Eating less meat may help reduce osteoporosis risk, studies show
Baku, February 11 (AZERTAC). Want to reduce the risk of osteoporosis? Eat less meat, Cornell researchers say.
In fact, they say, reducing the amount of meat in the diet may do more to reduce the risk of osteoporosis than increasing calcium intake.
A series of studies from the Cornell-China-Oxford Project on Nutrition, Health and Environment, by nutritional biochemist T. Colin Campbell and his colleagues, conclude that reducing meat intake reduces the risk of losing bone density. Osteoporosis is a condition, usually associated with aging, in which bone density decreases, making people susceptible to breaks and fractures.
Whether dairy products offer protection from osteoporosis, however, is still undetermined, according to the researchers. If dairy products are consumed in a diet high in animal protein, any potential benefit for increased bone density would be undermined. That's because animal protein, including that from dairy products, may leach more calcium from the bones than is ingested, said Campbell, professor of nutritional biochemistry at Cornell and director of the Cornell-China-Oxford Project, the most comprehensive project on diet and disease ever conducted.
"This phenomenon could explain why Americans, who ingest much higher levels of calcium, have much higher rates of osteoporosis and hip fractures compared with many Chinese and other Asians who consume few dairy products and ingest low amounts of calcium," Campbell said. Hip fractures in the United States, for example, are approximately five times more frequent than in China.
Osteoporosis is a potentially disabling disease of later life in which the bones deteriorate and easily fracture; the disease affects 25 million Americans, 80 percent of whom are women.
Campbell, with Banoo Parpia, Cornell senior research associate on the China project, Ji-Fan Hu, a former graduate student at Cornell, and other Chinese collaborators analyzed the role of dietary calcium in bone density by following closely the diets of 800 women from five counties that have very different diets in China. The Mongolians in one county, for example, consume a nomadic diet of high meat and dairy protein with few vegetables and fruits; the Sichuan diet, on the other hand, is primarily vegetarian with only shavings of meat used for flavorings.
The researchers measured the women's food consumption for three days, collected information on bone density and calcium absorption and excretion from blood and urine tests, and then controlled for factors such as height, weight and age in their analysis. Analyses of these data suggest that increased levels of animal-based proteins, including protein from dairy products, "almost certainly contribute to a significant loss of bone calcium while vegetable-based diets clearly protect against bone loss," Campbell reported.
This view is consistent with evidence comparing bone fracture rates among different countries, which shows that countries having the highest calcium intakes also have the highest fracture rates. It is also consistent with other studies on nutritionally rich "Western" diets and "Western" diseases showing that low-calcium, vegetarian diets are associated with increased bone density; that casein, milk's principal protein, is a well-established contributor to high blood cholesterol in the Western world; and that casein significantly enhances the development of tumor growth in experimental animals.
"Vegetarians obtain plenty of calcium and appear to have higher rates of bone density, which predispose them to lower rates of osteoporosis," said Campbell, who reported last year that Americans will not reduce their rates of cancer, cardiovascular disease and other chronic, degenerative diseases until they shift from an animal-based diet to a plant-based diet. Animal-based diets tend to be high in fat and low in fiber; plant-based diets are generally low in fat and high in fiber and other substances such as antioxidants, which are proving to be important in preventing cancer.
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