Vitamins B, C, D or trace elements: more than one in five French people regularly consume food supplements, mainly in winter, according to health authorities. Objective: to strengthen their natural defenses, particularly to fight the flu, which is very virulent this winter. A "myth" for virologist Océane Sorel, alias The French Virologist on social networks: "On paper, it's attractive. But it's just marketing. 'Boosting your immunity' doesn't mean much."
To function properly, our immune system needs a cocktail of nutrients, vitamins and minerals. But these contributions are generally provided by food. Sometimes, pregnant women, the elderly or those who follow a "vegan" diet can have deficiencies. "But to know, you still have to go and see a doctor, and then it would not be a question of +boosting+ the immune system but just of restoring its normal functioning," insists Océane Sorel.
“Boost your immunity” is a non-specific health claim
Contrary to popular belief, it does not exist "magic potion" for the "make more efficient", adds Professor Irène Margaritis, deputy director of risk assessment at the National Agency for Food, Environmental and Occupational Health Safety (ANSES).
Unlike medicines, food supplements are not subject to marketing authorisation. They cannot claim therapeutic effects, and the positive health effects they may display are regulated by the European Union. “Boost your immunity” is thus a non-specific health claim.
"It can only be used in addition to an authorised health claim, for example 'vitamin C contributes to the normal functioning of the immune system'.", explains Claire Guignier, director of public affairs and communications for the National Union of Food Supplements, Synadiet. "A number of active ingredients have demonstrated their effectiveness in the proper functioning of the immune system", she says.
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“Products sold on the Internet are much less controlled”
According to the General Directorate for Competition, Consumer Affairs and Fraud Control (DGCCRF), out of 78 websites selling food supplements checked in 2015 (latest figures available), 80% did not comply with the rules. On Instagram, the temple of well-being tips, commercial collaborations promoting these products are proliferating.
This growing phenomenon worries Professor Irène Margaritis: "Products sold on the internet are much less controlled, and some products have a composition that is very different from that displayed." In pharmacies, sales of food supplements have jumped by 56% since 2019, according to a barometer from the non-prescription health products lobby, NéreS.
And if the benefits against viruses are often zero, the risks are not, warn professionals. Zinc, for example, creates copper deficiencies. As for vitamin D, Anses had warned in 2023 about cases of overdose in infants linked to the taking of food supplements.
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"We wrongly think that these are just vitamins, that they are harmless"
"We wrongly think that they are just vitamins, that they are harmless, but they are not sweets," recalls Océane Sorel. The health agency had also warned in 2023 that herbal food supplements could present risks – sometimes serious – to health. Aloe vera, for example, is contraindicated in cases of intestinal obstruction, inflammatory bowel disease, among others; echinacea in cases of immune system pathology or taking medications affecting the immune system; ginkgo biloba in cases of epilepsy in particular.
“Some substances can also interact with medications, making them more toxic or ineffective.”, warns Professor Irène Margaritis. With a turnover in France of more than two billion euros, according to Synadiet, the global sector is nevertheless booming.
"The 'immunity boost' business capitalizes on people's fear", says Océane Sorel. However, there are other ways to prevent winter infections, including the flu: vaccination - "the only real way to boost your immunity", maintains the virologist - but also barrier gestures, ventilation, and hand washing.
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