Vitamin D supplementation does not improve human skeletal muscle contractile properties in insufficient young males.

What Was Tested

This randomized controlled trial looks at Vitamin D, K2, Magnesium and Zinc.

Vitamin D may be a regulator of skeletal muscle function, although human trials investigating this hypothesis are limited to predominantly elderly populations.

The researchers aimed to assess the effect of oral vitamin D3 in healthy young males upon skeletal muscle function.

Who Took Part

The abstract describes 22 participants taking part.

PubMed indexes the participants as adults, men only.

Muscle function was assessed in n = 22 participants by isokinetic dynamometry and percutaneous isometric electromyostimulation at baseline and at week 6 and 12.

How the Study Was Run

The design is described as randomized, double-blind and placebo-controlled.

Because people in this Vitamin D, K2, Magnesium and Zinc study were split into groups at random, differences between the groups are less likely to reflect who happened to join each one.

Blinding on both sides kept the participants and researchers unaware of who received Vitamin D, K2, Magnesium and Zinc.

The comparison arm used a placebo, so changes seen with Vitamin D, K2, Magnesium and Zinc could be set against what happens without it.

Serum 25[OH]D and intact parathyroid hormone (iPTH) were measured at baseline and at week 4, 8 and 12.

What Was Measured

Topics PubMed links to this paper include Dietary Supplements, Muscle Contraction, Muscle, Skeletal, Parathyroid Hormone, Vitamin D and Vitamins.

What This Means in Plain Language

The paper is a randomized, double-blind and placebo-controlled study of Vitamin D, K2, Magnesium and Zinc in 22 participants.

With fewer than 40 people, it is a small study, so it is better read as an early signal for further research than as a settled answer.

Its findings take up roughly 6 sentences of the abstract and are left out here on purpose; the source paper is the place to read them.

The publication is from 2014 (European journal of applied physiology), a journal based in Germany.

More context: the Vitamin D, K2, Magnesium and Zinc compound page, all human trials.