Low vitamin D status: does it increase the risk of corona infection?


There are rumors circulating on the Internet that you can protect yourself from corona with vitamin D medication. That sounds tempting – but a new study, praised for its methodology, has now investigated whether it is true.

Low vitamin D status is not a risk factor for coronavirus infection, according to a new U.S. study. Although there seems to be such a connection when looking at the data alone, the researchers explain in the journal “Jama Open Network”.

However, if influencing factors such as age, gender, ethnicity, body mass index, blood pressure, smoking status and place of residence are included, there is no connection whatsoever. Thus, people with comparatively low vitamin D levels do not have a higher risk of contracting Sars-CoV-2 than people with an optimal supply of the vitamin.

No significant correlation

The scientists around Yonghong Li from the US laboratory company Quest Diagnostics in San Juan Capistrano (US state of California) had analyzed data from the employee health program with annual screenings from 2019 and 2020.

A total of 18,148 people between the ages of 37 and 56 were included, about two-thirds of them women. According to the findings, before the pandemic began, about 60 percent of those screened had vitamin D levels of less than 30 nanograms per milliliter (ng/ml), and another 25 percent or so had even lower levels (less than 20 ng/ml).

Antibodies to Sars-CoV-2 were detected in about five percent of the subjects (900) during the study period. To be sure, the employees and relatives who tested positive had lower vitamin D levels on average than those who tested negative.

However, when other factors that markedly influence corona risks were taken into account, no significant association emerged. For example, people who were significantly overweight (BMI of 30 or more), men and women with hypertension, smokers, and men and women without a college degree were on average more likely to have vitamin D deficiency.

These limitations exist

Other, smaller studies had previously suggested a possible association, but in many cases the many factors that influence corona risk were not considered. In addition, vitamin status was often measured either a very long time before or only in the course of the covid 19 disease – so that, according to experts, it is not possible to deduce from the measured value whether a measured deficiency did not arise as a result of the infection.

According to the authors, one of the limitations of the new analysis is that not all corona infections can be detected via antibodies – among other things because these fade after a certain time. The study does not make a statement about the severity of covid-19 disease as a function of vitamin D status.

Commenting on the study in Jama Open Network, U.S. health expert Michael Polis praised the methodology of the analysis. “This study shows that one well-designed, appropriately sized observational study can provide more definitive evidence than multiple smaller, poorly designed studies.”

What is vitamin D?

Vitamin D is the umbrella term for a group of fat-soluble vitamins. Unlike other vitamins, the body can make vitamin D on its own – from sunlight, specifically UV-B radiation of certain wavelengths.

However, recommendations to take vitamin D supplements have been making the rounds on the Internet for quite some time – currently often justified with references to the fact that an infection with the coronavirus or a severe course of a Covid 19 disease could be prevented in this way.

Federal institute warns of risks

So far, there is no scientifically proven evidence for this. Authorities such as the German Federal Institute for Risk Assessment (BfR) repeatedly warn of the health risks of taking vitamin D supplements on their own, especially those with higher doses.




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