Vitamin D for runners: what's being used and what the research says
We report what runners are using and what the research says. We don't recommend taking any supplement. Talk to your GP or a registered sports dietitian before trying one.
Quick answer
Research suggests it doesn't. In a meta-analysis of 13 trials in athletes, none of the seven that tested performance found a benefit, even when low levels were corrected[1]. Sports bodies class vitamin D as a supplement for low status, not a performance aid[2][3]. The NHS says everyone should consider 10 micrograms a day in autumn and winter[4].
- Research
- Weak (proposed)For running performance: trials found no gain, even when low levels were raised to normal.
- Proposed by our editor; not yet confirmed by an expert reviewer.
- WADA status
- Permitted
- Distances in the research
- 800 m–5K: limited research10K–half: not studiedMarathon: not studiedUltra: limited research
What is vitamin D?
Vitamin D is a fat-soluble vitamin that works like a hormone. The body makes most of it from sunlight on the skin, and food provides only small amounts[4][2].
Supplements contain vitamin D3 (colecalciferol) or D2 (ergocalciferol). The Australian Institute of Sport says D3 is now considered preferable, and lists vitamin D in Group A of its framework as a medical supplement rather than a performance supplement[2].
Also called: vitamin D3, colecalciferol, cholecalciferol, vitamin D2, ergocalciferol.
Why is vitamin D getting attention?
Low levels are common in athletes: in a meta-analysis of 51 studies, 30% of adult elite athletes had levels below 50 nmol/L[5].
In the UK, sunlight isn't strong enough to make enough vitamin D between October and early March[4]. In a UK study of army recruits, only 9% of men and 36% of women had adequate levels in winter[6].
Many runners take it: in a survey of 135 US collegiate cross-country runners, 34% used vitamin D[7].
How does vitamin D work?
Vitamin D helps regulate the amount of calcium and phosphate in the body, which are needed to keep bones, teeth and muscles healthy[4].
It also acts on genes in most tissues. The IOC describes the evidence on muscle function as equivocal, probably because studies started from different vitamin D levels[3].
Does vitamin D improve running performance?
No, based on the trials so far. In a meta-analysis of 13 trials in athletes, none of the seven that tested performance found a benefit, even when low levels were corrected[1]. A 2025 network meta-analysis found no significant effect on endurance performance[8].
800 m to 5K (Limited research)
In a randomised trial of 137 army recruits in winter, raising vitamin D to adequate levels did not improve a 1.5-mile run[6]. In recreational runners, 8 weeks of supplements from October didn't change VO2max[9].
10K to half marathon (Not studied)
We found no trials of vitamin D with a 10 km or half-marathon result. Across trials in athletes, a network meta-analysis found no significant effect on endurance performance[8].
Marathon (Not studied)
We found no randomised trials of vitamin D that tested marathon performance. In the meta-analysis of trials in athletes, none that tested performance found a benefit[1].
Ultra (Limited research)
In a randomised trial of 35 ultramarathon runners, a single large dose the day before a race of up to 240 km made no significant difference to split times at any checkpoint[10].
The key studies, in order
- 2017Meta-analysis13 trials, 532 athletes: supplements raised vitamin D levels, but none of the seven trials that tested performance found a benefit, even when low levels were corrected. [1]
- 2018TrialUK army recruits: few had adequate levels in winter. In a randomised trial of 137 men, raising levels with D3 or simulated sunlight did not improve a 1.5-mile run, strength or power. [6]
- 2018ConsensusEvidence on vitamin D and muscle function is equivocal. Deficiencies should be identified before supplementing, and even vitamin products have rarely contained banned substances. [3]
- 2018Expert reviewNo performance benefit from raising levels far above sufficiency. Athletes at risk should be tested before correcting low levels, and mega or one-off bolus doses should be avoided. [11]
- 2021Survey135 US collegiate cross-country runners: 34% took vitamin D, and use was higher among runners with a past bone stress injury. [7]
- 2021Trial35 male ultramarathon runners: one 150,000 IU dose the day before a race of up to 240 km made no significant difference to split times at any checkpoint. [10]
- 2022Meta-analysis51 studies, 5,456 elite athletes: 30% of adults and 39% of adolescents had vitamin D levels below 50 nmol/L. [5]
- 2025Meta-analysis30 trials, 693 athletes: vitamin D had no significant effect on endurance performance (very low certainty), and no supplement studied changed VO2max. [8]
- 2026Trial45 recreational runners and non-runners: 2,000 IU a day for 8 weeks from October raised vitamin D levels but did not change VO2max or jump height. [9]
What the research can't tell us yet
Most participants were men: the 1.5-mile run trial was in 137 male army recruits[6], and the ultramarathon trial included only men[10].
