vegans Archives - Health Tips From The Professor

What Can Twins Tell Us About Diet?

January 30, 2024 by Dr. Steve Chaney

What Are The Pros And Cons Of Twin Studies?

Author: Dr. Stephen Chaney

Why is the advice on healthy diets so confusing? One blog claims the vegan diet is best. Another says it is the keto diet is best. The Mediterranean diet is popular, but other experts claim the DASH or MIND diet might be better. Blogs champion diets ranging from the familiar to downright weird.

If you try to keep up with the science, it seems like the science is constantly changing. Each week you see headlines saying the latest study shows diet “X” is best – and “X” keeps changing. Why is that? Why do studies on healthy diets keep coming up with conflicting conclusions?

I have discussed the strengths and weaknesses of clinical studies and why they provide conflicting results in detail in previous issues of “Health Tips From the Professor”. However, one factor I have not discussed in detail is the effect of genetics on how we utilize foods, something called nutrigenomics.

Simply put, we are all genetically different. The way we utilize foods is different. The effect that foods have on our bodies is different. I have touched on that briefly in a previous article discussing individual difference in blood sugar response to various foods. But that is just one of many examples.

We do not yet know enough about gene-nutrient interactions to use genomic data to accurately predict which diets are best. Again, I have covered that topic in a previous issue of “Health Tips From the Professor”. However, we do know that genetic differences have a big influence on which diet is best for us. And most clinical studies on diets do not even attempt to take genetic differences into account.

That is where twin studies come in. Identical twins (monozygotic twins) have an identical genetic makeup and usually have an identical environment until they become adults. So, when I saw an identical twin study (MJ Landry et al, JAMA Network Open, 6(11):e2344457, 2023) comparing a vegan diet (only plant foods) with an omnivorous diet (both animal and plant foods), I wanted to review it and share it with you.

How Was The Study Done?

Identical twins were recruited from the Stanford Twin Registry. Twenty-two identical twin pairs were chosen for this study. Their characteristics were average age = 40, BMI = 26% (moderately overweight), sex = 77% female, ethnicity = 73% white, followed by an approximately equal representation of Asian, black, multiracial, and Pacific Islander.

One unanticipated characteristic of this group of twins was that 70% of them still lived together and cooked together, so their environment was also very similar.

One twin of each pair was put on a healthy vegan diet and the other on a healthy omnivorous diet for 8 weeks. Both diets were designed by dietitians. The diets emphasized fruits, vegetables, and whole grains while limiting added sugars and refined grains.

Both diets were healthier than the diets the twins were eating prior to the study. Finally, the participants were not told how much to eat, and were not instructed to lose weight.

For the first four weeks the participants were provided with all their meals by a nationwide food delivery company. The participants were also provided with training on purchasing and preparing healthy foods for their diet. This prepared them for the last 4 weeks of the study in which they purchased and prepared their own meals.

Participants visited the Stanford Clinical and Translational Science Research Unit at the beginning of the study and at the end of weeks 4 and 8 for weight measurement and a fasting blood draw.

Adherence to the diets was measured by a series of unannounced interviews to administer a 24-hour dietary recall questionnaire. These were scheduled for the weeks they visited the clinic.

What Can Twins Tell Us About Diet?

Even though the sample size was small, there were three statistically significant results.

LDL-cholesterol was reduced by 12% for the twin on the vegan diet, while it remained unchanged for the twin on the omnivorous diet.

The fasting insulin level was reduced by 21% for the twin on the vegan diet, while it remained unchanged for the twin on the omnivorous diet. This suggests the twin on the vegan diet was experiencing improved blood sugar control after just 8 weeks.

The twin on the vegan diet lost 4 pounds in 8 weeks, while weight remained the same for the twin on the omnivorous diet. This occurred even though neither twin was instructed to eat less nor to lose weight. It is most likely a consequence of the lower caloric density of the vegan diet (See my discussion of caloric density in last week’s issue of “Health Tips From the Professor”.

The changes in LDL-cholesterol and fasting insulin were remarkable because none of the twins in this study had elevated LDL-cholesterol or problems with blood sugar control at the beginning of the study.

The authors of this study concluded, “In this randomized clinical trial of the cardiometabolic effects of omnivorous vs vegan diets in identical twins, the healthy vegan diet led to improved cardiometabolic outcomes compared with a healthy omnivorous diet. Clinicians can consider this dietary approach as a healthy alternative for their patients.”

[Let me decipher the term cardiometabolic for you. The decrease in LDL-cholesterol is associated with heart health – the cardio portion of the term. The decrease in fasting insulin is associated with decreased risk of diabetes. Since diabetes is considered a metabolic disease, this is the metabolic portion of the term.]

Were There Any Downsides To The Vegan Diet?

