Vitamin D is essential for the proper functioning of the body. In winter, its synthesis is naturally reduced due to less sunlight and lower skin exposure. Depression and infections are then more frequent. Food, tablets, without prescription … Advice to avoid deficiencies.
Vitamin D is essential for the proper functioning of our body. During the winter months, when its synthesis is naturally reduced due to shorter days, less sunlight, and lower skin exposure, acute lower respiratory infections are more common, as well in adults than children. “Vitamin D is believed to play an important role in regulating the immune system, and can potentially protect against infections. Its supplementation could reduce the incidence and deleterious effects of these conditions,” said the WHO. When to take vitamin D What are the sources of vitamin D ? In what foods can you find it? Can we buy it in pharmacies? Advice.
What is the effect of vitamin D on the coronavirus?
Several studies have highlighted the possible benefits of vitamin supplementation to prevent severe forms of Covid-19. The latest is American. It was conducted by Dr. Sweta Chekuri, of the Albert Einstein College of Medicine in New York on 124 adult patients with low levels of vitamin D, measured 90 days before their hospitalization for Covid-19. The researchers compared the results of patients who received supplements of at least 1,000 units of vitamin D per week to those who did not receive supplementation. Result: Patients who received supplementation are less likely to require ventilation and have a reduced risk of death. In January 2021, 73 French-speaking experts and 6 French learned societies gathered around Prof. Cédric Annweiler, head of the Geriatrics department at Angers University Hospital, and Prof. Jean-Claude Souberbielle, both specialists in vitamin D, called for additional vitamin D the French population as a whole, and not only the elderly or at risk of a severe form of COVID-19. “A growing number of scientific studies show that vitamin D supplementation (without replacing vaccination) could help reduce SARS-CoV-2 infection as well as the risk of severe forms of COVID-19, resuscitation and death “ indicates a press release of the French Society of Geriatrics and Gerontology which supports the approach, published on January 19. This supplementation should be done before infection with the virus or upon diagnosis. According to these scientists, vitamin D would have an effect on Covid-19 by:
- modulating the expression of ACE2, used by the virus to infect human cells.
- regulating innate and adaptive cellular immunity through the production of peptides that have antiviral and anti-inflammatory activity.
- preventing hypovitaminosis which appears to be a risk factor for a severe form of Covid-19.
→ The University Hospital of Angers has been carrying out a randomized clinical trial COVIT-TRIAL since December 2020 to test the effect of a very high dose of vitamin D administered as soon as the infection is diagnosed compared to a standard dose of vitamin D on the risk of death from Covid-19 in frail elderly people who have contracted the infection. 10 French hospitals and nursing homes are participating. The results are expected in the coming weeks.
→ A Spanish study published October 27, 2020, in the Journal of Clinical Endocrinology & Metabolism has shown that among 216 people hospitalized because of Covid-19, 82% had vitamin D deficiency. They did not find a relationship between vitamin D concentrations or vitamin deficiency and the severity of the disease, including mortality, but felt that large randomized controlled trials are ” needed to precisely define the role of the disease. vitamin D supplementation in future waves of Sars-CoV-2 ” .
→ Preliminary data from Norwegian researchers has suggested that users of cod liver oil may have a reduced risk of Covid-19 and a lower risk of serious illness if infected. “To find out whether cod liver oil itself really offers protection against Covid-19, a randomized study is needed,” says Arne Søraas, a medical scientist in the microbiology department at Oslo University Hospital. The study on cod liver oil will include at least 70,000 participants, making it one of the largest clinical studies ever conducted in Norway. During the study, half of the participants will take a daily dose of cod liver oil, while the other half will receive a placebo product. This study will be partially funded by the company Orkla, producer of cod liver oil.
→ In April 2020, a preliminary study published on medrxiv showed that people who were deficient in vitamin D had a 15% increased risk of developing a severe form of Covid-19 disease and twice the risk of death than people who did not deficient. According to the authors, vitamin D would reduce the severity of COVID-19 by suppressing the storm of cytokines (responsible for the inflammatory process) in COVID-19 patients.
Warning: taking vitamin D does not guarantee that you will not be infected with the coronavirus.
When to do a vitamin D test?
The blood test for vitamin D has long been prescribed to check the proper absorption of calcium by the body, especially in people with bone and dental problems, and in the elderly. “But today, this dosage is recognized as being unnecessary by epidemiological studies. In fact, the vast majority of the population is deficient in vitamin D, so this dosage does not teach much”, explains Dr Fouré. . In fact, the Haute Autorité de Santé produced a report in 2013 in which it underlines that the usefulness of this dosage has not been demonstrated, in most cases.
The HAS still recommends the dosage in these cases:
- follow-up after kidney transplantation,
- follow-up after surgery for obesity in adults
- follow-up in the elderly prone to falls.
