A new study by American researchers from Johns Hopkins University, University of Michigan, University of Chicago and St John Fisher College has shown that vitamin D supplementation can lower risk of COVID-19 severity and even reduce spread of SARS-CoV-2.
The study findings were published in the peer reviewed journal: Scientific Reports
Vitamin D supplementation during the pandemic was associated with a significant 20% and 28% reduction in laboratory-confirmed COVID-19 rates for vitamin D3 and vitamin D2, respectively.
Vitamin D3 was associated with a significant 33% decrease in mortality within 30-days of COVID-19 infection.
This decrease in COVID-19-related mortality is identical to the 33% observed in the Andalusian data for calcifediol when prescribed 15 days before hospitalization and similar to the 25% associated reduction in mortality for cholecalciferol21. For vitamin D2 the associated reduction in mortality was 25% but was not statistically significant.
These associated reductions in risk are substantial and justify more significant exploration and confirmation using RCTs. This is particularly important given the high rates of vitamin D deficiency in the US population and COVID-19.
There were also striking differences in our results across our patient subgroups. First, compared to white patients, Black patients supplemented with vitamin D3 experienced a greater associated reduction in COVID-19 infection rates relative to controls than white patients (29% decrease versus an 18% decrease).
Future research is needed to determine the mechanism by which vitamin D supplementation is more effective among Black patients.
Baseline vitamin D serum levels and cumulative dosage also moderated the effect of vitamin D3 treatment. Specifically, patients with lower serum levels receiving higher dosages of vitamin D3 experienced the greatest associated reduction in infection.
In response to these findings, physicians might consider regularly prescribing vitamin D3 to patients with deficient levels to protect them against COVID-19 infection and related mortality. The 50,000 IU dosage may be especially beneficial.
When we extrapolate our results for vitamin D3 supplementation to the entire US population in 2020, there would have been approximately 4 million fewer COVID-19 cases and 116,000 deaths avoided.
We calculated these values by applying our estimated 20% average reduction in infection and 33% reduction in mortality after infection for vitamin D3 to a total of 19,860,000 cases and 351,999 deaths through 202029.
In the VA, there have been 343,094 cases and 14,981 known deaths through 10/2/2021. Applying our estimates to the VA, where there would be 69,000 fewer cases and 4900 fewer deaths between March 2020 and October 202130.
These back-of-the-envelope calculations may be conservative given possible reductions in COVID-19 transmission due to the general population risk reduction from broader supplementation.
Conversely, these estimates may also be inflated if the study population had a higher prevalence of low vitamin D serum levels than the general population due to propensity score matching on supplementation.
Still, given our findings, the absence of severe side effects, and the widespread availability of vitamin D3 at low cost, vitamin D3 presents a unique opportunity to reduce the spread and severity of the COVID-19 pandemic.