Vitamin D vs. Long COVID

Returning to the vitamin D study, the rest of the headline suggested that taking vitamin D upon getting COVID may reduce symptoms of long-term COVID (LTCOVID), a serious aftereffect of a COVID infection that can impact the nervous and muscular system. Brain fog, chronic fatigue, and pain are some of the common symptoms.

The reason for hope with LTCOVID symptoms is that those subjects who continued to supplement with vitamin D showed a lower propensity for LTCOVID symptoms than the placebo group. It was not statistically significant with 21% of the vitamin D group showing symptoms of LTCOVID versus 25% in the placebo group, but it provided hope for further research; there were no differences in serious adverse events between the placebo and vitamin D groups.

Two things I found interesting: first, those subjects in either group who had normal vitamin D levels in their blood didn’t have an advantage over those who had very low or low levels of vitamin D. That surprised me as one would think that having a good baseline would be protective in some way. Maybe not.

Second, whether vitamin D impacted COVID as to length of symptoms, it showed that vitamin D supplementation at the first symptom of COVID may be protective. The amounts used in the study were two days at 9,600 IU and then 3,200 IU daily for eight weeks or more, based on the length of the study.

Why would vitamin D be beneficial after a person contracted the virus? Speculation by two researchers, one of the authors and a scientist from another lab, was that vitamin D boosts the immune system by reducing inflammation during the infection. The only way we’ll know for sure is by doing more research.

For now, it’s up to you and your healthcare professionals how best to deal with your next COVID infection. Vitamin D seems to be a viable option.

What are you prepared to do today?

        Dr. Chet

Reference: J Nutr. 2026. https://doi.org/10.1016/j.tjnut.2026.101398