Vitamin D Supplementation May Be Beneficial for Long COVID

THURSDAY, March 12, 2026 (HealthDay News) -- Vitamin D3 supplementation does not change the four-week incidence of health care utilization or COVID-19-related outcomes among adults with newly diagnosed COVID-19 but may reduce the risk for long COVID, according to a study published online March 12 in the Journal of Nutrition.Davaasambuu Ganmaa, M.D., Ph.D., from Brigham and Women's Hospital and Harvard Medical School in Boston, and colleagues examined the effect of vitamin D3 supplementation on health care utilization and other clinical outcomes among adults with COVID-19 in a parallel two-group randomized controlled trial. Adults with newly diagnosed COVID-19 were cluster-randomized with up to one of their cohabiting contacts to oral vitamin D3 supplementation (loading dose 9,600 IU/day for two days then 3,200 IU/day for four weeks) or placebo (863 and 884 participants, respectively).The researchers observed no significant difference between the groups in the four-week cumulative incidence of health care utilization among index participants (cumulative incidences, 0.28 versus 0.29; odds ratio, 0.97; 95 percent confidence interval, 0.75 to 1.24). Prespecified secondary treatment and prevention outcomes also did not differ significantly. A nonsignificant trend toward benefit of vitamin D3 on the prevalence of long COVID at eight weeks was seen in per-protocol analyses (odds ratio, 0.78; 95 percent confidence interval, 0.59 to 1.03). There were no safety concerns noted."While we didn't find that high-dose vitamin D reduced COVID severity or hospitalizations, we observed a promising signal for long COVID that merits additional research," senior author JoAnn E. Manson, M.D., M.P.H., Dr.P.H., also from Brigham and Women's Hospital, said in a statement.One author disclosed ties to Capitainer AB, a company commercializing the blood collection devices used in this study; support was provided by the Tishcon Corporation, Takeda, and Capitainer.Abstract/Full Text (subscription or payment may be required).Sign up for our weekly HealthDay newsletter