Protein Saves Bone in Elders

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 elders.

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 the 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, all in Boston, Mass. Lead author Marian T. Hannan at the Hebrew center collaborated with Katherine L. Tucker at the USDA center and others. The USDA center is funded by the department’s chief scientific research agency, the Agricultural Research Service.

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, according to Hannan.

With data from 615 participants in the Framingham (Mass.) Osteoporosis Study, the researchers examined the relationship between their protein intakes in 1988-89 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 nine ounces of steak and a cup of tuna salad.

The group with the next lowest intake--equivalent to about two cups of cottage cheese--also lost significantly more bone than the highest-intake group, but only at the hip. People can search the USDA food composition tables for the protein content of more than 6,000 foods at:

http://www.nal.usda.gov/fnic/cgi-bin/nut_search.pl

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