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Vitamin D and the Implications With COVID-19

If you’re like me, you may feel like you are reading something new everyday about how to support your immune system, what herb or supplement to take, ect. And if you're like me again, you want to trust the information and know that it comes from a science based resource. With regards to COVID-19, this is even more important. Today we’re looking at the role of vitamin D in the body and it’s rising level of value in minimizing the effects and duration of the virus in our bodies. There are numerous correlations between individuals that are most likely to be deficient in vitamin D and those that are considered most at risk for COVID-19 and it’s complications. (Benskin) I hope this to be a trusted source of information that will benefit you and your family’s health.

Before we dive into the specifics, let’s look at what vitamin D does in the body. Then we’ll explore the research that has been coming forward in the past few months, and finally, how you can ensure during the dark winter months you are safely getting enough of this “sunshine vitamin.”

How Vitamin D works in Your Body

The “sunshine vitamin” is so aptly named because we primarily get it from exposure to the UVB rays from the sun, and then it gets converted in the body two separate times before it becomes usable. When UVB rays from the sun meet the skin, this is where the first conversion happens using cholesterol and the liver. It’s at this stage that we are able to test the blood for vitamin D levels. The recommended level is found to be 30 ng/ml with 100 ng/ml or higher at risk for toxicity (Benskin). The second conversion happens in the kidneys and this is where it becomes calcitriol and is usable by the cells in our body. Vitamin D is utilized for many functions in the body. There is evidence of receptor sites on cells that support bones, muscles, intestines, the immune and cardiovascular systems, the pancreas, the uterus, and the brain (Nair).

That’s a lot for this little vitamin to do, and it must be pretty important if there are so many organs in our body that have receptor sites!

Who is at Risk for Vitamin D Deficiency?

It probably goes without saying that the less sun exposure you get, the less vitamin D you get. This is true for anyone who is home-bound, wearing sunscreen, clothing that blocks exposure, and living at a latitude above 37˚in the Northern Hemisphere (think Denver and above). Studies have also correlated air pollution and density of clouds to also decrease sun exposure. (Benskin)

Less intuitive though, is people with darker skin tones. Darker skin absorbs more melanin during exposure to UVB rays, which actually decreases their ability to convert the radiation to vitamin D (Nair).

Also, individuals who are overweight/obese have lower vitamin D levels due to how vitamin D is stored in subcutaneous fat and the ability for the body to release it is disrupted.

Lastly, a population dear to my heart, is during pregnancy and in young children. Studies show that the need for vitamin D increases when you are growing a little one, with deficiency rates as high as 20-40%. (Lee) Once born, breastfed babies are recommended to supplement vitamin D either directly or through mom’s breastmilk due to higher risk of deficiency.

Correlations with COVID-19

If you’ve read the news, you’ve likely seen and heard that those at risk for complications from COVID-19 are the obese, diabetic, and elderly. Recent studies, though, are also showing that “people with sufficient vitamin D levels in the United States have as much as a 54% reduced risk of getting infected with COVID-19” (Melville), and there is a strong correlation between having adequate blood levels of vitamin D and decreased COVID-19 disease severity. This is even after adjusting for factors including age, sex, body mass index (BMI), smoking, and history of chronic medical conditions. (Melville) It is important to note that the high risks groups stated above historically have lower levels of vitamin D, but so does a large part of the healthy population, 41% to be exact! (Forrest) So why is this? This is what I wanted to know and here is what I found.

Inflammation, Cell regeneration, and the Cytokine Storm.

The most important piece that is being reported with vitamin D is it’s relationship with inflammation . We know that in severe cases of Covid-19, people’s immune systems become overactive and produce what you have probably heard of as a “cytokine storm.” Vitamin D has been shown to “regulate the production of inflammatory cytokines and immune cells.” (Liu) It’s a complex process, but we can basically think about vitamin D as an immunomodulator, helping the immune system stay calm and focused.

Another negative outcome we are seeing from these cytokine storms is cellular damage, specifically along endothelial cells (those that line the organs and blood vessels). When these cells die, you begin seeing leakage of vessels, low platelet counts, and intravascular coagulation. (Hojyo) A main function of vitamin D in the body is with cell regeneration. It is possible with higher levels of vitamin D in the body, this damage may be mitigated or lessened and more healing can begin. (Shintaro)

It is important to note that many of the studies mentioned are based on observation. There has been little time to perform randomized trials and experiments to accurately relate vitamin D alone to its ability to diminish the effects of COVID-19 on individuals.

