Determinants of vitamin D status in healthy men and women aged 40-80 years

Objectives: To determine the contribution of life style and health related factors on vitamin D status in middle-aged and older men and women. Study design: A cross-sectional single-center study in 400 male subjects (40-80 years) and 402 postmenopausal female subjects (56-73 years), conducted in a University Medical Center in the central part of the Netherlands (52 degrees northern latitude). Main outcome measures: Medical history, vitamin D, calcium and alcohol intake, physical activity, Body Mass Index, Blood pressure, smoking, total fat body mass and total lean body mass were measured using DEXA. Laboratory analysis included 25-hydroxyvitamin D (25OHD) and sex hormones. Results: Thirty-six percent of men and 51% of women had 25OHD less than 50 nmol/L. In summertime men had significant higher 25OHD as compared to women (81.5 vs 53.3 nmol/L, P =.000) but this difference disappeared come winter. In a saturated model, male gender (B =.16, P =.008), and season (summer vs winter B =.30, P =.000) remained statistically significant. In men, physical activity and season explained 21% of the variance. In women, household physical activity (B =.13, P =.03), sport physical activity (B =.02, P =.02) and estradiol (B = -.003, P =.048) remained in the model,. Conclusion: In healthy middle-aged and older men and postmenopausal women, male gender and season were important predictors of vitamin D status. In men, physically activity and season, explained 21% of the variance in vitamin D status. In women, physical activity and estradiol explained 9.3% of the variance in vitamin D.