Vitamin D and covid-19: the failures that led the study to be taken off the air by a scientific journal

  • Rachel Schraer
  • Health Reporter

2 hours ago

Credit, Getty Images

As covid-19 has spread across the world over the past year, another danger has also spread: misinformation about how to treat it. Sometimes, misinformation is created even around ideas that contain some background of truth – and this can be the most difficult type of “fake news” to fight.

This is the case of vitamin D, the subject of intense debate about a potential use as a treatment for covid-19.

As will be seen later in this report, the original study that had shown an alleged success of vitamin D became the target of criticism because it did not follow methods robust enough to point to those conclusions.

In other words, this study, carried out in Spain, did not respect important scientific criteria so that its results could be safely indicated to the population. It was withdrawn from circulation by the publication and is now the subject of an investigation.

Meanwhile, at the moment, another more rigorous study is being conducted in England.

It was from this controversy that false information began to spread about the alleged effectiveness of vitamin D against covid-19.

Why vitamin D?

Many treatments well known to Brazilians have been suggested for covid-19.

Hydroxychloroquine, ivermectin and vitamin D – all of these drugs are or have been, at some point, studied.

It is important to remember that suggesting that a treatment can be effective and then discovering that this is not true is part of the normal scientific process.

The problem is that nowadays, online surveys, in initial stages or of low quality, have been shared out of context. And the confusion this creates can be exploited by people who promote conspiracy theories.

There is some logic behind why vitamin D may be useful in the treatment or prevention of covid-19.

It plays a role in immunity and is already recommended, for example, in the UK – where everyone should take the supplement in the winter (with those at higher risk for vitamin D deficiency being advised to take it throughout the year).

So far, however, no research has shown a sufficiently convincing effect to support the use of higher doses of vitamin D to prevent or treat disease, which may change in the future.

Thus, it is understandable that the use of vitamin D to prevent covid-19 has spread over the internet as a health advice. However, some have gone much further, suggesting on online forums like Reddit that governments “barely mention” the effectiveness of vitamin D and instead focus on “vaccines and police status tracking”.

Or claiming that the vitamin is being ignored because the World Health Organization (WHO) is “paid for by the large pharmaceutical industry”.

The arguments can be easily overturned – starting with the fact that vitamins themselves are a billion-dollar industry.

What do the studies say?

Many studies have shown an association between vitamin D and covid-19, but the evidence is merely empirical – meaning that other factors are not being controlled and monitored to accurately determine a cause and effect relationship.

That is, the conclusions of these studies are not robust enough: for this to happen, it would be necessary, for example, a clinical trial known as randomized, in which people receive a treatment or a simulated version, or placebo, so that scientists can be sure that the result is caused by the treatment.

Observational studies show that certain groups are more likely to have vitamin D deficiencies and to catch covid-19 – in general, older people, people with obesity and people with darker skin (including black and South Asian people).

It may be that a deficiency is the reason these groups are most at risk, or there may be other health and environmental factors that lead to a drop in vitamin D levels and greater susceptibility to the virus.

Vitamin levels may also drop as a result of the disease, rather than being the cause.

We will only be able to isolate vitamin D as the cause by conducting properly controlled randomized tests, such as what is currently being performed at Queen Mary’s University in the United Kingdom.

Studies in Spain

An article from the University of Barcelona called attention, claiming to have conducted exactly this type of study.

He suggests that vitamin D has an impressive success, with an 80% reduction in intensive care admissions and a 60% reduction in covid deaths.

This result was widely shared on the internet.

But since then, the study has been taken offline for “concerns about the description of the research”. The scientific journal The Lancet, which originally published it, is now conducting an investigation into the article.

The problem is that this retraction was not shared in the same way as the original article.

In the study, vitamin D was administered to all patients in wards, rather than randomly to individuals, as it should have been done in a rigorous survey.

And the covid-19 study patients who died already had radically different levels of the vitamin before treatment, suggesting that they were more seriously ill even before taking the vitamin.

Still, the idea that vitamin D can be an effective treatment against covid-19 has won numerous adherents.

Conservative MP David Davis, who called on Parliament to introduce vitamin D supplementation to hospitals, told the BBC that, despite the downturn, he believed the study still showed that vitamin D was important and argued that the government should finance more research on the subject.

Aurora Baluja, an anesthesiologist and intensive care physician in Spain, who reviewed the Barcelona study for the The Lancet, said the type of “extreme” effect found in the article “was never found” in a randomized controlled trial.

She said that while vitamin D deficiency was a “well-established risk factor” among people who die in intensive care, “vitamin D supplementation alone has always failed to reduce the risk for these patients.”

Baluja explains that the deficiency is often caused by something much deeper, such as malnutrition or kidney failure.

Thus, it would not be vitamin D deficiency that would be causing the death of patients.

What is the problem?

When some discoveries fit people’s worldview – for example, that “things in nature can’t hurt,” explained Professor Sander Van der Linden, a social psychologist at the University of Cambridge – the likelihood of them being shared tends to be bigger.

On the internet, there are several groups debating about covid-19. Some advocate natural medicines and alternative medicine; others are ideologically against vaccination. Sometimes these different groups end up coming together around an idea that fits both beliefs.

Anti-vaccine people are “deeply connected to other topics – religion, herbs and alternative medicine, the natural community,” said Professor Van der Linden. As a result, messages like “you don’t need a vaccine, you can just take vitamin D” end up spreading through these groups, without being clearly identified as part of a campaign against vaccines.

Vitamin D is relatively safe (although high doses can cause kidney stones), so this type of advice may not seem like the most harmful among the incorrect information circulating on the internet.

The danger, explains Professor Van der Linden, is when people suggest that the supplement is a miracle cure and should be used as an alternative to vaccines, masks and social detachment.

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