Can taking vitamin D really eliminate all COVID-19 deaths?

Vitamin D has been touted as a panacea for illness for nearly a century and, amid a pandemic, keeps making headlines.

But could vitamin D provide a means to end COVID-19 deaths altogether? That’s what one image in a popular Instagram post suggests: "Vitamin D levels of 50 ng/mL correlates to zero mortality rate from COVID," it says with the code "PMID8541492" written out below it.

The unit of measurement is nanograms per milliliter. And the "PMID" code references a specific study accessible on PubMed.gov, a database of published health and science research. In this case, the research cited was a meta-analysis — an analysis of previous studies — that examined research and data on vitamin D levels in patients who were hospitalized with COVID-19.

A close reading of the research shows this Instagram claim is misleading in that it oversimplifies the findings. It also ignores that, overall, research has been murky on the impact vitamin D has on immunity, and, more recently, whether it improves COVID-19 outcomes. 

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The title of the original publication indicates that zero mortality is just theoretical. It uses the less definitive term "close to zero": COVID-19 Mortality Risk Correlates Inversely with Vitamin D3 Status, and a Mortality Rate Close to Zero Could Theoretically Be Achieved at 50 ng/mL 25(OH)D3: Results of a Systematic Review and Meta-Analysis.

There is no doubt that vitamin D — a nutrient we consume and hormone our bodies produce — plays an important role in one’s skeletal system and overall health. Harvard’s T.H. Chan School of Public Health writes on its website that "laboratory studies show that vitamin D can reduce cancer cell growth, help control infections, and reduce inflammation."

But COVID-era research on vitamin D’s impact has been mixed.

In May 2020, Glenn Grothman, a Republican congressman from Wisconsin, said that research illustrated a correlation between vitamin D deficiencies and higher COVID-19 mortality rates. We rated that True, as early studies supported the claim. 

But in March 2021, when PolitiFact looked into a claim that "vitamin D, vitamin C, colloidal silver and black seed oil can kill the coronavirus," we found that research on vitamin D and COVID-19 had become less hopeful.

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Recent research points to growing skepticism about vitamin D’s effectiveness against COVID-19. An October 2021 meta-analysis in the Nutritional Journal that found "vitamin D deficiency or insufficiency was not significantly linked to susceptibility to COVID-19 infection or its associated death." Researchers at the American University of Beirut also came to a similar finding in their meta-analysis published in the Metabolism Clinical and Experimental journal in March 2021. 

"There is insufficient evidence to recommend either for or against the use of vitamin D for the prevention or treatment of COVID-19," reads a page on a section of the National Institutes of Health website dedicated to explaining what research says about COVID-19 and various supplements. 

Margherita T. Cantorna, professor of molecular immunology at Pennsylvania State University echoed this sentiment. "I think the conclusions made and reported via Instagram are premature and not based on the science," Cantorna told PolitiFact. She said it’s still unknown whether an increase of vitamin D will help or hurt in terms of fighting COVID-19. 

On the other hand, other researchers have come to more promising conclusions, including well-known vitamin D researcher Dr. Michael Holick, professor of medicine at Boston University and author of "The Vitamin D Solution." He and other researchers published a study in March 2021 using COVID-19 patient outcomes at Boston University Medical Center. Its findings showed a clear link between vitamin D sufficiency at 30 nanograms per milliliter, and a decreased risk of mortality among elderly patients without obesity.

But Holick said the Instagram post oversimplified what research actually shows. "I think that it is more realistic based on the literature, including ours, that vitamin D level concentrations above 40 ng/mL reduce risk of morbidity and mortality by about 50%," said Holick. He said his research has also observed a reduction in infectivity by about 50% when vitamin D levels are at least 34 nanograms per milliliter. 

Lorenz Borsche, one of the authors of the study cited in the Instagram post, said that he believes there is a clear correlation between vitamin D and successful COVID-19 outcomes, but that zero mortality is unachievable. 

An Instagram post claimed "vitamin D levels of 50 ng/mL correlates to zero mortality rate from COVID."

The post references a review of research that determined that a "mortality rate close to zero" could be possible. An author on the study said the Instagram post oversimplifies the paper’s findings.

It also ignores the fact that research into how vitamin D levels affect mortality from COVID-19 is not conclusive. 

We rate this claim False.