This study also highlighted two well-known limitations of vegan diets.

Although the differences were not statistically significant, the authors expressed concern that vitamin B12 intake was less for twins on the vegan diet than twins on the omnivorous diet even though the vegan diet was designed by dietitians.

The authors noted that B12 deficiency among vegans is well known, and said, “Long-term vegans are typically encouraged to take a cyanocobalamin (vitamin B12) supplement.

Although both groups had excellent adherence to their assigned diets, those assigned to the vegan diet expressed a lower satisfaction with the diet, which suggests long-term adherence to the diet after the study ended was unlikely.

The authors said, “Although our findings suggest that vegan diets offer a protective cardiometabolic advantage compared with a healthy omnivorous diet, excluding all meats and/or dairy products may not be necessary because research suggests that cardiometabolic benefits can be achieved with modest reduction in animal foods and increases in healthy plant-based foods compared with typical diets.”

“We believe that lower dietary satisfaction in the vegan group may have been attributable to the strictness of the vegan diet…Some people may find a less restrictive diet preferable for LDL-cholesterol-lowering effects.”

I concur.

What Are The Pros And Cons Of Twin Studies?

The Pros are obvious. Most dietary studies cannot take genetic differences into account and have difficulty accounting for environmental differences. In this study genetics was identical for each twin pair and their environment was very similar. It offers a unique advantage over other studies.

But the strength of this study is also its greatest weakness. Because the general population is genetically and environmentally diverse, it is difficult to extrapolate the results to the general population.

If this were the only study to show cardiometabolic benefits of a plant-based diet, it would simply be an interesting observation.

But there are several studies showing that the vegan diet is associated with lower weight and reduced risk of heart disease and diabetes.

And there are dozens of studies showing that primarily plant-based omnivorous diets reduce the risk of heart disease and diabetes.

This study is fully consistent with those studies.

The Bottom Line

A recent study put identical twins on either a healthy vegan diet (only plant foods) or a healthy omnivorous diet (both animal and plant foods) for 8 weeks. At the end of 8 weeks:

LDL-cholesterol was reduced by 12% for the twin on the vegan diet, while it remained unchanged for the twin on the omnivorous diet.

The fasting insulin level was reduced by 21% for the twin on the vegan diet, while it remained unchanged for the twin on the omnivorous diet. This suggests the twin on the vegan diet was experiencing improved blood sugar control after just 8 weeks.

The twin on the vegan diet lost 4 pounds in 8 weeks, while weight remained the same for the twin on the omnivorous diet. This occurred even though neither twin was instructed to eat less or to lose weight. It is most likely a consequence of the lower caloric density of the vegan diet.

The changes in LDL-cholesterol and fasting insulin were remarkable because none of the twins in this study had elevated LDL-cholesterol or problems with blood sugar control at the beginning of the study.

For more information on the pros and cons of this 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.

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My posts and “Health Tips From the Professor” articles carefully avoid claims about any brand of supplement or manufacturer of supplements. However, I am often asked by representatives of supplement companies if they can share them with their customers.

My answer is, “Yes, as long as you share only the article without any additions or alterations. In particular, you should avoid adding any mention of your company or your company’s products. If you were to do that, you could be making what the FTC and FDA consider a “misleading health claim” that could result in legal action against you and the company you represent.

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

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About The Author

Dr. Chaney has a BS in Chemistry from Duke University and a PhD in Biochemistry from UCLA. He is Professor Emeritus from the University of North Carolina where he taught biochemistry and nutrition to medical and dental students for 40 years. Dr. Chaney won numerous teaching awards at UNC, including the Academy of Educators “Excellence in Teaching Lifetime Achievement Award”. Dr Chaney also ran an active cancer research program at UNC and published over 100 scientific articles and reviews in peer-reviewed scientific journals. In addition, he authored two chapters on nutrition in one of the leading biochemistry text books for medical students.

For the past 35 years Dr. Chaney and his wife Suzanne have been helping people improve their health holistically through a combination of good diet, exercise, weight control and appropriate supplementation.

Can Vegans Have Strong Bones?

December 14, 2021 by Dr. Steve Chaney

When Is Supplementation Important?

Author: Dr. Stephen Chaney

Whole food, vegan diets are incredibly healthy.

They have a low caloric density, which can help you maintain a healthy weight.

They are anti-inflammatory, which can help prevent all the “itis” diseases.

They are associated with reduced risk of diabetes, heart disease, and some cancers.

Plus a recent study has shown that vegans age 60 and older require 58% fewer medications than people consuming non-vegetarian diets.

