COVID-19, vitamin D
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More than 80 percent of 200 patients hospitalized in Spain with COVID-19 had low levels of vitamin D, a new study found.

The study, which was published Tuesday in the Journal of Clinical Endocrinology & Metabolism, found that the majority of patients being treated for COVID-19 at a hospital in the northern city of Santander suffered from a deficiency of vitamin D.

Researchers at the University of Cantabria determined that just 82 percent of the 216 patients had inadequate levels — compared to around 47 percent of people in a control group who didn't have the virus.

The vitamin, which promotes healthy bones and supports immune system function, is produced by the body naturally when it's exposed to sunlight, though it can also be obtained from eating foods such as fatty fish, egg yolks, mushrooms and cheese.

Patients with deficiencies of the sunlight vitamin in the study were also more likely to have hypertension and heart disease, as well as experience longer hospital stays.

Researchers, however, didn't find any link between vitamin D deficiency and severity of the illness, with no significantly higher rates of ICU admission, ventilator use, or death among those with inadequate levels of the sunshine vitamin.

The study marked the latest research trying to determine whether vitamin D deficiencies contribute to worse cases of COVID-19 — or if the correlation can be explained by patients who are high risk for the virus, such as older populations and the immunosuppressed, being more likely to have lower levels of the vitamin.

In the study, vitamin D supplements were also given from the point of admission to 19 patients, who were evaluated separately from the rest of the group.

However, the group that took the supplements had a "slightly minor unfavorable" compared to those who didn't receive them — experiencing poorer oxygenation levels, requiring more medication to help with inflammation and were found to be more likely to be admitted to the intensive care unit.

But researchers said the findings might be explained by the six out of 19 people taking the supplements who had recently been on corticosteroids or immunosuppressants in the prior three months, which could have impacted the severity of their illness.

Dr. José L. Hernández, who was the study's co-author, said he still recommends supplements to patients with deficiencies.

"Vitamin D treatment should be recommended in COVID-19 patients with low levels of vitamin D circulating in the blood since this approach might have beneficial effects in both the musculoskeletal and the immune system," he said in a statement.

But other experts have previously warned that more research is needed before prescribing the vitamin to ward off serious cases.

"Although there is some evidence that low vitamin D is associated with acute respiratory tract infections, there is currently insufficient evidence for vitamin D as a treatment for COVID-19 and over-supplementing must be avoided as it could be harmful," Birmingham University professor Carolyn Greig previously told the Times of India.