Low vitamin D levels are linked with higher risk for severe COVID-19, but treatment that boosted vitamin D levels in critically ill COVID-19 patients did not shorten their hospital stay or lower their odds of intensive care unit admission, needing mechanical ventilation, or dying, doctors in Brazil found.

They randomly assigned 240 hospitalized patients with severe COVID-19 to receive either a single high dose of vitamin D3 or placebo.

In a paper posted on medRxiv ahead of peer review, they report that after the treatment, only 6.7 percent of the patients in the vitamin D group had “deficient” levels of the nutrient, compared to 51.5 percent of patients in the placebo group. Even so, there was no difference in patients’ outcomes between the two groups.

The same was true when the researchers focused only on the 116 patients with vitamin D deficiency before the treatment.

The authors say theirs is the first randomized trial of its kind to show that vitamin D supplementation “is ineffective to improve hospital length of stay or any other clinical outcomes among hospitalized patients with severe COVID-19.”