The idea that vitamin D supplements can reduce the susceptibility and severity of Covid-19 is seductive – it offers a simple and elegant solution to a very complex and lethal problem. But analyzes covering large European data sets suggest that enthusiasm for the sun’s vitamin may be wrong.
Two articles yet to be peer-reviewed examined the link between vitamin D and Covid-19 levels and both came to the same conclusion: evidence of a direct link between vitamin D deficiency and Covid results is lacking.
Quick guide
Let’s do physical exercise: how exercise can help increase your response to the Covid vaccine
Can a brief workout increase your protection against Covid-19? Although many immunologists have studied the role of stress in responses to vaccines, some researchers have turned their attention to exercise, with some intriguing results.
Consider the following experiment by Professor Kate Edwards of the University of Sydney, who asked a group of young adults to perform some biceps and side lifts for 25 minutes, about six hours before receiving a flu shot. As expected, these people showed a high immune response to the injection over the next 20 weeks, compared to participants who rested on the day of the injection. Confirming these beneficial effects, Edwards later found that exercise could also increase responses to the pneumonia vaccine.
In addition to increasing effectiveness, a short workout can calm the side effects of a vaccine. Performing 15 minutes of exercises for the upper body – before or after the injection – has been shown to reduce the swelling and fever that sometimes come from the HPV vaccine, for example.
How can it be? One possibility is that the slight wear on our muscles, as we exercise, can trigger a mild reaction in the immune system. When the vaccine is administered, the body is therefore well prepared to deal with the antigen within the injection more efficiently – increasing the benefits of the vaccine while reducing potential discomfort.
A group of researchers mined a database of hundreds of thousands of participants, mostly white, to understand whether giving vitamin D could decrease their likelihood of having severe or symptomatic Covid.
The researchers looked at the records of people with certain genetic markers that make them predisposed to vitamin D deficiencies, something that is not influenced by factors like age and other underlying conditions. They found no evidence for the idea that the supplements protect against Covid.
Another study compared the prevalence of vitamin D deficiency in 24 European countries with Covid infections, recovery and mortality data.
The lead author, Dr. Michael Chourdakis, of Aristotle University, Greece, said the analysis avoided the methodological limitations of previous studies, using only recent data on vitamin D, and did not include only subsets of the population, for example, people in nursing homes. elderly.
In addition, instead of using average levels of vitamin D, which can be distorted by certain parts of a population with very high or very low concentrations, they specifically examined the levels of deficiency.
“There is an information overload on the benefits of vitamin D … vitamin D has been praised for many things,” he said, “although we have very limited data for that.”
He added that the study was methodologically sound and the data showed no significant correlation between vitamin D and Covid infections, recovery or mortality.
Those who traditionally exhibit vitamin D deficiency – older adults and ethnic minority populations – are the same groups that have been disproportionately affected by Covid-19. Prolonged blocks and subsets of population protection have also increased time spent indoors, away from vitamin D-rich sunlight. And in general, vitamin D has helped the immune response to respiratory infections – so supplements seem like an answer intuitive.
But the evidence about Covid so far – although some of it is positive – is circumstantial. Some researchers argue that it is not robust enough to favor a policy of giving supplements to the entire population, especially due to the impact it can have on individual behavior and the possible negative physical side effects of taking too much.
In a recent review, the National Institute of Excellence in Health and Care (Nice) agreed that there was still a lack of evidence for vitamin D supplementation to prevent or treat Covid and that more research was needed.
“We are scientists – we believe in data. We feel that the current data suggests that vitamin D will not protect against Covid’s results. We would be happy to consider any data that suggests otherwise, ”Dr. Brent Richards, a clinical scientist at McGill University with a focus on endocrinology, epidemiology and biostatistics, who is one of the authors of the genetic study.
“But it is important to remember that in the field of vitamin studies, the general public is familiar with vitamins and a high level of confidence that we do not see in other types of interventions. Therefore, people very much want this solution to be a vitamin-based solution – and sometimes this is not always the case. “
A recent case in point is a study by scientists at the University of Barcelona that suggested that giving high doses of vitamin D to patients with coronaviruses when admitted to the hospital could reduce deaths by an impressive 60%, which led to calls from the former secretary of the Brexit and MP David Davis for therapy to be implemented in hospitals.
But some scientists pointed that although the data is presented as a randomized study of vitamin D supplementation, it appears that the individuals were not randomized, but the hospital wards were. Different wards tend to receive different patients, depending on the level of illness and risk.
Eventually, the study – which had not been peer-reviewed – was removed from the medical journal The Lancet’s server as a result of concerns that triggered an investigation into the newspaper.
Meanwhile, randomized controlled trials designed to definitively answer whether vitamin D status plays a direct role in Covid infections and results are underway. “What is missing at the moment is really a definitive trial that demonstrates a cause and effect relationship,” said Adrian Martineau, professor of respiratory infection and immunity at Queen Mary University in London, who is leading this study.
“You cannot discard the circumstantial evidence …[but] it is not the highest level of evidence. I think there is a philosophical question – if you have an intervention that has a good chance of working and is completely safe, why not implement it while you wait to find out given the public health emergency? “