The results of a new clinical trial suggest that vitamin D supplements do not help people hospitalized with moderate to severe covid-19. Elsewhere, a controversial and preliminary article that suggested that vitamin D offered a benefit has now been pulled by Lancet due to “concerns” about the research design.
Vitamin D has emerged as a new covid-19 panacea for some on social media, replacing earlier favorites like hydroxychloroquine. There is an abundance of evidences that many people could use more vitamin D daily in their lives, especially during the winter. The deficiency of this vitamin, which can be taken as a supplement or synthesized in the skin in strong sunlight, can certainly affect the general health of people. But the evidence that vitamin D plays an important factor in the severity of covid-19 or that its supplementation could help treat ongoing cases is far less robust.
At the end of January, a study released on the SSRN prepress server – run by The Lancet newspaper – seemed to change that image. The authors claimed to have found that calcifediol (a by-product of vitamin D) reduced the risk of mortality in covid-19 patients hospitalized in Spain by 60% compared to people who received standard treatment. For comparison, tocilizumab, an arthritis medication, was recently found to reduce mortality in critically ill patients with covid-19 by 4% in a large study in the UK – modest results that are promising enough to enshrine it as a standard treatment along with steroids for critical cases.
But it wasn’t long before outside scientists started for raise questions with these results. For example, the study design was described as a randomized, observational study by the authors at different points in the article – two very different things. Randomized controlled trials, in which some people are randomly assigned to receive treatment, are considered the gold standard of clinical evidence because they can best confirm that a drug is having a real beneficial effect on a disease. Observational studies, in which scientists simply look at the differences between groups of people who receive different care, are important in medicine, but their conclusions are often viewed with more caution, because it is more difficult to know whether a particular treatment actually caused the effect. Other criticisms of the document included the lack of relevant patient data (such as baseline vitamin D levels in some patients), as well as possible statistical flaws. And, of course, the results would still be preliminary, no matter what, not having gone through the peer review process yet.
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On Friday, the Lancet removed your prepress server article, citing “concerns about the survey description in this article”. He also announced that he would start an investigation into the study.
Meanwhile, the results of what appears to be a genuine randomized vitamin D trial for covid-19 have been Published Wednesday in the Journal of American Medical Association – the largest study of its kind to date. Researchers in Brazil said they randomized 240 people with moderate to severe covid-19 in the hospital to receive a single large dose of vitamin D (200,000 IU, compared to the daily dose of 600-800 IU recommended for the average adult) or a placebo.
Altogether, they found no difference in length of hospital stay between people who took vitamin D and those who did not. There was also no difference in the mortality rate or other important measures, such as the likelihood that someone would need invasive ventilation. And although the treatment seemed safe, one patient had an episode of vomiting probably related to it.
“The results do not support the use of high doses of vitamin D3 for the treatment of moderate to severe COVID-19,” wrote the authors.
The JAMA study is still just an essay, and nothing should be decided in medicine based on a single study. And again, not many people are getting the amount of vitamin D they need, so there is nothing wrong with checking your levels with the help of a doctor. But the pandemic has seen countless other potential treatments come and go with little effectiveness to show this.
In general, it is difficult to test the specific effect of vitamin D intake on any condition, because it is usually an indicator of other things. Someone with high levels of vitamin D may also be someone who exercises outdoors frequently, for example, and it may be exercise or your overall good health that really provides a protective boost.
If vitamin D has a benefit for covid-19, it is likely to be modest at best. And the lack of enthusiasm about it the treatment is certainly not evidence of a major conspiracy in which doctors are minimizing vitamin D just to be able to charge for more expensive drugs, as some have suggested. After all, the most successful and life-saving drug for covid-19 so far is dexamethasone, a generic steroid that can cost less than $ 10 per treatment.