The trials are small and varied: the meta-analysis found large differences between studies[1], and the network meta-analysis rated the endurance evidence very low certainty[8].
In one study of 967 recruits, higher vitamin D levels went with slightly faster 1.5-mile times. That is an association: raising levels in the trial that followed did not improve performance[6].
How is vitamin D used in studies?
The NHS says adults need 10 micrograms (400 IU) of vitamin D a day, and that everyone should consider a daily 10 microgram supplement in autumn and winter. It says not to take more than 100 micrograms (4,000 IU) a day unless a doctor advises otherwise[4].
Trials used 2,000 IU a day for 8 weeks[9], 1,000 IU a day falling to 400 IU[6], and a single 150,000 IU dose[10]. Some research doses are above the NHS limit.
A review of vitamin D in athletes found no performance benefit from raising levels far above normal, and says very large or one-off doses should be avoided[11].
| What studies used | When | Ref. |
|---|---|---|
| 2,000 IU of vitamin D3 a day for 8 weeks | October to December, in recreational runners | [9] |
| 1,000 IU a day for 4 weeks, then 400 IU a day for 8 weeks | Winter, in army recruits | [6] |
| A single 150,000 IU dose | 24 hours before an ultramarathon | [10] |
| 3,000 to 5,000 IU a day | Raised low levels in athletes (meta-analysis) | [1] |
What are the side effects, and who should be careful?
The NHS says taking too many vitamin D supplements over a long period can cause too much calcium to build up in the body (hypercalcaemia), which can weaken the bones and damage the kidneys and the heart[4].
You can't overdose on vitamin D from sunlight, but the NHS advises covering up or protecting your skin to reduce the risk of skin damage[4].
Be careful if
- You have kidney problems, high calcium levels or sarcoidosis: the NHS asks you to tell your doctor before taking vitamin D[12].
- You take other medicines, such as digoxin, some water tablets or epilepsy medicines: they can interact with vitamin D[13].
- You're thinking of high doses without a blood test: a review of athletes says those at risk should be tested before correcting low levels[11].
Is vitamin D allowed in competition?
Vitamin D is not on the World Anti-Doping Agency's Prohibited List[14].
The IOC notes that even common vitamin and mineral products have, rarely, been found to contain prohibited substances, and athletes are responsible for anything found in their sample[3].
Independent quality-assurance schemes, often called batch testing, check supplement products for prohibited substances[3]. WADA says using a product from one of these schemes can reduce, but not eliminate, the risk of an anti-doping violation[14], and the IOC says no product can be guaranteed entirely safe[3].
Myth or evidence?
5 things runners hear about vitamin D. Pick an answer to see what the research says.
1.Vitamin D supplements make you run faster.
2.Low vitamin D is common in athletes.
Show the answer
Evidence. In a meta-analysis, 30% of adult elite athletes had levels below 50 nmol/L[5].
3.If you train outdoors in the UK, you can't be low in winter.
Show the answer
Myth. Between October and early March, UK sunlight isn't strong enough to make enough vitamin D[4].
4.More vitamin D is always better.
5.Vitamin D is banned in competition.
Show the answer
Myth. It is not on the WADA Prohibited List[14].
Have you tried vitamin D?
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Frequently asked questions
- Does vitamin D improve running performance?
- Research suggests it doesn't: in a meta-analysis of 13 trials in athletes, none of the seven that tested performance found a benefit[1].
- How much vitamin D does the NHS advise?
- Adults need 10 micrograms (400 IU) a day, and everyone should consider a daily 10 microgram supplement in autumn and winter. The NHS says not to take more than 100 micrograms (4,000 IU) a day[4].
- Do runners who train outdoors get enough vitamin D in winter?
- Not necessarily. The NHS says that between October and early March we don't make enough vitamin D from sunlight[4], and most UK army recruits in one study had low levels in winter[6].
- Is vitamin D3 better than D2?
- The Australian Institute of Sport says D3 is now considered the preferable form[2].
- Can you take too much vitamin D?
- Yes. The NHS says too much over a long period can cause calcium to build up in the body, which can weaken the bones and damage the kidneys and the heart[4].
References
- [1]
Farrokhyar F, Sivakumar G, Savage K, et al. Effects of vitamin D supplementation on serum 25-hydroxyvitamin D concentrations and physical performance in athletes: a systematic review and meta-analysis of randomized controlled trials. Sports Medicine, 2017.
Meta-analysis13 trials, 532 athletes: supplements raised vitamin D levels, but none of the seven trials that tested performance found a benefit, even when low levels were corrected.
doi.org/10.1007/s40279-017-0749-4 - [2]
Australian Institute of Sport AIS Sports Supplement Framework: Group A and linked fact sheets. Australian Sports Commission, 2026.
