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VERIFY: Why vitamin D is beneficial to some, but not a COVID-19 'cure'

A variety of viral claims about Vitamin D say it can boost your immune system or possibly stop COVID.

A U.K. study is looking at the link between COVID-19 deaths and a lack of vitamin D. With the mysteries of a new coronavirus and COVID-19, people often look for a magic bullet – the one thing that might prevent or cure the illness. Some point to Vitamin D as a possibility, but do the facts support that?


Are COVID-19 deaths linked to deficiencies in vitamin D? Would taking a vitamin D supplement ward off COVID-19 or make it less serious?


There is evidence to the idea that vitamin D can benefit some people's ability to fight any sickness -- including COVID-19. This benefit is almost exclusively seen by people who were previously deficient in vitamin D.

What's also known is that vitamin D is not a COVID-19 cure.

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Preliminary results from a study by scientists from the Queen Elizabeth Hospital Foundation Trust and the University of East Anglia in the United Kingdom have linked low levels of vitamin D to COVID-19 mortality rates across Europe, ScienceAlert.com reports.

The question is whether the lack of vitamin D played a role in the deaths or if it was a coincidence. That’s because low levels of vitamin D are more common in people 65 and older, the obese, diabetics and those with cardiovascular disease. Those people are also at high risk if they contract COVID-19.

While the evidence isn’t definitive regarding the coronavirus, vitamin D is known for boosting the immune system and thus might reduce the severity of COVID-19 just as it appears to do with other respiratory viruses. The key is getting enough vitamin D on a steady basis; waiting until feeling sick won’t help.

Several clinical trials and pooled studies show that vitamin D supplementation “lowers the odds of developing acute respiratory tract infections -- most of which are assumed to be due to viruses -- by 12% to 75%,” says the Harvard T.H. Chan School of Public Health.

“These studies included both the seasonal and pandemic flu caused by H1N1 virus in 2009. The beneficial effect of supplementation was seen in patients across all ages, and individuals with pre-existing chronic illnesses," the school said.

The National Center for Biotechnology Information, part of the National Institutes of Health, goes further.

"To reduce the risk of infection, it is recommended that people at risk of influenza and/or COVID-19” consider taking vitamin D3 ... "For treatment of people who become infected with COVID-19, higher vitamin D3 doses might be useful.”

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But in a “rapid review,” the Centre for Evidence-Based Medicine, part of Oxford University, casts doubt.

“We found no clinical evidence on vitamin D in COVID-19. There was no evidence related to vitamin D deficiency predisposing [patients] to COVID-19, nor were there studies of supplementation for preventing or treating COVID-19.” It is unclear whether that is because COVID-19 is new.

However, the CEBM added, “There is some evidence that daily vitamin D3 supplementation over weeks to months may prevent other acute respiratory infections.”

Sunlight is the best source of vitamin D, which is made in the skin. For light-skinned people, 15 minutes of sunshine on the arms and legs two or three times a week is enough. The darker the pigmentation and the older a person is, the more sunlight is needed to produce vitamin D. Latitude also affects vitamin D, with residents of the northern U.S. more likely to get less sun exposure. Sunscreen also affects absorption.

Foods rich in vitamin D include fatty fish, egg yolks, and fortified milk and orange juice, but it is hard to get enough from diet alone. If choosing a supplement, research suggests vitamin D3 is usually the better choice over vitamin D2.

But too much vitamin D can damage the heart, blood vessels and kidneys as well as lead to kidney stones, the NIH warns. Before starting a vitamin D regimen, talk to your doctor and don’t take more than the label says.

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