Protein consumption is an important predictor of lower limb bone mass in elderly women

BACKGROUND: The effect of protein intake on bone density is uncertain, and evidence exists for beneficial effects of both low and high protein intakes. OBJECTIVE: The objective was to study the relation between protein consumption and bone mass in elderly women with allowance for other lifestyle factors affecting bone metabolism. DESIGN: We conducted a cross-sectional and longitudinal study of a population-based sample of 1077 women aged 75 +/- 3 y. At baseline, protein consumption was measured with a food-frequency questionnaire, and bone mass and structure were measured by using quantitative ultrasound of the heel. One year later, hip bone mineral density (BMD) was measured by using dual-energy X-ray absorptiometry. RESULTS: Subjects consumed a mean (+/-SD) of 80.5 +/- 27.8 g protein/d (1.19 +/- 0.44 g protein/kg body wt). Regression analysis showed a positive correlation between protein intake and qualitative ultrasound of the heel and BMD after adjustment for age, body mass index, and other nutrients. The dose-response effect was best characterized by protein consumption expressed in tertiles, such that subjects in the lowest tertile (<66 g protein/d) had significantly lower qualitative ultrasound of the heel (1.3%) and hip BMD (2.6%) than did the subjects in the higher tertiles (>87 g protein/d). CONCLUSION: These data suggest that protein intakes for elderly women above current recommendations may be necessary to optimize bone mass.