Consensus statementLists vitamin D in Group A under medical supplements, separately from the performance supplements. Says D3 is now considered the preferable form.
www.ausport.gov.au/ais/nutrition/supplements/group_a - [3]
Maughan RJ, Burke LM, Dvorak J, et al. IOC consensus statement: dietary supplements and the high-performance athlete. British Journal of Sports Medicine, 2018.
Consensus statementEvidence on vitamin D and muscle function is equivocal. Deficiencies should be identified before supplementing, and even vitamin products have rarely contained banned substances.
doi.org/10.1136/bjsports-2018-099027 - [4]
NHS Vitamin D: vitamins and minerals. NHS, 2026.
RegulatorAdults need 10 micrograms a day; everyone should consider a daily 10 microgram supplement in autumn and winter. Do not take more than 100 micrograms (4,000 IU) a day.
www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/ - [5]
Harju T, Gray B, Mavroedi A, et al. Prevalence and novel risk factors for vitamin D insufficiency in elite athletes: systematic review and meta-analysis. European Journal of Nutrition, 2022.
Meta-analysis51 studies, 5,456 elite athletes: 30% of adults and 39% of adolescents had vitamin D levels below 50 nmol/L.
doi.org/10.1007/s00394-022-02967-z - [6]
Carswell AT, Oliver SJ, Wentz LM, et al. Influence of vitamin D supplementation by sunlight or oral D3 on exercise performance. Medicine and Science in Sports and Exercise, 2018.
Randomised controlled trialUK army recruits: few had adequate levels in winter. In a randomised trial of 137 men, raising levels with D3 or simulated sunlight did not improve a 1.5-mile run, strength or power.
doi.org/10.1249/MSS.0000000000001721 - [7]
Barrack M, Fredericson M, Dizon F, et al. Dietary supplement use according to sex and triad risk factors in collegiate endurance runners. Journal of Strength and Conditioning Research, 2021.
Survey135 US collegiate cross-country runners: 34% took vitamin D, and use was higher among runners with a past bone stress injury.
doi.org/10.1519/JSC.0000000000003848 - [8]
Deng B, Li H, Chen C, et al. Dietary supplement strategies during conditioning training in athletes: a network meta-analysis of peak and mean anaerobic power, VO2max, and endurance performance. Food Science and Nutrition, 2025.
Meta-analysis30 trials, 693 athletes: vitamin D had no significant effect on endurance performance (very low certainty), and no supplement studied changed VO2max.
doi.org/10.1002/fsn3.71243 - [9]
Gervasi M, Fernández-Peña E, Zeppa SD, et al. Effects of vitamin D supplementation during autumn and winter on blood biomarkers and physical performance in runners and non runners. Scientific Reports, 2026.
Randomised controlled trial45 recreational runners and non-runners: 2,000 IU a day for 8 weeks from October raised vitamin D levels but did not change VO2max or jump height.
doi.org/10.1038/s41598-026-38528-1 - [10]
Mieszkowski J, Borkowska A, Stankiewicz B, et al. Single high-dose vitamin D supplementation as an approach for reducing ultramarathon-induced inflammation: a double-blind randomized controlled trial. Nutrients, 2021.
Randomised controlled trial35 male ultramarathon runners: one 150,000 IU dose the day before a race of up to 240 km made no significant difference to split times at any checkpoint.
doi.org/10.3390/nu13041280 - [11]
Owens DJ, Allison R, Close GL Vitamin D and the athlete: current perspectives and new challenges. Sports Medicine, 2018.
Expert reviewNo performance benefit from raising levels far above sufficiency. Athletes at risk should be tested before correcting low levels, and mega or one-off bolus doses should be avoided.
doi.org/10.1007/s40279-017-0841-9 - [12]
NHS Who can and cannot take colecalciferol. NHS, 2026.
RegulatorTell your doctor before taking vitamin D if you have high calcium levels, kidney problems or kidney stones, or sarcoidosis, among other conditions.
www.nhs.uk/medicines/colecalciferol/who-can-and-cannot-take-colecalciferol/ - [13]
NHS Taking colecalciferol with other medicines and herbal supplements. NHS, 2026.
RegulatorSome medicines interact with vitamin D, including digoxin, some water tablets, epilepsy medicines and steroids.
www.nhs.uk/medicines/colecalciferol/taking-colecalciferol-with-other-medicines-and-herbal-supplements/ - [14]
World Anti-Doping Agency The Prohibited List. World Anti-Doping Agency, 2026.
RegulatorThe substances and methods prohibited in sport. Vitamin D is not on it.
www.wada-ama.org/en/prohibited-list
Who wrote and reviewed this
Written by Grant MacMillan, Editor, RunV. Not yet reviewed by an expert.
Last checked against its references . Next review due . How pages are reviewed · How we grade research
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