It is a well-known fact that vitamin D performs several important functions, from boosting immune health to regulating blood pressure. Over the past decade, multiple studies have also provided evidence that taking vitamin D could reduce the odds of developing infections like the common cold and the flu.

Given these precedents and the ongoing pandemic, scientists are now eager to determine if vitamin D could also help protect against COVID-19, the disease caused by the Wuhan coronavirus. In a recent study, researchers from Ireland and the U.K. looked at the prevalence of vitamin D deficiency in European countries with varying severity of COVID-19 infection and found a significant correlation between vitamin D levels and COVID-19 risk and death rates.

Optimizing vitamin D status could have potential benefits for COVID-19 patients

The researchers found this association after looking at studies on the vitamin D status of older adults in European countries affected by COVID-19. The researchers chose countries based on their infection rates. The team also obtained COVID-19 death rates for these countries from the World Health Organization.

Upon assessing these data, the researchers found that typically “sunny” countries, such as Spain and Italy (Northern Italy), have surprisingly higher rates of vitamin D deficiency. These countries have also experienced some of the highest COVID-19 infection and death rates in Europe.

On the other hand, northern European countries, such as Norway, Finland and Sweden, had higher mean concentrations of vitamin D despite getting less sunlight due to their geographic location. These countries also reported lower rates of COVID-19 infection and deaths.

The situation is more or less the same in other countries like Ireland, Germany, France and the United Kingdom. Like the Nordic countries up north, these countries have also reported lower rates of COVID-19 infection and deaths.

Furthermore, the researchers found that higher vitamin D levels are more common in the northern European countries due to supplementation and formal fortification policies. Their overall vitamin D status also reflected intake of natural dietary sources, not just fortified foods.

In contrast, countries with the highest vitamin D deficiency rates among the countries sampled had no such fortification policies. These countries also appeared to be more adversely affected by COVID-19.

Given this strong observational evidence, the researchers suggested that optimizing vitamin D status to public health recommendations could enhance overall immune response for better protection against COVID-19 and its outcomes. (Related: Boost your immune system with dietary selenium and vitamin D.)

The researchers also noted that adequate supplementation and increased intake of vitamin D-rich foods appear to be the best course of action given quarantine restrictions preventing people from going out and sunbathing to get their vitamin D.

Nonetheless, research like this is still exploratory, said lead author Eamon Laird, a researcher at Trinity College Dublin. He and his colleagues believe that clinical trials are needed to provide concrete evidence of their observation. Laird and his team’s findings were published in the Irish Medical Journal.