Which Foods Affect Stroke Risk?

Why Is Diet And Stroke Risk So Confusing?

strokeOne day we are told vegetarian diets reduce our stroke risk. The next day we are told they increase stroke risk. It’s the same with red meat, dairy, and eggs. We keep getting mixed messages. It’s enough to make your head spin. Why is diet and stroke risk so confusing?

Part of the problem is that there are two distinct types of stroke. The technical names for them are ischemic stroke and hemorrhagic stroke.

An ischemic stroke occurs when an artery in the brain becomes blocked, shutting off blood flow and damaging part of the brain. This is usually caused by the gradual buildup of fatty deposits and cholesterol plaques in the arteries. When a blood clot forms and lodges in one of the narrowed arteries leading to the brain, an ischemic stroke occurs.

  • Ischemic strokes account for 87% of all strokes.
  • Ischemic strokes are associated with obesity, elevated cholesterol, diabetes, high blood pressure, and smoking.

A hemorrhagic stroke occurs when a weakened blood vessel bursts and bleeds into the surrounding region of the brain. Because our brains are surrounded by a protective skull, that blood has nowhere to go. Pressure from the buildup of blood damages brain cells in the vicinity of the bleed.

  • Hemorrhagic strokes account for only for only 15% of strokes but are responsible for 40% of stroke deaths.
  • The most common cause of a hemorrhagic stroke is the localized enlargement of a blood vessel due to chronic high blood pressure. This weakens the wall of the blood vessel, making it prone to rupturing.

Part of the confusion about diet and stroke risk is because many earlier studies did not distinguish between the two types of stroke.

  • If the studies just measured the incidence of stroke, the data were dominated by ischemic strokes (87% of strokes are ischemic).
  • However, if the studies focused on stroke deaths, hemorrhagic stroke made a larger contribution to the data set (40% of stroke deaths are hemorrhagic).

Fortunately, recent studies have started to focus on the effect of diet on ischemic and hemorrhagic strokes separately. However, many of those studies have been too small to accurately assess the effects of diet on hemorrhagic stroke.

The latest study (TYN Tong et al, European Heart Journal, ehaa007, published February 24, 2020) is one of the largest studies to look at the effect of diet on both kinds of stroke. It has enough patients in the hemorrhagic group to get an accurate estimate of the effect of diet on hemorrhagic stroke.

How Was The Study Done?

Clinical StudyThis study analyzed data on diet and stroke from 418,329 participants in the EPIC (European Prospective Investigation into Cancer and Nutrition). Although the study has cancer in the title, it actually investigated the effect of nutrition on multiple diseases (Presumably, the study title was chosen because EPIC is a more appealing acronym than EPID (European Prospective Investigation into Diseases and Nutrition)).

The participants were recruited from 9 European countries (Denmark, Germany, Greece, Italy, the Netherlands, Norway, Spain, Sweden, and the UK). The average age of participants was 50, and they were followed for an average of 12.7 years.

At the beginning of the study participants completed country-specific dietary and lifestyle questionnaires.

The dietary assessment was a food frequency questionnaire that asked participants about their dietary intake for the year prior to enrollment in the study. The food frequency data were used to estimate daily intake of red meat, processed meat, poultry, fish, dairy products, eggs, grains, fruits, vegetables, legumes, nuts, seeds, and dietary fiber (It measured total fiber and fiber from grains, fruits and vegetables individually).

The outcome measured was the incidence of ischemic and hemorrhagic strokes during the 12.7-year follow-up.

Which Foods Affect Stroke Risk?

Heart Healthy DietFor ischemic stroke:

  • Each 200 gram/day increase in consumption of fruits and vegetables decreased ischemic stroke risk by 13% (200 grams roughly corresponds to one large apple or one large orange without the skin).
  • Each 10 gram/day increase in consumption of fiber decreased ischemic stroke risk by 23%. Most of this decreased stroke risk was due to fiber from whole grains, fruits, and vegetables.
    • Each 4 gram/day increase in fiber from whole grains decreased ischemic stroke risk by 10%.
    • Each 4 gram/day increase in fiber from fruits and vegetables decreased ischemic stroke risk by 12%.
  • Dairy foods decreased ischemic stroke risk with the following breakdown:
    • Each cup of milk decreased ischemic stroke risk by 5%.
    • Each half cup of yogurt decreased ischemic stroke risk by 9%.
    • Each ounce of cheese decreased ischemic stroke risk by 12%.
  • Each 50 grams/day (2 ounces) of red meat increased ischemic stroke risk by 14%.
    • However, red meat was only half as likely to increase risk of ischemic stroke when the diet was also rich in fruits, vegetables, whole grains, and legumes.

