Vitamin D supplements may reduce the risk of getting COVID-19, especially for Black people

• Getting extra vitamin D may lower the risk of coronavirus infection, according to a new study.
• Black people were less likely to have COVID-19 if they had more of the nutrient, researchers found.
• Research on vitamin D is mixed, but it could be one tool in helping people vulnerable to the virus.

There's new evidence that getting more than the recommended amount of vitamin D may protect you from contracting COVID-19, particularly if you're Black.

Higher levels of vitamin D were associated with increasingly lower risk of coronavirus infection in Black people, according to a study published March 19 in JAMA Open Network.

Researchers from the University of Chicago looked at data from 4,314 people who were tested for COVID-19 between March and early April 2020, checking their vitamin D levels based on the past year's worth of medical records.

They found that Black people who had the recommended levels of vitamin D (or slightly above) were more than twice as likely to test positive for COVID-19 as peers with higher-than-recommend levels of the nutrient. And those below recommended vitamin D levels were even more likely to get sick.

For white people, however, there was no apparent link between vitamin D levels and coronavirus infection rates.

This study was an expansion of a previous study from the same research team which found that people with vitamin D deficiency were twice as likely to get COVID-19.

The researchers wanted to see if increasing vitamin D beyond what is typically considered to be "enough" for optimal health could potentially protect against coronavirus.

"This supports arguments for designing clinical trials that can test whether or not vitamin D may be a viable intervention to lower the risk of the disease, especially in persons of color," Dr. David Meltzer, lead author of the study and chief of hospital medicine at the University of Chicago Medicine, said in a press release.

COVID-19 disproportionately affects Black and brown people, and vitamin D might be one solution

People of color may be disproportionately at risk of vitamin D deficiency, which could in part explain why they have been hardest-hit by the virus. The human body naturally produces vitamin D when skin is exposed to sunlight. People with darker skin take longer to produce the nutrient because they have more melanin, which blocks UV rays from the sun.

However, there is also strong evidence that systemic racism - from poor access to healthcare to fewer socioeconomic resources - is a driving factor behind the high rates of COVID-19 among people of color, and a supplement is not a silver bullet to outweigh that.

Evidence on vitamin D and coronavirus outcomes has been mixed

A growing body of research has studied whether vitamin D may help prevent COVID-19 or related complications, but evidence so far is mixed.

There's good data showing a link between higher vitamin D and lower risk of severe COVID-19. A small study published in October 2020 found that coronavirus patients who were given a highly potent form of vitamin D were significantly less likely to need intensive care, and none of them died.

Experts have advocated for supplementing vitamin D as a precaution, particularly for vulnerable people such as the elderly and those with pre-existing conditions as well as people of color. They advise that every adult get 4,000 IUs of vitamin D per day, 10 times the current dose recommended by health officials.

Several studies, though, have found no evidence that vitamin D can cause better outcomes. There are many factors in the research that could explain these disparities in the results, such as how much vitamin D is taken and at what stage of exposure to coronavirus (before infection, shortly after, or late in the illness).

We do know that vitamin D plays an important role in immune system health, and can be protective against other respiratory viruses. More research could help medical experts better understand whether vitamin D can help COVID-19 patients or prevent infection in the first place, and how much is ideal.

"So far, the data has been relatively inconclusive. Based on these results, we think that earlier studies may have given doses that were too low to have much of an effect on the immune system, even if they were sufficient for bone health. It may be that different levels of vitamin D are adequate for different functions," Meltzer said in the press release.