The risk of hospitalization or death from heart disease is 32% lower in vegetarians than in people who eat meat and fish, according to a British study.
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, Francesca Crowe, PhD, the studys lead author from the University of Oxford in the United Kingdom, said in a news release.
For the study, scheduled for publication in the March issue of the American Journal of Clinical Nutrition, researchers examined almost 45,000 volunteers from England and Scotland who were enrolled in the European Prospective Investigation into Cancer and Nutrition-Oxford study, of whom 34% were vegetarian. Such a significant representation of vegetarians is rare in studies of this type, the researchers said, and allowed for more precise estimates of the relative risks between the two groups.
The Oxford researchers arrived at the figure of 32% risk reduction after accounting for factors such as age, smoking, alcohol intake, physical activity, educational level and socioeconomic background.
Participants were recruited to the study throughout the 1990s, and completed questionnaires regarding their health and lifestyle when they joined. These included detailed questions on diet and exercise, and other factors affecting health such as smoking and alcohol consumption. Almost 20,000 participants also had their blood pressure recorded, and gave blood samples for cholesterol testing.
The volunteers were tracked until 2009, during which time researchers identified 1,235 cases of heart disease. This comprised 169 deaths and 1,066 hospital diagnoses, identified through linkage with hospital records and death certificates.
The researchers found 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 typically had lower body mass indices and fewer cases of diabetes as a result of their diets, although these were not found to significantly affect the results. If the results are adjusted to exclude the effects of BMI, vegetarians remain 28% less likely to develop heart disease.
The study abstract is available at http://ajcn.nutrition.org/content/early/2013/01/30/ajcn.112.044073.abstract.