By Michael Baron, MD, MPH


Adequate Vitamin D levels may decrease risk for a more virulent course of infection with the SARS-CoV-2 virus, the virus that causes the Covid-19 infection.

I am not selling vitamins, and I am not an infectious disease or immunology expert. I am a triple board certified physician with a degree in public health and 30-years of medical practice experience. I read and understand the medical literature. Like many non-ICU physicians, I’ve been sidelined from the work taking place in our hospitals. So, this is my contribution to help reduce the morbidity and mortality caused by this pandemic. If this article helps to reduce our morbidity and mortality rates by even one patient, then I’ve been successful.

The Quick Science

Vitamin D is produced in the skin from ultraviolet B (UVB) sunlight exposure. Ultraviolet B rays are one of the types of rays that the sun sends down to Earth. From the skin it is changed into an active hormone that increases calcium absorption from food in the intestine. The calcium is then used to keep the skeleton strong.

Vitamin D also supports the immune system through a number of pathways. One of which is that vitamin D modulates the response of white blood cells, preventing them from releasing too many inflammatory proteins called cytokines. In severe cases that involve acute respiratory failure, the SARS-CoV-2 virus is known to cause an excess release of the specific type of cytokines that cause more inflammation or are pro-inflammatory.

Most vitamin D comes from production in the skin rather than our diet. In the winter months when exposure to sunlight is reduced, vitamin D production is reduced. Other factors that reduce vitamin D levels include increased skin pigmentation, use of SPF protection, old age, and obesity.

The Quick Literature Review


The seasonal and geographic differences for respiratory tract infections may be explained, at least in part, by Vitamin D deficiency. The recent article in the Journal Aging Clinical and Experimental Research showed that both Italy and Spain have both experienced high COVID-19 mortality rates and that both countries have lower average vitamin D levels than most northern European countries. This may be explained by the patterns of sun avoidance in southern Europe, especially by the elderly and also that skin is more pigmented in these regions, reducing natural vitamin D synthesis. Northern Europe with lower mortality rates from Covid-19 has higher average levels of vitamin D due to the consumption of cod liver oil and vitamin D supplements.


Another article published in the respected British Medical Journal in 2017, before Covid-19 was identified, showed the seasonal variation of influenza or flu can be explained by sun exposure and vitamin D production in the summer months. It also suggested that daily dosing of a vitamin D supplement is better than a single large dose at decreasing the severity of viral respiratory infections.


Having read this review article in early March, I have been waiting for the government agencies, CDC, INH, HHS, WHO to issue advisories to take supplemental vitamin D. They haven’t come … or at least I haven’t seen them. My only guess is that the government health agencies don’t want to promote a false sense of security by touting a supplement that is not a cure. But we need every weapon we can muster against this pandemic.

Vitamin D does nothing to prevent the illness caused by Covid-19. It cannot replace social distancing or quarantining. It absolutely should not give anyone a false sense of security or thought that it provides immunity from the disease. Vitamin D supplementation does not provide immunity. It does not replace a vaccine.

Vitamin D supplementation does show strong indications that it can decrease the morbidity of the SARS-CoV-2 virus. In addition, there are no known negative side effects to therapeutic supplemental Vitamin-D. Since Covid-19 has killed over 80,000 people in our country, maybe this information should be disseminated as a low-tech way to help decrease morbidity.

If you take vitamin D supplementation, please follow the guidelines on the bottle or check with your doctor as to the appropriate dose and any interactions with other medications. As with any supplement, an extreme amount of vitamin D can be lethal. Do not administer vitamin D supplements to children without checking with their pediatrician. Pregnant women should also check with their obstetrician before taking vitamin D.

Cannell, J. J., R. Vieth, J. C. Umhau, M. F. Holick, W. B. Grant, S. Madronich, C. F. Garland, and E. Giovannucci. “Epidemic influenza and vitamin D.” Epidemiology & Infection 134, no. 6 (2006): 1129-1140.
Martineau, Adrian R., David A. Jolliffe, Richard L. Hooper, Lauren Greenberg, John F. Aloia, Peter Bergman, Gal Dubnov-Raz et al. “Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data.” bmj 356 (2017): i6583.
Petre Cristian Ilie, Simina Stefanescu and Lee Smith. “The role of vitamin D in the prevention of coronavirus disease 2019 infection and mortality” Aging Clinical and Experimental Research.

May.Bonus Blog.Dr Michael-BaronMichael Baron, MD, MPH attained his Medical Degree, Master in Public Health and completed an internal medicine internship at Tulane University School of Medicine. He completed his first residency in anesthesiology at Washington University School of Medicine and his psychiatry training at Vanderbilt University School of Medicine. He has maintained his certifications in anesthesiology, psychiatry and addiction medicine.
He has practiced in the Nashville area since 1998 in a variety of settings including private practice, teaching hospitals and residential treatment centers. Baron has specialized in treating chronic pain and addiction. In 2006, he published original research showing that chronic opioid use increased chronic pain scores.
Baron was appointed to the Tennessee Board of Medical Examiners (BME) in 2010 and reappointed in 2015. Additionally, served as chair of the Controlled Substance Monitoring Database committee from 2014 where he helped write the Tennessee Chronic Pain Guidelines, as well as many different Department of Health rules. He resigned from the Board of Medical Examiners and the Controlled Substance Monitoring Database committee in January 2017 to accept the position of medical director of the Tennessee Medical Foundation – Physician Health Program.