Essential fats may prevent bone loss

Maintaining a proper balance of dietary fats may ward off much of the bone loss associated with postmenopausal osteoporosis, states a study by scientists at the Indiana University School of Medicine, Bloomington, and Purdue University, West Lafayette, Ind.

The researchers found that diets with a low ratio of omega-6 fatty acids to omega-3 fatty acids minimizes the bone loss typically brought on by estrogen deficiency, which is common in post-menopausal females. Omega-6 is found in foods such as grains and beef, while omega-3 is contained in products like walnuts and salmon.

"Many people don't realize it, but our bones are not static structures," explains Mark Seifert, professor of anatomy and cell biology at Indiana University. Bones undergo a process called "remodeling," in which they continuously are broken down and rebuilt. Two types of cells govern this process--bone resorption cells, which remove small portions of bone, and bone building cells, which fill in the gaps. Estrogen blocks some of the inflammatory compounds associated with bone resorption, which may explain why osteoporosis typically progresses after estrogen levels fall with the onset of menopause.

"Our lab and others have shown that omega-3 fatty acids help promote bone formation," reports Bruce Watkins, professor and director of Purdue's Center for Enhancing Foods to Protect Health. "We also have shown that higher intakes of omega-6 fatty acids lead to an increased production of compounds associated with bone loss."

While both types of fats are essential for human health, diets with a high ratio of omega-6 to omega-3 fatty acids often are associated with cardiovascular disease, cancer, and inflammatory and autoimmune diseases. A low ratio, however, is believed to promote cardiovascular health, improve memory and, as the study demonstrates, protect bone health.

"We saw in this study that omega-3 fatty acids are associated with a better blood profile of bone health, and with higher bone mineral density, in the absence of estrogen," Watkins notes. "A five-to-one dietary ratio of omega-6 to omega-3 fatty acids led to a conservation of bone mineral content that we didn't see with a 10-to-one ratio."

The average American's dietary ratio is approximately 10 to one, which is inflated by the types of foods people eat and the methods used to produce those foods, especially those containing vegetable oils. "Our foods are different today than they were yesterday," he says. "Omega-6 fatty acids have been an important part of our diet but, over the past 80 years, the human diet has shifted in a way that increased the ratio of omega-6 to omega-3 fatty acids."

The omega-6 fatty acids in today's animal feed incorporate right into the animals' tissues where they become part of the eggs, poultry, meats, and pork served in households and restaurants across the country.

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