The healthful advantages of a vegan diet - one that excludes all forms of animal protein - have been espoused by its proponents in the popular press. In the wake of recently published results of a study done at University of California, San Francisco, a headline proclaimed "animal protein may increase risk of bone loss." However, before swearing off fish, eggs and meat forever, researchers at Hebrew Rehabilitation Center for Aged Research and Training Institute caution the public to take a look at their recently published report in the Journal of Bone and Mineral Research indicating that overall protein intake as well as animal protein consumption promotes bone health. Senior investigator at the Research and Training Institute and lead author on the Boston study, Marian Hannan, Sc.D., cautions, "The California study is very interesting and yielded results that need to be investigated further, but it is only part of a larger puzzle."
Dr. Hannan's research examined the relation between baseline dietary protein and subsequent 4-year change in bone mineral density (BMD) for 391 women and 224 men of ages 68 to 91 years from the population-based Framingham Osteoporosis Study. Lower protein consumption was significantly related to bone loss suggesting that protein intake is important in maintaining bone or minimizing bone loss in elderly persons. Further, the study showed that higher intake of animal protein does not appear to affect the skeleton adversely in this elderly population.
Dr. Hannan's study confirms the findings of several other studies of population samples considerably larger than the California study, which also showed protein to have a positive effect on bone overall. Two earlier randomized controlled trials showed that increased protein intake dramatically improved outcomes after hip fracture and subsequent work showed that protein supplements reduce bone loss with other kinds of fracture.
What this all means for the public at large is that the science of nutrition is complex and cannot be expressed in simple dietary proclamations. Before making any extreme changes in diet, individuals should consult their physician or a trained nutritionist. Older individuals are particularly vulnerable because they may suffer conditions that make protein intake particularly important to the healing process. Vegetable proteins are often lacking important amino acids and must be consumed in combinations to make them as complete and, thus equal, to the quality of animal protein. Although Dr. Hannan whole-heartedly agrees that a wide variety of fruits and vegetables are essential to a healthy diet she believes that the claim that consumption of animal protein puts an older person at risk for bone loss is "irresponsible at this juncture in the research."