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.

Is Fish Oil Really Snake Oil?

Does Fish Oil Reduce Heart Disease Risk?

Author: Dr. Stephen Chaney

Fish OilOne of my readers recently sent me a video titled “Is Fish Oil Just Snake Oil?” and asked me to comment on it. The doctor who made the video claimed that the most recent studies had definitively shown that omega-3 fatty acids, whether from fish or fish oil, do not decrease the risk of heart attack, stroke or cardiovascular death. He went on to say that the case was closed. There was no point in even doing any more studies.

My reader, like many of you, was confused. Wasn’t it just a few years ago we were being told that clinical studies have shown that omega-3 fatty acids significantly reduce the risk of heart disease? Hadn’t major health organizations recommended omega-3 fatty acids as part of a heart health diet? What has changed?

The answer to the first two questions is a resounding YES, and “What has changed?” is THE story.  Let me explain.

Fish Oil And Heart Disease Risk In Healthy People

If we look at intervention studies in healthy people (what we scientists refer to as primary prevention studies) the results have been pretty uniform over the years. In a primary prevention setting, fish oil cannot be shown to significantly reduce the risk of heart disease (Rizos et al, JAMA, 308: 1024-1033, 2012).

That’s not unexpected because it is almost impossible to show that any intervention significantly reduces the risk of heart disease in healthy populations. For example, as I pointed out in recent Health Tips From the Professor (“Do Statins Really Work?” and “Can An Apple A Day Keep Statins Away?”) you can’t even show that statins significantly reduce heart attack risk in healthy populations.

If you can’t prove that statins reduce the risk of heart attacks in a healthy population, it should come as no surprise that you can’t prove that fish oil reduce heart attacks in a healthy population. To answer that question we need to look at whether fish oil reduces the risk of heart attacks in high risk populations.

Fish Oil And Heart Disease Risk In Sick People – The Early Studies

Most of the early  studies looking at the effect of fish oil in patients at high risk of cardiovascular disease (what we scientists refer to as secondary prevention studies) reported very positive results.

For example, the DART1 study (Burr et al, Lancet, 2: 757-761, 1989) and the US Physician’s Health Study (Albert et al, JAMA, 279: 23-28, 1998) reported a 29% decrease in total mortality and a 52% decrease in sudden deaths related to heart disease in patients consuming diets rich in omega-3 containing fish.

Even more striking was the GISSI-Prevenzione study (Marchioli et al, Lancet, 354: 447-455, 1999; Marchioli et al, Eur. Heart J, 21: 949-952, 2000; Marchioli et al, Circulation, 105: 1897-1903, 2002). This was a very robust and well designed study. It looked at the effect of a fish oil supplement providing 1 g/day of omega-3 fatty acids on the risk of a second heart attack in 11,323 patients who had survived a non-fatal heart attack within the last 3 months – a very high risk group.

The results were clear cut. Over the next 3.5 years supplementation with fish oil reduced overall death by 15% and sudden death due to heart disease by 30% compared to a placebo. And, if you looked at the first 4 months, when the risk of a second heart attack is highest, the fish oil supplement reduced the risk of overall death by 41% and sudden death by 53%.

The authors estimated that treating 1,000 heart attack patients with 1 g/day of fish oil would save 5.7 lives per year. That is almost identical to the 5.2 lives saved per 1,000 patients per year by the statin drug pravastatin in the LIPID trial (NEJM, 339: 1349-1357, 1998).

No wonder the American Heart Association said that patients “could consider fish oil supplementation for heart disease risk prevention.”

Fish Oil And Heart Disease Risk In Sick People – The Latest Studies

Heart Health StudyHowever, the most recent studies have been uniformly negative. For example, the ORIGIN trial (Bosch et al, NEJM, 367: 309-318, 2012) treated 12,536 patients who were considered at high risk of heart disease because of diabetes or pre-diabetes with either 1 g/day of fish oil or a placebo. This was also a robust, well designed study, and it found no effect of the fish oil supplement on either heart attacks or deaths due to heart disease.