For hemorrhagic stroke:

  • Each 20 gram/day increase in consumption of eggs increased hemorrhagic stroke risk by 25% (20 grams roughly corresponds to about 1/2 of a small egg or 1/3 of a jumbo egg).
  • This study did not measure the effect of salt intake on hemorrhagic stroke risk.

No other foods measured in this study had a significant effect on hemorrhagic stroke risk.

high blood pressureHowever, hemorrhagic stroke is highly associated with high blood pressure. When we look at the influence of foods on high blood pressure, here are the Harvard School of Medicine recommendations for keeping blood pressure low:

  • Eat more fish, nuts and beans in place of high-fat meats.
  • Choose fruits and vegetables instead of sugary, salty snacks and desserts.
  • Select whole grains rather than refined grains.Eat fruit instead of drinking fruit juice.
  • Use unsaturated fats like olive, canola, soybean, peanut, corn or safflower oils instead of butter, coconut oil, or palm-kernel oil.
  • Use herbs, spices, vinegar, and other low-sodium flavorings instead of salt; Choose low-sodium foods whenever possible.

Why Is Diet And Stroke Risk So Confusing?

egg confusionAs I mentioned at the start of this article, part of the reason that the headlines about diet and stroke risk are so confusing is:

  • Many studies did not distinguish between the two types of stroke.
  • Other studies were too small to reliably estimate the effect of food on hemorrhagic stroke risk.

However, there are still some unexplained inconsistencies among recently published studies. It is these inconsistencies I would like to address. For example:

1) In a recent issue of Health Tips From the Professor I reported on a major study (500,000 people followed for 8.9 years) in China. That study came to the opposite conclusion about eggs and risk of hemorrhagic than the EPIC study I discussed above. It found:

  • People consuming one egg per day had a 26% decrease in hemorrhagic stroke risk and a 28% decrease in hemorrhagic stroke deaths compared to people who never or rarely consumed eggs.

In other words, the two studies came to opposite conclusions. In the China study eggs decreased risk of hemorrhagic stroke. In the European study (EPIC) eggs increased risk of hemorrhagic stroke. The reason for this discrepancy is not clear, but one can speculate it might be explained by differences in the underlying diets of the two countries:

  • In China the diet is primarily plant-based. The addition of an egg/day may provide needed protein, fat, and cholesterol (Some cholesterol is essential. We just overdo it in this country).
  • In Europe the diet is already high in protein, saturated fat, and cholesterol. Getting more of them from eggs may not be such a good thing.

In short, if your diet is primarily plant-based, the addition of an egg/day may be a good thing. However, if your diet is already high in meat, saturated fat, and cholesterol, the addition of an egg/day may not be a good thing.

Vegan Foods2) In another recent issue of Health Tips From the Professor I reported on the EPIC-Oxford study that claimed vegetarians had 20% increased risk of hemorrhagic stroke compared to meat eaters.

Interestingly, the EPIC-Oxford study represented a very small portion (~10%) of the overall EPIC study and differed from the rest of the EPIC study in two important ways.

  • It looked at the effect of diets rather than foods on stroke risk.
  • Oxford was the only one of the 22 research centers involved in the EPIC study to invite people following a vegetarian diet to enroll in the study, so it had a much higher proportion of vegetarians than other centers that participated in the study.

The current study did not find any evidence that fruits, vegetables, nuts, seeds, beans, or whole grains influenced the risk of hemorrhagic stroke. In other words, in this much larger data set there was no evidence that the foods associated with a vegetarian diet increased hemorrhagic stroke risk.

However, most of the participants in larger EPIC study were also eating meats. They were not following a pure vegetarian diet.

As I said previously, “If the data on hemorrhagic stroke risk in the EPIC-Oxford study are true, it suggests it may not be a good idea to completely eliminate meat from our diet. However, you don’t need to add much meat to a vegetarian diet. The fish eaters in this study were consuming 1.4 ounces of fish per day. That was enough to eliminate the increased risk of hemorrhagic stroke.”

What Does This Mean For You?

Questioning WomanFor ischemic stroke (blockage of blood flow to the brain), which is the most common form of stroke, the data are clear cut:

  • Fruits, vegetables, whole grains and dairy foods are good for you. (Your mother was right.)
  • Red meat is not so good for you. However, the bad effect of red meat on ischemic stroke risk can be reduced by including plenty of fruits, vegetables, and whole grains in your diet.
  • These conclusions are consistent with multiple previous studies, and the mechanisms of these effects are well established.

