-vegetarian diets and ask what effect these proteins had on heart disease.  This was a good study of protein and heart disease.

How Was The Study Done?

protein and heart disease heart healthThis study (M. Tharrey et al, International Journal of Epidemiology, 2018, 1-10 doi: 10.1093/ije/dyy030 ) utilized a database of 81,337 men and women over age 25 who were enrolled in the Adventist Health Study-2 between 2002 and 2007.

At the time of enrollment, a very detailed food frequency questionnaire was administered. The participants were divided into groups based on the most prevalent protein source in their diet as follows:

  • Grains: This group averaged 44% of their protein intake from grains.
  • Processed foods: This category included protein from cheese, eggs, and milk. However, it also included processed plant proteins and protein from cold breakfast cereals.
  • Meats: The largest protein contributors to this category were red meat, processed meat, and poultry. Fish made only a minor contribution.
  • LFV (Legumes, fruits & vegetables): Legumes were the biggest protein contributors in this category.
  • Nuts and seeds: This included peanuts, tree nuts and seeds.

The participants in the study were followed for an average of 9.4 years during which there were 2276 cardiovascular deaths. The study then asked what effect protein intake from each of these food groups had on cardiovascular risk.

 

Meat Protein and Heart Disease?

 

protein and heart disease meatsSome of the findings from this study were expected, but some were surprising. When studying protein and heart disease for example:

  • When they compared people getting the most protein from meat with those getting the least (24% versus 1% of their protein intake from meat), the risk of cardiovascular death was increased by 61%. This is consistent with several previous studies suggesting that meat, particularly red meat, increases the risk of heart disease.
  • When they compared people getting the most protein from nuts and seeds with those getting the least (18% versus 2%), the risk of cardiovascular death was decreased by 40%. Again, this is consistent with previous studies suggesting that nuts and seeds reduce the risk of heart disease.
  • They found no significant effect of protein intake from grains on cardiovascular death. This could be considered as surprising because whole grains are an excellent source of fiber, which reduces the risk of heart disease. However, the difference in protein intake between the groups getting the most protein from grains versus the least was relatively small (34% versus 19%). In addition, the study did not differentiate between whole grains and refined grains.
  • There was a slight, but non-significant, increased risk of cardiovascular death for people getting the highest amount of protein from processed foods. This is also a bit surprising. It may be because the survey included both meat-based and vegetarian processed foods in the processed foods classification, and there are many processed foods that are marketed specifically to vegetarians.
  • There was also no significant effect of protein from legumes, fruits and vegetables on cardiovascular death. This is also surprising and will be discussed below.

The authors concluded “Our results suggest that healthy choices can be advocated based on protein sources, specifically preferring diets low in meat intake and with a higher intake of plant proteins from nuts and seeds.”

What Does This Mean For You?

protein and heart disease nuts and seedsThis study does not fundamentally alter what we know about diet and heart disease risk. That is because this study focused solely on the protein and heart disease not on the foods and heart disease. The data were statistically corrected for every other beneficial and detrimental effect of those foods. For example:

  • The people in this study with the highest intake of processed foods were more likely to be overweight and physically inactive. They were also more likely to be smokers. These factors increase the risk of cardiovascular disease. However, the data were statistically adjusted to remove these considerations from the analysis.
  • The people in this study with the highest intake of whole grains, legumes, fruits and vegetables also had the highest intake of fiber, antioxidants, and B vitamins. These factors decrease the risk of heart disease. However, the data were statistically adjusted to remove these considerations from the analysis.

In short, processed foods are still probably bad for the heart, but that is not due to the protein component of processed foods. Similarly, whole grains, legumes, fruits, and vegetables are still good for the heart, but it is not the protein component of these foods that conveys the heart-healthy benefits.

Where the study breaks new ground and leaves some unanswered questions is with the effect of meat, nuts, and seeds on heart disease risk. For example:

  • The American Heart Association has recently released a Presidential Advisory statement warning that the saturated fat in meats increases heart disease risk. However, the data in the present study were statistically adjusted to remove the effect of saturated fat from the analysis. Thus, this study suggests that the protein in red meat also contributes to heart disease risk. If this is confirmed by subsequent studies, it is an important advance. It might mean, for example, that grass-fed beef is no healthier than conventionally raised beef.

