There is “definitive evidence” that taking vitamin D supplements can help reduce the risk of COVID-19 progressing to severe levels where intensive care is needed, a recent analysis of five existing clinical trials suggests.
According to a team of scientists from Italy, the purpose of their study was to verify whether there is a strong association between the protective effect of vitamin D supplementation and the risk of death and intensive care unit (ICU) admissions in COVID-19 patients.
For the study, Protective Effect of Vitamin D Supplementation on COVID-19-Related Intensive Care Hospitalization and Mortality: Definitive Evidence from Meta-Analysis and Trial Sequential Analysis, published online in January in Pharmaceuticals, the scientists searched four databases and identified 78 studies relevant to the topic. Only five randomized controlled trials out of those were deemed suitable for the analysis.
Each trial was then given a detailed meta-analysis, followed by a trial sequential analysis (TSA) using a computer program.
“A meta-analysis per se does not allow us to state whether the results are truly positive or false-positive. In addition, the inclusion of studies with large effect sizes and significant heterogeneity separates us from the truth,” the scientists explained. “For this reason, a TSA is mandatory to verify the reliability of meta-analysis results.”
The team also evaluated the potential bias in each study from six aspects, such as bias in the measurement of the outcome, bias in the selection of the reported results, and bias due to missing outcome data. Only one study had a low risk of bias in all criteria.
“Despite the presence of randomized clinical trials with some concerns about the risk of bias, the new meta-analyses and TSAs found a significant association between the protective role of vitamin D supplementation and ICU hospitalization in patients with COVID-19,” the scientists concluded.
“At the same time, TSAs underlined the need for further studies to confirm the significant association between the beneficial effect of vitamin D supplementation and mortality,” they added.
While all five trials showed positive effects of vitamin D on COVID outcomes, the scientists said they found the treatment method used in one particular study to be the most convincing, largely because of the sheer number of patients involved.
In that study, published in June 2021 in the Journal of Clinical Endocrinology & Metabolism, a total of 447 COVID-19 patients admitted to a Barcelona, Spain, hospital were given 21,620 IU on day 1 and 10,810 IU on days 3, 7, 15, and 30. As a result, 21 (4.7 percent) out of 447 patients treated with vitamin D at admission died, compared to 62 deaths (15.9 percent) out of 391 patients who didn’t receive vitamin D.
The National Institutes of Health (NIH) advises against Americans taking more than 4,000 IU of vitamin D per day unless otherwise instructed by their health care providers, warning that “getting too much vitamin D can be harmful.”
The NIH states on its website, “Very high levels of vitamin D in your blood can cause nausea, vomiting, muscle weakness, confusion, pain, loss of appetite, dehydration, excessive urination and thirst, and kidney stones.
“Extremely high levels of vitamin D can cause kidney failure, irregular heartbeat, and even death. High levels of vitamin D are almost always caused by consuming excessive amounts of vitamin D from dietary supplements,” it continues. “You cannot get too much vitamin D from sunshine because your skin limits the amount of vitamin D it makes.”