But vegan diets are incomplete, and as I have said previously, “We have 5 food groups for a reason”. Vegan diets tend to be low in several important nutrients, but for the purposes of this article I will focus on calcium and vitamin D. Vitamin D is a particular problem for vegans because mushrooms are the only plant food that naturally contain vitamin D, and the vitamin D found in mushrooms is in the less potent D2 form.

Calcium and vitamin D are essential for strong bones, so it is not surprising that vegans tend to have less dense bones than non-vegans. But are these differences significant? Are vegans more likely to have broken bones than non-vegans?

That is the question the current study (DL Thorpe et al, American Journal of Clinical Nutrition, 114: 488-495, 2021) was designed to answer. The study also asked whether supplementation with calcium and vitamin D was sufficient to reduce the risk of bone fracture in vegans.

How Was This Study Done?

The data for this study were obtained from the Adventist Health Study-2. This is a study of ~96,000 members of the Seventh-day Adventist Church in North America who were recruited into the study between 2002 and 2007 and followed for up to 15 years.

Seventh-day Adventists are a good group for this kind of study because the Adventist church advocates a vegan diet consisting of legumes, whole grains, nuts, fruits, and vegetables. However, it allows personal choice, so a significant number of Adventists choose modifications of the vegan diet and 42% of them eat a nonvegetarian diet.

This diversity allows studies of the Adventist population to not only compare a vegan diet to a nonvegetarian diet, but also to compare it with the various forms of vegetarian diets.

This study was designed to determine whether vegans had a higher risk of hip fractures than non-vegan Adventists. It was performed with a sub-population of the original study group who were over 45 years old at the time of enrollment and who were white, non-Hispanic. The decision to focus on the white non-Hispanic group was made because this is the group with the highest risk of hip fractures after age 45.

At enrollment into the study all participants completed a comprehensive lifestyle questionnaire which included a detail food frequency questionnaire. Based on the food frequency questionnaire participants were divided into 5 dietary patterns.

Vegans (consume only a plant-based diet).
Lacto-ovo-vegetarian (include dairy and eggs in their diet).
Pesco-vegetarians (include fish as well as dairy and eggs in their diet).
Semi-vegetarians (include fish and some non-fish meat (primarily poultry) as well as dairy and eggs in their diet).
Non-vegetarians (include all meats, dairy, and eggs in their diet). Their diet included 58% plant protein, which is much higher than the typical American diet, but much less than the 96% plant protein consumed by vegans.

Every two years the participants were mailed follow-up questionnaires that included the question, “Have you had any fractures (broken bones) of the wrist or hip after 2001? Include only those that came from a fall or minor accident.”

Can Vegans Have Strong Bones?

The results of this study were striking.

When men and women were considered together there was an increasing risk of hip fracture with increasing plant-based diet patterns. But the differences were not statistically significant.

However, the effect of diet pattern on the risk of hip fractures was strongly influenced by gender.

- For men there was no association between diet pattern and risk of hip fractures.

- For women there was an increased risk of hip fractures across the diet continuum from nonvegetarians to vegans, with vegan women having a 55% higher risk of hip fracture than nonvegetarian women.

The increased risk of hip fractures in vegan women did not appear to be due to other lifestyle differences between vegan women and nonvegetarian women. For example:

- Vegan women were almost twice as likely to walk more than 5 miles/week than nonvegetarian women.

- Vegan women consumed more vitamin C and magnesium, which are also important for strong bones, than nonvegetarian women.

- Vegan women got the same amount of daily sun exposure as nonvegetarian women.

The effect of diet pattern on the risk of hip fractures was also strongly influenced by supplementation with calcium and vitamin D.

- Vegan women who did not supplement with calcium and vitamin D had a 3-fold higher risk of hip fracture than nonvegetarian women who did not supplement.

- Vegan women who supplemented with calcium and vitamin D (660 mg/day of calcium and 13.5 mcg/day of vitamin D on average) had no increased risk of hip fracture compared to nonvegetarian women who supplemented with calcium and vitamin D.

In interpreting this study there are a few things we should note.

- The authors attributed the lack of an effect of a vegan diet on hip fracture risk in men to anatomical and hormonal differences that result in higher bone density for males.

- In addition, because the average age of onset of osteoporosis is 15 years later for men than for women, this study may not have been adequately designed to measure the effect of a vegan diet on hip fracture in men. Ideally, the study should have enrolled participants who were at least 60 or older if it wished to detect an effect of diet on hip fractures in men.

- Finally, because the study enrolled only white, non-Hispanic women into the study, it does not tell us the effect of a vegan diet on women of other ethnicities. Once again, if there is an effect, it would likely occur at an older age than for white, non-Hispanic women.

The authors concluded, “Without combined supplementation of both vitamin D and calcium, female vegans are at high risk of hip fracture. However, with supplementation the excessive risk associated with vegans disappeared.”

