Epic Peas

Heart Disease, Stroke, and Vegetarian Diets

Do vegetarian diets pose little more risk of strokes and a little less risk of heart disease? That’s the possibility researchers are raising in the BMJ this week. So what’s a committed vegetarian supposed to do with this information?

Advice in an editorial from Mark Lawrence and Sarah McNaughton seems solid to us. Keep this report in perspective. Because this is just one study in one population. In fact, most of the science around vegetarian diets suggests that they offer a perfectly healthy way to eat.

Sound Research

Make no mistake. This bit of research is perfectly sound – given the caveat that it’s observational. The diet of a population is a complicated thing to study. Like most observational studies, this one relies on self-reports of what people are eating. And self-reports are a rich source of bias. People misremember. They tell you they’re eating their peas because they’re supposed to. But maybe they forget those chips they ate.

The observational caveat is also important. Diet is a marker for many other behaviors. So people who choose a vegetarian diet may have other health-related behaviors that this research simply can’t capture. Thus, we can’t assume that it’s surely the vegetarian diets that explain these differences in risk.

Another important note on these findings deserves mention. The risks observed here are relatively small – 10 to 20 percent. Nothing to ignore, but easily explained by residual confounding and other technical issues.

Good Reason for Follow-Up

Given all those caveats – as well as the strengths – of this study, the advice to follow up cautiously makes sense. Can other researchers replicate this finding? Could subtle deficiencies explain the observation of a modest increase in stroke risk? The researchers mention vitamin B12, D, essential amino acids, and some fatty acids. Vegetarians in this cohort tended to have lower levels of these nutrients.

But Nothing to Fear

So on balance, we have good questions arising from this study. But nothing that should scare people away from a vegetarian diet. As ever though, it does make sense to pay attention to things like B12 that can be harder to get on a vegetarian diet.

Click here for the study and here for the editorial. For further reporting from the BBC, click here.

Epic Peas, photograph © Theo Crazzolara / flickr

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September 7, 2019

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