Millions of COVID Cases Avoidable If Every American Took Vitamin D Supplements: Study

A container of vitamin D capsules in an undated fie photo. (Mark Lennihan/AP Photo)

A study of American veterans suggests that nationwide distribution of vitamin D supplements could have prevented over 110,000 COVID-19 deaths and millions more infections from the virus.

The lack of vitamin D in the human body has long been linked to poor immunity, which makes people more prone to viral infection. Several studies have shown that those with vitamin D deficiency are at higher risk of getting COVID-19 and experiencing severe symptoms. However, not much light has been shed on whether vitamin D treatment can reduce the risk of death from COVID-19.

The study, published earlier this month in Scientific Reports, a sub-journal of Nature, looks into the relationship between vitamin D2 and D3 supplementation and the risk of dying from COVID-19 within 30 days following infection.

Using data provided by the U.S. Department of Veteran Affairs (VA), the research team conducted an analysis of 199,498 veterans who were treated with vitamin D3 and 33,216 veterans treated with D2 between the pre-pandemic period from Jan. 1, 2019 to Dec. 31, 2020, and during the pandemic from March 1, 2020 to Dec. 31, 2020. Each patient was matched one-on-one with an untreated VA patient as control.

The researchers also conducted a subgroup analysis based on race and gender. It is known that people with darker skin typically have lower vitamin D levels than those with lighter skins, since more melanin reduces people's ability to synthesize vitamin D from the sun. Women have also been found to have greater vitamin D blood levels than men.

The Findings

According to researchers, vitamin D2 and D3 supplementation during the pandemic reduced the probability of COVID-19 infection by 20 and 28 percent, respectively. At an average daily dosage of 50,000 IUs, there was a 49 percent reduction in COVID-19 infection in patients who have lower-than-normal vitamin D blood levels.

The study also found that vitamin D3 supplementation was related to a 33 percent lower risk of dying within 30 days of COVID-19 infection, although vitamin D2 treatment didn't produce statistically significant results in that regard.

When it comes to gender, the research team found that vitamin D3 is about as effective in reducing COVID-19 infection rates for male as for female patients. They also observed a greater reduction in COVID-19 infection rates for black D3-treated patients (28 percent) than white counterparts (18 percent) when compared with untreated controls.

"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," wrote the researchers from Johns Hopkins University and Universities of Michigan and Chicago.

"We calculated these values by applying our estimated 20 percent average reduction in infection and 33 percent reduction in mortality after infection for Vitamin D3 to a total of 19,860,000 cases and 351,999 deaths through 2020," they explained.

In the VA, there have been 343,094 cases and 14,981 known deaths from March through October 2020. Using the same calculation, the researchers estimated that there would be 69,000 fewer cases of veterans being infected and 4,900 fewer deaths during that period.

The researchers did admit, though, that their calculation might have underestimated the potential benefit of having every American take vitamin D supplements during the pandemic. Conversely, their estimates might also be inflated if their subjects had a higher prevalence of vitamin D deficiency than the general U.S. population.

"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," they concluded.

Previous Study

Earlier this year, a team of Mexico-based researchers found that vitamin D supplementation can help prevent COVID-19 without serious adverse events, regardless of the individual's vitamin D status.

The study, published in the Archives of Medical Research, involved 321 frontline health care workers from four hospitals in Mexico City, who all tested negative for COVID-19 between July 15 and Dec. 30, 2020. The participants were randomly assigned to receive either 4,000 IUs of vitamin D or a placebo each day for 30 days.

A total of 94 people in the vitamin D group and 98 people in the placebo group completed follow-up in the study. Researchers found a significantly lower infection rate of COVID-19 in the vitamin D group (6.4 percent) than in the placebo group (24.5 percent).

"The results of our double-blind, placebo-controlled, prospective study demonstrate that vitamin D supplementation is effective in preventing SARS-CoV-2 infection in high risk, frontline healthcare personnel," the report reads.