Simply put, vegan diets are very healthy. They reduce the risk of heart disease, high blood pressure, diabetes, some cancers, and inflammatory diseases.

However, the bad news is:

Vegan women have a lower intake of both calcium and vitamin D than nonvegetarian women.

Vegan women have lower bone density than nonvegetarian women.

Vegan women have a higher risk of hip fracture than nonvegetarian women.

The good news is:

Supplement with calcium and vitamin D eliminates the increased risk of hip fracture for vegan women compared to nonvegetarian women.

When Is Supplementation Important?

Much of the controversy about supplementation comes from a “one size fits all” mentality. Supplement proponents are constantly proclaiming that everyone needs nutrient “X”. And scientists are constantly proving that everyone doesn’t need nutrient “X”. No wonder you are confused.

I believe in a more holistic approach for determining whether certain supplements are right for you. Dietary insufficiencies, increased need, genetic predisposition, and diseases all affect your need for supplementation, as illustrated in the diagram on your left. I have discussed this approach in more detail in a previous issue (https://www.chaneyhealth.com/healthtips/do-you-need-supplements/) of “Health Tips From the Professor”.

But today I will just focus on dietary insufficiencies.

Most Americans consume too much highly processed fast and convenience foods. According to the USDA, we are often getting inadequate amounts of calcium, magnesium, and vitamins A, D, E and C. Iron is also considered a nutrient of concern for young children and pregnant women.

According to a recent study, regular use of a multivitamin is sufficient to eliminate most these deficiencies except for calcium, magnesium, and vitamin D. A well-designed calcium, magnesium and vitamin D supplement may be needed to eliminate those deficiencies.

In addition, intake of omega-3 fatty acids from foods appears to be inadequate in this country. Recent studies have found that American’s blood levels of omega-3s are among the lowest in the world and only half of the recommended level for reducing the risk of heart disease. Therefore, omega-3 supplementation is often a good idea.

Ironically, “healthy” diets are not much better when it comes to dietary insufficiencies. That is because many of these diets eliminate one or more food groups. And, as I have said previously, we have 5 food groups for a reason.

Take the vegan diet, for example:

There is excellent evidence that whole food, vegan diets reduce the risk of heart disease, diabetes, inflammatory diseases, and some cancers. It qualifies as an incredibly healthy diet.

However, vegan diets exclude dairy and meats. They are often low in protein, vitamin B12, vitamin D, calcium, iron, zinc, and long chain omega-3 fatty acids. Supplementation with these nutrients is a good idea for people following a vegan diet.

The study described above goes one step further. It shows that supplementation with calcium and vitamin D may be essential for reducing the risk of hip fractures in vegan women.

There are other popular diets like Paleo and keto which claim to be healthy even though there are no long-term studies to back up that claim.

However, those diets are also incomplete. They exclude fruits, some vegetables, grains, and most plant protein sources.

A recent study reported that the Paleo diet increased the risk of calcium, magnesium, iodine, thiamin, riboflavin, folate, and vitamin D deficiency. The keto diet is even more restrictive and is likely to create additional deficiencies.

And it is not just nutrient deficiencies that are of concern when you eliminate plant food groups. Plants also provide a variety of phytonutrients that are important for optimal health and fiber that supports the growth of beneficial gut bacteria.

In short, the typical American diet has nutrient insufficiencies. “Healthy” diets that eliminate food groups also create nutrient insufficiencies. Supplementation can fill those gaps.

The Bottom Line

Vegan diets are incredibly healthy, but:

They eliminate two food groups – dairy, and meat protein.

They have lower calcium and vitamin D intake than nonvegetarians.

They also have lower bone density than nonvegetarians.

The study described in this article was designed to determine whether vegans also had a higher risk of bone fractures. It found:

Vegan women who don’t supplement have a 3-fold higher risk of hip fracture than nonvegetarian women.

The increased risk of hip fractures in vegan women did not appear to be due to other lifestyle differences between vegan women and nonvegetarian women.

Supplementation with calcium and vitamin D (660 mg/day of calcium and 13.5 mcg/day of vitamin D on average) eliminated the difference in risk of hip fracture between vegan women and nonvegetarian women.

In the article above I discuss the importance of supplementation in assuring diets are nutritionally complete.

In short, the typical American diet has nutrient insufficiencies. “Healthy” diets that eliminate food groups also create nutrient insufficiencies. Supplementation can fill those gaps.

For more details about the study and a discussion of which supplements may be needed to assure nutritionally adequate diets, 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.

Are Vegan Diets Bad For Your Bones?