Similarly, a recent meta-analysis looking at the combined effects of 14 randomized, double-blind, placebo-controlled trials in patients at high risk of heart disease found no significant effect of fish oil supplements on overall deaths, sudden death due to heart disease, heart attacks, congestive heart failure or stroke (Kwak et al, Arch. Int. Med., 172: 686-694, 2012).

No wonder you are confused by all of the conflicting studies. You must be wondering: “Is the American Heart Association wrong?” “Are fish oil supplements useless for reducing heart disease risk?”

What Has Changed Between The Early Studies & The Latest Studies?

When a trained scientist sees the outcome of well designed clinical studies change over time, he or she asks: “What has changed in the studies?” It turns out that a lot has changed.

1)     In the first place the criteria for people considered at risk for heart attack and stoke have changed dramatically. Not only has the definition of high cholesterol” been dramatically lowered, but cardiologists now treat people for heart disease if they have inflammation, elevated triglycerides, elevated blood pressure, diabetes, pre-diabetes or minor arrythmia.

For example, the GISSI-Prevenzione study recruited patients who had a heart attack within the past three months, while the ORIGIN study just looked at people who had diabetes or impaired blood sugar control. While both groups could be considered high risk, the patients in the earlier studies were at much higher risk for an imminent heart attack or stroke – thus making it much easier to detect a beneficial effect of omega-3 supplementation.

2)     Secondly, the standard of care for people considered at risk for heart disease has also changed dramatically. In the earlier studies patients were generally treated with one or two drugs – generally a beta-blockers and/or drug to lower blood pressure. In the more recent studies the patients generally receive at least 3 to 5 different medications – medications to lower cholesterol, lower blood pressure, lower triglycerides, reduce inflammation, reduce arrhythmia, reduce blood clotting, and medications to reduce the side effects of those medications.

Since those medications perform many of the beneficial effects of omega-3 fatty acids, it is perhaps no surprise that it is now very difficult to show any additional benefit of omega-3 fatty acids in patients on multiple medications.

The bottom line is that we are no longer asking the same question. The earlier studies were asking whether fish oil supplements reduce the risk of heart attacks or cardiovascular death in patients at high risk of heart disease. The more recent studies are asking whether fish oil supplements provide any additional benefits in a high risk population that is already on 3-5 medications to reduce their risk of heart disease.

However, the people who are writing the headlines you are reading (and the videos you are watching) are not making that distinction. They are pretending that nothing has changed in the way the studies are designed. They are telling you that the latest studies contradict the earlier studies when, in fact, they are measuring two different things.

Is Fish Oil Really Snake Oil?

Was the doctor who made the video “Is Fish Oil Just Snake Oil?” correct in saying that omega-3 fatty acids are ineffective at reducing the risk of heart disease? The answer is yes and no.

If you take the medical viewpoint that the proper way to treat anyone at the slightest risk of heart disease is with 3-5 medications – with all of their side effects, the answer seems to be pretty clear cut that adding fish oil to your regimen provides little additional benefit.

However, that is not the question that interests me. I’d like to know whether I can reduce my risk of heart attack and cardiovascular death by taking omega-3 fatty acids in place of those drugs – as the original studies have shown.

I’m sure many of my readers feel the same way.

The Bottom Line

  • Studies performed prior to 2000 have generally shown that fish oil supplements reduce the risk of a second heart attack in patients who have previously had a heart attack. One study even suggested that they were as effective as statin drugs at reducing heart attack risk in this population.
  • Recent studies have called into question the beneficial effects of fish oil supplements at reducing the risk of heart disease. However, these studies were performed with lower risk patients and the patients were on 3-5 medications to reduce their risk of heart attack or stroke.
  • The recent studies are no longer evaluating whether fish oil supplements can reduce the risk of heart disease. They are asking whether they have any additional beneficial effects for people taking multiple medications. That’s a totally different question.
  • So ignore the headlines saying that fish oil is snake oil. If you are content taking multiple medications to reduce your risk of heart disease, it is probably correct to say that omega-3 fatty acids provide little additional benefit.
  • However, if you are interested in a more holistic, drug-free approach to reducing your risk of heart disease, I still recommend omega-3 fatty acids as part of a heart healthy diet, as does the American Heart Association.

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.

Can Soft Drinks Cause Heart Disease?

