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Eating a vegetarian diet rather than consuming meat has been linked with a significantly lower risk of coronary heart disease.
While the environmental case for going vegetarian is unequivocal and powerful, the long-term health impacts of adopting a vegetarian or vegan diet are still poorly understood. To help fill the gap, Tammy Tong at the University of Oxford and her colleagues grouped 48,000 people in the UK by diet and followed them over 18 years.
The results showed vegetarians had a 22 per cent lower risk of heart disease than their meat-eating counterparts. The finding, which is in line with some previous research, could be explained by vegetarians generally having lower cholesterol levels.
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But the analysis has a sting in the tail: vegetarian diets were also associated with a 20 per cent high risk of stroke than that seen in meat-eaters. The reason could be vegetarians missing out on some nutrients only found in meat, such as the B12 vitamin. But that deficiency can be addressed with supplements, says Tong.
While that might give people pause before joining the UK’s estimated 1.7 million vegetarians and vegans, Tong says it’s important to look at absolute numbers. Over a ten-year period in the cohort she studied, vegetarians had 10 fewer cases of heart disease per 1000 people than meat-eaters, but just three more cases of stroke per 1000. “You can say the lower risk of heart disease does outweigh the higher risk of stroke in this cohort,” she says.
Mark Lawrence and Sarah McNaughton of Deakin University, Australia, writing in a commentary in the BMJ, say the stroke risk should be kept in perspective, as it is a result from just one study and the increase is modest relative to meat-eaters.
Other possible explanations for the links were controlled for, including education, smoking, alcohol, exercise and fruit, vegetable and fibre intake. However, the results were not adjusted for income, and could also be explained by other unknown lifestyle factors among vegetarians, says Tong.
She wouldn’t advocate people go vegetarian solely on the findings, but they should consider them. “Switching to a vegetarian diet is very much a personal choice,” she says.
Sarah Berry of King’s College London, who was not involved in the research, says: “Given the increase in vegetarianism for ethical and health reasons, and the likelihood that this is going to continue to gain momentum, this study addresses key issues regarding some of the purported health effects of a vegetarian diet over a meat diet.”
Thomas Sanders of King’s College London adds it is important to remember vegetarian diets are only health if they are well-balanced.
Journal reference: British Medical Journal, DOI: 10.1136/bmj.l4897
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