Briefly, the literature on Vitamin D’s role in immune health has exploded in the past 10 years, particularly in relation to viral infections and autoimmune disorders. Approximately 80% of the literature is new in the past decade and much of it has been published overseas. There are studies showing that Vitamin D sufficiency is important to reduce mortality in ventilated patients. There is a large and growing literature on Vitamin D’s role in preventing viral infections and reducing their severity.
The populations at highest risk of severe cases of COVID-19 (the elderly and those with underlying health conditions) and the timing of the outbreak (end of winter in the Northern Hemisphere when population Vitamin D levels are typically lowest) are consistent with deficient Vitamin D status being a risk factor for COVID-19. The relatively small percentage of infections in children may reflect children’s higher milk consumption since milk is fortified with Vitamins A and D. Vitamin D is both a vitamin and a steroid hormone with hundreds of roles in our bodies.
A 2018 study based on NHANES data from 2001-2010 found that 28.9% of American adults were Vitamin D deficient (serum 25(OH)D<20ng/ml) and an additional 41.4% of American adults were Vitamin D insufficient (serum 25(OH)D between 20ng/ml and 30ng/ml). Americans who were black, less-educated, poor, obese, current smokers, physically inactive or infrequently consumed milk had higher prevalence of Vitamin D deficiency. Those with intestinal disorders (Crohn’s or celiac) that reduce dietary uptake of Vitamin D and those with liver or kidney diseases that may reduce the body’s conversion of Vitamin D to its active form may also be at increased risk of deficiency regardless of age. Vitamin D is a fat-soluble steroid hormone that regulates over 200 genes in the human body.
Questions that need answers
Based on the breadth of the research on Vitamin D in acute respiratory disorders and the many viral infections in which Vitamin D status plays a role, the following questions need to be answered:
- Are hospitalized COVID-19 patients Vitamin D deficient (serum 25(OH)D levels < 20ng/ml) or insufficient (levels between 20ng/ml and 30ng/ml)?
- Are hospitalized COVID-19 patients more Vitamin D deficient than would be expected in matched controls?
- Are hospitalized COVID-19 patients who need intensive care more Vitamin D deficient?
- Does giving high-dose Vitamin D to COVID-19 patients reduce their need for mechanical ventilation and/or reduce the amount of time that they require mechanical ventilation?
- Does giving high-dose Vitamin D to health-care workers reduce their risk of COVID-19?
- If Vitamin D deficiency is found in severe COVID-19 patients, what recommendation should be made to the general public, particularly those who are quarantined and/or fighting infections at home?
While only time and studies will give us definitive answers to these questions, Vitamin D testing is widely available, supplements are inexpensive and in a COVID-19 critical care setting we should consider anything that might reduce the number of cases, hospitalizations and deaths. Even a 10% reduction in one of these metrics would have a major impact.
The literature supports the importance of Vitamin D sufficiency
There are studies suggesting that sufficient Vitamin D reduces the risk of acute respiratory infections. Also, the literature supports the importance of Vitamin D sufficiency in reducing morbidity and mortality in critical care settings. This is a sample of the literature. …