Vegetarians are a third less likely to need hospital treatment for heart disease or die from it, claim researchers.
The largest study of its kind found vegetarians have healthier hearts than those who eat meat or fish.
It is thought the benefits come from lower blood pressure and improved cholesterol levels through eating low-fat diets based on vegetables, whole grains and fruit.
The study of almost 45,000 volunteers included a high proportion of vegetarians - 34 per cent - and mostly women, which resulted in "clear findings", said researchers.
Co-author Professor Tim Key, deputy director of the Cancer Epidemiology Unit at the University of Oxford, said: "The results clearly show the risk of heart disease in vegetarians is about a third lower than in non-vegetarians."
An estimated three million Britons, around 5 per cent, are vegetarian and never eat meat or fish.
The study recruited English and Scottish volunteers who completed questionnaires on health and lifestyle, diet, exercise, smoking habits and alcohol consumption.
Almost 20,000 also had their blood pressures recorded and gave blood samples for cholesterol testing.
Over an average follow-up period of 11.6 years, scientists recorded 1,066 hospital admissions due to heart disease, and 169 deaths. Being vegetarian reduced the risk of death or hospital admission from heart disease by 32 per cent, after adjusting for factors such as age, sex, physical activity, smoking, alcohol consumption, education and social background.
The study was published in the American Journal of Clinical Nutrition. The main reason for the difference is thought to be the effect of a low-fat vegetarian diet on cholesterol and blood pressure.
Vegetarians had lower levels of harmful cholesterol in their blood and reduced systolic, or maximum, blood pressure. In addition they tended to be slimmer, with a lower body mass index, and they were less likely to be affected by diabetes.
Dr Francesca Crowe, author of the study at the Cancer Epidemiology Unit at the University of Oxford, said: "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."
Red meat, especially processed meat, contains ingredients that have been linked to increased risk of chronic diseases, such as cardiovascular disease and cancer. These include heme iron, saturated fat, sodium, nitrites, and certain carcinogens that are formed during cooking. Eating more vegetables and fruit may also help through their antioxidant effects, combating harmful naturally occurring chemicals in the body.
Official advice from the Department of Health in 2010 said cutting down on red meat could reduce the risk of bowel cancer.
A study of 120,000 Americans last year made similar findings. It showed a greater risk of premature death, including heart disease, from diets high in red meat which could be cut by substituting other forms of healthy protein.
British Heart Foundation dietician Tracy Parker said: "This reminds us that we should try to eat a balanced and varied diet - whether this includes meat or not."
- DAILY MAIL