Could Vitamin D Decrease Your Risk Of COVID-19? Here's What We Know
If there's one thing the entire world can agree on right now, it's that COVID-19 is top of mind. As the pandemic continues to be a reality, many people are taking extra measures to stay healthy and support immune strength—that includes getting more sleep, eating nutrient-rich foods, and breaking a sweat with plenty of at-home exercise.
Recently, a number of scientists and doctors have been discussing another measure to support immune and respiratory health: vitamin D.
The nutrient is associated with keeping a number of your body's systems running smoothly, including musculoskeletal, gastrointestinal, endocrine, and cardiovascular. And now, some experts even believe supplementing with vitamin D might help reduce the risk of COVID-191.*
It's important to acknowledge that at this time, however, there's no confirmed cure or guaranteed way to avoid contracting COVID-19. As far as preventive measures2 go, the Centers for Disease Control and Prevention (CDC) officially recommends washing your hands with soap and water frequently, socially distancing yourself from other people, covering your nose and mouth with a face mask in public, shielding your mouth and nose when you cough or sneeze, and disinfecting frequently used surfaces regularly.
COVID-19 is still very new, and since there's a lack of research on the topic, it's too early to know if vitamin D may help stave off the virus.* Still, there is a solid body of research, including some newer studies, that support vitamin D's connection to immunity and lung health.*
Vitamin D and immunity.
Vitamin D, which is classified as both a fat-soluble vitamin and a hormone, plays an important role in immune function3, according to a fact sheet published by the National Institutes of Health (NIH).
While scientists' understanding of the interaction between vitamin D and the immune system4 has developed significantly over the last 20 to 30 years, there are still a number of questions researchers are working to understand. That said, "There’s no disagreement between scientists and doctors that vitamin D is important for the immune system," Harvard geneticist David Sinclair, Ph.D., told mbg in a recent interview. "Our immune cells need vitamin D to function."
Vitamin D is thought to play a crucial role in promoting immune response5 by enhancing the production of antimicrobial agents, according to a research review published in the Central European Journal of Immunology.* What's more, findings from a recent in vitro study imply vitamin D activates certain genes6 involved in the immune response.*
"Immune cells are favorably affected by vitamin D levels," Heather Moday, M.D., previously told mbg.* And on the other end of the spectrum, "vitamin D deficiency is associated7 with increased frequency of infection."* There is also mounting evidence linking vitamin D deficiency7 and autoimmune diseases, such as rheumatoid arthritis and irritable bowel syndrome, according to a research review published in the Journal of Investigative Medicine.
Vitamin D deficiencies are more common than you may think: One study estimates that 1 billion8 children and adults worldwide are deficient. While there's not a defined optimal range for vitamin D, "people who have about 40 ng/mL to 60 ng/mL in their blood tend to have the lowest mortality but also do better when they get viral infections," says Sinclair.
Functional medicine doctor Mark Hyman, M.D., similarly recommends aiming for levels over 30 ng/mL, but not more than 80 ng/mL. You can ask your doctor to test whether you're in this range.
Vitamin D and respiratory health.
Many experts have also drawn associations between vitamin D and lung health.* Namely, researcher Rhonda Patrick, Ph.D., was one of the first scientists to speak openly about the potential of vitamin D protecting against lung injury.*
One meta-analysis published in BMJ, for example, specifically looked at the overall effect of vitamin D supplementation on respiratory tract infections9. Researchers reviewed data from 10,933 participants and found vitamin D supplementation was safe and reduced the risk of acute respiratory tract infection among all subjects.* The researchers also noted that patients who were very vitamin D deficient experienced the most benefit.*
A different research review stated that vitamin D deficiency is very common among patients with respiratory diseases10, and there may be a connection between the two. However, further research is needed before drawing any conclusions.
While it's not yet possible to confirm that taking vitamin D will prevent you from getting a respiratory infection (particularly COVID-19), research does indicate that maintaining healthy levels of vitamin D can support lung health.*
How to get more vitamin D.
The most common way to get vitamin D is by spending time outdoors in the sun. However, if you aren't able to absorb ample sunshine—whether that's because it's winter or you're sheltering-in-place—you may need to get vitamin D from other sources.
For example, there are a number of vitamin-D-rich foods that you can incorporate into your diet. Some of the best sources include fatty fish (such as salmon, tuna, and mackerel), fish liver oils, egg yolks, mushrooms, and fortified products, according to the NIH11. However, most foods don't have high enough levels of the hormone, says Hyman, which means you may need to supplement to reach adequate levels.*
"It's typically recommended between 2,500 and 4,000 units of vitamin D3 per day to bring adults to adequate levels of 30 nanogram per day," says Sinclair. However, if you're really deficient, you may need to take even more. That said, "you don't want to overdo it," he adds. "You can have too much vitamin D." That's why it's important to speak to your doctor before supplementing with excess amounts of vitamin D.
While some recent papers suggest that supplementing with vitamin D may help prevent the risk of COVID-19, there isn't currently enough clinical research to draw definite conclusions.* That said, based on what we do know, taking vitamin D supplements has a range of other potential benefits for your health, such as immune and respiratory support.*
Kristine Thomason is the health and fitness director at mindbodygreen. Kristine is a New York University graduate with a degree in journalism and psychology, and also a NASM-certified personal trainer. She has spent her editorial career focused on health and well-being, and formerly worked for Women’s Health and Health. Her byline has also appeared in Men’s Health, Greatist, Refinery29, HGTV, and more. In her current role she oversees, edits, and writes for the health, food, and movement sections of mindbodygreen.