earlier this year in the spring, 76 spanish covid-19 patients with acute respiratory infection were hospitalized. dr. jose manuel quesada-gomez gave
50 of them high doses of calcifediol — the equivalent of swallowing two fistfuls of fast-acting vitamin d supplement pills. only two per cent of the vitamin d group ended up in the intensive care unit and none died, while 50 per cent of the other group required advanced care and two died. these are remarkable results — almost too good to be true.vitamin d has been around for nearly a century, but mainly as a dietary supplement to improve bone health. this small study adds to a new chapter in the debate around the so-called sunshine vitamin, and whether it can be used to treat covid-19. enthusiasts now say it may be a game-changing treatment for the potentially deadly virus, able to ramp up the body’s natural defenses to fight it off — it even made trump’s presidential treatment list.since the pandemic began, a
plethora of studies have been published connecting
covid-19 outcomes to vitamin d levels. in a study of
covid-19 mortality in indonesia, the majority of the 780 individuals who died were vitamin d deficient. multiple groups have also published retrospective case-control studies establishing strong correlations between
low vitamin d levels and increased
covid-19 risk or
severity. and it is hard to ignore the striking overlap in the risk factors for severe covid-19 and vitamin d deficiency, including older age,
obesity, and darker skin.however, none of these studies can prove cause-and-effect, so they are
quickly discounted in many circles. the small study from spain has been criticized for not using a double-blind placebo control group, relying on small sample sizes, and using multiple other treatment methods on top of calcifediol. challengers also note that they don’t take into account
confounding variables, like
obesity, or account for reverse causality.
vitamin d disappointment
the medical community is particularly sensitive to these experimental design flaws because of past disappointments with vitamin d. ten years ago, there was a wave of vitamin d enthusiasm — doctors and scientists thought it had the potential to revolutionize cancer,
diabetes, autoimmune illnesses, and more. then, a series of large clinical trials dashed these hopes, leaving behind a lingering resistance to overzealous claims.“it’s absolute bullshit,” says dr. charles hardin at massachusetts general. “there is no good evidence that vitamin d is helpful in covid,” and it is bottom of the barrel in terms of clinical trial priority. he is frustrated by the newfound interest in vitamin d, because so many large studies have yielded null results and it draws attention away from more important treatment possibilities.as an author of one of these failed clinical trials on vitamin d, professor adrian martineau at the queen mary university of london doubts that it could change the course of covid-19 infection. he describes two treatment opportunities: reduce virus proliferation in the first phase and suppress the inflammatory response in the second phase of the disease. to be a valuable treatment option, vitamin d has to
prove effective above and beyond antivirals or immunosuppressants already prescribed.vitamin d advocates, like dr. william grant from the
sunlight, nutrition, and health research center, are frustrated by this dismissive response.“they’ll flat out say… there’s no evidence and vitamin d doesn’t have any impact on covid. but by evidence, they mean clinical trials. they totally discount observational studies, ecological studies, biological mechanisms, [and] everything else,” he says. “they just want to treat it like a drug and look at it on a clinical trial.”he adds that without this “gold standard” clinical trial, the medical community may never see vitamin d as more than a dietary supplement. however, professor john adams has just started one.trained as an endocrinologist at harvard, adams has been studying how vitamin d modulates the immune system for three decades in his laboratory at the university of california, los angeles. the team has found that after vitamin d is made in the skin and converted into its active form, it enters immune cells called macrophages. these large pac-man-like cells are the first line of defence against invading viruses. vitamin d activates them and
charges up the innate immune response. “so we consider the use of vitamin d as you would consider the use of an antibiotic… not as something that you give as a vitamin or a dietary supplement.”his group is recruiting 168 vitamin d deficient patients with mild to moderate covid-19 infections for their double blind, placebo-controlled, randomized clinical trial. the plan is to treat these patients with a high dose of calcifediol — the same fast-acting vitamin d pill used in the smaller spanish study. the researchers hypothesize that the treatment has to be applied early to affect a major change in the course of the disease, just like an antibiotic.“what we’re doing is giving fuel to the inflammatory system or the innate immune system to deal with the
challenge of covid as effectively as it possibly can,” he says.this strategy aims to handle the virus before any larger adaptive immune system response or cytokine storm is triggered. martineau concedes that vitamin d may be able to
reduce the severity of covid-19, but gives it a “50/50” chance of having any effect over and above other drugs.adams expects results by next spring. vitamin d may or may not become more than a dietary supplement — capable of protecting nearly one billion
vitamin d deficient people in the world from covid-19. “we are hopeful… but it’s a controlled study. it is a scientific study,” he says. “it may turn out not to be effective therapy, but at least we’ll know one way or another.”
robin blades is a fellow in global journalism at the dalla lana school of public health at the university of toronto.don’t miss the latest on covid-19, reopening and life. subscribe to healthing’s daily newsletter covid life.
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