Subject:        High animal protein intake increases risk of bone loss and
fractures in elderly women, UCSF study finds

EMBARGOED FOR RELEASE: 22 DECEMBER 2000 AT 05:00
ET US

     Contact: Leslie Harris
     [2][log in to unmask]
     415-885-7277
     [3]University of California, San Francisco


     Elderly women who get a much higher intake of their dietary
protein
     from animal products rather than vegetables have an increased
risk of
     bone loss and hip fracture, a University of California, San
Francisco
     study has found, suggesting women may be able to improve
bone health
     by eating more vegetables.

     "We should be encouraged to eat more vegetables and realize
that our
     diets play an important role for our bones as we get older," said
     lead author Deborah Sellmeyer, MD, UCSF assistant professor
of
     medicine and director of the Bone Density Clinic at UCSF
Medical
     Center at Mount Zion. "There are lots of things we can do to
improve
     bone health."

     The study will be published in the January issue of the American
     Journal of Clinical Nutrition.

     In the study, researchers gave 1,035 women enrolled in the Study of
     Osteoporotic Fractures a food frequency questionnaire, asking how
     much they ate of 64 different kinds of foods. They broke the food
     down into grams of protein, potassium, salt and other categories.
     They scrutinized the protein part more carefully, determining how
     much protein the women were getting from animal products compared
     with vegetables.

     The women, ages 65 to 80, were grouped into three categories: those
     with a high ratio of animal to vegetable protein, a middle range
     ratio and low ratio, Sellmeyer explained. Researchers took the ratio
     and compared it with bone mineral density, bone loss and fractures in
     a seven year follow up period.

     While there was no difference in initial bone mineral density among
     the groups of women, the high ratio category had three times the rate
     of bone loss as the women in the low group during the follow up
     period. The high group also had 3.7 times the rate of hip fractures
     compared to the low group. This is after researchers adjusted for
     age, weight, estrogen use, tobacco use, exercise, total calcium
     intake and total protein intake.

     "We adjusted for all the things that could have had an impact on the
     relationship of high animal protein intake to bone loss and hip
     fractures," Sellmeyer said. "But we found the relationship was still
     there."

     The most significant possible reason for this link between high
     animal protein and bone loss and hip fractures is because animal
     products have a high amount of acid, Sellmeyer said. Too much acid
     may be detrimental to bone health. While vegetables have some acid,
     they have much higher levels of base. Base is a bicarbonate, a
     substance that works to neutralize acid. The body works to achieve a
     balance between base and acid and gets rid of excess acid through
     urine.

     "Our bodies don't like too much acid so our kidneys help us adjust by
     excreting the acid in urine," Sellmeyer said. "But as we get older,
     our kidneys are less and less capable of excreting the acid."

     This causes bone-which is built of base and other components-- to
     step in to neutralize the acid. As a byproduct of this action, the
     bone dissolves over time-causing it to lose mass and calcium.

     "We believe this happens very slowly, over decades," Sellmeyer
     said. Decreased bone mass makes fractures more likely.

     While it appears that increasing vegetable protein intake and
     decreasing animal protein intake can decrease the risk of bone loss
     and hip fracture in elderly women, Sellmeyer stressed that the point
     of the study is not to recommend women give up eating meat or cheese.

     "Protein is very important in maintaining strong bones and muscles.
     We don't want people to stop eating animal protein," she said. "But
     we do want people to work in more fruits and vegetables into their
     diets--not only because of the impact it could have on bone health,
     but also the impact it can have on lowering the risk of heart
     disease, diabetes and other illnesses. This study is yet another
     reason to eat more fruits and vegetables."

                                    ###

     Other study authors are Katie L. Stone, PhD, specialist in the UCSF
     School of Medicine; Anthony Sebastian, MD, UCSF professor of medicine
     and co-director of the General Clinical Research Center, and Steven
     R. Cummings, MD, UCSF professor of medicine.

     The National Institutes of Health funded this study.
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