Optimal dosage of vitamin D supplementation in obese patients with low serum levels of 25-Hydroxyvitamin D. A systematic review

Abstract

The purpose of this study was to assess the evidence for an appropriate dose-response of vitamin D supplementation in patients with obesity with inadequate vitamin D serum levels. We performed a systematic review consulting Medline, Embase and Cochrane Library up to September 2020 to identify studies that included (1) adult obese individuals with vitamin D serum levels below 75 nmol/l, (2) receiving cholecalciferol or calcidiol therapy (3) vitamin D serum levels assessment. The electronic search identified 705 potentially eligible studies, 11 of which were included and analysed. The heterogeneity of the studies did not permit a meta-analysis. Five studies (45.5%) were of high quality. Oral daily cholecalciferol resulted the route of administration that prevailed in most studies. We found that a minimum dose of =>2000UI/day might be needed to normalize 25OHD serum levels. Conversely, oral calcidiol <300IU/day failed to achieve 25OHD sufficiency. Exposed evidence suggests that vitamin D requirements remain higher in patients with obesity compared to lean patients. In order to normalize 25OHD serum levels, patients taking cholecalciferol might need to triple the actual recommended vitamin D doses. In contrast, calcidiol doses are still to be clarified. • Cholecalciferol ’treatment dose in patients with obesity might triple the requirements of non-obese ones. • Calcidiol optimal oral dosage is still to be elucidated. • Recommended dietary allowance for vitamin D may need to take into account patients' body weight and body mass index.