Does vitamin D protect against COVID-19?

In the absence of a COVID-19 cure or vaccine, scientists are investigating whether Vitamin-D may reduce the risk of COVID-19 infection or the severity of the disease. Indeed, the idea of ​​taking a vitamin to ward off COVID-19 infections is certainly appealing.

Although some recent studies have suggested a link between low vitamin D levels and a higher risk of developing the disease, experts believe that it is not enough to prove that vitamin D itself protects against the disease or if other factors play a role.

A study published September 3 in JAMA network openfound that the risk of COVID-19 infection in people with vitamin D deficiency was almost twice as high as in people with adequate vitamin levels. Another study published October 27 in Das Journal of Clinical Endocrinology & Metabolismfound that hospitalized COVID-19 patients had higher levels of vitamin D deficiency than a control group of patients who did not have COVID-19 but whose vitamin D status was measured before the pandemic.

Those associations don’t prove that vitamin D deficiency causes an increased risk of COVID-19, said Adrian Martineau, who studies respiratory infections and immunity at Queen Mary University in London and was not involved in either study. “But it’s suggestive and enough to warrant further investigation to find out whether or not there is a real cause and effect relationship,” Martineau told Live Science.

Connected: 9 Good Sources of Disease-Fighting Vitamin D.

A protective effect?

There are several reasons to hypothesize that vitamin D could reduce the risk of COVID-19, Martineau said. Vitamin D has been shown to increase the immune system’s response to viruses and dampen its inflammatory response. An excessive inflammatory response marks severe COVID-19 cases, he said.

According to a meta-analysis by Martineau first published in the journal in 2017 BMJ and updated to include newer studies on the preprint server this July medRxivVitamin D supplementation generally reduced the risk of acute respiratory infections compared to placebo. (However, the meta-analysis did not include any studies on COVID-19.)

Additionally, there is an overlap between the groups of people at higher risk of vitamin D deficiency, such as the elderly and people with darker skin, and those at higher risk for COVID-19, Martineau said. “People put two and two together and thought, ‘Well, that’s a remarkable coincidence when it is actually a coincidence.”

An earlier study was published in the journal on May 6th Aging clinical and experimental research found that in 20 European countries, the lower the average vitamin D level, the higher the rate of coronavirus cases and deaths for a given country.

However, not all studies have suggested a protective effect. A study published in the journal May 7th Diabetes & metabolisches Syndrom found no statistically significant association between vitamin D levels and COVID-19 risk when the researchers considered other factors that might influence COVID-19 risk.

The chicken or the egg

In the JAMA Network Open study, researchers examined the relationship between likely vitamin D levels and risk of COVID-19 in 489 people who took a COVID-19 test at the university between March 3 and April 10 of Chicago Medicine and their vitamin D levels were measured the previous year. The study researchers found that the risk of testing positive for COVID-19 increased in people whose vitamin D levels were likely to be deficient – those who had low vitamin D on their last test and who hadn’t changed their treatment – 1.77 times higher than in patients whose vitamin D levels were likely sufficient. This emerges from the researchers’ analysis, which took into account other differences between the two groups that could influence COVID risk.

The study by the Journal of Clinical Endocrinology & Metabolism compared the vitamin D levels of 216 patients hospitalized with COVID-19 at Marqués de Valdecilla University Hospital in Santander, Spain, March 10-31, with a control group of 197 Patients who had vitamin D levels tested the previous year as part of another study. Of the COVID-19 patients, 82% were vitamin D deficient compared to 47% of the control patients, a statistically significant difference.

One strength of the University of Chicago study is that vitamin D levels were measured before patients were tested for COVID-19, Martineau said. For the Spanish study, however, the vitamin D levels of the patients were measured after they had tested positive for COVID-19. “You can’t tell the chicken from the egg. In other words, the COVID could have caused or be a result of the low vitamin D levels, ”Martineau said. Since the University of Chicago study was observational – participants weren’t randomly assigned to take vitamin D or not – it still doesn’t prove that vitamin D deficiency increases the risk of COVID, said Martineau.

Dr. David Meltzer, a University of Chicago researcher who led the study there, agrees. “None of this proves that vitamin D deficiency causes COVID,” Meltzer said, referring to his study and other links between vitamin D and COVID risk. “People who are generally sicker may be more likely to have low vitamin D levels,” he added.

To try to answer the question about chicks and eggs, Martineau a study Participants will be randomized to take different doses of vitamin D. Then it will be checked whether taking more vitamin D reduces the risk of COVID-19 or the severity. The ClinicalTrials.gov database lists around 30 such studies on vitamin D and COVID, according to information The scientist.

Should people start popping supplements during the studies? Martineau’s advice would be yes, but only if you don’t already meet current guidelines for dietary vitamin D intake. In the United States, the recommended daily vitamin D intake is 600 international units (IU) for adults aged 70 and under and 800 IU for adults aged 71 and over National Health Supplements Office. “My recommendation would be to follow this advice as this is known to have benefits for bones and muscles, and the chances are it may also have benefits against COVID, although this remains unproven,” Martineau said. However, Martineau does not recommend that people start taking higher doses of the vitamin unless additional data is available on how dosage and COVID-19 risk are related.

Originally) released on Live Science.