Potentially modifiable determinants of vitamin D status in an older population in the Netherlands: the Hoorn Study

Background: Inadequate vitamin D status is common in many populations around the world. Objective: The aim was to evaluate potentially modifiable determinants of vitamin D status in an older population. Design: This was a cross-sectional study from a population-based cohort including 538 white Dutch men and women aged 60-87 y. Vitamin D status was assessed by plasma 25-hydroxyvitamin D [25(OH)D] concentrations. Results: In the winter period, 51% of the subjects had 25(OH)D concentrations < 50.0 nmol/L. Greater body fatness and less time spent on outdoor physical activity were associated with worse vitamin D status. Regular use of vitamin D-fortified margarine products [odds ratio (OR) in a comparison of intake of >= 20 g/d with none: 0.41; 95% CI: 0.20, 0.86; P for trend < 0.001], fatty fish (OR for servings of >= 2/mo versus none: 0.41; 95% CI: 0.16, 1.04; P for trend = 0.01), and vitamin D-containing supplements (OR for >= 1/d versus none: 0.33; 95% CI: 0.17, 0.63; P for trend < 0.001) were inversely associated with vitamin D inadequacy [25(OH)D < 50.0 nmol/L]. We estimated that combined use of margarine products (20 g/d), fatty fish (100 g/wk), and vitamin D supplements (>= 1/d) was associated with a 16.8 nmol/L higher 25(OH)D concentration than was the use of none of these. However, none of the participants reached these intakes for all 3 factors. Conclusion: Because few foods are vitamin D-fortified and the amounts of vitamin D in supplements are low, it is difficult to achieve adequate vitamin D status through increasing intakes in the Netherlands and in countries with similar policies.