Gender differences in the prevalence of vitamin D deficiency in a southern Latin American country: a pilot study

Aim: This study aimed to study the prevalence of vitamin D deficiency, assessing the influence of sex, age, and season of the year. Methods: A cross-sectional study was conducted with 1329 healthy subjects (668 women and 661 men) aged 18-89 years in Santiago, Chile. Age (years), body mass index, medical history, working status, sex, and date of blood sample were collected. Results: Men were slightly older than women (53.1 +/- 18.2 vs. 50.0 +/- 15.6 years; p < 0.01) and a higher percentage worked outside the home (73.1% vs. 51.9%, p < 0.001). The mean serum concentration of 25-hydroxyvitamin D (25(OH)-D) was 23.3 +/- 9.3 ng/ml in women and 20.9 +/- 9.5 ng/ml in men (p < 0.001). The levels of 25(OH)-D by season were 26.7 +/- 9.0, 23.6 +/- 9.7, 19.4 +/- 8.5, and 19.1 +/- 9.5 ng/ml (for summer, fall, winter, and spring, respectively; p < 0.05). The prevalence of vitamin D deficiency increases with age, rising from 36.5% under 40 years to 48.0% over 60 years (p < 0.004). Male sex, winter and spring, and age showed negative correlation with levels of 25(OH)-D (p < 0.05). Multivariate linear regression showed a final model that incorporates: age (coefficient: -0.06; 95% confidence interval [CI]: -0.09 to -0.03; p < 0.001), male sex (coefficient: -2.00; 95% CI: -2.96 to -1.05; p < 0.001), summer (coefficient: 7.30; 95% CI: 6.17 to 8.43; p < 0.001), and fall (coefficient: 4.27; 95% CI: 3.04 to 5.50; p < 0.001). Conclusions: Vitamin D deficiency is more prevalent in men than in women, in the elderly, and during the winter and spring seasons.