By Dr. Clare Oliver-Williams, PhD, University of Cambridge — The Conversation UK — 9 April 2021
Around half a million British people are now vegan, with a 300% increase in the number of American vegans in the past 15 years. One of the frequently cited reasons for adopting a vegan diet is that it is good for the heart — that it can not only prevent heart disease but even reverse it. But as a new review by researchers at the University of Cambridge found, this is not necessarily true. In fact, there is currently little evidence to suggest a vegan diet protects the heart or can reverse heart disease.
Vegan diets do have benefits: high consumption of whole grains, fruit and vegetables means more fibre and phytonutrients, which have anti-inflammatory and antioxidant properties. Vegans tend to have lower weight, lower blood pressure and lower levels of bad cholesterol. But unless carefully constructed, a vegan diet can lack vital nutrients — particularly certain omega-3 fatty acids (easily found in seafood), as well as selenium, iodine and vitamin B12, low levels of which can be detrimental to heart health and lead to thyroid problems, muscle disorders and anaemia.
The Cambridge research team searched for all studies investigating vegan diets and heart health, finding only three — though together covering more than 73,000 people including more than 7,000 vegans. None found vegans were protected against heart disease, heart attacks or stroke compared to omnivores. There was even a suggestion that vegans may be more likely to experience an ischaemic stroke (caused by a blood clot in the brain), though whether this is caused by the diet or is coincidental is uncertain. One smaller study found that people who maintained a vegan diet for more than three years were six times less likely to have another serious heart problem or stroke, but the sample was small and the results need larger studies to confirm.
The review concluded that veganism may have other health benefits — vegans are less likely to develop cancer, high blood pressure and diabetes, and tend to have healthier weight and lower blood glucose — but its specific effect on heart disease, the world’s leading cause of death, needs to be much better understood before firm claims can be made.