May 25, 2021 by Dr. Steve Chaney

The Secrets To A Healthy Vegan Diet

Author: Dr. Stephen Chaney

Osteoporosis is a debilitating and potentially deadly disease associated with aging. It affects 54 million Americans. It can cause debilitating back pain and bone fractures. 50% of women and 25% of men over 50 will break a bone due to osteoporosis. Hip fractures in the elderly due to osteoporosis are often a death sentence.

As I discussed in a previous issue of “Health Tips From The Professor”, a “bone-healthy lifestyle requires 3 essentials – calcium, vitamin D, and weight bearing exercise. If any of these three essentials is presence in inadequate amounts, you can’t build healthy bones. In addition, other nutrients such as protein, magnesium, zinc, vitamin B12, and omega-3 fatty acids may play supporting roles.

Vegan and other plant-based diets are thought to be very healthy. They decrease the risk of heart disease, diabetes, and some cancers. However, vegan diets tend to be low in calcium, vitamin D, zinc, vitamin B12, protein, and omega-3 fatty acids. Could vegan diets be bad for your bones?

A meta-analysis of 9 studies published in 2009 (LT Ho-Pham et al, American Journal of Clinical Nutrition 90: 943-950, 2009) reported that vegans had 4% lower bone density than omnivores, but concluded this difference was “not likely to be clinically relevant”.

However, that study did not actually compare bone fracture rates in vegans and omnivores. So, investigators have followed up with a much larger meta-analysis (I Iguacel et al, Nutrition Reviews 77, 1-18, 2019) comparing both bone density and bone fracture rates in vegans and omnivores.

How Was This Study Done?

The investigators searched the literature for all human clinical studies through November 2017 that compared bone densities and frequency of bone fractures of people consuming vegan and/or vegetarian diets with people consuming an omnivore diet.

Vegan diets were defined as excluding all animal foods.

Vegetarian diets were defined as excluding meat, poultry, fish, seafood, and flesh from any animal but including dairy foods and/or eggs. [Note: The more common name for this kind of diet is lacto-ovo vegetarian, but I will use the author’s nomenclature in this review.]

Omnivore diets were defined as including both plant and animal foods from every food group.

The investigators ended up with 20 studies that had a total of 37,134 participants. Of the 20 studies, 9 were conducted in Asia (Taiwan, Vietnam, India, Korea, and Hong-Kong), 6 in North America (the United States and Canada), and 4 were conducted in Europe (Italy, Finland, Slovakia, and the United Kingdom).

Are Vegan Diets Bad For Your Bones?

Here is what the investigators found:

Bone density: The clinical studies included 3 different sites for bone density measurements – the lumbar spine, the femoral neck, and the total body. When they compared bone density of vegans and vegetarians with the bone density of omnivores, here is what they found:

Lumbar spine:

- Vegans and vegetarians combined had a 3.2% lower bone density than omnivores.

- The effect of diet was stronger for vegans (7% decrease in bone density) than it was for vegetarians (2.3% decrease in bone density).

Femoral neck:

- Vegans and vegetarians combined had a 3.7% lower bone density than omnivores.

- The effect of diet was stronger for vegans (5.5% decrease in bone density) than it was for vegetarians (2.5% decrease in bone density).

Whole body:

- Vegans and vegetarians combined had a 3.2% lower bone density than omnivores.

- The effect of diet was statistically significant for vegans (5.9% decrease in bone density) but not for vegetarians (3.5% decrease in bone density). [Note: Statistical significance is not determined by how much bone density is decreased. It is determined by the size of the sample and the variations in bone density among individuals in the sample.]

Bone Fractures: The decrease in bone density of vegans in this study was similar to that reported in the 2009 study I discussed above. However, rather than simply speculating about the clinical significance of this decrease in bone density, the authors of this study also measured the frequency of fractures in vegans, vegetarians, and omnivores. Here is what they found.

Vegans and vegetarians combined had a 32% higher risk of bone fractures than omnivores.

The effect of diet on risk of bone fractures was statistically significant for vegans (44% higher risk of bone fracture) but not for vegetarians (25% higher risk of bone fractures).

These data suggest the decreased bone density in vegans is clinically significant.

The authors concluded, “The findings of this study suggest that both vegetarian and vegan diets are associated with lower bone density compared with omnivorous diets. The effect of vegan diets on bone density is more pronounced than the effect of vegetarian diets, and vegans have a higher fracture risk than omnivores. Both vegetarian and vegan diets should be appropriate planned to avoid dietary deficiencies associated with bone health.”

The Secrets To A Healthy Vegan Diet

The answer to this question lies in the last statement in the author’s conclusion, “Both vegetarian and vegan diets should be appropriate planned to avoid dietary deficiencies associated with bone health.”

The problem also lies in the difference between what a nutrition expert considers a vegan diet and what the average consumer considers a vegan diet. To the average consumer a vegan diet is simply a diet without any animal foods. What could go wrong with that definition? Let me count the ways.

