Do Vegetarians Have A Higher Risk Of Stroke?

What Are The Benefits And Risks Of A Vegetarian Diet?

Vegetarian FoodsVegetarian 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?

clinical-studyLet’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?

balance scaleThe 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?

strokeNow, 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?

strengths-weaknessesThe 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?

benefits-risksLet’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:

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” (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.

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.

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.

Do Vegetarians Live Longer?

What Are The Health Benefits Of A Vegetarian Diet?

Author: Dr. Stephen Chaney

“Vegetarians don’t live longer, it just seems that way.” Many of you have probably heard that joke, but is it true? Are vegetarians healthier? Do vegetarians live longer? Is meat going to kill you? Let’s take a deep dive into the pros and cons of vegetarianism.

What Is Vegetarianism?

Vegetarianism encompasses a wide range of diets. At one extreme is the vegan diet. Vegans eat only plant derived foods. They don’t eat fish, meat, milk, eggs, or honey. It also goes without saying they eat only whole foods (whole grains, plant proteins, and fruits & vegetables) and avoid things like sodas, sugary foods, junk foods, and convenience foods. The most extreme form of veganism, popularized by such recent movies as “Eating You Alive” and “What the Health,” also eliminates all oils. This keeps fat at <10% of total calories.

do vegetarians live longerTo avoid confusion, I will refer to this as a “very low fat vegan diet.”  I will use the term “vegan diet” to refer to the more common veganism that includes vegetable oils in the diet. The vegan diet is still 100% plant based. It is also still relatively low in fat, generally in the 20-30% range. Since the fat comes from plants, it is predominantly the healthy monounsaturated and polyunsaturated fats.

Lacto-ovo vegetarians add low fat dairy foods and eggs to a plant based diet. The Ornish diet is a modified lacto-ovo vegetarian diet that also eliminates all oils and keeps fat at <10% of calories. Pesco-vegetarians add fish to a plant based diet, and semi-vegetarians add limited amounts of meat to a plant based diet.

Can Vegetarian Diets Reverse Atherosclerosis?

Let me start with studies on the very low fat vegan and Ornish diets. In addition to the diet, both programs emphasize regular exercise and stress reduction practices. Adherents to both plans generally achieve a serum total cholesterol of 150 or less. The Ornish diet and lifestyle program was designed to reduce the risk of cardiovascular disease, and it has been very well studied from that perspective. In studies of patients with severe atherosclerosis (clogged arteries) for periods of up to 5 years, the Ornish program results in a significant reduction in the degree of atherosclerosis (unclogs the arteries), inflammation, cardiac events (heart attack, stroke, etc.), and cardiac deaths (H.S. Dod et al, American Journal of Cardiology, 105: 362-367, 2010 ). vegetarianism good for the heartStudies with the very low fat vegan diet are more limited, but suggest that it also reverses atherosclerosis and reduces cardiac deaths (C.B. Esselstyn et al, Journal of Family Practice, 63: 356-364, 2014 ).

Before moving on to other forms of vegetarianism, let me make the point that these are the only diets that have been shown to actually reverse atherosclerosis. That is a big deal.

 

The Seventh-Day Adventist Studies

Perhaps the largest group of studies on the health effects of vegetarians has been conducted on the Seventh-day Adventist population located in Southern California. Seventh-day Adventists believe that “God calls us to care for our bodies, treating them with the respect a divine creation deserves.” 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 lacto-ovo vegetarian, pesco-vegetarian, or semi-vegetarian diets.

That diversity has not only allowed studies of the Adventist population to not only compare a vegetarian diet to the standard American diet of the non-Adventist population living in the same area, but also to compare the various forms of vegetarian diets. There are dozens of published studies and several reviews on this topic. I will cite only the most recent review here (L.T. Le  and J. Sabate, Nutrients, 6: 2131-2147, 2014 ), but I will provide a complete list in my upcoming book.

