Vitamin D has various forms. It’s inactive or initial form cholecalciferol is produced in the skin when exposed to sunlight, and can also  be ingested from a few natural foods including: fatty fish, mushrooms exposed to sunlight, and supplements including those commonly added to cow’s milk found in the grocery store.

This ingested or skin-produced form of vitamin D is inactive, and must undergo two modifications called hydroxylations to become active vitamin D, called calcitriol. These two steps occur first in the liver , then in the kidneys. Calcitriol has multiple biologic effects and acts in many ways as a hormone. It is involved in controlling calcium and phosphate levels and metabolism; this involves intestinal absorption and bone metabolism. It has other effects on cell growth, neuromuscular physiology, immune function, and limits inflammation.

Several scientific observations support the role of Vitamin D in both the prevention and treatment of Covid-19. First is that persons deficient in vitamin D are more likely to test positive for the SARS-CoV2 virus. Second is that persons who experience acute respiratory failure with this virus, are more likely to be Vitamin D deficient. Third is that patients hospitalized with covid-19 have been found to be much less likely to require admission to the intensive care unit, if they are given high doses of Vitamin D.   Fourth, is a correlation found that Hispanic and Black sub-populations have higher incidences of vitamin D deficiency, and are also disproportionately affected by Covid-19.

Moderate sun exposure, and/or ingesting vitamin D supplements are reasonable ways to ensure adequate vitamin D levels. 1000 to 3000 IU’s of Vitamin D are common and well tolerated doses.

Many physicians recommend Vitamin D supplementation of 3000 IU daily for prevention and treatment of covid-19.