People following vegetarian and vegan diets may be exposing themselves to a greater risk of stroke, a new study published in the BMJ has found. The study, which analysed data from the EPIC-Oxford study (a major long-term research project looking at diet and health) followed 48,000 people over 18 years. It found that non-meat eaters had a 20% higher risk of stroke than meat eaters.
The reasons for this are not clear, said lead researcher Tammy Tong, a nutritional epidemiologist at the Nuffield Department of Population Health at the University of Oxford.
'There is some evidence which suggests that very low cholesterol levels might be associated with a slightly higher risk of hemorrhagic stroke,' she said. Other research has indicated that no-meat diets might be low in nutrients such as vitamin B12, deficiencies of which have been linked to stroke risk.
However researchers said this was more than offset by vegetarians having a 13% lower risk of heart disease. 'It does seem that the lower risk of coronary heart diseases does exceed the higher risk of stroke, if we look at the absolute numbers,' said Tong.
Other experts urged caution with the findings. Dr Frankie Phillips, from the British Dietetic Association, highlighted that the study was observational. 'They looked at what people ate and followed them for years, so it's an association, not cause-and-effect,' she says.
'This is data that's been collected from a couple of decades ago. It might well be that the typical vegetarian diet today looks very different to a vegetarian or vegan diet from 20 or 30 years ago.'