This and other reviews have concluded that vegetarians weigh less, have less inflammation, have lower cholesterol levels and have lower risk of diabetes, heart disease, and hypertension than non-vegetarians. When we compare the various forms of vegetarianism, vegan diets appear to offer somewhat greater protection against obesity, hypertension, diabetes, and cardiovascular mortality than lacto-ovo and semi-vegetarian diets. The health benefits of vegetarian diets also seem to be somewhat greater for men than for women. One might speculate that might be because the average American male has a worse diet than the average American female. So, when men adopt a vegetarian diet, it may represent a greater improvement.

The reviews also looked at the nutritional adequacy of vegetarian diets. Vegetarian diets in general are very rich in antioxidants, most B vitamins, and polyphenols. Nutrients of concern for vegan diets are vitamin B12, vitamin D, calcium, iron, zinc, and long chain omega-3 fatty acids. Of those, vitamin B12 and long-chain omega-3 fatty acids are the ones most likely to require supplementation. Adequate levels of the other nutrients can be achieved by a well-designed vegan diet.

I would add protein to the list. Don’t misunderstand me. It is possible to get adequate protein on a vegetarian diet that includes beans and other legumes as a protein source. However, vegan advocates have been telling people they get all the protein they need from broccoli and other vegetables. That is incredibly bad advice, especially for seniors who are likely to suffer from sarcopenia (age related loss of muscle mass). Broccoli only provides 3 grams of protein per serving. You would need 15 servings to meet the protein RDA for women and almost 19 servings for men. Unfortunately, I often run across seniors who think they are getting all the protein they need from green salads and steamed vegetables. The bad advice from vegan advocates may be condemning them to unnecessary frailty in their old age.

What about the health claims of the low carbohydrate diets? Most of those “health benefits” are inferred from changes in blood parameters that occur over the first few weeks or months someone adopts those diets. There are no long-term data showing that low carbohydrate diets reduce the prevalence of diabetes, heart disease or cancer. Moreover, the few studies that compare low carbohydrate and vegetarian diets suggest the vegetarian diet is superior. For example, a recent study (M. Miller et al, Journal of the American Dietetic Association, 109: 713-717, 2009 ) compared the Atkins diet (the granddaddy of the low carb diets) with the Ornish diet. People on the low-fat Ornish diet had significantly lower LDL-cholesterol, apoB, and C-reactive protein (a marker of inflammation) and had better arterial function than people on the high fat Atkins diet.

Do Vegetarians Live Longer?

What about the original question. Do vegetarians live longer? The answer isn’t clear. The Adventist Health Studies have reported that Adventist men live 6-7 years longer and Adventist women live ~4 years longer than their non-Adventist neighbors. However, the Adventist population may have other characteristics that contribute to their longevity. I will cover that in the section on “Blue Zones” in my upcoming book. In contrast, a very recent Australian study(S. Mihrshahi et al, Preventive Medicine, 97: 1-7, 2017 ) concluded that all-cause mortality was virtually identical for vegetarians and non-vegetarians. However, the authors of this study speculated that vegetarians in Australia have become less healthy in recent years because they are now consuming more high-sugar, processed “vegetarian” foods. Remember what I said about “Big Food Inc.” not being your friend.

What Does This Mean For You?

do vegetarians live longer or notThere are a few simple take-home messages from the research on the various forms of a vegetarian diet:

  • The Ornish diet and the very low fat vegan diet are the only diets shown to reverse atherosclerosis. If you have serious heart disease and would like to minimize your reliance on drugs and surgery, you should consider them. You will, of course, want to let your doctor know what you are doing.
  • Vegetarians are leaner and significantly healthier than non-vegetarians.
  • Vegans are slightly healthier than lacto-ovo and semi-vegetarians, but even vegetarians who include some dairy, eggs & meat in a primarily plant-based diet are much healthier than most Americans.
  • Vegetarians may not live longer, but they do live healthier longer.

