- 25-hydroxyvitamin D, which measures vitamin D levels in the body, is lowest during the winter. Notably, this is when the COVID-19 outbreak began. Individuals should monitor vitamin D through the winter months as a precaution against a deficiency. 
- Individuals hoping to protect against COVID-19 should consider taking 10,000 IU/d of vitamin D3 for a few weeks before lowering the dose to 5000 IU/d.
- For those already infected with COVID-19, it is hypothesized taking the higher dose may still provide some benefit. 

Kenyon College

Michigan State University

Vitamin D is a nutrient that is both endogenously synthesized in the skin and consumed dietarily.  Its biologically active form [1,25-(OH)2D] is a known negative regulator of the Renin-Angiotensin System (RAS).  1,25-(OH)2D has been shown to increase ACE2 expression and suppress the inflammatory outcomes caused by angiotensin II (Ang II).  Additionally, vitamin D can modulate the immune system by inhibiting B-cell and T-cell proliferation as well as inducing T-regulatory cells, which suppress pro-inflammatory cytokines and increase anti-inflammatory cytokines.  These processes may make vitamin D a useful molecule in treating or preventing a SARS-CoV-2 infection.

Using Vitamin D to Mitigate COVID-19

Grant, W. B., Lahore, H., McDonnell, S. L., Baggerly, C. A., French, C. B., Aliano, J. L., & Bhattoa, H. P. (2020). Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths. Nutrients, 12(4), 988. doi:10.3390/nu12040988
https://www.mdpi.com/2072-6643/12/4/988

Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths

- The majority of randomized controlled trials have shown vitamin D does not decrease the risk of COVID-19 infection. However, observational studies have shown a correlation between the two. Researchers believe the disparity may be based in the difficulty of coordinating these studies, as participants may began with varying vitamin D levels, and the dosages between studies may not be consistent. 
- Studies have found that individuals with chronic diseases are likely to also have low vitamin D levels. It is unclear if risk of infection correlates with chronic disease and not vitamin D or a combination of the two. 

Clinical and Epidemiological Findings Regarding Vitamin D and COVID-19 

Proposed Vitamin D Dosage to Mitigate COVID-19

- Studies have found doses of up to 10,000 IU/d vitamin D3 are entirely safe and do not cause adverse effects. Higher doses, up to 600,000 IU/d, were found to protect against other diseases, including asthma, though hypercalcemia was reported among participants. These high doses are not recommended. 
- While several studies have proven the safety of vitamin D, many countries do not have guidelines for supplying individuals with vitamin D supplements, and many remain skeptical of the health benefits. 
- Individuals may choose to increase their vitamin D levels by instead consuming flour and dairy products, though this is not as effective as a supplement. 
- Currently, the exact link between vitamin D and COVID-19 remains unclear, and more research is needed. 

Uncertainty in Using Vitamin D to Mitigate COVID-19

Influenza, HIV, and hepatitis C have been associated with Vitamin D deficiency as a predisposition to these diseases. 
Lower Vitamin D levels in calves has been reported to increase risk for bovine coronavirus.

Learn Before

Related