Knowledge and practice of vitamin D supplementation in the German general population: results from a cross-sectional online survey

Abstract Aim We aimed to provide updated data on the use of vitamin D supplements in the German general population and to investigate their knowledge regarding vitamin D. Subject and methods In November 2024, 4156 participants aged 16 to 65 years were recruited using quota-based sampling. Questions included the use of vitamin D supplements, knowledge of potential health benefits of vitamin D, risk groups for vitamin D deficiency, and sources of vitamin D. In weighted analyses, 4160 cases were included. Multinomial logistic regression was used to explore the determinants of supplement use. Results In the 12 months prior to the survey, 22.9% took vitamin D supplements all year round, and 28.7% took them intermittently (e.g., only in winter). One third (34.1%) had ever been advised to take vitamin D by a health professional. The use of vitamin D supplements was positively associated with female sex, higher physical activity, and having been advised to take vitamin D by a health professional, while the associations with age and tanning behavior were inconclusive. The most frequently cited health effects of vitamin D were strengthening the immune system (71.0%), improving mood (48.8%), and skin health (44.8%). Conclusion In Germany, the use of vitamin D supplements is recommended only for groups with a medically diagnosed vitamin D deficiency. Despite this recommendation, the majority of participants took vitamin D without medical advice. It appears necessary to improve the public knowledge about the potential health effects of vitamin D supplementation and the risk groups for vitamin D deficiency.