Sugar and white flour are vegan. A vegan expert thinks of a vegan diet as a whole food diet – primarily fruits, vegetables, whole grains, beans, nuts, and seeds. A vegan novice includes all their favorites – sodas, sweets, and highly processed foods. And that may not leave much room for healthier vegan foods.

2) Big Food, Inc is not your friend. Big Food tells you that you don’t need to give up the taste of animal foods just because you are going vegan. They will just combine sugar, white flour, and a witch’s brew of chemicals to give you foods that taste just like your favorite meats and dairy foods. The problem is these are all highly processed foods. They are not healthy. Some people call them “fake meats” or “fake cheeses”. I call them “fake vegan”.

If you are going vegan, embrace your new diet. Bean burgers may not taste like Big Macs, but they are delicious. If need other delicious vegan recipe ideas, I recommend the website https://forksoverknives.com.

3) A bone healthy vegan diet is possible, but it’s not easy. Let’s go back to the author’s phrase “…vegan diets should be appropriate planned to avoid dietary deficiencies associated with bone health.” A vegan expert will do the necessary planning. A vegan novice will assume all they need to do is give up animal foods.

As I said earlier, vegan diets tend to be low in calcium, vitamin D, zinc, vitamin B12, protein, and omega-3 fatty acids. Let’s look at how a vegan expert might plan their diet to get enough of those bone-healthy nutrients.

- Calcium. The top plant sources of calcium are leafy greens and soy foods at about 100-250 mg (10-25% of the DV) of calcium per serving. Some beans and seeds are moderately good sources of calcium. Soy foods are a particularly good choice because they are a good source of calcium and contain phytoestrogens that stimulate bone formation.

A vegan expert makes sure they get these foods every day and often adds a calcium supplement.

- Protein. Soy foods, beans, and some whole grains are the best plant sources of protein.

It drives me crazy when a vegan novice tells me they were told they can get all the protein they need from broccoli and leafy greens. That is incredibly bad advice.

A vegan expert makes sure they get soy foods, beans, and protein-rich grains every day and often adds a protein supplement.

- Zinc. There are several plant foods that supply around 20% the DV for zinc including lentils, oatmeal, wild rice, squash and pumpkin seeds, quinoa, and black beans.

A vegan expert makes sure they get these foods every day and often adds a multivitamin supplement containing zinc.

- Vitamin D and vitamin B12. These are very difficult to get from a vegan diet. Even vegan experts usually rely on supplements to get enough of these important nutrients.

4) Certain vegan foods can even be bad for your bones. I divide these into healthy vegan foods and unhealthy “vegan” foods.

- Healthy vegan foods that can be bad for your bones include.

- - Pinto beans, navy beans, and peas because they contain phytates.

- - Raw spinach & swiss chard because they contain oxalates.

- - Both phytates and oxalates bind calcium and interfere with its absorption.

- - These foods can be part of a healthy vegan diet, but a vegan expert consumes them in moderation.

- Unhealthy “vegan” foods that are bad for your bones include sodas, salt, sugar, and alcohol.

- - The mechanisms are complex, but these foods all tend to dissolve bone.

- - A vegan expert minimizes them in their diet.

5) You need more than diet for healthy bones. At the beginning of this article, I talked about the 3 essentials for bone formation – calcium, vitamin D, and exercise. You can have the healthiest vegan diet in the world, but if you aren’t getting enough weight bearing exercise, you will have low bone density. Let me close with 3 quick thoughts:

- None of the studies included in this meta-analysis measured how much exercise the study participants were getting.

- The individual studies were generally carried out in industrialized countries where many people get insufficient exercise.

- The DV for calcium in the United States is 1,000-1,200 mg/day for adults. In more agrarian societies dietary calcium intake is around 500 mg/day, and osteoporosis is almost nonexistent. What is the difference? These are people who are outside (vitamin D) doing heavy manual labor (exercise) in their farms and pastures every day.

In summary, a bone healthy vegan lifestyle isn’t easy, but it is possible if you work at it.

The Bottom Line

A recent meta-analysis asked two important questions about vegan diets.

Do vegans have lower bone density than omnivores?

2) Is the difference in bone density clinically significant? Are vegans more likely to suffer from bone fractures?

The study found that:

Vegans had 5.5%–7% lower bone density than omnivores depending on where the bone density was measured.

Vegans were 44% more likely to suffer from bone fractures than omnivores.

The authors of the study concluded, ““The findings of this study suggest that…vegan diets are associated with lower bone density compared with omnivorous diets, and vegans have a higher fracture risk than omnivores…Vegan diets should be appropriate planned to avoid dietary deficiencies associated with bone health.”

