Vitamin D is useless in COVID-19, Brazilian doctors from the University of São Paulo have found. The study was published in the Journal of American Medical Association Vitamin D deficiency in the body is a known risk factor for COVID-19, which is why many scientists have looked at vitamin D as a remedy for the symptoms of the disease. However, most of the studies were of rather low quality, conducted in a small number of patients, and might not have a control group. The new study enrolled 240 patients, about 56 years old, who, due to the severity of COVID-19 symptoms, ended up in the hospital, but did not require mechanical ventilation. Half of the patients at the beginning of treatment received a single dose of vitamin D (200 thousand IU), half received a placebo. Vitamin D had no significant effect on the course of the disease. Mortality in the first group was 7.6%, in the second - 5.1%. 16% of patients from the first group and 21.2% from the second were admitted to the intensive care unit. As a result, 7.6% of patients in the first group required mechanical ventilation, in the second - 14.4%. The need for mechanical ventilation in patients of the first group persisted for an average of 15 days, in patients of the second - 12.8 days. Overall, the differences between the results of both groups were statistically insignificant, the researchers conclude. However, vitamin D did not cause any significant harm either - the only side effect was vomiting, which appeared in one of the patients. "The findings do not support the use of a high dose of vitamin D3 for the treatment of moderate to severe COVID-19," the authors write. Although this work has become the largest study of the effects of vitamin D on COVID-19 so far, there were still not enough patients to get reliable results, the researchers admit. In addition, the majority of patients had a normal level of vitamin D in the body - a pronounced deficiency was observed in only a quarter. In addition, the study focused on patients with moderate to high severity. It is possible that vitamin D may be beneficial for less severe symptoms - studies of other drugs have shown a dependence of the effect on the severity of the disease. "Given the lack of highly effective therapy for COVID-19, other than perhaps corticosteroids, it is important to be open to emerging vitamin D research results, despite the smaller sample sizes and severe limitations of some of the work," the researchers said. This study also refuted the results of recent controversial work published by Spanish doctors in the Lancet and subsequently withdrawn. The authors claimed that by using calcifediol, a vitamin D metabolite, they were able to reduce patient mortality by 60%. However, the scientists who read the article had many questions about the methodology - for example, the authors wrote about their study as observational and randomized at the same time, but these approaches contradict each other. In randomized studies, patients are randomly divided into several groups, in observational studies, they do not interfere with treatment and only record possible results. The first approach is much more effective; the results of the second should be interpreted with great care. Also, it was not known about the initial level of vitamin D in some patients and a number of other indicators that could affect the result. In addition, the study was not peer-reviewed and presented only preliminary results. As a result, the editors of the journal decided to remove the material from the site, explaining that they have questions about the design of the study. They intend to find out what other violations were committed by the authors. In general, it is difficult to study the individual, independent effects of vitamin D on patients. For example, a person who regularly does outdoor exercise will likely have vitamin D levels within normal limits. However, it is likely not so much vitamin D that will protect against COVID-19, but generally good health. If vitamin D is of any benefit to COVID-19, the effect is likely to be modest. However, it should not be neglected in any case - a lack of vitamin D not only increases the risk of infection, but also affects many processes in the body.
