Short answer: Please take Vitamin D3 (Cholecalciferol) 2,000-5,000iu per day- can’t hurt and might help.

Vitamin D supplementation has been a contentious topic long before COVID-19. We have known through population studies that low Vitamin D is associated with a variety of illnesses, including autoimmune disorders, cancer, diabetes and infectious illnesses. However, association does not equal causation. Low Vitamin D could be an indicator of being sick, without necessarily causing the illness. To demonstrate a causal relationship, you would need to study whether treatment with Vitamin D reduced the rate of illness.

In the last two years, two large randomized controlled trials have demonstrated that Vitamin D supplementation did NOT reduce the incidence of cancer, heart disease, overall mortality or development of diabetes. These studies have reduced some of the enthusiasm for Vitamin D supplementation.

Then COVID-19 struck.  As the virus swept the globe, researchers noted geographical differences in lethality, with population studies noting worse outcomes in countries with lower Vitamin D levels. Also, groups with lower Vitamin D levels (such as those with dark skin, the elderly and the obese) have had worse outcomes.

Vitamin D modulates how our immune system functions, supporting our innate immunity, the ability to defend against novel infections. It also prevents overreaction in the form of cytokine storm, the dreaded cause of respiratory failure in COVID-19. These functions create a plausible explanation for why low Vitamin D could lead to worse outcomes. Randomized controlled studies are underway that may settle the issue, but with no results yet, what to do now?

Most decisions regarding COVID-19 are made with new and incomplete information, forcing clinicians to weigh the estimated risks and benefits to select the best option. In that context, Vitamin D supplementation represents a very large potential benefit given the current data demonstrating a strong association between deficiency and worse outcomes.

What about the risks?

The debate around nutritional supplementation contains an often-obscured distinction: the difference between a blanket recommendation for the general population and replacement for those with a documented deficiency. The current NIH Office of Dietary Supplements recommendations are for Vitamin D supplementation in the 400iu to 800iu range depending on age. These relatively low doses are felt to be safe even for a small subset of the population that may have kidney stones and/or elevated calcium levels.

For the last decade or so, I have been closely following the Vitamin D levels in my patients. About 75% of you initially had low Vitamin D levels. (Congratulations on following doctor’s orders to cover up and use sunscreen when heading outdoors!) The majority of my patients have achieved normal levels with supplementation in the 2,000-5000iu range. However, I have needed to prescribe much higher levels and have never had a patient experience an adverse reaction. There are two groups of patients that require caution with Vitamin D supplementation: those with a history of kidney stones and those with elevated calcium levels. If you fall into either group, we are (hopefully) already following your Vitamin D levels closely. Everyone else can safely take Vitamin D3 (cholecalciferol) in the 2,000-5000iu range.

Eventually, we may have a more definitive answer to whether Vitamin D reduces the risk of COVID-19 infection. In the meantime, I believe the prudent course would be to have Vitamin D levels solidly in the normal range. Just in case…

As usual, please contact me with any questions or concerns.

Sincerely,
Barry Rotman, MD