I review the latest sports nutrition research every week, looking beyond the headlines to understand what the findings actually mean for athletes. This week, a large review examined whether vitamin D supplementation can improve muscle mass, strength, and physical performance.

 

The study

The researchers investigated whether vitamin D supplementation can improve muscle mass, strength, and physical performance.

They conducted a systematic review and Bayesian network meta-analysis of 54 randomised controlled trials involving more than 10,000 participants.

The analysis compared four daily vitamin D dose ranges, with and without calcium, against placebo.

Researchers looked at:

• Muscle mass
• Knee extensor strength and handgrip strength
• Physical performance, including walking speed, the timed up-and-go test, and the six-minute walk

 

The results

Vitamin D supplementation did not significantly improve muscle mass, knee extensor strength, or any of the physical performance measures at any dose.

There was one exception. Taking more than 2,000 IU of vitamin D per day alongside calcium produced a small improvement in handgrip strength, averaging 1.36 kg.

However, this was below the estimated threshold for a clinically meaningful improvement. The result also disappeared when researchers excluded trials with a higher risk of bias.

 

Why it matters

Vitamin D is often marketed as a muscle and performance supplement. But this analysis found no convincing evidence that taking more vitamin D improves muscle mass, strength, or physical performance.

For runners, cyclists, and hybrid athletes, the findings suggest that taking extra vitamin D is unlikely to make you stronger or improve your performance.

Important note: The research focused on performance-related outcomes. It did not look at whether correcting a genuine vitamin D deficiency is beneficial.

It also did not look at whether correcting a deficiency can indirectly improve performance, such as by helping you get sick less often so you can train more regularly.

 

My thoughts

This is a good example of why research matters.

Vitamin D plays a role in muscle function, growth, and strength. So, it's easy to assume that taking more will help you build muscle or get stronger.

But having a role in a process doesn't mean supplementing with it improves the outcome.

That's exactly what this research shows. Despite vitamin D's role in muscle function, supplementation didn't meaningfully improve muscle mass or strength.

Is vitamin D still important? Absolutely. Especially when you're not getting enough sunlight, such as during winter.

The practical takeaway: know your vitamin D status, correct a deficiency if you have one, and don't assume a higher dose will deliver extra benefits in the gym or on the course.

A multivitamin like Blonyx Multivit+ can help cover nutritional gaps. Think of it as a way to cover your bases, not a shortcut to better performance.