For hemorrhagic stroke (bleeding from a weakened blood vessel in the brain) the data are not as clear cut.

  • If you are consuming a primarily plant-based diet, eggs appear to reduce your risk of hemorrhagic stroke.
  • If you are consuming a diet with lots of meat, saturated fat, and cholesterol, adding eggs may increase your risk of hemorrhagic stroke.
  • A vegetarian diet may increase your risk of hemorrhagic stroke. But you don’t need to add much meat to a vegetarian diet. Consuming 1.4 ounces of fish per day appears to be enough to eliminate the increased risk of hemorrhagic stroke.
  • The mechanisms of these effects of food on hemorrhagic stroke are unclear, so these conclusions may be modified by subsequent studies.

In terms of an overall take-home lesson on diet and stroke risk, my advice is: “A primarily plant-based diet is a good idea, but you don’t need to become a vegan purist. Nor do you want to follow fad diets that eliminate whole food groups. We have 5 food groups for a reason. Eliminating any of them may not be a good idea.”

The Bottom Line

A recent study examined the effect of various foods on the risk of the two major forms of stroke.

For ischemic stroke (blockage of blood flow to the brain), which is the most common form of stroke, the data are clear cut:

  • Fruits, vegetables, whole grains and dairy foods are good for you. (Your mother was right.)
  • Red meat is not so good for you. However, the bad effect of red meat on ischemic stroke risk can be reduced by including plenty of fruits, vegetables, and whole grains in your diet.
  • These conclusions are consistent with multiple previous studies, and the mechanisms of these effects are well established.

For hemorrhagic stroke (bleeding from a weakened blood vessel in the brain) the data are not as clear cut.

  • If you are consuming a primarily plant-based diet, eggs appear to reduce your risk of hemorrhagic stroke.
  • If you are consuming a diet with lots of meat, saturated fat, and cholesterol, adding eggs may increase your risk of hemorrhagic stroke.
  • A vegetarian diet may increase your risk of hemorrhagic stroke. But you don’t need to add much meat to a vegetarian diet. Consuming 1.4 ounces of fish per day appears to be enough to eliminate the increased risk of hemorrhagic stroke.
  • The mechanisms of these effects of food on hemorrhagic stroke are unclear, so these conclusions may be modified by subsequent studies.

In terms of an overall take-home lesson on diet and stroke risk, my advice is: “A primarily plant-based diet is a good idea, but you don’t need to become a vegan purist. Nor do you want to follow fad diets that eliminate whole food groups. We have 5 food groups for a reason. Eliminating any of them may not be a good idea.”

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.

 

Is The Impossible Burger Healthy For You?

Is The Impossible Burger Healthy For the Planet?

Vegan BurgerAmericans love their meat. In 2018 we averaged over 200 pounds of meat per person. If we just focus on beef, we eat about 54 pounds per year. That’s equivalent to four quarter pounders a week!

But we are also getting the message that too much meat, especially red meat, may be bad for us. Nearly 40% of us are trying to eat a more plant-based diet.

The problem is that we love the convenience of fast food restaurants, and we love our burgers. Plus, in the past the meatless burgers on the market were, in a word, disappointing. Their taste and texture left something to be desired. You really needed to be committed to a plant-based diet to eat them in place of a regular burger.

That all changed a few years ago with the introduction of the and new generation of meatless burgers – the Impossible Burger and the Beyond Burger. They had the taste and texture of a real burger, but they were completely plant-based. What wasn’t to like?

  • Both companies claimed that their meatless burgers were healthier for the planet than regular burgers. For example, Impossible Food’s mission statement is: “Animal agriculture occupies almost half the land on earth, consumes a quarter of our freshwater, and destroys our ecosystems. So, we’re doing something about it: We’re making meat using plants, so that we never have to use animals again”.
  • Neither company claims their burgers are healthier for you. However, because their burgers are plant-based, the almost universal assumption has been that they are healthier than regular burgers.

Since their introduction they have taken the world by storm. You can find them in almost every supermarket and in many of your favorite fast food restaurants. Now that they are omnipresent, it is perhaps time to step back and take a closer look at this new generation of meatless burgers. In this article, I will ask two questions:

  • Are they healthier for you than regular burgers?
  • Are they healthier for the planet than regular burgers?

For the sake of simplicity, I will focus on the Impossible Burger with occasional comparisons with the Beyond Burger. It is beyond the scope of this article to compare these burgers with the many other meatless burgers that are now starting to flood the marketplace.

What’s In The Impossible Burger?

  • When we think of a burger, the first thing we think of is protein. The Impossible Burger gets its protein from soy, while the Beyond Burger gets its protein from peas.

