Serum 25-hydroxyvitamin D is related to indicators of overall physical fitness in healthy postmenopausal women

Objective: Inadequate vitamin D status is related to increased adiposity, risk of falls, and muscle weakness, particularly in older people. We hypothesized that serum 25-hydroxyvitamin D [25(OH)D] is related to physical fitness indices (androidal fat, whole body lean mass, balance, strength) in healthy postmenopausal women. Methods: Covariates for fitness indices included age or years since menopause, weight, 25(OH)D, energy expenditure, and calcium intake. Overall and regional (androidal fat mass = waist + hip fat) body composition was assessed (N = 242) via dual-energy x-ray absorptiometry. Results: Regression analyses revealed that 71% of variability (P <= 0.0001) in androidal fat mass was accounted for by weight (53.0%, P <= 0.0001), white blood cell (WBC) count (2.0%, P <= 0.0001), supplemental calcium (1.7%, P = 0.0004), years since menopause (1.1%, P = 0.0034), 25(OH)D (1.0%, P = 0.0051), and vegetable servings (0.6%, P = 0.027); 64% of variability (P <= 0.0001) in lean mass was accounted for by weight (63.1.%, P <= 0.0001), WBC count (1.4%, P = 0.0038), and 25(OH)D (1.0%, P = 0.013); 12% of variability (P <= 0.0001) in balance (right + left leg) was accounted for by age (3.8%, P = 0.0019), 25(OH)D (2.0%, P = 0.025), and WBC count (1.8%, P = 0.032); 14% of variability (P <= 0.0001) in handgrip strength (right + left) was accounted for by weight (9.3%, P <= 0.0001), 25(OH)D (2.4%, P = 0.013), WBC count (2.1%, P = 0.019), and age (1.6%, P = 0.044); and 22% of variability (P <= 0.0001) in torso strength was accounted for by site (15.0%, P <= 0.0001) and weight (4.6%, P = 0.0003). Conclusions: Serum 25(OH)D was the common contributor to physical fitness indices (androidal fat mass, lean mass, balance, handgrip strength) in healthy postmenopausal women.