Meat Bad For Your Bones?
Different sources of dietary protein may have different effects on bone metabolism. Animal foods provide predominantly acid precursors while vegetable food protein is accompanied by base precursors not found in animal foods.
Imbalances between dietary acid and base precursors may have an adverse effect on bone. A study has been conducted to test the hypothesis that a high dietary ratio of animal to vegetable foods, quantified by protein content, increases bone loss and the risk of fracture.
Researchers gave more than 1,000 women aged 65 to 80 a questionnaire, which covered 64 different kinds of foods. They then broke the results down to show how much of each group the women ate and looked at how much protein the women received from animal products compared to vegetables. They were then categorized into those who ate a high level of animal protein, a medium and a low level. Bone density of the women was measured using dual-energy X-ray absroptiometry.
Women with a high animal to vegetable protein ratio had a higher rate of bone loss at the femoral neck than did those with a lower ratio and a greater risk of hip fracture. These associations were unaffected by adjustment for age, weight, estrogen use, tobacco use, exercise, total calcium intake, and total protein intake.
Elderly women with a higher dietary ratio of animal to vegetable protein intake have a more rapid femoral neck bone loss and a greater risk of hip fracture than those with a low ratio. This suggests that an increase in vegetable protein intake and a decrease in animal protein intake may decrease bone loss and a risk of hip fracture.
Sellmeyer DE, Stone KL, Sebastian A, et al. A high ratio of dietary animal to vegetable protein increases the rate of bone loss and the risk of fracture in postmenopausal women. The American Journal of Clinical Nutrition
2001:73, pp. 118-122.