Put Down That Soda

Author: Dr. Stephen Chaney

 soda-drink-300x181Can Soft Drinks Cause Heart Disease? For today’s “Health Tip” I’m going to paraphrase a quote from your some of your favorite action flicks: “Put down that soda and back away and nobody gets hurt.”

You see, the news about soft drinks keeps getting worse and worse! You’ve probably already heard that soft drink consumption leads to weight gain, pre-diabetes and possibly even diabetes because calories in liquid form do not affect appetite to the same extent as calories in solid form.

Soft Drink Consumption increases the risk of heart attack and stroke in women:

As if that weren’t bad enough, three recent studies suggest that soft drinks consumption is also associated with increased risk of heart attacks and stroke.

The first study looked at sweetened beverage consumption and risk of coronary heart disease in women (Fung et al, Am. J. Clin. Nutr., 89: 1037-1042, 2009).

This study followed 88,520 women enrolled in the Nurses Health Study for 24 years. Consumption of sugar-sweetened beverages (either sodas or non-carbonated sugar-sweetened beverages such as Hawaiian Punch, lemonade and other non-carbonated fruit drinks) was assessed from food-frequency questionnaires administered 7 times during the 24 years. And the total incidence of coronary events (both fatal and non-fatal) was recorded.

The results were striking. When they compared women who consumed as little as one sugar-sweetened beverage per day with women who consumed those beverages less than once per month, the increased risk of coronary heart disease was 23%. And when they compared women who consumed more than two sugar-sweetened beverage per day with women who consumed those beverages less than once per month, the increased risk of coronary heart disease was a whopping 35%.

Sodas are just as harmful for men:

And, in case you guys thought you were off the hook, a study has just been published showing similar results in men (de Koning et al, Circulation, March 12, 2012, Epub ahead of print). This study was a 22 year follow up of 42,883 men enrolled in the Men’s Health Professional study. The study design and results were very similar to the ones obtained previously in the Nurses Health Study except that this study did not distinguish between subjects consuming one sugar sweetened beverage a day and those consuming more than one each day.

When they compared men who consumed one or more sugar sweetened beverage a day to men who never consumed sugar-sweetened beverages, the increased risk of coronary heart disease was 20%.

Diet sodas are just as bad as regular sodas:

 Finally, you may be saying that this information doesn’t apply to you because you only consume diet sodas or artificially sweetened non-carbonated beverages.

Unfortunately, you may not be off the hook either!

Another study published in January 2012 reported that diet soft drink consumption is also associated with increased risk of coronary heart disease – including strokes (Gardener et al, J. Gen. Intern. Med., DOI: 10.1007/sl11606-011-1968-2). This study followed 2564 men and women enrolled in the Northern Manhattan Study for 10 years.

The people in this study who consumed more than one diet soda or artificially sweetened beverage/day were 43% more likely to have a vascular event (heart attack or stroke) then the people consuming less than one diet beverage/month. This study is in line with previous studies showing that diet soda consumption is associated with increased risk of pre-diabetes and type 2 diabetes.

And, as I have pointed out in my previous “Health Tips”, there is no convincing evidence that diet sodas actually help prevent weight gain. Sure there are several published studies showing that when dietitians supervise the diets of the study participants, you can achieve weight loss by substituting diet beverages for sugar containing beverages.

However, two major studies have shown that when you look at free-living populations, consumption of diet beverages is associated with just as much weight gain as consumption of sugar containing beverages (Dhingra et al, Circulation,116: 480-488, 2007; Fowler et al,

Obesity, 16:1894-1900, 2008). Apparently, without a dietitian looking over our shoulder, we manage to make up for those lost calories somewhere else!

The Bottom Line:

So what’s the bottom line for you?

You should be aware that these studies just look at associations – not cause and effect – and they can be skewed by the characteristics of the study populations. For example, there were some striking inconsistencies between the 3 studies I cited that are likely due to differences in the population groups that they sampled. However, despite some differences from one study to the next, the weight of accumulating evidence seems to suggest that sodas – both sugar containing and diet – are really not good for us.

So it’s back to my original advice: “Just put down that soda and nobody gets hurt.” Water is sounding better and better!

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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