The research, taken from the UK arm of the European Prospective Investigation into Cancer and Nutrition (EPIC) study managed by Oxford scientists, finds that the risk of hospitalisation or death from ischemic heart disease (IHD) is slashed by almost a third in British people following a vegetarian diet when compared to fellow meat-eaters.
Writing in the American Journal of Clinical Nutrition, the research team suggest that a vegetarian diet could significantly reduce people's risk of heart disease by reducing important risk factors for the development of the disease – including cholesterol and blood pressure.
“Most of the difference in risk is probably caused by effects on cholesterol and blood pressure, and shows the important role of diet in the prevention of heart disease,” said Dr Francesca Crowe from the Cancer Epidemiology Unit at University of Oxford – who led the study.
“There was no evidence that the association between vegetarianism and IHD differed between smokers and nonsmokers, lean and overweight participants, or those with a low or a high risk of IHD at baseline,” Crowe and her colleagues write.
The new analysis looked at almost 45,000 volunteers from England and Scotland enrolled in the EPIC-Oxford study – of whom 34% were vegetarian. Crowe and her co-workers noted that such a significant representation of vegetarians was rare in studies of this type, and therefore allowed researchers to make more precise estimates of the relative risks between the two groups.
As a result, the new data is the largest ever UK-based study to compare heart disease risk between vegetarians and non-vegetarians, said the Oxford scientists.
“Vegetarians had a 32% lower risk of IHD than did nonvegetarians after adjustment for age, smoking, alcohol, physical activity, educational level, and Townsend Deprivation Index and use of oral contraceptives or hormone therapy for menopause in women,” they reported.
“On the basis of the absolute rates of hospitalisation or death from IHD, the cumulative probability of IHD between ages 50–70 y was 6.8% for nonvegetarians compared with 4.6% for vegetarians.”
The study showed that vegetarians had lower blood pressures and cholesterol levels than non-vegetarians, which is thought to be the main reason behind their reduced risk of heart disease.
“Vegetarians had a better lipid profile than did nonvegetarians, probably because of a higher ratio of polyunsaturated to saturated fat in their diet,” they explained.
Vegetarians also typically had lower body mass indices (BMI) and fewer cases of diabetes as a result of their diets, although these were not found to significantly affect the results – and if the results were adjusted to exclude the effects of BMI, vegetarians were still 28% less likely to develop heart disease, said the team.
Professor Tim Key, co-author of the study and deputy director of the Cancer Epidemiology Unit, University of Oxford, said the results “clearly show” that the risk of heart disease in vegetarians was lower than in comparable non-vegetarians.
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi: 10.3945/ajcn.112.044073
“Risk of hospitalization or death from ischemic heart disease among British vegetarians and nonvegetarians: results from the EPIC-Oxford cohort study”
Authors: Francesca L Crowe, Paul N Appleby, Ruth C Travis, Timothy J Key