The Role of Vitamin D in Covid-19


Within the last six months, the United States has undergone the devastating loss of more than 205,000 individuals to the Covid-19 virus, with greater than 7 million people currently infected from the novel disease. During that timeframe, science has searched for methods to reinforce the immune system of both healthy and compromised persons in order to protect them from a virus that has transformed the way we live, work, and educate our families.

While nothing can take the place of social distancing, hand washing, or masks, people have been clamoring for more. They want to know about supplements that may decrease the risk of infection or lessen the impact of the disease if they are infected. As infectious disease experts have cautioned, the basics continue to be important: adequate sleep and a healthy diet, however, research has also begun to demonstrate that supplementation with a few key agents may have a role to play in Covid-19.

Severe Disease

As findings go in healthcare, significant research is often linked to observing undesirable patient outcomes first. This happened with findings published by the University of Chicago, as well as countries such as Spain and Italy, when it was discovered that Vitamin D deficiencies might be linked to Covid-19 infections, and possibly more severe disease. The University of Chicago examined 489 patients who had vitamin D levels tested in the year prior to being checked for Covid-19. Those who had low vitamin D levels (less than 20 ng/ml) were almost twice as likely to test positive for Covid-19 as those whose vitamin D levels were within normal range. The reason why this is significant is because vitamin D plays a role in the body’s immune function, and deficiencies are quite common.4

Over 50% of Americans are deficient in vitamin D. This may be even more notable in African American and Latino populations who live in cities such as Chicago where the weather in winter makes it extremely difficult to get sun exposure.1

Vitamin D is relatively inexpensive and utilizing it on a varied scale could be easily implemented for a range of populations, pending further study.

Current Knowledge

Dr. Anthony Fauci has agreed that being deficient in vitamin D does have an impact on your susceptibility to infection. He also stated that he takes vitamin D supplements and he would not mind recommending that others do so.3

Although it is recommended that the best start for vitamin D supplementation is a healthy diet, not many adults in the United States have been able to purchase the foods that would get us the amount of vitamin D we need. Foods such as salmon and other fatty fish, eggs yolks, mushrooms, and fortified milk would provide the vitamin, but the pandemic has forced countless adults to purchase frozen and packaged foods that are less nutritious.

Interestingly, a recent meta-analysis of 40 research studies found that daily long-term doses of vitamin D seemed to protect against URI’s. Other studies have found associations between Covid-19 infection and vitamin D. Physicians in Spain noted a link between more serious Covid-19 infections and low vitamin D levels, as did physicians in Italy, where it was noted that patients deficient in vitamin D were more likely to die.3

It is believed by the researchers studying the effects of vitamins on the Covid-19 patients that not only did vitamin D play a significant role in immune function, but that it also minimized the role of the “cytokine storm” seen in severely ill Covid-19 patients requiring intubation/ventilation, providing a moderating response and thus avoiding an immune overreaction that led to multisystem collapse.1


Vitamin D deficiency may be exacerbated by many conditions aside from a lack of exposure to sunlight. Older age, darker skin, and medication use such as steroids may also lead to lower levels of 25-hydroxyvitamin D concentrations below 20ng/ml. Vitamin D supplementation is inexpensive and the vitamins may be found in nearly every pharmacy and grocery. According to the Endocrine Society, adults may need to take 1,500 to 2,000 IU/day of vitamin D to maintain levels above 30ng/ml. Maintaining an adequate store of vitamin D will assist the body’s intrinsic immune function. Once ingested, both vitamins D2 and D3 function nearly the same, however, studies demonstrate that vitamin D3 will raise serum levels faster and maintain levels longer than D2.

People who are unsure if they need to supplement with vitamin D may ask their primary provider to order a blood test to examine 25-hydroxyvitamin-D levels prior to starting a supplement. Vitamin D toxicity is extremely rare, but it does occur. The risks of too much vitamin D include hypercalcemia, which can damage the kidneys. The upper limit of Vitamin D intake is 60 ng/ml., and this occurs over time.

Additional Supplements that May Prove Helpful

Studies in birds have shown that Vitamin C may protect them against Avian Coronavirus, thus scientists have hypothesized that Vitamin C may also protect humans against infection. Human trials are underway to determine how much efficacy Vitamin C may offer to protect children and adults against the novel coronavirus in both the United States and China. In the interim, Dr. Anthony Fauci has stated that supplementation with either Vitamin C and Zinc or both may be helpful in preventing upper respiratory infections.2

Zinc has a role in antibody and white blood cell protection and fights infections. Because of its role in the immune process, zinc is also being studied as an agent that may be useful in the fight against the novel coronavirus.2


While Americans have searched for answers to the horrific pandemic that has arrived this past six months, it appears one of the tools we need may be staring right into our eyes, causing us to turn away from its glare. Although we cannot replace the basics of handwashing, social distancing, masks, and a vaccine when it arrives, supplementation with vitamin D may prove helpful in keeping our immune systems free from respiratory infection. At the least, therapeutic vitamin D levels may be the difference between severe infection and mild disease! Get adequate rest, get protected against influenza, and take your supplements.

Be well, be safe, be protected.


  1. “Vitamin D can reduce coronavirus risk by 54%: Boston University doctor.” Cohan, A., September 17, 2020, updated September 19, 2020, Boston Herald.
  2. “Covid-19 and supplements: What we know now.” Bauer, S., Kapoor, A., Rath, M. & Thomas, S., June 16, 2020. Cleveland Clinic Resources.
  3. “Vitamin D can help reduce Covid-19 risks: Here’s how.” Curley, B, September 13, 2020, Healthline Media.
  4. “Vitamin D deficiency may raise risk of getting Covid-19.” Rubin, G., September 3, 2020, The University of Chicago Medicine.

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