For Immediate Release: October 15, 2009
NN: Is Vegetarian Healthier?
Week of November 30, 2009
Contact: Alice Bender, (202) 328-7744
Is Vegetarian Healthier?
Karen Collins, MS, RD, CDN
American Institute for Cancer Research
Current health recommendations consistently call for a plant-based diet to reduce risk of a broad spectrum of chronic diseases. What’s less clear is whether or not that means that a vegetarian diet is the healthiest diet of all. Vegetarians as a group tend to be healthier than non-vegetarians. Yet research suggests that vegetarian eating is one way, not the only way, to create the specific eating habits linked with good health.
Large population studies comparing incidence of heart disease among vegetarians and non-vegetarians show a clear advantage for vegetarians; overall mortality rates and diabetes incidence also tend to be lower. A combined analysis of five large studies showed that non-vegetarians had a 32 percent higher rate of mortality due to heart disease than did vegetarians. Vegetarians showed less than half the incidence of diabetes as non-vegetarians in a study of California Seventh-day Adventists; diabetes among vegans (vegetarians who consume no animal products at all) was even lower.
Impact of vegetarian diets on cancer incidence is less clear. Vegetarians showed 12 percent lower overall cancer risk than meat eaters in one large British population study, but non-meat eaters who did eat fish showed equally reduced risk. Vegetarians showed an even greater decrease in risk for particular types of cancer, but it was never any lower than that of those who ate fish but no meat. Some research shows less colon cancer among vegetarians, but some does not. Red meat and processed meat are linked to increased risk of colorectal cancer, but fish and milk be protective.
Part of the problem in studying the health benefits of vegetarian eating is that it’s not all the same. Vegans eat no animal products; lacto-ovo vegetarians do consume dairy and eggs. Pesco-vegetarians don’t eat meat or poultry, but do eat fish, and semi-vegetarians eat meat or poultry, but less than once a week.
We don’t really know how much of the health protection of a vegetarian diet comes from avoiding meat or dairy and how much is due to the nutrients, fiber and protective compounds in plant foods such as vegetables, fruits, whole grains, beans and nuts. Most vegetarians do tend to eat more of these healthy foods than non-vegetarians. But replacing meat-oriented meals with these whole plant foods will almost surely have an entirely different health impact than meatless meals based mainly on processed refined grains, with limited variety of vegetables and plenty of sweets and soft drinks.
Furthermore, studies showing better health among vegetarians don’t reflect dietary differences alone. Studies show consistently that vegetarians as a group are more likely to be non-smokers and more physically active than non-vegetarians. Vegetarians are also less likely to be overweight. Excess body fat is strongly linked to heart disease, diabetes and cancer risk. But vegetarian eating won’t automatically lead to a healthy weight if it still includes excessive portions and foods concentrated in calories from oils and sugars.
Although a vegetarian diet has a positive influence in supporting weight control, specific food choices may be the overriding influence of plant-based diets on health. Traditional Mediterranean-style eating patterns, which are plant-based diets that include fish regularly but also may include modest amounts of meat occasionally, were identified as the principal eating style tied to lower incidence of heart disease in one recent review of available data. Diets highest in fruits, vegetables, whole grains, legumes, poultry and fish and lowest in refined grains, French fries, and red and processed meats were linked with 36 percent lower incidence of heart disease among women in the Nurses’ Health Study. And for lower cancer risk, it’s low body fat, regular physical activity and a plant-based diet with a wide range of vegetables, fruits and other fiber-containing foods that can lower risk of cancer by about one-third.