Can stocking up on vitamins prevent you from winter viruses? The idea is beautiful, and often passed down within families, but is it effective? The National Institute of Health and Medical Research (Inserm) recently took stock of what works and what does not.
Vitamins: essential… but not miraculous
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Inserm reminds us that vitamins are essential for the normal functioning of our body. They participate in cellular regeneration, energy production, the formation of red blood cells and even defense against external attacks. But they are not medicines, nor direct protection against the viruses that circulate in winter.
The Institute distinguishes two large families:
- Fat-soluble vitamins (A, D, E, K), which can be stored in the body (liver, adipose tissues);
- Water-soluble vitamins, notably vitamin C and B vitamins, which are not stored and must be supplied regularly through food.
Despite everything, a varied and balanced diet is generally sufficient to cover our needs, which makes supplements a supplement – and not a systematic necessity.
Vitamin C, darling of our winters… rightly so?
Vitamin C enjoys an excellent reputation in winter. It has many useful functions: it supports the health of blood vessels, facilitates the absorption of iron and protects our cells thanks to its antioxidant activity.
But Inserm is very clear: “There are no solid scientific studies showing that supplemental vitamin C prevents colds, reduces their duration, or significantly reduces the occurrence of winter infections in a healthy population.”
In other words, if it remains essential to our health, in normal doses via food, it does not constitute a remedy against seasonal viruses, contrary to what certain advertisements or posts on social networks might suggest.
Vitamin D: an often justified exception
Among all the vitamins, vitamin D is the one whose supplementation can be relevant, especially in winter.
Unlike vitamin C, it is not mainly provided by food, but synthesized by the skin under the influence of the sun. However, in winter, our exposure to the sun is significantly reduced, which can lead to a drop in blood levels.
Inserm emphasizes that a lack of vitamin D can have significant consequences:
- Weakening of the bone system in children (rickets);
- Osteomalacia or muscular disorders in adults;
- Decrease in certain immune functions.
A truth that expert Laure Martinat, doctor and expert in phyto-aromatherapy, recently confirmed in our pages:
“The only vitamin we really need as a supplement is vitamin D. It is necessary at all ages, it should be taken all year round, except people living in very sunny regions.”
She also insists: “You should ideally know your plasma level via a blood test with your doctor, then adapt the quantity to take.
This recommendation is in line with scientific publications: vitamin D deficiency is well documented as frequent in winter, and its supplementation may be justified in people at risk or those who have a deficiency.
Zinc, other micro-nutrients… and practical advice
Other micronutrients such as zinc also play a role in immunity, particularly for fragile or elderly people. As Laure Martinat explains:
“Zinc is found particularly in fish, shellfish, certain cereals… Elderly people are often deficient due to lack of correct dietary intake, a cure is therefore relevant in this particular case.”
But, here again, Inserm reminds that it is not because a nutrient is necessary for the proper functioning of the body that its systematic supplement necessarily protects against winter infections – equality of dosage or “boost” effect has not been scientifically demonstrated for the general population.
The limits and risks of vitamin supplements
Finally, the institute also warns against excess vitamins. Fat-soluble vitamins, for example, can accumulate in the body. An overdose can cause serious side effects (liver problems, hypercalcemia with risk of kidney stones or heart problems). In addition, certain supplements can interact with medications or have specific effects depending on the profile (smokers, sick people, etc.). For these reasons, as Laure Martinat summarizes:
“You should always seek advice from your doctor or pharmacist… It is important to get good advice before buying because they are not all the same.”
In short: what to remember for this winter?
- A balanced diet remains the basis. Fruits, vegetables, fatty fish and various products cover most of our vitamin needs;
- Vitamin D may require supplementation, especially in winter, but only after medical advice and appropriate dosages;
- Vitamin C is not a miracle cure for infections, although it remains essential for the proper functioning of the body;
- Supplements do not replace a healthy lifestyle, appropriate nutrition or preventative measures (such as vaccination and hand hygiene).
