Update on Vegetarian Stroke Risk

Michael Greger M.D. FACLM · October 9, 2023 · Volume 63

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Those eating more plant-based diets have lower risk of having a stroke, including both bleeding and clotting strokes.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Healthy plant-based diets have been associated with lower all-cause mortality, up to a 34 percent lower risk of death from any cause over an average of an eight-year period, just being in the top versus bottom quarter of healthy plant-based consumption. If sustained, that could translate into more than four extra years of life. A meta-analysis of a dozen studies prospectively following more than a half a million people for up to 25 years similarly found significantly lower heart disease and overall death rates among those eating more plant-based. It’s no surprise, a systematic review concluded, since plant-based diets may arrest or even reverse our number one killer—cardiovascular disease.

Those eating wholly plant-based tend to be significantly slimmer, with lower LDL cholesterol, triglycerides, blood sugars, blood pressures, significantly less inflammation, and less carotid artery wall thickening (a sign of atherosclerosis measured via ultrasound in the neck)––as good as what you see in endurance athletes who’ve run an average of 50,000 miles, which is like twice around the globe.

And changes in risk factors can happen fast, as evidenced by results from one- to three-week ad libitum (eat-all-you-want) plant-based “kickstart” programs. For example, the results from the first few hundred participants of the at-home 15-day Jumpstart program created by the nonprofit Rochester Lifestyle Medicine Institute were recently published. On a whole food plant-based diet, obese patients lost an average of 7 pounds without controlling portions or counting calories or carbs. Diabetics saw their fasting blood sugars drop 28 points. Those with LDL cholesterol over 100 experienced a 33-point drop (comparable to some statin drugs), and hypertensive individuals experienced a 17-point drop in systolic blood pressure, which is better than drugs––and all within just two weeks!

Studies dating back nearly 40 years show those eating meat-free diets also have improved blood “rheology,” meaning fluidity or flowability, which may play a role in cardiovascular protection. Subsequent interventional studies putting the cross-sectional findings to the test, show that switching people to a plant-based diet can improve rheology measurements within three to six weeks. Might the blood of vegetarians flow a bit too well, though?

In 2019, a study of thousands of British vegetarians called EPIC-Oxford found that they were at higher risk of hemorrhagic (bleeding) stroke. They had such a lower risk of heart disease that they still had less cardiovascular disease overall (and a half dozen studies show no overall increased risk of stroke mortality).

But why the greater stroke incidence? I suggested it might be vitamin B12 deficiency, which can lead to excessive levels of a stroke-associated metabolite called homocysteine that is normally detoxified by B12. This is thought to be the reason why vitamin B12 supplementation can improve artery function of vegetarians. Vitamin B12 supplements or fortified foods are critical for anyone eating plant-based, but my 12-part video series on vegetarians and stroke risk triggered by the 2019 publication was all in vain. It turns out vegetarians don’t appear to have higher stroke risk after all.

In response to the EPIC-Oxford results, researchers around the world scrambled to see if the findings were merely a fluke. In 2020, UK Biobank, a massive study following more than 400,000 volunteers, confirmed that vegetarians had lower cardiovascular disease rates and, importantly, no increased incidence of stroke. And two studies from Taiwan found vegetarians had significantly lower risk of stroke. Following tens of thousands of vegetarians for up to ten years, they only had about half the stroke risk compared to nonvegetarians (including a 64 percent lower risk specifically of hemorrhagic stroke).

By 2021, Harvard researchers had finished and published their analyses of the 200,000+ participants of the Nurses’ Health Study, the Nurses’ Health Study II, and the Health Professionals Follow-Up Study. They too found no increased stroke risk for vegetarians, and indeed a decreased risk of stroke among those eating healthy plant-based diets. A meta-analysis putting all the studies together found that indeed the EPIC-Oxford data appeared to be a fluke after all––finding, if anything, a lower risk of stroke in a subgroup analysis.

A 2022 systematic review concluded that vegetarian and low-animal product diets are associated with a significantly lower risk of bleeding strokes, a significantly lower risk of clotting strokes, and a significantly lower risk of total strokes across the board.

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Doctor's Note

Check out the Rochester Lifestyle Medicine Institute’s jumpstart programs here.

The vitamin B12 video I mentioned is Vegetarians and Stroke Risk Factors—Vitamin B12 and Homocysteine?. It is part of my extended series on the topic, and here are the rest:

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