Prevalence of vitamin D deficiency in a population-based study: Results from the Heinz Nixdorf Recall Study

Introduction: 25-OH vitamin D (Vit D) status is associated with a variety of diseases, including bone, cardiovascular and metabolic disorders. In Germany, Vit D levels of < 20 ng/ml are classified as insufficient. Aim of this study was to analyze the current status of Vit D levels and the prevalence of deficiency in an unselected population of middle-aged to old people in a metropolitan area of Western Germany.

Methods: The Heinz Nixdorf Recall study, initiated to study new cardiovascular risk factors, was designed as a prospective population-based study with participants randomly selected from registries of residence of the cities of Bochum, Essen and Mulheim, Germany. A total of 4814 participants aged 45 – 75 years were recruited and Vit D serum levels were measured (Nichols Advantage).

Results: We excluded 665 participants because of missing values. Of the remaining 4.149 subjects, median Vit D level was 19.8 ng/ml (Interquartile range Q25-Q75: 14.4 – 26.6 ng/ml), with lower levels for women (18.9 ng/ml, Q25-Q75: 13.4 – 25.5 ng/ml, n = 2.089) than men (20.9 ng/ml, Q25-Q75: 15.4 – 27.6 ng/ml, n = 2.060). The prevalence of Vit D deficiency (< 20 ng/ml) was 50.6% (95%-CI: 49.0 – 52.3) with a ratio of 55% women. In the dark season (November-March) Vit D median values were lower (men: 17.2 ng/ml (Q25-Q75: 12.9 – 23.4), women: 16.6 ng/ml (11.5 – 23.1)) than in the sunny season (men: 23.4 ng/ml (17.9 – 30.0), women: 20.1 ng/ml (15.3 – 27.3)). In elderly women (65 – 75 years) median values were lowest (dark season: 14.6 ng/ml (10.3 – 20.3); sunny season: 17.7 ng/ml (13.4 – 23.8). In men there was no age effect.

Conclusion: Vit D deficiency, according to the national DVO (Dachverband Osteologie) guideline, was observed in about the half of our study population. Whether supplementation at all or to which extent benefits patients has to be elucidated since age- and sex specific cut off points are lacking.