In evaluating the results of this study, I took a detailed look at the pros and cons of vegan diets and concluded, “A bone healthy vegan lifestyle isn’t easy, but it is possible if you work at it.”

For more details about study and my recommendations for a bone healthy vegan lifestyle 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.

Do Vegetarians Have A Higher Risk Of Stroke?

December 10, 2019 by Dr. Steve Chaney

What Are The Benefits And Risks Of A Vegetarian Diet?

Vegetarian diets are thought to be very healthy. Clinical studies show that vegetarian diets are associated with decreased risk of heart disease, diabetes, cancer, Alzheimer’s disease, and much more. What’s not to like?

That’s why the recent headlines claiming that vegetarian diets may increase the risk of stroke were so surprising. Advocates of meat-heavy diets like the Paleo and Keto diets were overjoyed. These results fit in with their view that we should be eating more meat protein and less plant protein. Nutrition experts, on the other hand, were asking: “What’s going on?” “How can this be?”

Those of you who are regular readers of “Health Tips From the Professor” know that I am an advocate of primarily plant-based diets. Thus, I felt a responsibility to analyze the study (TYN Tong et al, British Medical Journal, 366: 14897, 2019) behind the headlines impartially and give you, my readers, clear guidelines for the healthiest possible diet.

How Was The Study Done?

Let’s start with some background:

· A major study called the “European Prospective Investigation Into Cancer and Nutrition” (EPIC) has been underway since the early 90’s.

· The British component of this study is known as the EPIC-Oxford study.

· While the study has “cancer” in it’s title, it was designed to measure the impact of nutrition on many diseases. In this case, the study focused on heart disease and stroke.

· Finally, enrollment in the EPIC-Oxford study was designed to give a high proportion of vegetarians in the study population.

The EPIC-Oxford study enrolled 48,188 participants with no previous history of heart disease, stroke, or angina between 1993 and 2001. A detailed diet analysis was performed upon enrollment and again in 2010. Based on these data, the participants were divided into three groups:

1) Meat eaters (24,428 participants).

2) Fish eaters (7,506 participants). This group consumed fish but no other meats. People with this eating style are often called pescatarians.

3) Vegetarians (16, 254 participants). This group consumed dairy and eggs, but no meat. People with this eating style are often called lacto-ovo vegetarians.

4) The diet analysis also identified participants who were vegans (no animal foods). However, this group was too small to obtain statistically significant comparisons, so they were included with the lacto-ovo vegetarians in the vegetarian group.

Data on heart disease and stroke were obtained from the UK’s health service records through March 31st, 2016. The average time of follow-up for participants in the study was 18.1 years.

Without going into greater detail, this was a very large, well-designed study.

How Did The Diets Of The Three Groups Compare?

The first step in analyzing this study is to ask how the diets of the three groups compared.

Compared to meat eaters, the fish eaters consumed:

· No meat other than fish.

· Slightly less milk and significantly more cheese.

· Slightly more fruits & vegetables.

· Significantly more legumes & soy foods, nuts & nut butter.

· Slightly more carbohydrate and slightly less protein.

· Slightly less saturated fat and slightly more polyunsaturated fat.

· Around 260 fewer calories per day.

Compared to fish eaters, the vegetarians consumed:

· No meat.

· Slightly less milk & cheese.

· About the same amount of fruits & vegetables.

· Significantly more legumes & soy foods, nuts & nut butter.

· Slightly more carbohydrate and slightly less protein.

· About the same saturated and polyunsaturated fat.

· Around 125 fewer calories per day.

On average, the vegetarians consumed about 1 cup of milk and one ounce of cheese per day. The fish eaters consumed 1.4 ounces of fish per day.

In terms of comparisons:

· The biggest differences were between the fish eaters and the meat eaters. It would be fair to say that the fish eaters consumed a primarily plant-based diet with added fish and dairy.

· The biggest differences between the vegetarians and fish eaters was that the fish eaters got a significant percentage of their protein from fish, while the vegetarians got a significant amount of their protein from plant sources. Otherwise, their diets were fairly comparable.

Finally, the 10-year follow-up diet analysis showed that most participants stuck with their initial diet.

Do Vegetarians Have A Higher Risk Of Stroke?

Now, for the study results:

· Compared to meat eaters, fish eaters had 13% lower risk of heart disease, and vegetarians had a 22% lower risk of heart disease.

o For vegetarians this corresponds to 10 fewer cases of heart disease per 1,000 people over 10 years.

· Compared to meat eaters, vegetarians had a 20% higher risk of stroke, mostly due to an increased risk for hemorrhagic stroke.

o For vegetarians this corresponds to 3 additional cases of stroke per 1,000 people over 10 years.

· The risk of stroke was essentially identical for fish eaters and meat eaters.