Coconut OilHowever, soy and pea protein don’t give you the mouth feel, flavor, red color, and texture of a beef burger.

  • The mouth feel of a burger comes from its saturated fat. Both the Impossible Burger and Beyond Burger use coconut oil as their source of saturated fat.
    • Coconut oil has gained a reputation as a “healthier” saturated fat. However, as I have discussed in my book, “Slaying The Food Myths”, we have no long term studies on the health effects of diets high in coconut oil. We don’t really know whether it is healthier than other saturated fats.
  • The taste and color of a beef burger come from its heme content. Heme does not occur in the parts of plants we eat. However, heme is involved in nitrogen fixation, so it is found in the roots of some legumes.
    • The Impossible Burger has genetically engineered yeast to produce a type of heme called leghemoglobin that is found in soy roots. The Beyond Burger uses beet juice extract and annatto for the color and unspecified “natural flavor” for the flavor.
  • To get the texture of a beef burger, both the Impossible Burger and the Beyond Burger use maltodextrin, modified food starch, and a variety of other ingredients. They are both highly processed foods.
  • Iron is another important nutrient you expect to get from a beef burger. The Impossible Burger contains 4.5 mg of iron and the Beyond Burger contains 5.4 mg of iron.
    • However, that is only part of the story. When iron is attached to a heme molecule, it is more efficiently absorbed by our bodies. Beef burgers and the Impossible Burger contain heme iron. The Beyond Burger does not.
  • In addition, the Impossible Burger adds in the vitamins, including B12, that we would expect to get from a beef burger. The Beyond Burger does not.

What Are The Pluses Of The Impossible Burger?

thumbs upThere are some definite pluses for the Impossible Burger and Beyond Burger:

  • Both the Impossible Burger and Beyond Burger are made from plant-based ingredients rather than from meat.
  • Both are cholesterol free.
  • Both contain modest amounts of fiber (3 grams for the Impossible Burger and 2 grams for the Beyond Burger), while a meat burger contains none.
  • Both are good sources of iron, and the iron in the Impossible Burger is heme-iron, which is efficiently absorbed by our bodies.

What Are The Minuses of the Impossible Burger?

thumbs downThere are, however, some definite minuses as well.

  • Both the Impossible Burger and Beyond Burger are high in saturated fat. The Impossible Burger is higher in saturated fat and the Beyond Burger contains the same amount of saturated fat as a real burger. That’s important because the latest advisory of the American Heart Association warns that saturated fat increases our risk of heart disease (I have discussed this finding in detail in a previous issue of “Health Tips From the Professor”).
    • The saturated fat in both burgers comes from coconut oil. However, as I discussed above, we don’t know whether coconut oil is better or worse for us than other saturated fats. The relevant studies have not been done.
  • Both the Impossible and Beyond burgers are high in sodium. They have almost 5-times more sodium than a beef burger.
  • The heme in red meat catalyzes the formation of N-nitroso compounds in our gut which increase the risk of colon cancer. We do not know whether the form of heme added to Impossible Burgers catalyzes the same reaction, but it is likely.
  • Both plant-based burgers are low in protein compared to a beef burger (~20 grams versus 27 grams). On the other hand, 20 grams of protein is reasonable for a single meal.
  • The plant proteins used for these burgers (soy for the Impossible Burger and pea for the Beyond Burger) are highly processed. They lack the phytonutrients found in the unprocessed proteins.
    • The isoflavones found in soy are thought to decrease the risk of cancer and osteoporosis.
    • The phytonutrients found in peas have antioxidant and anti-inflammatory benefits. They are also thought to decrease the risk of certain cancers.
  • The Impossible Burger is GMO. The leghemoglobin is produced by genetically engineered yeast, and the soy is also GMO.
  • Neither the Impossible Burger nor Beyond Burger are certified organic. Organic certification refers to how the plant was grown. Both burgers are highly processed. Many of the ingredients in both burgers came from factories, not farms.

Is The Impossible Burger Healthy For You?

Eating Impossible BurgerNow, it is time to return to the original question: “Is the Impossible Burger healthy for you?” Since it is plant-based, it would be easy to assume that it is healthier than a burger made from beef. However, when you look more closely, it is not clear that it is healthier.

The manufacturers of the Impossible Burger and similar burgers have gone to the laboratory and have been successful at creating meatless burgers with the taste, mouth feel, and texture of real burgers. However, these improvements have come with a price.

