Dietary protein intake and bone mass in women

Population-based strategies to combat osteoporosis are urgently needed. The role of nutrition in such strategies has been particularly contentious. We examined the relationship among six key nutrients that are thought to affect bone metabolism and bone mineral density in the axial and appendicular skeleton using data from a population-based study in the northern United States. Data on the dietary intake of calcium, phosphorus, vitamin D, protein, fat, and total energy were obtained from a 7-day dietary record. Bone density measurements were made by dual photon absorptiometry in the lumbar spine and proximal femur, and by single photon absorptiometry in the distal and midradius. Among the 72 premenopausal women studied, there was a statistically significant positive association between protein intake and bone mineral in the distal radius and proximal femur, which was not altered by adjustment for age, weight, and physical activity. Among 218 postmenopausal women, no such relationship was found between protein intake and bone mineral, and the only significant findings in this group were negative associations between fat consumption and bone density in the lumbar spine and radius. Our results suggest that dietary protein intake may be a determinant of the peak bone mass attained by premenopausal white women. The relevance of this finding for the design of population strategies to maximize skeletal growth requires further investigation.