Vitamin A antagonizes calcium response to vitamin D in man.

What Was Tested

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

For unknown reasons, the highest incidence of osteoporosis is found in northern Europe.

In these populations, the sunlight exposure is limited and the vitamin A intake is high.

Who Took Part

The abstract describes 9 subjects taking part.

PubMed indexes the participants as adults, both men and women.

How the Study Was Run

The researchers set it up as a randomized, double-blind, placebo-controlled and crossover 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.

Blinding on both sides kept the subjects 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.

In the crossover set-up each of the subjects took both Vitamin D, K2, Magnesium and Zinc and the comparison in turn, acting as their own control.

What Was Measured

PubMed files the paper under topics including Calcitriol, Calcium, Diterpenes, Retinyl Esters and Vitamin A.

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 9 subjects.

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.

The publication is from 2001 (Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research), a journal based in England.

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