The vitamin D intervenes at several levels in our body: bone tissue, muscle tissue, immune system. It increases the concentrations of calcium and of phosphorus in the blood. There are two ways to meet our vitamin D needs. First, there is sun exposure, UV-B in particular, present between April and September in France. Second, there is the consumption of foods rich in vitamin D such as oily fishsome mushroomsegg yolk, chocolate black, butter… In France, nearly one in two adults is vitamin D deficient.
Vitamin D deficiency and severe forms
the Dr. Amiel Dror and his team were interested in the link between blood levels of 25-hydroxyvitamin D (25(OH)D) before the contamination over there Covid-19 and severity of the disease. The study included patients from an Israeli hospital between April 7, 2020 and February 4, 2021 who tested positive for SARS-CoV-2 (PCR test) and having a dosage blood vitamin D levels prior to infection (n=253). Among the patients who made a severe form of Covid-19there were more patients with deficiency vitamin D before infection. More specifically, patients with a vitamin D deficiency were 14 times more likely to have a severe form than non-deficient patients.
More interestingly, the mortality in non-deficient patients was less than 5% while it was 25.6% in deficient patients. However, these results should be qualified by the fact that the elderly are often deficient in vitamin D (the body’s ability to synthesize vitamin D decreases with age) and by the fact that age is one of the main risk factors to make a serious Covid.
Dose vitamin D
Beyond the risk of having a serious form of Covid-19 disease, vitamin D deficiency exposes individuals to muscle disorders and bone disorders (osteomalacia, rickets, fractures). So how do we know if we are vitamin D deficient? There is a blood test for vitamin D, but it is reimbursed by health insurance only in certain very specific situations: suspicion of rickets, suspicion of osteomalacia, in renal transplant recipients, before and after a bariatric surgery, in elderly people prone to repeated falls. If other studies were to confirm a link between vitamin D and severe forms of Covid-19, it could well be that the dosage of vitamin D becomes widespread.
Covid-19 and vitamin D: what should we think?
Article by Julien Hernandez published on 01/22/2021
During this pandemic, we have heard, and we still hear, a lot about vitamin D in the context of Covid-19. What should we think ?
Vitamin D… If we listen to certain allegations, they would have unsuspected virtues on a colossal number of affections pathological. Each wintera small part of the French population (more or less important depending on the type of sub-population studied) is deficient, according to epidemiological data of Public Health France. Within the body, it plays various roles of major importance, the best known of all being perhaps that of the absorption of calcium and phosphorus at the intestinal level widely popularized and crudely popularized by the marketing slogan ” Vitamin D helps calcium bind to bones. It is also the only affections in which it is recommended apart from the manifest deficiency: theosteoporosis and rickets.
The scientific literature abounds with data concerning vitamin D and pathological conditions of all kinds. We will focus in this article on the evidence we have on the use of the latter in the context of Covid-19 following a forum published by a group of doctors in The Practitioner’s Review.
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Mechanistic and retrospective arguments…
The forum of this collective of doctors bases a large part of its argument on mechanistic arguments, that is to say on the biochemical roles that vitamin D plays within our body, and on other emanating from studies. retrospective observation. We have already discussed the problem of mechanistic arguments at length in this article on the history clinical trials and their necessity. These issues remain unchanged.
Regarding observational data, it would seem that people with Covid-19 are more deficient than the general population. But the authors of the forum recall a few lines later that the people for whom we currently have the most data in the context of Covid-19 are hospitalized people. The latter therefore form forms serious enough to require a stay in hospital or, in the worst case, in intensive care. We also know that age and overweight constitute risk factors for the severity of Covid-19 infection, but not that these are subpopulations that are also more deficient in vitamin D. With the data in our possession, it is impossible to say, at the time current, if vitamin D deficiency is indeed involved in the severity of the disease. Similarly, several studies cited by the collective conclude that there is no identified causal link between vitamin D and the severity of Covid-19. In the most large observational study they cite, the association between circulating vitamin D levels and disease severity is not significant after adjusting for confounding factors.
…and no clinical arguments!
No clinical argument solidemanating fromrandomized studies large scale, is used to support the gait. One intervention study cited carries on a derisory number of patients. Participants receive a treatment called the best therapy available (which is none other than hydroxychloroquine/azythromicin dual therapythe effectiveness of which has been invalidated) with or without vitamin D. This protocol does not allow the authors to conclude in favor of the treatment and suggests that other larger trials should be carried out. others pilot intervention studies have been carried out but no conclusion in favor of a positive benefit/risk balance of the treatment can be seriously asserted to date.
Therefore, it is unknown whether vitamin D at any stage of the disease may be helpful. A recent Mendelian observational study suggests vitamin D does not prevent severe forms of Covid-19. An article published in the Journal of American Medicine Association also criticizes the craze around vitamin D. Review Prescribe considers that uncertainty reigns on the subject. A review from 2017 produced by the World Health Organization (WHO) on vitamin D and respiratory infections reminded us how low the level of evidence was and how heterogeneous the studies were, making it difficult to draw conclusions. A recent article published in Nutrition Reviews evokes plausible utility in people who are truly deficient (less than 10 nanograms per milliliter) and those at high risk of going through intensive care if they contract Covid-19 (who generally represent the same subgroups). All these data put together constitute an unconvincing body of evidence to support the claims of the tribune who wish to supplement in prevention the whole population or at least the populations at risk.
Questions of priorities and logistics
Two key points should be remembered. First, we have a vaccine campaign “on the arms”. Let’s strive to make it a success without putting more constraints on the pharmaceutical laboratories, the systems offorwarding medicines and community pharmacies. Second, imagine that vitamin D is effective and beneficial in the prevention and treatment of Covid-19 — which does not seem to be the case when we look at all the data on the question: what its effect size? In other words, would supplementation really have a significant impact on deaths or hospital saturation? Is it really necessary to allocate resources and mobilize means for a product whose effects are, a priori, also uncertain? Logistical questions also arise for such measures. First, the screening. France has had enough trouble achieving the goals it set itself in matter of Covid-19 screening. How would we detect all vitamin D deficiencies in such a short time?
If we do not screen, how to adapt the dosage according to the supposed deficiency? Because vitamin D can, at very high doses in the blood, cause side effects, and a level above the recommended long-term threshold values has also been associated with higher mortality (this forms an inverted U or J curve). In addition, other variables are added to theequation. As Véréna Bourbia, doctor in logistics geography, explains to us, ” it is necessary to take into account the means of production (laboratories) and their possibility (assignments of machines, raw materials, etc.), the recommendations and the characteristics of the product (what dosage, how many shots, in what format, etc.) , the volume storage and conservation requirements so that vitamin D can be stored in sufficient quantity without impacting other drugs. »
Finally, there are other ways to correct a possible vitamin D deficiency than supplementation, such as eating Pisces fat (especially liver of cod) or, from the month of April, expose oneself daily and sporadically to the Sun. Achieving the goal of a non-deficient population over the long term is commendable. Dispersing our efforts in the fight against Covid-19 is less so. It seems that all our efforts should focus on vaccination or on therapies that really bring hope.
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