BACKGROUND: Scientific studies point to a significant global vitamin D deficiency. The recommended dose of vitamin D for the adult population in Central Europe is 800-2000 IU/day. The aim of our study was to determine whether doses of 1000 IU or 2000 IU of vitamin D3 are adequate to achieve the sufficiency reference values of [25(OH)D]. METHODS: Seventy-two healthy volunteers, average age twenty-two, took part in the study. The study was conducted from October to March in order to eliminate intra-dermal vitamin D production. Vitamin D3 in an oleaginous mixture was used. The participants used either 1000 IU or 2000 IU/daily for two 60-day periods with a 30-day break. RESULTS: The dose of 1000 IU, taken for 60 days, increased vitamin D levels relatively little. Furthermore, serum vitamin D levels decreased in the 30 days following the cessation of supplementation. Taking 2000 IU daily led to a sharp increase in serum levels which plateaued 30 days after the subjects stopped using vitamin D3 drops. CONCLUSIONS: Both doses, taken daily, can help maintain adequate vitamin D levels during the winter months. A daily dose of 2000 IU, however, maintained the desired levels of vitamin D for a longer period.

Department of Clinical Biochemistry and Hematology University Hospital and Faculty of Medicine in Pilsen Charles University 323 00 Pilsen Czech Republic

Department of Immunochemistry University Hospital and Faculty of Medicine in Pilsen Charles University 323 00 Pilsen Czech Republic

Department of Pharmacology and Toxicology Faculty of Medicine in Pilsen Charles University 323 00 Pilsen Czech Republic

Faculty of Science Palacky University in Olomouc 779 00 Olomouc Czech Republic

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