Protein Saves Bone in Elders
ARS News Service, USDA, April 6, 2001

It's no secret that people need ample calcium and vitamin D to maintain strong bones, even in their twilight years. Now, a study suggests that protein intake may be important in reducing bone loss in older people. In the study, the 70- to 90-year-old men and women with the highest protein intakes lost significantly less bone over a four-year period than those who consumed half or less protein. Animal protein, as well as overall protein intake, was associated with preserving bone.

The study was conducted by researchers with the Hebrew Rehabilitation Center for Aged, Research and Training Institute; Boston University; and the Jean Mayer USDA Human Nutrition Research Center on Aging, in Boston, MA. Marian T. Hannan at the Hebrew Center collaborated with Katherine L. Tucker at the USDA Center and others.

The findings run counter to studies of younger people that found diets high in protein, especially animal protein, cause the body to excrete more calcium. However, they confirm several other large population studies showing protein to have a positive overall effect on bone.

With data from 615 participants in the Framingham, MA, Osteoporosis Study, researchers examined the relationship between protein intakes in 1988–1989 and changes in bone mineral density four years later. They accounted for all factors known to increase risk of bone loss.

Participants who reported the lowest daily protein intakes—roughly equivalent to half a chicken breast—had lost significantly more bone in the hip and spine four years later than those with the highest intakes—equivalent to about 9 oz of steak and 1 cup of tuna salad. The group with the next lowest intake—equivalent to about 2 cups of cottage cheese—also lost significantly more bone than the highest intake group, but only at the hip.

The USDA food composition tables contain the protein content of more than 6,000 foods and can be viewed at http://www.nal.usda.gov/fnic/cgi-bin/nut_search.pl.

ARS News Service contact: Judy McBride, phone 301/504-1628, e-mail jmcbride@ars.usda.gov

Scientific contact: Katherine L. Tucker, Jean Mayer USDA Human Nutrition Research Center on Aging, Boston, MA., phone 617/556-3351, fax 617/556-3344, e-mail tucker@hnrc.tufts.edu.