RCTHumann = 342026Poland

Differential and Dose-Dependent Redistribution of Vitamin D Metabolites After Acute High-Intensity Exercise in Mixed Martial Arts Athletes and Untrained Men: Pilot Study.

Journal: NutrientsPublished: 2026DOI: 10.3390/nu18071061

Plain-language summary

This study looked at how high-intensity exercise and vitamin D3 supplements affect vitamin D levels differently in trained athletes versus untrained men. It compared 22 mixed martial arts athletes and 12 untrained men, giving them different doses of vitamin D3 (3500 or 6000 IU/day) or a placebo, then testing their anaerobic performance and vitamin D levels before and after intense exercise. The study found that trained athletes needed a higher dose (6000 IU/day) to reach sufficient vitamin D levels and saw performance gains, while untrained men reached sufficiency with 3500 IU/day. Exercise also temporarily shifted vitamin D levels in opposite directions for athletes versus untrained men.

Key findings

  • 6000 IU/day of vitamin D raised levels in MMA athletes and improved power and work output.
  • 3500 IU/day was enough for untrained men to reach sufficient vitamin D levels.
  • Exercise increased vitamin D metabolites in athletes but lowered them in untrained men taking supplements.

How to analyze the study yourself

Study type
Randomized controlled trials directly test interventions but may not reflect real-world conditions outside the study setup.
Population
Healthy young men, split between trained MMA athletes and untrained controls.
Funding
Not reported
Watch for
This study found that trained athletes needed 6000 IU/day of vitamin D3 to reach sufficient levels and boost performance, while untrained men hit sufficiency with 3500 IU/day. If you train intensely, it may be worth checking your vitamin D levels and adjusting your dose accordingly.