In many other aspects, vegetarians were healthier than meat-eaters. For example, they:

· Weighed less.

· Had lower blood pressure.

· Had lower total and LDL cholesterol.

· Were less likely to have developed diabetes during the study.

· Were less likely to have required long-term treatment for other illnesses.

What Are The Strengths And Weaknesses Of The Study?

The strength of this study is obvious. It was a very large, well-designed study. The study also lasted a long time. Participants in the study were followed for almost 20 years.

There are two clear weaknesses, however:

1) Numerous previous studies have confirmed that vegetarian diets decrease heart disease risk by about 20%. However, none of those previous studies have reported an increase in stroke risk. This study is an outlier.

2) There is no clear mechanism that explains why a vegetarian diet might increase stroke risk. Based on previous observations that statin drugs increase the risk of hemorrhagic stroke, the authors suggested the increased stroke risk might be due to lowered LDL cholesterol levels.

This mechanism is speculative at present. Furthermore, if true, it would suggest that any intervention (drug or nutritional) that lowers LDL cholesterol would increase stroke risk.

In the words of the authors:

· “The present study has shown that British adults who were fish eaters or vegetarians had lower risks of heart disease than meat eaters, but that vegetarians had higher risks of stroke.

· Future work should include further measurements…to identify which factors may cause the observed associations. [In plain English: We need to understand how vegetarian diets might increase stroke risk before we put too much weight on the results of this study.]

· Additional studies in other large-scale cohorts with a high proportion of non-meat eaters are needed to confirm the generalizability of these results and assess their relevance for clinical practice and general health.” [In plain English: More studies are needed to confirm this observation before we start changing our recommendations about what constitutes a healthy diet.]

What Are The Benefits And Risks Of A Vegetarian Diet?

Let’s assume for a minute that the results of this study are accurate and take a closer look at the benefits and risks of a vegetarian diet. Here is my assessment:

1) This report is troubling, but it may not be correct. The association of vegetarian diets with a slight increase in stroke risk has only been seen in a single study. This study needs to be confirmed before we become too concerned about vegetarianism increasing stroke risk.

2) On the balance, vegetarian diets should still be considered very healthy. They lower the risk of heart disease, high blood pressure, diabetes, some cancers, inflammatory diseases and possibly even Alzheimer’s disease.

3) However, I have often said that we have 5 food groups for a reason, and it is not a good idea to eliminate whole food groups. In the past, I have used that statement to critique diets that leave out important plant food groups like fruit, whole grains, and legumes.

If the data on stroke risk in this study are true, it suggests it might also not be a good idea to leave out meat. However, you don’t need a lot of meat. The fish eaters in this study were consuming 1.4 ounces of fish per day. That was enough to eliminate the increased risk of stroke.

4) In addition, you don’t have to be a vegan purist to enjoy the health benefits of a primarily plant-based diet. As I describe in my book, “Slaying The Food Myths”, primarily plant-based diets ranging from vegan through pescatarian and semi-vegetarian to Mediterranean and DASH are all incredibly healthy.

I personally follow a semi-vegetarian diet but often recommend Mediterranean and DASH diets to others because they are the easiest primarily plant-based diets for the average American to follow.

5) Finally, if you have a family history, or are at high risk, of stroke, I recommend prudence until we know more. You may wish to adopt a version of primarily plant-based diets that incorporates some meat (That would be in the pescatarian to DASH range of primarily plant-based diets). Your heart will thank you, and you won’t increase your risk of stroke.

The Bottom Line

A recent study enrolled 48,188 British adults; divided them into meat eaters, fish eaters, and vegetarians; followed them for 18.1 years; and looked at their risk for heart disease and stroke. The results were:

· Compared to meat eaters, fish eaters had 13% lower risk of heart disease, and vegetarians had a 22% lower risk of heart disease.

o For vegetarians this corresponds to 10 fewer cases of heart disease per 1,000 people over 10 years.

· Compared to meat eaters, vegetarians had a 20% higher risk of stroke, mostly due to an increased risk for hemorrhagic stroke.

o For vegetarians this corresponds to 3 additional cases of stroke per 1,000 people over 10 years.

· The risk of stroke was essentially identical for fish eaters and meat eaters.

Here is my perspective:

4) In addition, you don’t have to be a vegan purist to enjoy the health benefits of a primarily plant-based diet. As I describe in my book, “Slaying The Food Myths” (https://slayingthefoodmyths.com), primarily plant-based diets ranging from vegan through pescatarian (the fish eaters in this study) and semi-vegetarian to Mediterranean and DASH are all incredibly healthy.

I personally follow a semi-vegetarian diet but often recommend Mediterranean and DASH diets to others because they are the easiest primarily plant-based diets for the average American to follow.

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.