High-dose vitamin D changed bone-related blood markers after an ultramarathon
A small trial in male runners examined blood chemistry around a race, leaving effects on bone strength or injury unresolved.
Based on the published abstract. The full paper may contain additional methods, results and limitations.
The 30-second takeaway
Runners given a single high dose of vitamin D before an ultramarathon had a larger immediate rise in a bone-turnover marker than runners given placebo. This suggests a short-term change in bone metabolism under extreme exertion. The study does not establish stronger bones, fewer injuries or a performance benefit from supplementation.
The trial included a small, specialized group of male runners and measured short-term blood markers. The abstract provides no evidence about lasting skeletal benefits or clinical safety.
What researchers found
Blood PINP, a bone-turnover marker
Vitamin D versus placebo immediately after the race; a statistically significant between-group difference, with no numerical effect estimate reported.
What the main result measures
The reported difference concerned PINP, a blood marker included in the bone-turnover assessment. Changes in its concentration describe a biological response to the race; they do not directly measure bone strength or recovery.
Keep the dose in context
The experiment tested a single high dose around an extreme endurance event. Its findings apply to that setting and group, and do not establish whether routine supplementation would help other runners or the wider population.
The original publication
Single high-dose vitamin D supplementation impacts ultramarathon-induced changes in serum levels of bone turnover markers: a double-blind randomized controlled trial.
Stankiewicz B, Kochanowicz A, Brzezińska P et al.
J Int Soc Sports Nutr · 2025
- PubMed ID
- 40963202
- Record checked
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