The positive association of total protein intake with femoral neck strength (KNHANES IV).

ABSTRACT

Data gathered from a nationally representative cohort demonstrate that higher dietary protein intake was positively associated with the composite indices of femoral neck strength in both men and women, suggesting that higher protein intake may contribute to lower risk of hip fracture through the improvement of bone strength. INTRODUCTION: Despite the general belief that higher protein intake may be helpful for bone homeostasis, its impact on human bone health is still debated. Furthermore, the association of dietary protein intake with femoral neck (FN) strength, which can predict fracture risk independently of bone mineral density (BMD), has not been thoroughly studied. METHODS: This is a population-based, cross-sectional study from Korea National Health and Nutrition Examination Surveys, including 592 men aged 50 years or older and 590 postmenopausal women. The composite indices of FN strength, such as the compression strength index (CSI), bending strength index (BSI), and impact strength index (ISI), were generated by combining BMD, body weight, and height with the femoral axis length and width, which were measured by dual-energy X-ray absorptiometry. RESULTS: After adjustment for confounders, total protein intake (g/kg/day) positively correlated with all three FN composite indices in both genders (P = 0.006 to 0.035), except for BSI showing marginal significance in postmenopausal women (P = 0.093). Consistently, compared with subjects in lowest total protein intake quartile, those in the highest quartile showed markedly higher CSI, BSI, and ISI values (P = 0.043 to < 0.001), with a dose-response manner across increasing total protein intake quartile categories in both men and women (P for trend = 0.028 to < 0.001). CONCLUSIONS: These findings provide the clinical evidence that higher dietary protein intake can play a beneficial role on bone health through the increase of FN strength relative to load in adults.