However, it is unclear why meat protein increases heart disease risk. One recent study has suggested that meat-based diets favor a population of gut bacteria that metabolize a compound called carnitine, also found in meat, into a metabolite that increases heart disease risk. However, this mechanism has not yet been confirmed.

[Note: The effects of saturated fats and carnitine on heart disease risk are covered in detail in my new book “Slaying the Food Myths.” In my book I carefully analyze the arguments of saturated fat proponents as well as saturated fat opponents.]

  • Conventional wisdom has attributed the heart health benefits of nuts and seeds to their omega-3 fatty acids. However, the data in this study were statistically adjusted to remove the effect of omega-3 fatty acids from the analysis. Thus, this study suggests that the protein in nuts and seeds decreases heart disease risk.

Once again, the mechanism of this effect is unclear. The authors suggest it might be due to higher levels of the amino acids glutamate and arginine in seed and nut protein. However, these two amino acids are abundant in a variety of plant-based proteins. Their presence in nut and seed proteins would not appear to be sufficient to confer a special heart health benefit.

In short, this is the first study of this kind and the mechanisms of the effects described are unclear. Thus, one cannot yet definitively claim that meat protein is bad for the heart and nut and seed proteins are good for the heart.

Whether it is the protein component of these foods that affects heart health is relatively unimportant. It does not change what we know about diet and heart health. As discussed in “Slaying The Food Myths,” multiple studies show that meat-based diets increase heart disease risk and primarily plant-based diets decrease heart disease risk. Multiple studies also show that nuts and seeds decrease heart disease risk.

 

The Bottom Line:

 

A recent study looked at the effect of the protein content of various foods on heart disease risk. The study reported:

  • Meat protein increased the risk of cardiovascular deaths by 61%.
  • Proteins from nuts and seeds decreased the risk of heart disease deaths by 40%.
  • Proteins from processed foods, grains, legumes, fruits, and vegetables had no effect on cardiovascular deaths.

This study does not fundamentally alter what we know about diet and heart disease risk. That is because this study focused solely on the protein component of various foods rather than the foods themselves. The data were statistically corrected for every other beneficial and detrimental effect of those foods. Because of that:

  • Processed foods are still probably bad for the heart
  • Whole grains, legumes, fruits and vegetables are still good for the heart.
  • Meat, especially red meat, is probably bad for the heart, while nuts and seeds are good for the heart.

The major new information provided by this study is that:

  • The increased risk of heart disease associated with meats is not just due to their saturated fat content. Meat protein may also increase heart disease risk. If confirmed by subsequent studies, this is an important finding because it suggests that lean cuts of meat and grass-fed beef may not eliminate heart disease risk.
  • The decreased risk of heart disease associated with nuts and seeds is not just due to their omega-3 content. Nut and seed proteins may also decrease heart disease risk.

For more details, read the article above:

 

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

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Latest Article

Can Plant-based Diets Be Unhealthy?

Posted September 10, 2019 by Dr. Steve Chaney

Do Plant-Based Diets Reduce Heart Disease Deaths?

Author: Dr. Stephen Chaney

 

plant-based diets vegetablesPlant-based diets have become the “Golden Boys” of the diet world. They are the diets most often recommended by knowledgeable health and nutrition professionals. I’m not talking about all the “Dr. Strangeloves” who pitch weird diets in books and the internet. I am talking legitimate experts who have spent their life studying the impact of nutrition on our health.

Certainly, there is an overwhelming body of evidence supporting the claim that plant-based diets are healthy. Going on a plant-based diet can help you lower blood pressure, inflammation, cholesterol and triglycerides. People who consume a plant-based diet for a lifetime weigh less and have decreased risk of heart disease, diabetes, and cancer.

But, can a plant-based diet be unhealthy? Some people consider a plant-based diet to simply be the absence of meat and other animal foods. Is just replacing animal foods with plant-based foods enough to make a diet healthy?

Maybe not. After all, sugar and white flour are plant-based food ingredients. Fake meats of all kinds abound in our grocery stores. Some are very wholesome, but others are little more than vegetarian junk food. If you replace animal foods with plant-based sweets, desserts, and junk food, is your diet really healthier?

While the answer to that question seems obvious, very few studies have asked that question. Most studies on the benefits of plant-based diets have compared population groups that eat a strictly plant-based diet (Seventh-Day Adventists, vegans, or vegetarians) with the general public. They have not looked at variations in plant food consumption within the general public. Nor have they compared people who consume healthy and unhealthy plant foods.

