Vitamin D do not have a beneficial effect on muscle function, strength, or mass in non-athletes and may in some cases even have a negative effect, according a new review of previous studies published in the Journal of Bone and Mineral Research.
Effects of vitamin D supplementation did not differ from placebo. Image credit: Virat Maurya.
“Data regarding effects of vitamin D on muscle function are inconsistent,” said lead author Dr. Lise Sofie Bislev from the Aarhus University Hospital and Aarhus University and colleagues.
“Discrepancies between observational and placebo-controlled studies are an indisputable fact.”
“The objective of our study was to investigate the effects of vitamin D supplementation versus placebo on muscle health.”
For their systematic review and meta-analysis, the authors performed a systematic search of randomized controlled trials published until October 2020 in Medline, Embase, and Google Scholar.
They included studies in humans (except athletes) on supplementation with vitamin D2 or D3 versus placebo, regardless of administration form (daily, bolus, and duration) with or without calcium co-supplementation.
The pre-defined end-points were maximum muscle strength measured as handgrip, elbow flexion, elbow extension, knee flexion, and knee extension.
In total, 54 randomized controlled trials involving 8,747 individuals were included. The majority of the studies used dosages over 2,800 IU/day.
Overall, there were no benefits of vitamin D over placebo for improving muscle health.
On the contrary, vitamin D appeared to have detrimental effects in terms of increased time spent performing what’s called the ‘timed up and go’ test, a decrease in maximum strength at knee flexion, and a tendency towards a reduced score of the short physical performance battery.
“Care should be taken recommending vitamin D supplementation to improve muscle strength and function in people with normal or only slightly impaired vitamin D status,” Dr. Bislev said.
“We need to study further whether it may benefit muscles in those with severe vitamin D deficiency, however.”
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Lise Sofie Bislev et al. Vitamin D and Muscle Health: A Systematic Review and Meta-analysis of Randomized Placebo-Controlled Trials. Journal of Bone and Mineral Research, published online August 17, 2021; doi: 10.1002/jbmr.4412
