Associations between body composition, physical activity, and diet and radial bone microarchitecture in older adults: a 10-year population-based study

Bone strength is important to prevent osteoporotic fractures and determined by bone mass and microarchitecture. This study suggests that having higher lean mass and lower fat mass, avoiding western dietary patterns, and improving steps per day may all be important for maintaining bone mass and microarchitecture in aging.

Purpose: To describe associations between exposures of lean mass and fat mass, dietary patterns, serum 25-hydroxyvitamin D (25(OH)D), physical activity and grip strength, and bone outcome measures including bone mineral density and microarchitecture in older adults.

Methods: Data on 201 older adults (mean age 72 years, female 46% at 10.7-year follow-up (phase 4) from a population-based cohort study collected at baseline and follow-up at 2.6 (phase 2), 5.1 (phase 3), and 10.7 years (phase 4) were analyzed. Exposures were lean and fat mass, dietary patterns, physical activity (steps per day), serum 25(OH)D concentrations, and grip strength during follow-ups. Bone measures at phase 4 including areal bone mineral density (aBMD) at the spine, hip, and whole body by dual-energy X-ray absorptiometry, and radial cortical and trabecular bone microarchitecture by high-resolution peripheral computed tomography (HRpQCT). The cumulative average values of exposures were calculated. Multivariable linear regression was used to analyze associations between exposures and bone measures.

Results: Lean mass was beneficially associated with the hip, spine, and total body aBMD, radial cortical and trabecular bone area, and trabecular number and separation (β ranged from - 0.39/standard deviation (SD) to 0.73/SD). Fat mass was detrimentally associated with radial compact cortical and inner transitional zone bone area, vBMD, and porosity (β ranged from - 0.21 to 0.22/SD). Western dietary pattern scores were detrimentally associated with radial total and cortical bone vBMD and porosity (β ranged from - 0.20 to 0.20/SD). Steps per day were beneficially associated with inner transitional zone area and thickness (β = 0.12/SD and 0.19/SD), but no other measures. Grip strength and serum 25(OH)D were not associated with any radial bone measures.

Conclusions: Lean mass was beneficially associated with aBMD, radial bone area, and trabecular bone microarchitecture. Fat mass had detrimental associations with radial bone area, vBMD, and porosity. A western dietary pattern was detrimental for radial bone microarchitecture while more steps per day (but not grip strength or 25(OH)D) appeared beneficial.