  • The Impossible Burger and similar burgers are higher in saturated fat than a beef burger. This means they may be just as likely to increase the risk of heart disease as a beef burger.
  • The Impossible Burger contains as much heme as a beef burger, which means it may be just as likely to increase the risk of cancer as a beef burger.
  • The Impossible Burger and similar burgers are highly processed. That means:
    • The plant proteins no longer contain the phytonutrients thought to be responsible for some of their health benefits.
    • They also don’t contain the vitamins you would expect to find associated with the plant proteins.
  • The Impossible Burger and similar burgers are not organic. Even worse, the Impossible Burger is GMO.

On balance, we can’t really assume the Impossible Burger is any healthier than the beef burgers it replaces. Plus, if you include the usual condiments and add fries and a soft drink, any slight health benefits of the Impossible Burger will be lost.

It would be much healthier to choose a bean burger. They don’t taste like beef, but many of them are quite tasty. Plus, if you do some label reading, you can find ones that use only whole, unprocessed ingredients.

For example, I looked up the Organic Sunshine brand South West Black Bean burgers. It only provides half as much protein as an Impossible Burger, but all the ingredients are organic, non-GMO, and minimally processed. Note: I am not recommending a particular brand. However, with a little research I am confident you can find a healthy meatless burger with a taste you will enjoy.

Is The Impossible Burger Healthy For the Planet?

impossible burger good for planetNow, let’s look at the second question: “Is the Impossible Burger healthy for the planet?” The answer to this question seems obvious. As the Impossible Burger company states in their mission statement: “Animal agriculture occupies almost half the land on earth, consumes a quarter of our freshwater, and destroys our ecosystems”. It seems logical that any meatless burger would be an improvement.

If we are talking about a minimally processed black bean burger, like the one I described above, the answer is a clear yes. It is healthier for the planet. However, when you look more closely at the Impossible Burger, the answer isn’t as clear.

  • As coconut oil has increased in popularity massive areas of untouched, forested land have been cleared for coconut plantations.
    • These forested areas provide an essential ecosystem for animals and provide natural storm protection by absorbing rainwater. Therefore, coconut oil, like beef, also destroys our ecosystems.
    • In addition, many of the coconut plantations use large amounts of chemical fertilizers which contribute to phosphate pollution and algae overgrowth in lakes, rivers, and coastal ocean areas. This also degrades our environment.
  • The Impossible Burgers and similar meatless burgers contain many highly processed ingredients. Each of these ingredients imposes its own environmental burden. For example:
    • Coconut oil is often processed with hexane, which is categorized as a hazardous air pollutant by the Environmental Protection Agency.
    • In addition, coconut oil is primarily grown in the Philippines, Indonesia, and India. Transporting it to this country generates significant greenhouse gas emissions.
    • And, of course, coconut oil represents only one of the many highly processed ingredients in the Impossible Burger and similar meatless burgers.

In short, the Impossible Burger may be slightly healthier for the planet than a beef burger, but it is much less environmentally friendly than your typical, minimally processed, bean burger.

The Bottom Line

Two weeks ago, I wrote about recent headlines claiming that the best advice for the American public was to eat as much red meat as they like. I looked at the study behind the headlines and pointed out the many flaws in that study.

Last week I wrote about headlines claiming that red meat was just as heart healthy as white meat. I looked at the study behind the headlines and showed it was an excellent example of how the beef industry influences the design of clinical trials to minimize the health risks of red meat. It is also an example of how the media misleads and confuses the public about the effect of nutrition on their health.

What the studies I reviewed the last two weeks really showed was that very small amounts (2-3 ounces) of very lean red meat is probably OK as part of a healthy diet like the Mediterranean diet. Larger servings of fattier cuts of red meat as part of the typical American diet is problematic.

However, if you love your burgers, what are you to do? Are the meatless burgers like the Impossible Burger and Beyond Burger that are showing up in your favorite fast food restaurants the answer? Specifically, you are probably asking:

  • Is the Impossible Burger, and similar burgers, healthy for you?
  • Is the Impossible Burger, and similar burgers, healthy for the planet?

I looked at the composition, pluses, and minuses of this new generation of meatless burgers in this article. The bottom line is:

  • On balance, the Impossible Burger is only slightly healthier than the beef burgers it replaces. And, if you include the usual condiments and add fries and a soft drink, any slight health benefits of the Impossible Burger will be lost.

It would be much healthier to choose a bean burger. They don’t taste like beef, but many of them are quite tasty. Plus, if you do some label reading, you can find ones that are organic, non-GMO, and use only whole, unprocessed ingredients.

  • Similarly, the Impossible Burger may be slightly healthier for the planet than a beef burger, but it is much less environmentally friendly than your typical, minimally processed, bean burger.

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.

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.

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