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.
In the first 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.’
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.
In the second study, data released by researchers at the Loma Linda University, USA, found that people following a vegetarian diet have a number of health benefits compared to those who consume meat -- and top of those benefits is a longer lifespan, with vegetarian men living an average of 9.5 and women an average of 6.1 years longer than meat munching counterparts.
The data -- presented at the Academy of Nutrition and Dietetics' 2012 Food & Nutrition Conference & Expo -- come from the Adventist Health Study-2 cohort, which is currently midway to completion. The study is following 96,000 US and Canadian citizens -- including thousands of Seventh-day Adventists -- to ascertain the potential health implications of vegetarian and meat based diets.
Seventh-day Adventists have long been known as advocates of a vegetarian diet.
Lead researcher, Gary Fraser revealed that the preliminary findings from the new study show that vegans are, on average, 13 kilograms lighter than meat eaters and five units lighter on the Body Mass Index (BMI) scale than meat-eaters.
Fraser also claimed that pesco-vegetarians and semi-vegetarians who limit animal products, but still eat meat once a week or so, have 'intermediate protection' against lifestyle diseases.
The study data suggests that vegetarian Adventist men tend to live to an average of 83.3 years, while vegetarian women live 85.7 years -- this is an average of 9.5 and 6.1 years respectively longer than other Californian citizens, Fraser explained.
- Vegans are, on average, 30 pounds lighter than meat eaters.
- Vegans are also five units lighter on the BMI scale than meat-eaters.
- Vegetarians and vegans are also less insulin resistant than meat-eaters.
Tim Key's 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.
A lifelong commitment to a vegetarian diet may also lower a woman's risk of developing breast cancer, as well as preventing and treating chronic diseases including heart disease, obesity, diabetes, and other cancers.
Natasha Longo has a master's degree in nutrition and is a certified fitness and nutritional counselor. She has consulted on public health policy and procurement in Canada, Australia, Spain, Ireland, England and Germany.