[ad_1]
If there is one thing you can count on in this pandemic, it is this: At least once a month, a new article will appear in the media claiming that vitamin D helps prevent Covid-19.
The case is simple: we know that vitamin D – the “sunshine vitamin” – is involved in immune function, could it help us fight the virus?
Some, like Labor MP Rupa Huq, are fairly certain of the answer. Tuesday (January 12) she wrote an article in the Evening standard where she described vitamin D as a “wonder” that “gives us all hope to eradicate this terrible disease”. She wrote that its benefits are “stifled” – maybe, she suggested, because cheap vitamins can’t be monetized by Big Pharma and are less glamorous than a vaccine.
Huq’s article appeared a few days after the publication of a Observer article describing how she and David Davis, the Conservative MP, had become unlikely allies on this topic, campaigning to reduce what they see as vitamin D deficiency. Huq and Davis are frustrated that organizations such as Public Health England say there isn’t enough evidence to promote the vitamin, which Davis says “could potentially save tens of thousands of lives” during the pandemic.
Why make do experts disagree with Huq and Davis? What does the evidence say about vitamin D and Covid-19? You might think that after almost a year of studying, we would have a pretty good idea of the answer. Far from there.
Most of the research on Covid-19 / vitamin D comes in the form of observational studies – where researchers look at the correlation between blood levels of vitamin D and the risk of getting Covid-19, or the severity of it. disease. Right now, there have been a good number of such studies and researchers have done meta-analyzes to put all the data together and try to draw general conclusions.
If you just skim through these meta-analyzes, the case may sound upbeat. A The meta-analysis found that while vitamin D was not associated with the risk of contracting Covid-19, severe cases were more likely to result in deficiency. Another found that depending on how you measure it, sometimes a higher vitamin D level is associated with a lower risk of infection and hospitalization. A third found lower levels of vitamin D in Covid-19 patients compared to those without the disease.
[See also: Stuart Ritchie on the “three Cs” key to preventing the spread of coronavirus]
Exciting, isn’t it? Not really. Much of the research is of low quality, with small samples and questionable analyzes. More importantly, observational research is hampered by what epidemiologists call “confusion.” For example, if the elderly, or those with darker skin, are more at risk of vitamin D deficiency and they are more at risk of developing severe Covid-19 for other reasons, this type of study could incorrectly link deficiency to disease. – even if one does not cause the other.
What we need are randomized trials, where researchers give Covid-19 patients either vitamin D or a placebo and test whether the vitamin causes a better result. Surprisingly, only two exist to date. The first was a Spanish study which found that Covid-19 patients given some type of vitamin D supplement tended to do better. The above Observer According to one article, this study “came close to providing compelling evidence that low vitamin D levels play a central role in increasing death rates.” This is dramatically far from reality: it was a pilot study with only 76 participants, and some defaults in its design.
The second is a little bigger study from Brazil, which found no benefit of vitamin D supplementation convincingly enough for patients with severe Covid. It is yet to be published in a peer-reviewed journal, but oddly it is not mentioned by supporters of vitamin D.
You might be thinking: what’s the downside? Vitamin D is inexpensive. We all stay indoors during lockdown and therefore have less sunlight. Even if vitamin D doesn’t help fight Covid-19, surely it’s a good idea to take supplements anyway? But it’s a motte-and-bailey argument – where someone makes a very specific and controversial claim, that claim is attacked and they fall back to a much more general – but more defensible position. We weren’t talking about general benefits of vitamin D – we were talking about the benefits of Covid-19. And the honest answer at this point is that the science has failed to enlighten us: we just don’t know if it’s having an effect.
And there are disadvantages. There is a new, more transmissible variant of Covid-19, and we need people to be extra careful not to catch it. Promote the idea that there is a simple and dramatically effective solution – “wonder”! – which strengthens our immune system and prevents disease could easily lull people into a false sense of security: “I took my vitamin D capsule, so maybe I can do without the mask today.”
A lot other vitamin D and Covid-19 trials are underway, so we’ll have a more definitive answer soon. Until then, let’s ditch the exaggerated claims about quasi-magical substances and sinister conspiracies. It may sound unsatisfying, but as with many parts of the coronavirus debate, the only reasonable scientific view on vitamin D is uncertainty.
[See also: Stuart Ritchie on Covid-19 and the problem of anti-vaxxers]
[ad_2]
Source link