There are also several subtle, but equally important, implications from these studies:

  • You can forget the claims you must be a vegan purist to obtain any health benefits from vegetarianism.If you watch movies like “Eating You Alive” or “What the Health”, you are led to believe you will suffer terrible health consequences if you add any dairy, eggs, or meat to a vegan diet. In fact, the evidence for reversing atherosclerosis is stronger for the Ornish diet, which is a lacto-ovo-vegetarian diet, than it is for a pure vegan diet. For several other health outcomes, the vegan diet is slightly more effective, but both lacto-ovo-vegetarian and semi-vegetarian diets are much healthier than the standard American diet.
  • Vegetarian diets are whole food diets.If you start adding in processed and convenience foods, even if they are labeled “vegan,” you are likely to lose all the health benefits of a vegetarian diet.
  • You can forget claims that you get all the protein you need from vegetables like broccoli. That is incredibly bad advice which is likely to condemn seniors to unnecessary frailty in old age.
  • You can forget the claims that you must avoid carbs at all costs. The proponents of the low carb diets will tell you that recommendations to limit fat are based on a lie. They tell you that fat is good for you and carbs will cause you to gain weight, increase inflammation, and increase your risk of diabetes, heart disease, and cancer. You are told to avoid grains and any other foods containing carbohydrate, including some fruits and vegetables. The “danger” of carbohydrates is only true for the refined grains, sugary sodas and junk foods in the standard American diet. Vegetarian diets emphasize whole grains, fruits and vegetables. They are high in carbohydrate and low in fat, and they reduce weight, inflammation, diabetes, heart disease, and some cancers.
  • You can forget most claims of weight loss. Most low carb diets tout rapid initial weight loss. Unfortunately, most of that weight comes back a year or two later. Only vegetarian diets are associated with lower weight over a period of many years.

In summary, a pure vegan diet is probably the healthiest form of vegetarianism, but it is difficult to follow. Vegetarian diets that are primarily plant based, but contain small amounts of dairy, eggs, or meat are also very healthy, and may be easier for the average American to follow.

 

The Bottom Line

 

Vegetarianism encompasses a wide range of diets. The standard vegan diet is entirely plant-based. There is a very low fat version of the vegan diet that also eliminates all oils. Lacto-ovo-vegetarian diets include some dairy and eggs. Semi-vegetarian diets include some meat. The Ornish diet is a very low fat version of the lacto-ovo-vegetarian diet.

There are a few simple take-home messages from the research on the various forms of a vegetarian diet:

  • The Ornish diet and the very low fat vegan diet are the only diets shown to reverse atherosclerosis.
  • Vegetarians are leaner and significantly healthier than non-vegetarians.
  • Vegans are slightly healthier than lacto-ovo– and semi-vegetarians, but even vegetarians who include some dairy, eggs & meat in a primarily plant-based diet are much healthier than most Americans.
  • In a head to head comparison, the Ornish diet was significantly healthier than the Atkins diet.
  • Vegetarians may not live longer, but they do live healthier longer.

There are also several subtle, but equally important, implications from these studies:

  • You can forget the claims you must be a vegan purist to obtain any health benefits from vegetarianism. Primarily plant-based diets with small amounts of dairy, eggs or meat are also very healthy.
  • Vegetarian diets are whole food diets. If you start adding in processed and convenience foods, even if they are labeled “vegan,” you are likely to lose all the health benefits of a vegetarian diet.
  • You can forget claims that you get all the protein you need from vegetables like broccoli. That is incredibly bad advice which is likely to condemn seniors to unnecessary frailty in old age.
  • You can forget the claims that you must avoid carbs at all costs. That is only true for the refined grains, sugary sodas and junk foods in the standard American diet. Vegetarian diets are high in carbohydrate, low in fat, and  very healthy.
  • You can forget most claims of weight loss. Only vegetarian diets are associated with lower weight over a period of many years.

In summary, a pure vegan diet is probably the healthiest form of vegetarianism, but it is difficult to follow. Vegetarian diets that are primarily plant based, but contain small amounts of dairy, eggs, or meat are also very healthy, and may be easier for the average American to follow.

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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