Higher levels of vitamin D than traditionally considered sufficient may help prevent COVID-19 infection – particularly in black patients – or lead to less severe results, two new studies in the United States suggest.
Disability and infection
In the first, a large single-center observational study published late last week in Open JAMA network, University of Chicago researchers retrospectively evaluated the electronic health records of patients who took a vitamin D test in the year prior to the COVID-19 test from March 3 to April 10, 2020. Those checked or treated for low levels of vitamin D in the previous 2 weeks coronavirus tests were excluded.
Of the 4,638 patients, the risk of a positive coronavirus test result in black patients was 2.64 times higher if they had a vitamin D level of 30 to 39.9 nanograms per milliliter (ng / mL) than if they had concentrations of at least 40 ng / mL. And the chance of infection decreased by 5% for each 1 ng / mL increase in patients with a vitamin D level of at least 30 ng / mL, the concentration generally considered sufficient. Similar associations were not found for white patients.
Among the 4,638 patients, 27% were deficient in vitamin D (less than 20 ng / mL), 27% had insufficient levels (20 to less than 30 ng / mL), 22% had concentrations of 30 to less than 40 ng / mL and 24% had levels above 40 ng / mL. Black patients tend to have lower levels of vitamin D than their white counterparts (36% vs 16% at 20 ng / mL).
Seven percent of all participants tested positive for COVID-19, including 5% of white patients and 9% of blacks. In the multivariate analysis that tracks the time since the vitamin D level was last measured, the positive results of the COVID-19 test were significantly associated with vitamin D levels in black, but not white, patients.
Compared with patients with a concentration of at least 40 ng / mL, those with less than 20 ng / mL were 2.55 times more likely to be diagnosed with COVID-19, while those with 30 to more than 40 ng / mL were 2.64 times more likely. The estimated rates of coronavirus infection in black patients, stratified by vitamin D level, were 9.72% for a concentration of 20 ng / ml, 6.47% of 20 to 30 ng / ml, 10.10% of 30 less than 40 ng / ml and 3.82% to 40 ng / ml or higher.
The mean age of the patients was 52.8 years, 69% were women, 49% were black, 43% were white and 8% were of another race or ethnicity. Vitamin D levels are influenced by exposure to sunlight and diet or supplements.
The study’s lead author, David Meltzer, MD, PhD, said in a press release from the University of Chicago Medical Center that the current vitamin D guidelines come primarily from bone health studies. “But there is also evidence that vitamin D can improve immune function and decrease inflammation,” he said.
“Based on these results, we think that previous studies may have given very low doses to have a significant effect on the immune system, even if they were sufficient for bone health. It may be that different levels of vitamin D are suitable for different functions.”
Researchers are now recruiting for two clinical trials that test whether daily vitamin D supplementation can reduce the risk and severity of COVID-19, particularly for black people. “Currently, the recommended vitamin D intake for adults is 600 to 800 international units (IU) per day,” said Meltzer in the statement. “The National Academy of Medicine said that taking up to 4,000 IU per day is safe for the vast majority of people, and there is a risk of hypercalcemia [excessively high calcium levels] increases at levels above 10,000 IU per day. “
Probability of mechanical ventilation, death
The second study, presented at virtually the annual Endocrine Society meeting last week, involved 124 adults with low vitamin D content measured up to 90 days before hospitalization for COVID-19 to compare the results of those who received at least 1,000 units of vitamin weekly with those who didn’t, according to a society press release.
Patients who took supplements of at least 1,000 units of vitamin D per week were slightly less likely to need mechanical ventilation or to die from their infections (33.3% vs 37.5%), although the finding was not statistically significant. More than half of the patients who were supposed to take supplements due to a disability did not.
The study’s co-author, Corrine Levitus, DO, of Montefiore Health System and Albert Einstein College of Medicine, said in the statement that despite the lack of a definitive link between insufficient vitamin D and severe COVID-19, deficient patients should receive supplementation to protect against poor coronavirus results, as well as against osteoporosis. “We hope that this research will encourage doctors to discuss adding this supplement to their patients who are low in vitamin D, as this may reduce the chances of people developing severe COVID-19,” she said.