Last week in Brief19, we covered the failure of Zinc and Vitamin C as effective covid-19 treatments in the "Covid A to Z trial," published in JAMA. Many have promoted the possible benefits of these and other supplements, but none have yet to show a positive effect when studied, despite seemingly endless anecdotal reports. Another supplement often popularly suggested as a therapy on social media is Vitamin D.
A study conducted in Brazil and published last week in JAMA investigated whether this vitamin lives up to the hype. This well performed double-blinded, randomized, placebo-controlled trial took place at two sites in Sao Paulo. Enrollment of the 240 patients occurred over the summer of 2020 with follow up through early October. Subjects received either a single oral dose of 200,000 IU of Vitamin D3 or placebo. All of the included patients were moderately to severely ill with covid-19 and hospitalized at the time of enrollment.
The researchers primarily looked to see whether the average length of stay in the hospital was affected. Other "secondary" outcomes included death, admission to intensive care units, and the need for mechanical ventilation. To be sure that the patients were appropriate for study, baseline Vitamin D levels were checked when the patients were enrolled into the trial.
As seen in the other supplement studies, a single dose did not affect length of stay in the hospital, which hovered at around 7 days in both the patients who received Vitamin D and those receiving placebo. None of the important secondary outcomes indicated any sign of benefit either. Vitamin D levels significantly rose among the group of patients who received the Vitamin D, which was hardly a surprise.
These findings show that in the moderate to severely ill subset of covid-19, no beneficial effect was attributable to the administration of Vitamin D. One group not studied was covid-19 patients defined as mildly ill. Whether Vitamin D does or does not prevent the worsening of symptoms, improves symptoms, or decreases the rates of hospitalization or lengths of stay was untested in this trial, meaning that future research is still warranted.