What’s the link between vitamin D and COVID-19?


Although it’s been more than a year since the COVID-19 pandemic reached the United States, yet there are still many unanswered questions about the virus.

One of those questions is whether there’s a link between vitamin D and COVID-19. Some experts claim that having low vitamin D levels could put you at risk for more severe symptoms from COVID-19. But research results are mixed and limited.

So, should you start taking vitamin D during this pandemic? We spoke with Robert Tracy, MD, a family medicine specialist at St. Elizabeth Healthcare, to find out more.

Why do we need vitamin D?

Vitamin D plays an important role in helping your body absorb and regulate calcium, which is critical for bone health. Without the right amounts of vitamin D and calcium, you could be at risk for osteoporosis (weak bones) or osteomalacia (soft bones).

But vitamin D an also help your body’s immune system function correctly. Research has shown a link between vitamin D deficiency, infection risk and autoimmune diseases.

Can vitamin D help prevent COVID-19?

Because vitamin D may play a role in immune system response, some believe that low levels of the vitamin can make you more vulnerable to COVID-19.

But Dr. Tracy cautions that there’s still much to learn about the link between the two.

“Vitamin D does not prevent COVID-19, but patients that are vitamin D deficient seem to be more susceptible to the virus,” he says. “The medical literature is still unclear, but maintaining adequate vitamin D levels may be beneficial.”

Dr. Tracy is quick to point out vitamin D “does not trump other measures” that have been proven to reduce the risk of COVID-19. Vaccines, mask-wearing, hand washing or sanitizing and physical distancing are the most important steps you can take to reduce your risk.

Are there people who may benefit more from taking vitamin D?

One of the main sources of vitamin D is sunlight. Because of that, people with limited sun exposure — such as homebound older adults, people who work indoors and people who live in northern climates — may be at risk for vitamin D deficiency.

Certain health conditions and medicines can also affect how your body absorbs and uses vitamin D. These factors can increase the risk for vitamin D deficiency:

  • Chronic kidney disease
  • Cirrhosis (scarring of the liver)
  • Having bariatric surgery or surgery to remove part of the stomach
  • Hypoparathyroidism
  • Pancreatic disease
  • Small bowel disease
  • Taking certain medicines to prevent seizures (anticonvulsants)

How much vitamin D should I take?

Your body gets vitamin D from two main sources: sunlight and food. The average person should take 15-20 micrograms (mcg) of vitamin D each day, or 600-800 international units (IUs).

To get enough vitamin D, you’ll need about 10-15 minutes of sun exposure a few days a week. A well-balanced diet should provide enough vitamin D, but certain foods are more vitamin D-rich than others. For example:

  • 3 ounces of salmon has 14.2 mcg of vitamin D
  • 1/2 cup of mushrooms has 9.2 mcg of vitamin D
  • 1 cup of vitamin-fortified 2% milk has 2.9 mcg of vitamin D
  • One large egg has 1.1 mcg of vitamin D

Most adults who take a vitamin D supplement should take 25-50 mcg per day (or 1000-2000 IUs), Dr. Tracy says. However, you should speak to your doctor about the right dosage for you.

Can too much vitamin D cause side effects?

Taking too many vitamins (also called vitamin “toxicity”) can cause serious side effects. Too much vitamin D can cause hypercalcemia, a condition where there is too much calcium in the blood. Hypercalcemia can cause confusion, lethargy, weakness and kidney stones.

What should I do if I want to start taking vitamin D?

Before starting any new vitamin regimen, it’s crucial to talk to your primary care doctor. Your doctor can order a blood test to check your vitamin D levels. Once they have that information, they’ll recommend whether you need vitamin D supplements and how much you should take.

As for the link between vitamin D and COVID, Dr. Tracy says to keep an eye on the news and to speak with your doctor if you have any questions.

“This is an evolving field, so we need to continue to watch the medical literature and media outlets for updates,” he says.

Learn more

If you’re interested in starting a new vitamin routine, schedule a visit to talk with your primary care doctor. You can also search for a St. Elizabeth doctor in your area with our provider directory.