- the assay can also support the diagnosis of rickets or bone decalcification, in order to better determine the cause of these pathologies, or again to verify the effectiveness of certain treatments, in particular against osteoporosis.
Vitamin D deficiency: signs, risks …
A blood vitamin D concentration of fewer than 20 nanograms per ml of blood is considered insufficient. Deficiency is defined by a vitamin D level of fewer than 12 nanograms per mL of blood. Vitamin D deficiency can lead to
- A bone loss (related to abnormal bone development) and increased fragility causing rickets and fractures. This decrease in bone mass increases the risk of fracture. This risk is particularly high when physical practice is limited or non-existent.
- Of pain and muscle weakness can cause falls in the elderly.
- Vitamin D deficiency can also lead to fatigue.
Who is most at risk of being deficient?
Vitamin D insufficiency is very common in metropolitan France, especially at the end of winter and at the beginning of spring. According to the National Health Nutrition Study (2012), 80% of French people are affected. Several studies have shown that French women over the age of 50 are the most deficient in vitamin D in Europe. Severe deficits are rarer (around 5%) and more often affect the elderly. “We should supplement all women from the age of 50, and everyone from the age of 75. This is all the more necessary for bedridden people, in nursing homes for example,” adds Dr Fouré.
According to ANSES, the risk of vitamin D deficiency is higher in some people:
- people with dark or dark skin, for whom the synthesis of vitamin D via exposure to the sun is less effective,
- postmenopausal women, whose hormonal disruption can lead to bone demineralization, which increases the risk of fracture.
Vitamin D: in which foods?
In adults, food contributes 10 to 20% of vitamin D reserves, and this proportion is probably even lower in children, says the WHO . “The sun remains the richest source” confirms our interlocutor. This vitamin is mainly found in cod liver oil “but it would be necessary to absorb litres and litres to have a satisfactory intake”.
The foods richest in vitamin D are:
- Oily fish such as herring, sardines, salmon or mackerel (vitamin D3) (two servings per week)
- Organ meats, especially liver
- The egg yolk
- Dairy products, especially those fortified with vitamin D
- Butter and margarine
ANSES would like to remind you that it is important to vary and balance our diet throughout the year and to consume these foods regularly to cover your daily vitamin D requirements. The right benchmark: eat two servings of fish per week, including a portion of fatty fish. Ideally, prefer fresh fish, but if this is not possible, bet on canned sardines, herrings, mackerel in their natural state.
Vitamin D ampoule: what dosage to avoid overdose?
The recommended dose is one ampoule of 100,000 units every two months, during periods of low sunlight (or 600 to 800 units per day). Usually, we take one at the onset of winter and another at the beginning of spring. ” Paradoxically, an overdose of vitamin D can lead to the weakening of the bones”, indicates Yves Fouré. This is called hypervitaminosis. ” The use of food supplements containing vitamin D can expose to excessively high intakes, which can cause hypercalcemia – high level of calcium in the bloodstream – leading to calcification of certain tissues,“, adds ANSES on its website in its article of April 17, 2020. In all cases, the use of food supplements must be made on dietary or medical indications.
The sun, a source of vitamin D
The sun and its ultraviolet rays constitute THE main source of vitamin D. “Vitamin D is synthesized by the skin under the action of the sun; but beware, prolonged exposure to UV increases the risk of skin cancer”, points out keep Dr Fouré.
• In spring, exposure to the sun for 15 to 20 minutes of the hands, forearms, and face ensures the daily intake of vitamin D.
Can we buy it in pharmacies without a prescription?
→ Vitamin D can be purchased in the form of food supplements, without a prescription, in pharmacies (or organic stores) “but the content is limited since it corresponds to the regulation of the food supplement” indicates the pharmacist Julien Tison.
→ Vitamin D can also be bought on prescription, in the form of drugs with a higher concentration (as for ZymaD®, ZymaDuo®, Uvedose ampoules, or in syrup).
How to avoid overdose?
Studies have highlighted the potential beneficial role of vitamin D on the immune system to counter the current epidemic which has led to an increase in its consumption in the population. Attention, warns the University Hospital of Lille on January 29: “The overdose of vitamin D is toxic, the risks are multiple: nausea, fatigue, bone risks, convulsions, coma. Be vigilant and do not consume vitamin D supplements without talking about it. to your doctor. Products available on the Internet can be very dangerous! “
These professionals recommend:
- If you are at risk or if you test positive for Covid-19, do not hesitate to discuss a vitamin D supplement with your doctor,
- If the attending physician considers it necessary, he will prescribe a vitamin D supplement in the form of an ampoule. Reliable treatment, on prescription and reimbursed by Social Security.
Thanks to Dr Yves Fouré, general practitioner, and to Julien Tison (comments collected on February 3, 2021).