The Role of Vitamin D in Infection Prevention

The considerable escalating impact of of CoVid-19 on both public health and the global economy requires us to implement every preventive health measure we have at our disposal. The optimization of our vitamin D status can easily be overlooked, as it is often presumed to be adequate from dietary intake and sun exposure.  Yet, more often than not, levels are found to be suboptimal in North Americans, especially amongst the elderly, people of color, poorly nourished, and financially challenged. 

Most of us already know that Vitamin D plays a vital role in healthy immune function and managing inflammation.  It is an essential component for innate immunity and boosts the anti-viral capabilities of our immune systems.  There is compelling evidence to suggest that the immune-modulating effects of vitamin D can help dampen the risk and lessen the severity of CoVid-19 infections as well as other upper respiratory tract infections(URTIs).1

A 2018 study published in the British Medical Journal demonstrated that vitamin D supplementation reduced the rate of URTIs by 12%. What was more remarkable was the 70% reduction seen in people who initially already severely deficient in vitamin D. 2

Three different studies from South Asia that suggest that people with severe vitamin D deficiency were 8X more susceptible to developing severe COVID illness than their vitamin D sufficient counterparts. 3

It is interesting to note that during the 1918 influenza pandemic, it was standard practice to put patients outside to get fresh air and sunshine. Open air therapy was the treatment of choice continued to be utilized until antibiotics were developed in the 1950s. It was even used to treat deadly tuberculosis, which was rampant at the time. Death rates declined from 40% to 13%, and both fresh air and sunlight were considered to be effective disinfectants. 4,5

How to get more vitamin D? Unfortunately, there are not very many foods in which vitamin D exists naturally. There is a moderate amount in fatty fish like salmon and mackerel, not likely enough to significantly increase your blood levels unless you consume them regularly. The only other options are to supplement and/or get adequate sun exposure, now that the weather is improving.

Sunlight is made up of UVA and UVB wavelengths. In order to optimize your vitamin D production, large portions of skin needs to be exposed to UVB rays for about 20 minutes/day. Anyone with darker skill will need longer in order to achieve this. The best time of day for UVB exposure is around noon. Balance is key as you don’t want to get sunburned.

This current pandemic has many of us feeling like there a so many factors over which we have no control. Getting plenty of fresh air and sunshine is just a couple of simple strategies to help ourselves. Sound medicine for body, mind and spirit.


  1. The Possible Role of Vitamin D in Suppressing Cytokine Storm and Associated Mortality in COVID-19 Patients Ali Daneshkhah, Vasundhara Agrawal, Adam Eshein, Hariharan Subramanian, Hemant Kumar Roy, Vadim Backman medRxiv 2020.04.08.20058578; doi:
  2. Vitamin D Supplementation Could Possibly Improve Clinical Outcomes of Patients Infected with Coronavirus-2019 (COVID-19) (April 9, 2020). Alipio, Mark, Available at SSRN: or
  3. Martineau Adrian R, Jolliffe David A, Hooper Richard L, Greenberg Lauren, Aloia John F, Bergman Peter et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data BMJ 2017; 356 :i6583
  4. Anon. Weapons against influenza. Am J Public Health 1918 Oct;8(10):787–8. doi: 10.2105/ajph.8.10.787.
  5. May KP, Druett HA. A micro-thread technique for studying the viability of microbes in a simulated airborne state. J Gen Micro-biol 1968;51:353e66. Doi: 10.1099/00221287–51–3–353.
Tasleem Kassam