nutritionhealthscienceinjury-prevention

Vitamin D and injuries in athletes: what the 2026 data showed

Two thirds of college athletes are short on vitamin D, and every 5 ng/mL drop raises the odds of injury by 13%. Here is who is at risk and what runners and triathletes should do about it.

MB
Maxim Belyaev

You are building volume, watching your sleep, counting protein — and by March you still end up with shin splints or some “unexplained pain in the foot”. One possible piece of the puzzle that rarely comes to mind: vitamin D. Recent data show that most athletes do not have enough of it, and that this is linked to a higher risk of injury.

What the research showed

A study published in Sports Health (2026) analysed data from 284 college athletes at a Division I university. Here is what blood 25(OH)D levels looked like:

  • 47,2% — insufficiency (20–31 ng/mL);
  • 17,6% — deficiency (<=19 ng/mL);
  • normal levels (>=32 ng/mL) — only a minority.

In other words, nearly two thirds of the athletes had below-normal vitamin D.

The headline finding: the odds of getting injured during the observation period were 13% higher for every 5 ng/mL decrease in vitamin D (odds ratio 1,13; p = 0,05). At the same time, the authors found no association between vitamin D levels and either the timing of injury or the length of recovery afterwards.

A separate note on strength and power. This study found a negative association between vitamin D and peak jump height (p = 0,04) and peak jump force (p = 0,01), but the authors themselves called these changes clinically insignificant. Put simply: vitamin D is not about jumping higher.

A 2026 review (Quality in Sport) adds context. The most consistent data concern bone health and the risk of bone stress injuries. The review also discusses vitamin D's role in recovery: supplementation may reduce markers of muscle damage and improve inflammatory status, but the results are contradictory. There is evidence linking low levels to ACL tears and to loss of muscle mass after ligament reconstruction. On immunity, vitamin D lowers pro-inflammatory cytokines and supports prevention of acute respiratory infections, especially where there was a deficiency to begin with. When it comes to athletic performance, though, the authors state it plainly: the evidence remains unconvincing.

Who is at risk

We get vitamin D mostly not from food, but from our skin under the action of UVB rays. Hence the risk list:

  • northern latitudes and winter — from late autumn to early spring, synthesis in the skin all but stops;
  • indoor training — pool, gym, indoor track, turbo trainer;
  • training early in the morning or in the evening — when the sun is low and there is almost no UVB;
  • darker skin — more melanin, more time needed in the sun;
  • covered-up clothing — tights, long sleeves, a windbreaker (that is, the typical runner's winter kit);
  • regular sunscreen on exposed areas.

Recognise yourself in three or more of these? You are most likely in that 65%.

What to do in practice

1. Get tested instead of guessing. What you need is serum 25(OH)D. The best moment to assess the worst-case scenario is late winter / early spring (February–March), when stores are at their lowest. A summer test shows you your maximum, not your problem.

2. Food and sun are the foundation. Real dietary sources: oily fish (salmon, mackerel, herring), egg yolk, fortified foods (dairy products and plant-based drinks with added vitamin D). Plus sensible time in the sun during the warm season — without burning.

3. Supplements — based on test results and with a doctor. Not “just in case” and not with a “preventive megadose”. Excess vitamin D can cause hypercalcaemia — that is not a harmless story. And remember: vitamin D works together with calcium — it regulates calcium absorption, so you need to look at both parts of the equation, not just one column on the lab form.

4. Connect it to your overall risk picture. If you have already had a stress fracture, if you are training in an energy deficit, losing weight in season, or — for women — your cycle has become irregular (signs of RED-S), then low vitamin D is not a separate problem but part of a single tangle: low energy availability + nutrient shortfall + high impact loading = a bone that cannot keep up with recovery.

Two myths worth killing:

  • “In summer everyone gets enough.” Enough for those who actually spend time in the sun with bare skin. The early-morning runner in tights and the office worker are not in that category. And stores fall by the end of winter regardless.
  • “The more, the stronger.” The data do not support the idea that high vitamin D makes you more powerful. In the Sports Health study, the association with jump measures was even negative — and clinically insignificant.

Limitations

The Sports Health study is level 4 evidence: a retrospective analysis of routinely collected medical data from a single university, 284 people. This is correlation, not proven causation: low vitamin D may be a marker of other things (little time outdoors, overall energy deficit, dietary composition). The p value of 0,05 sits right on the boundary. The sample consisted of college athletes from team and assorted sports, not endurance runners specifically. The 2026 review is narrative rather than systematic with meta-analysis, and it itself emphasises how contradictory the data on recovery and performance are.

Key points

  • Among college athletes, 47,2% had insufficiency and 17,6% had deficiency of vitamin D.
  • The odds of injury were 13% higher for every 5 ng/mL decrease in 25(OH)D.
  • The most reliable zone of effect is bone and bone stress injuries; the data on recovery and immunity are encouraging but inconsistent.
  • The effect on “pure” performance (strength, jumping) is weak and clinically insignificant.
  • Risk groups: northern latitudes, winter, indoor facilities, early/late training, darker skin, covered-up clothing.
  • Get 25(OH)D tested, preferably in late winter; food and sun are the foundation; supplements based on test results, without megadoses, together with calcium.

This material is for educational purposes and does not replace consultation with a specialist. Testing, interpretation of results and taking any supplements — only with your doctor.

Sources: Low Vitamin D Levels Are Associated With Increased Risk of Musculoskeletal Injuries in Collegiate Athletes. Sports Health, 2026. https://doi.org/10.1177/19417381251407674 · Vitamin D Deficiency in Athletes: A Narrative Review. Quality in Sport, 2026. https://apcz.umk.pl/QS/article/view/70004

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