Does Vitamin D protect against COVID-19? We don’t know. Maybe. Probably? We hope so! In any case, everyone should be taking a supplement, on the order of 2,000-4,000 I.U. (International Units) per day.
Low levels of Vitamin D are correlated with greater risk of COVID-19 infection and with more severe disease. Studies have shown that people who test positive for COVID-19 have lower levels of Vitamin D in their blood. Also, people who get more severe disease (i.e. need hospital care) have lower levels of Vitamin D.
These studies do not prove, however, that insufficiency of Vitamin D is the cause of infection or severe disease. Both the infection and the vitamin insufficiency could be caused by some third factor, like obesity or greater age. It will take a randomized, double-blind clinical trial to prove that raising Vitamin D levels actually protects against COVID-19. There are supposedly several studies in progress, set to report in early 2021.
If it is proven that Vitamin D protects against COVID-19, that would be a game-changer for public health. People with darker skin – Latinx and Black people in particular – have both lower levels of Vitamin D and greater levels of COVID-19 infection, severe disease, and death. Again no causative link has been proven. If the protective effects turn out to be real, widespread distribution of Vitamin D could reduce the disproportionate burden on people of color.
In the meantime, everyone should be taking a Vitamin D supplement. It’s cheap, widely available, and very safe when taken in reasonable amounts, up to 4,000 I.U. per day. Dr. Fauci takes 6,000 I.U. per day, which is on the high side, but he’s fairly old. I’m taking 10,000 I.U. per day because I have diabetes and extra body fat, which reduces absorption. Guidelines for supplementation can be found below.
- What to Know About Vitamin D and COVID-19; Healthline; October 7, 2020
- Can Vitamin D Protect Against COVID-19?; Mayo Clinic; October 2, 2020
- Exploring the Links Between Coronavirus and Vitamin D; New York Times; June 10, 2020
- Does Vitamin D Protect Against COVID-19?; Medscape; May 11, 2020 (includes video)
- Vitamin D Deficiency (and supplementation guidelines); American Association of Clinical Endocrinologists; 2019 (PDF)