Vitamin D Shows Potential to Reduce Long COVID Symptoms: JoAnn E. Manson, MD, MPH, DrPH

Vitamin D3 supplementation could potentially reduce the prevalence of long COVID symptoms at 8 weeks, according to a recent study published in The Journal of Nutrition.¹

Although the primary outcomes of the VIVID clinical trial (NCT04536298)—reduction in cumulative incidence of health care utilization and clinical outcomes of disease severity—were not influenced by vitamin D3 supplementation, it did demonstrate a trend, albeit statistically insignificant, toward a reduction in long COVID symptoms, warranting further investigation. The ideal trial design that might adequately compound these findings would be vitamin D3 supplementation prior to infections, corresponding author JoAnn E. Manson, MD, MPH, DrPH, Micheal and Lee Bell Professor of Women’s Health at Harvard Medical School and endocrinologist and epidemiologist physician at Brigham and Women’s Hospital, said in an interview with The American Journal of Managed Care^®.

“The next best option would be to do a large trial with vitamin D3 supplementation started at the very beginning of an infection, right after diagnosis,” she said, “and then looking at the effect of vitamin D3 supplements and reducing the severity of symptoms as well as the development of long COVID.”

The VIVID trial was a randomized, controlled, double-blinded trial assessing participants who were newly diagnosed with COVID-19. However, because the trial was conducted remotely during the pandemic, there was a “lag of several days” between patients’ diagnosis and initiation of treatment. This gap in treatment may have impacted adequate exposure to vitamin D3, as it can take up to or more than 8 weeks for blood concentration of the vitamin to reach an equilibrium.¹

“In the context of other evidence about vitamin D tamping down inflammation and reducing it, we've seen a major biomarker for inflammation,” Manson said. “This effect on tamping down inflammation and also reducing the risk of autoimmune diseases that vitamin D probably does have [may also] benefit [in] reducing long COVID, but we need a larger randomized [and definitive] trial to really test this hypothesis.”

Reference

1. Ganmaa D, Cook KA, Khudyakov P, et al. A randomized trial of vitamin D supplementation and COVID-19 clinical outcomes and long COVID: the vitamin D for COVID-19 trial. J Nutr. 2026;156(4). doi:10.1016/j.tjnut.2026.101398