Four weeks of vitamin D supplementation improves nitric oxide-mediated microvascular function in college-aged African Americans.

What Was Tested

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

After stable elevated blood flow was attained, 15 mM NG-nitro-l-arginine methyl ester (l-NAME; NO synthase inhibitor) was perfused at all sites to quantify the NO contribution to cutaneous vasodilation (%NO), calculated as the difference between local heating and l-NAME plateaus.

Who Took Part

According to the abstract, 9 men were involved.

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

Three intradermal microdialysis fibers placed in the ventral forearm were randomized for treatment with 10 μM Tempol, 100 μM apocynin, or lactated Ringer's solution (control).

How the Study Was Run

In design terms this was a randomized study.

The men were allocated by chance, so the Vitamin D, K2, Magnesium and Zinc group and the comparison group should start out alike.

Serum vitamin D concentrations [25(OH)D] were measured at each visit.

Local heating (39°C) induced cutaneous vasodilation; red cell flux was measured at each site (laser-Doppler flowmetry), and cutaneous vascular conductance (CVC = flux/MAP) was expressed as a percentage of maximum (28 mM sodium nitroprusside, +43°C) for each phase of local heating.

What Was Measured

Topics PubMed links to this paper include Black or African American, Age Factors, Dietary Supplements, Microvessels, Nitric Oxide, Skin and Vasodilation.

The authors tagged it with the keywords microvascular function and vitamin D.

What This Means in Plain Language

The paper is a randomized study of Vitamin D, K2, Magnesium and Zinc in 9 men.

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 2020 (American journal of physiology. Heart and circulatory physiology), a journal based in United States.

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