Vitamin D Supplementation and Sunlight Exposure on Serum Vitamin D Concentrations in 2 Parallel, Double-Blind, Randomized, Placebo-Controlled Trials.

What Was Tested

The paper reports a study of Vitamin D, K2, Magnesium and Zinc, published as a randomized controlled trial.

The researchers aimed to investigate the effects of vitamin D supplementation and sunlight exposure on vitamin D concentrations in Brazilian women living in high compared with low latitudes.

Why It Was Studied

Vitamin D concentrations are a function of sunlight exposure and dietary intake.

However, current dietary vitamin D recommendations do not consider differences in country-specific sunlight availability or spontaneous individual exposure.

Who Took Part

The age groups tagged for this paper are young adults and adults, women only.

In 2 parallel, double-blind, randomized placebo-controlled trials, Brazilian women living in England (51°N) composed "without ultraviolet B (UVB) exposure" groups and those living in Brazil (16°S) composed the "with UVB exposure" groups (mean age, 31.39 ± 8.7 years).

The effects of supplementation and UVB exposure were tested by the intention to treat with a linear mixed model.

How the Study Was Run

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

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.

As a double-blind Vitamin D, K2, Magnesium and Zinc study, the assignments were hidden from both participants and investigators until the end.

A placebo (an inactive look-alike) gave the Vitamin D, K2, Magnesium and Zinc group a baseline to be compared against.

The Vitamin D, K2, Magnesium and Zinc group and the comparison group ran side by side rather than switching.

Serum 25-hydroxyvitamin D [25(OH)D] concentrations, the primary outcome, were assessed by HPLC-MS/MS, vitamin D intakes were assessed by 4-day diet diaries, and sunlight exposure was assessed by UVB dosimeters.

What Was Measured

The subject headings attached to it are Cholecalciferol, Dietary Supplements, Seasons, Sunlight, Tandem Mass Spectrometry, Vitamin D and Vitamin D Deficiency.

The authors tagged it with the keywords Brazil, England, latitude, serum 25(OH)D and supplementation.

What This Means in Plain Language

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

Its findings take up roughly 5 sentences of the abstract and are left out here on purpose; the source paper is the place to read them.

The publication is from 2021 (The Journal of nutrition), a journal based in United States.

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