The relationship between bone mass, body composition, nutrient intake and physical activity level in healthy postmenopausal women.

Abstract

This one-year longitudinal study was designed to examine the association of changes in body composition, dietary factors, and physical activities on changes in bone mineral density (BMD) and content (BMC) among healthy postmenopausal women (N = 53). Subjects were Caucasian women who were not taking hormone replacement therapy and were at least three years past menopause. Calcium supplementation (1000 mg/day) were given to all the women to ensure adequate calcium intakes. Their body composition, total and regional BMC and BMD were measured using Single Photon Absorptiometry and Dual-energy X-ray Absorptiometry. Arizona Food Frequency Questionnaire and eight days dietary intake records were used to estimate nutrient intake. Physical activity was assessed by self-administrated physical activity questionnaires. Lean tissue mass (L TM) was a significant predictor for regional BMD and BMC (p<0.05). Changes in bone were correlated with each other at certain sites. Increased weight and BMI were associated with increased BMD and BMC at femoral sites (p<0.05). Changes in fat tissue mass (FTM) and %FTM significantly predicted changes in BMD and BMC (R² = 0.14 to 0.23). Saturated fat, dietary fiber and beta-carotene intakes positively, and protein intake negatively, contributed to changes in bone mass (p<0.05). Energy spend on low intensity activities had a negative relationship with change in lumbar BMD. Reduction of lumbar spine BMC was accelerated with increased time spent on non-weight bearing activities (p<0.05). Dietary factors and changes in body composition had ajoint-role in predicting changes in BMD and BMC.