How to Support Your Body with Vitamin D

With winter months approaching, it is more likely that you may be deficient in vitamin D. In addition to the above mentioned benefits and protections, even in non-pandemic times, I always am checking my patients levels and giving recommendations. Getting adequate sun exposure is not a likely source here in the US, and if you’re relying on food, you’ll need to be eating a lot of fatty fish, abundant amounts of mushrooms grown under UV lights, or fortified foods. (see chart below)

-Institute of Medicine

It is likely that you’ll need to consider supplementation along with diet. Recommendations in the United States vary between practitioners. Recommended supplementation can be as low as 1000 IU/day up to 8000 IU/day (Benskin). Many sources agree that anything above 8000 IU/day must be monitored by a doctor and should not be done long term. Those that recommend higher dosages do so for those at higher risk, deficient, and have complicating factors (such as medication that decreases calcium absorption).

I always use a trusted brand that contains vitamin D3 (cholecalciferol) in some sort of triglyceride. If you are vegan, be aware that most D3 comes from an animal source and to talk to your healthcare provider for vegan-friendly options. If you are pregnant or nursing, please go here for information specific to you and your unique relationship with vitamin D. It is possible to experience vitamin D toxicity, though it is rare. It is always important to make a plan with your healthcare provider to test your levels and supplement appropriate doses to YOUR body.

Summary and Takeaways

I think the most important message in all this research and information is to be aware of your own health status and what that means to your risk for COVID-19. If you fall into any of the categories at risk for vitamin D deficiency, I would recommend getting your levels checked by your healthcare provider. If this is not an option, then talk to your provider about a supplement dosage right for you.

If you’d like to learn more, get your levels tested, and start a plan for fully supporting your immune system you can contact me at:

Foundations Family Medicine 970-439-2104


Benskin L. L. (2020). A Basic Review of the Preliminary Evidence That COVID-19 Risk and Severity Is Increased in Vitamin D Deficiency. Frontiers in public health, 8, 513.

Hojyo, S., Uchida, M., Tanaka, K., Hasebe, R., Tanaka, Y., Murakami, M., & Hirano, T. (2020). How COVID-19 induces cytokine storm with high mortality. Inflammation and regeneration, 40, 37.

Ross AC, Taylor CL, Yaktine AL, Del Valle HB. Institute of Medicine Committee to Review Dietary Reference Intakes for Vitamin D and Calcium.. Overview of vitamin D. Washington: National Academies Press; 2011

Forrest, K. Prevalence and correlates of vitamin D deficiency in US adults. . 2011 Jan;31(1):48-54. doi: 10.1016/j.nutres.2010.12.001. PMID: 21310306

Lee JM, Smith JR, Philipp BL, Chen TC, Mathieu J, Holick MF. Vitamin D deficiency in a healthy group of mothers and newborn infants. Clin Pediatr (Phila) 2007;46:42–4

Liu, W., Zhang, L., Xu, H. J., Li, Y., Hu, C. M., Yang, J. Y., & Sun, M. Y. (2018). The Anti-Inflammatory Effects of Vitamin D in Tumorigenesis. International journal of molecular sciences, 19(9), 2736.

Melville, N. More Evidence That Vitamin D Sufficiency Equals Less Severe COVID-19. Medscape Medical News. September 30. Accessed Dec. 8th, 2020 from 2020

Nair, R., & Maseeh, A. (2012). Vitamin D: The "sunshine" vitamin. Journal of pharmacology & pharmacotherapeutics, 3(2), 118–126.

Ross AC, Taylor CL, Yaktine AL, Del Valle HB. Institute of Medicine Committee to Review Dietary Reference Intakes for Vitamin D and Calcium.. Overview of vitamin D. Washington: National Academies Press; 2011

Weir, E. K., Thenappan, T., Bhargava, M., & Chen, Y. (2020). Does vitamin D deficiency increase the severity of COVID-19?. Clinical medicine (London, England), 20(4), e107–e108.


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