The effects of season-long vitamin D supplementation on collegiate swimmers and divers.

What Was Tested

Researchers studied Vitamin D, K2, Magnesium and Zinc in this randomized controlled trial publication.

The purpose of this 6-month randomized, placebo-controlled trial was to determine the effect of season-long (September-March) vitamin D supplementation on changes in vitamin D status, which is measured as 25(OH) D, body composition, inflammation, and frequency of illness and injury.

Why It Was Studied

All athletes had sufficient 25(OH)D (> 32 ng/ml) at baseline (mean: 57 ng/ml).

Who Took Part

By PubMed's age tags, the people studied were teenagers, young adults and adults, both men and women.

How the Study Was Run

In design terms this was a randomized, double-blind and placebo-controlled study.

Random assignment meant chance, not the researchers, decided who got Vitamin D, K2, Magnesium and Zinc and who got the comparison, which limits bias.

Neither the participants nor the staff measuring them knew who was on Vitamin D, K2, Magnesium and Zinc, so expectations could not easily colour the readings.

Some participants received a placebo instead of Vitamin D, K2, Magnesium and Zinc, giving a reference point.

Bone turnover markers (NTx and BSAP), 25(OH)D, and inflammatory cytokines (TNF-alpha, IL-6, and IL1-β) were measured at baseline, midpoint, and endpoint.

Body composition was assessed by DXA and injury and illness data were collected.

What Was Measured

The subject headings attached to it are Body Fluid Compartments, Bone Density, Bone and Bones, Cytokines, Dietary Supplements, Femur and Lumbar Vertebrae.

What This Means in Plain Language

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

The publication is from 2013 (International journal of sport nutrition and exercise metabolism), a journal based in United States.

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