Serum 25-hydroxyvitamin D: distribution and determinants in the Swiss population

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Abstract
The serum 25-hydroxyvitamin D [25(OH)D] concentration was measured in a representative sample of the general adult population in Switzerland (n = 3276). The median concentration was 46 nmol/L and no significant difference was found between men and women. Between the ages of 25 and 74 y, 25(OH)D was not significantly correlated with age (r2 = 0.01 ). Six percent of the population was vitamin D deficient [ie, 25(OH)D ≤ 20 nmol/L] and between 34% and 95% had a relatively low concentration of vitamin D (ie, < 38 or < 95 nmol/ L, respectively). Among the determinants of low 25(OH)D were indicators of little sunshine exposure, such as the winter season [odds ratio (OR) 2.4, 1.5–3.7 (95% confidence interval)] and < 30 min of time spent outdoors daily by individuals > 65 y of age (OR 5.6, 1.5–21.2), as well as indicators of low nutritional intake of vitamin D, such as the absence of regular intake of butter or margarine (OR 2.0, 1.3–3.1) and the consumption of few dairy products (OR 1.7, 1.2–2.4).