The Potential Connection Between Vitamin D & COVID-19 Risk Levels

Because of the ever-changing nature of COVID-19, it is essential for all populations to take precautionary measures against the virus. However, there are certain groups who may be at higher risk of serious illness1. Along with age and preexisting conditions, recent research suggests vitamin D deficiency may also play a role in influencing disease severity2.

The study, led by epidemiologist Lee Smith, Ph.D., and research director Petre Cristian Ilie, M.D., Ph.D., was published in the journal Aging Clinical and Experimental Research. The researchers analyzed the potential link between average vitamin D levels in European countries and the severity of COVID-19 outcomes, and what they found could play an important role in coronavirus prevention moving forward.

Emerging research on vitamin D, immunity, and respiratory infections encouraged Smith and Ilie to look into its potential association with COVID-19 rates and mortality. 

Vitamin D has been shown to support the immune system3, while vitamin D deficiency has been linked to an increased frequency of infection.* "Our immune cells need vitamin D to function,” Harvard geneticist David Sinclair, Ph.D., recently told mindbodygreen. Researcher Rhonda Patrick, Ph.D., was one of the first to suggest that vitamin D may play a role in respiratory health specifically and could potentially protect against lung injury.*

While there is no known treatment for the coronavirus, a study published in the journal Nutrients in April suggested vitamin D supplementation may positively impact COVID-19 outcomes4.*

The study "identified a potential crude association between the mean vitamin D levels in various European countries with COVID-19 cases." 

Let's break that down: People in southern European countries, specifically Italy and Spain, were found to have higher rates of vitamin D deficiency than those in northern European countries. (Researchers believe this is because they tend to sit in the shade and avoid direct sun exposure more than those in the north.) These southern countries have also experienced higher rates of mortality from COVID-19, so there could be a correlation there.

The diets of northern Europeans—rich in cod liver oil, vitamin D supplements, and fortified milk and dairy products—may also contribute to their higher levels of vitamin D and lower levels of COVID-19 mortality.*

Vitamin D deficiency is also extremely common in older people, with up to 75% of the 70-and-up population in nursing homes or assisted living facilities having it. This could be yet another factor that's contributing the high COVID-19 mortality rates we have been seeing among the elderly around the world.

The researchers acknowledge their study has limitations, and more research is needed to draw a definite conclusion. "One must remember correlation does not necessarily mean causation," Smith said in a news release. There are still no treatments for the coronavirus at this time.

With that being said, vitamin D supplementation does has other proven health benefits, so they could be onto something here.* "Vitamin D has already been shown to protect against acute respiratory infections and it was shown to be safe," the study said. "It should be advisable to perform dedicated studies about vitamin D levels in COVID-19 patients with different degrees of disease severity."*