Does taking vitamin D make you stronger?

Short answer

No. An analysis that pooled 54 trials and 8,747 people found vitamin D did not increase strength, and when taken alongside strength training, strength rose no more than with a placebo.

Does taking vitamin D make you stronger?
'More vitamin D → better muscle function → more strength' — does this formula hold?
Studies linking low vitamin D to poor physical function made many people take vitamin D for strength. We checked whether raising your blood level with supplements actually makes you stronger.
An analysis of 8,747 people: strength did not rise
Same result in people with low levels
An analysis that pooled 54 placebo-controlled trials with 8,747 people found vitamin D did not increase grip, arm or leg strength, or muscle mass. Knee-bending strength was actually slightly lower. Looking only at people with low vitamin D levels, there was still no difference from placebo.
The one analysis that found a gain saw a tiny one
Close to 0 in people under 65
A 2014 analysis of 30 trials and 5,615 people reported a strength gain, but the effect score was a small 0.17. It was 0.25 in people 65 and older and 0.03, close to 0, in younger people. The effect was larger in people with very low blood levels.
Blood levels rose, but strength did not
354 people: much higher levels, no gain in overall strength
A 2024 analysis of 10 trials with 354 people found vitamin D raised blood levels a lot. But combined strength (grip, bench press, jump, thigh strength) did not rise meaningfully; only thigh strength did. A 2023 analysis of 436 people also found no gain in max strength or power.
Same result alongside strength training
8,000 IU a day for 12 weeks: level up 2.6 times, no strength difference
28 people low in vitamin D did strength training for 12 weeks while taking 8,000 IU a day or a placebo. Blood levels rose 2.6 times, but strength and lean mass (muscle and everything except fat) rose with no difference between the groups. A 2025 trial of 26 people taking 2,000 IU a day found the same.
More, for longer, still no gain
2,157 people, 3 years, 2,000 IU a day
In a trial where 2,157 people took 2,000 IU a day for 3 years, physical function, arm and leg muscle mass, and new cases of muscle loss did not differ from placebo. When 200 people took 60,000 IU monthly, leg function was the same, and 66.9% fell within 1 year versus 47.9% on 24,000 IU.
Bottom line: vitamin D is not a strength supplement
What built strength was training
Vitamin D raises your blood level, but not your strength. In trials that paired it with strength training, training was what built strength, and the two groups' gains did not differ. If strength is your goal, focusing on your training program works better than vitamin D.