Vegan Food Plate

Vegan Diet Cuts Risk of Heart Disease After Two Months?

Enthusiastic promoters of vegan diets are quite happy with headlines coming out of Stanford today. The Times of London captured the aspirational promise with their headline quite well: “Vegan diet cuts risk of heart disease after two months.” The Stanford University PR department was a little more subtle. They merely said “a vegan diet improves cardiovascular health.”

The only trouble is that the study is inadequate to support those bold claims.

A Good Study of 22 Identical Twins

Make no mistake. This is a good study that offers worthwhile insights. Publishing in JAMA Network Open, Matthew Landry and colleagues demonstrated in their eight-week study that a vegan diet can be a healthy option for people who want to manage cardiovascular risk factors. It involved 22 pairs of identical twins, with one twin in the pair randomized to receive a healthy vegan diet. The other twin served as a matched control and received a healthy omnivorous diet.

For four weeks the subjects got all their meals by delivery. Then for another four weeks they prepared their assigned diet meals themselves. At the end of those eight weeks, folks in the vegan diet group had lower LDL cholesterol, lower fasting insulin levels, and had lost about four pounds of weight compared to the control twins.

Sounds great, right?

Yes, but…

It’s important not to forget study limitations. For one thing, this was only an eight-week study. People in the vegan diet group were not as satisfied with the food as the control group was. When people don’t like the food on a diet, is it reasonable to assume this is a sustainable diet for the long term? We think not.

But not liking the food might have accomplish one thing for the vegan dieters. They ate less of the food – 174 to 187 fewer calories per day. That might explain the weight loss in the vegan group.

Another thing to note is that generalizations based on this very small and atypical sample would be bogus. The researchers note this themselves, saying that these are folks who were already pretty healthy and that their sample is lacking in diversity.

Risks versus Outcomes

Finally and maybe the most important thing to remember is that this is a study of surrogate end points. It did not report actual heart health outcomes. Only risk factors thought to correlate with heart health.

So, claiming that this vegan diet cuts the risk of heart disease in just eight weeks is a bit of a stretch when there’s no actual measurement of heart disease.

Click here for the study, here and here for some of the reporting on it.

Vegan Food Plate, photograph by Vyacheslav Argenberg, licensed under CC BY 4.0

Subscribe by email to follow the accumulating evidence and observations that shape our view of health, obesity, and policy.


December 1, 2023