Recent studies have suggested that Vitamin D deficiency is correlated with severe COVID symptoms, and one has showed that it is linked to increased risk of contracting COVID.
We’ve known for years that Vitamin D levels correlate with immune function. A meta-analysis and systematic review showed that supplementing with Vitamin D significantly reduced the risk of respiratory infections. The dosages used ranged from 800-2000 IU per day. Not surprisingly, the effect was greater for those who were deficient in Vitamin D, meaning they had blood levels < 25nmol/L.
Given its role in immune function and respiratory illness, researchers have been exploring whether vitamin D levels may help reduce the effects of COVID-19.
Some evidence suggests that having low Vitamin D might make you more likely to be hospitalized with COVID-19.
Researchers in Spain found that 80% of patients in one hospital with severe COVID-19 symptoms were vitamin D deficient. Hernandez et al, Journal of Clinical Endocrinology & Metabolism 2020.
Researchers in Iran found that there was a 51.5% decreased risk of death in COVID patients > 40 years old who had sufficient vitamin D levels (>30ng/mL) Maghbooli, ZM, et al PLoS ONE 2020.
Other research has indicated that low Vitamin D levels may make you more susceptible to getting COVID. (Kaufman, HW, Et al. PLoS ONE 2020). Researchers at the University of Chicago found that being vitamin D deficient (< 20nmol/L) nearly doubled your risk of testing positive for COVID. Meltzer, D JAMA Network Open 2020.
So Does this Mean That taking Vitamin D can prevent and Treat COVID-19?
The above studies don’t prove that vitamin D levels will reduce severe COVID cases. Nor does it mean that taking Vitamin D will significantly reduce risks on contracting COVID. But they certainly indicate that the connection needs to be explored.
The best way to establish the effectiveness of vitamin D supplementation would be to have randomized control studies. Then after several have been done, a more definitive conclusion can be made from meta-analyses and systematic reviews like the study mentioned above regarding respiratory infections.
Unfortunately, such studies can take a while to finish. Fortunately, researchers are moving fast given the seriousness of the pandemic and the relatively low risk of vitamin D supplementation.
Recently, researchers from Spain have already completed a randomized clinical study on using high doses of vitamin D to treat those who have been hospitalized with COVID. The findings are very promising: of the 50 who received it, only 1 regressed to needing the ICU and none died. Of the 26 patients who did not receive the vitamin D, 13 needed the ICU and 2 died. (Entrenas Castillo M, Entrenas Costa LM, Vaquero Barrios JM, et al. “. J Steroid Biochem Mol Biol. 2020).
More randomized control trials are underway to determine the effectiveness of Vitamin D supplementation on treating COVID.
So Should You Supplement with Vitamin D?
There is good evidence that having adequate vitamin D levels is essential for a variety of reasons, including immune function, bone health, and muscle strength. Now it seems we can add reduced COVID severity to one of its potential benefits.
There is also good evidence to suggest we don’t get enough vitamin D from our diet and from the sun, especially in certain climates or times of the year.
Add to that the fact that toxicity is very rare and the cost is low.
The effects of supplementation are likely related to your level of deficiency. Deficiency is regarded as having levels less than 30ng/mL by the Endocrine Society and most hospitals, although the National Academy of Medicine list 20 as the cut off. You can have your Vitamin D levels easily assessed by a blood test ordered by your doctor.
If you are deficient, there are varying strategies recommended to increase your levels. Some recommend taking 50000IU a week for 4-6 weeks, then reducing that level to 50000 every 2 weeks thereafter for maintenance until you maintain levels of 40-50ng/mL. This is the approach recommended by Dr. Michael Holick, MD, Professor at BU Medical Center and author of The Vitamin D Solution.
For those without deficiency, lower recommendations are given. Dr. JoAnn Manson, MD of Harvard Medical School who is conducting a study on the effects of Vitamin D supplementation as a treatment to reduce hospitalization and death for those diagnosed with COVID, advises supplementing with 1000-2000IU/day.
This might vary by your age, blood tests, sun exposure, and other factors so it’s best to discuss with your doctor.
Meanwhile, given what we know about vitamin D; the benefits, and the recent findings about vitamin D, it’s likely a good idea to supplement.