Protein Saves Bone in Elders

By Judy McBride
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 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.

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Comment: Studies of Paleolithic nutrition, like Eaton's study (NEJM, 1985) indicate that higher
protein diets are associated with bigger bones, and larger people. This study supports
that concept. General consensus that has been promoted in the health press has been that
higher protein intake causes bone loss, but this study from the very conservative United
States Department of Agriculture Human Nutrition Research Center supports the need for
a higher protein intake.