Effects of an Individualized vs. Standardized Vitamin D Supplementation on the 25(OH)D Level in Athletes.

Plain Language Summary

Vitamin D has hormone-like effects that exert its actions ubiquitously in the human body. This is why it is not only indispensable for general health but also plays a role in athletes’ performance. Vitamin D supplementation plays a central role in covering vitamin D needs. Especially in winter months, when the UV index is too low for endogenous vitamin D synthesis. This study aimed to 1) determine whether an individual loading dose formula for vitamin D supplementation is more effective than standardized supplementation, and 2) assess whether athletes can achieve a target Vitamin D3 - 25(OH)D level of 40 ng/mL. This study was a randomised controlled intervention study conducted during winter months in Germany. Ninety athletes with insufficient vitamin D levels (25(OH)D < 30 ng/mL) were randomly assigned to one of the two groups (standardised or individualised) and received either a universal dose: 2000 IU/day of vitamin D or a loading dose: 4000 IU/day, followed by a maintenance dose of 1000 IU/day. Results showed that: - The individualised group achieved significantly higher 25(OH)D levels (41.1 ± 10.9 ng/mL) compared to the standardised group (32.5 ± 6.4 ng/mL). - the daily maintenance dose for athletes should be higher than 1000 IU to maintain a 25(OH)D concentration of 40 ng/mL throughout the winter months. Authors concluded that their findings indicate that an individualised approach for insufficient vitamin D status correction offers a more reliable and controlled strategy than a standardised approach. Thus, practitioners should consider regular vitamin D monitoring throughout the winter months combined with a personalised vitamin D strategy.