The Association of Protein Intake and Bone Outcomes in Midwestern Post-menopausal Women

Abstract

Abstract Objectives Determine the extent to which baseline protein and amino acid intake is independently associated with measures of baseline bone outcomes in a cohort of post-menopausal women. Methods This study was a secondary analysis of participants in the Heartland Osteoporosis Prevention Study (HOPS) randomized controlled trial evaluating the effect of different osteoporosis interventions on post-menopausal women in the Midwest. Diets were evaluated via a Harvard Willett Semi-quantitative Food Frequency Questionnaire (FFQ) at baseline. Dual energy x-ray absorptiometry (DXA) scans were used to collect bone mineral density (BMD) and trabecular bone score (TBS) measurements. Single and multivariate linear regression of total protein intake (g/d and g/kg/d), proline (g), and lysine (g) with BMD and TBS locations were conducted. Student T-tests were used to compare the bone outcome differences between groups with protein intake above and below 1.2g/kg. Results There were 249 participants available for analysis. Mean total protein intake was 82.7 g with 62% consuming < 1.2/kg/d. After adjustment, for every additional gram intake of protein, lysine and proline, Hip BMD increased (Protein: β = 0.0005, P = 0.047; Lysine: β = 0.006, P = 0.04; Proline: β = 0.008, P = 0.04). Whole body BMD and TBS-1 were significantly associated with proline intake (Whole body BMD: β = 0.008, P = 0.04; TBS-1: β = −0.007, P = 0.02). After adjustment, women who consumed protein above 1.2 g/kg, had a Hip BMD 0.03 g/cm2 higher than those who consume protein below 1.2 g/kg (β = 0.03, P = 0.046). Lumbar BMD, Total L1-L4 BMD, TBS-2, TBS-3, TBS-4, and Total TBS were not significantly associated with protein or amino acid intakes after adjustment of covariates. Conclusions Higher protein intakes were associated with higher Hip BMD. Proline may play a controversial role in bone outcomes. Future research should investigate the role of dietary factors on BMD vs TBS. Funding Sources The original research was funded by the National Institute of Nursing Research of the National Institutes of Health under award number R01NR015029. No additional funding was used for the secondary analysis.