This study (H Kim et al, Journal of the American Heart Association, 8:e012865, 2019) was designed to fill that void.

 

How Was The Study Done?

plant-based diets studyThis study used data collected from 12,168 middle aged adults in the ARIC (Atherosclerosis Risk in Communities) study between 1987 and 2016.

The participant’s usual intake of foods and beverages was assessed by trained interviewers using a food frequency questionnaire at the time of entry into the study and again 6 years later.

Participants were asked to indicate the frequency with which they consumed 66 foods and beverages of a defined serving size in the previous year. Visual guides were provided to help participants estimate portion sizes.

The participant’s adherence to a plant-based diet was assessed using four different well-established plant-based diet scores. For the sake of simplicity, I will include 3 of them in this review.

  • The PDI (Plant-Based Diet Index) categorizes foods as either plant foods or animal foods. A high PDI score means that the participant’s diet contains more plant foods than animal foods. A low PDI score means the participant’s diet contains more animal foods than plant foods.
  • The hPDI (healthy plant-based diet index) is based on the PDI but emphasizes “healthy” plant foods. A high hPDI score means that the participant’s diet is high in healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) and low in animal foods.
  • The uPDI (unhealthy plant-based diet index) is based on the PDI but emphasizes “unhealthy” plant foods. A high uPDI score means that the participant’s diet is high in unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) and low in animal foods.

For statistical analysis the scores from the various plant-based diet indices were divided into 5 equal groups. In each case, the group with the highest score consumed the most plant foods and least animal foods. The group with the lowest score consumed the least plant foods and the most animal foods.

The health outcomes measured in this study were heart disease events, heart disease deaths, and all-cause deaths. Again, for the sake of simplicity, I will only include 2 of these outcomes (heart disease deaths and all-cause deaths) in this review. The data on deaths were obtained from state death records and the National Death Index. (Yes, your personal information is available on the web even after you die.)

 

Do Plant-Based Diets Reduce Heart Disease Deaths?

plant-based diets reduce heart deathsThe participants in this study were followed for an average of 25 years.

The investigators looked at heart disease deaths over the 25 years and compared people with the highest intake of plant foods to people with the highest intake of red meat and other animal foods. The results were:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

What Else Did The Study Show?

The investigators made a couple of other interesting observations:

  • The association of the overall diet with heart disease and all-cause deaths was stronger than the association of individual food components. This underscores the importance of looking at the effect of the whole diet on health outcomes rather than the “magic” foods you hear about on Dr. Strangelove’s Health Blog.
  • Diets with the highest amount of healthy plant foods were associated with higher intake of carbohydrates, plant protein, fiber, and micronutrients, including potassium, magnesium, iron, vitamin A, vitamin C, folate, and lower intake of saturated fat and cholesterol.
  • Diets with the highest amount of unhealthy plant foods were associated with higher intake of calories and carbohydrates and lower intake of fiber and micronutrients.

The last two observations may help explain some of the health benefits of plant-based diets.

 

Can Plant-Based Diets Be Unhealthy?

plant-based diets unhealthy cookiesNow, let’s return to the question I asked at the beginning of this article: “Can plant-based diets be unhealthy?” Although some previous studies have suggested that unhealthy plant-based diets might increase the risk of heart disease, this study did not show that.

What this study did show was that an unhealthy plant-based diet was no better for you than a diet containing lots of red meat and other animal foods.

If this were the only conclusion from this study, it might be considered a neutral result. However, this result clearly contrasts with the data from this study and many others showing that both plant-based diets in general and healthy plant-based diets reduce the risk of heart disease deaths and all-cause deaths compared to animal-based diets.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

There is one other subtle message from this study. This study did not compare vegans with the general public. Everyone in the study was the general public. Nobody in the study was consuming a 100% plant-based diet.

For example:

  • The group with the highest intake of plant foods consumed 9 servings per day of plant foods and 3.6 servings per day of animal foods.
  • The group with the lowest intake of plant foods consumed 5.4 servings per day of plant foods and 5.6 servings per day of animal foods.

In other words, you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet.

 

The Bottom Line

A recent study analyzed the effect of consuming plant foods on heart disease deaths and all-cause deaths over a 25-year period.

When the investigators looked at heart disease deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

A more subtle message from the study is that you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet. The people in this study were not following some special diet. The only difference was that some of the people in this study ate more plant foods and others more animal foods.

For more details on the study, read the article above.

 

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

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