New perspectives on vitamin D sources in Germany based on a novel mathematical bottom-up model of 25(OH)D serum concentrations.

PURPOSE: Up-to-date knowledge about vitamin D supply and serum concentration in Germany is not sufficient. Our purpose was to compare a novel holistic bottom-up modeling of 25(OH)D concentrations with vitamin D sources such as sunlight, food and supplements for all federal states taking seasonal and geographical variations into account. The second purpose was to update and detail vitamin D supply through food in Germany.

METHODS: To confirm the model of 25(OH)D concentrations, we used the population (1,763 men and 2,267 women, 18-79 years) participated in the representative German National Health Interview and Examination Survey 1998 and the integrated German Nutrition Survey.

RESULTS: The maximum model value is 67.5 nmol/L in July and minimum model value is 29.3 nmol/L in January, while the average model value is 45.0 nmol/L. Men have a mean daily intake of 137 IU (3.42 μg) and women of 112 IU (2.79 μg). Correlation between model and actual data is 0.77 (p = 0.003).

CONCLUSIONS: A comparison of the model data with population-based values showed good agreement. None of the vitamin D sources can provide the German population with enough vitamin D.