Bifidus, lactobacillus... What are we to believe in the health promises offered by these micro-organisms added to dairy products? Three specialists disentangle the true from the false of probiotics. Browsing the dairy and drugstore sections of supermarkets is now akin to a new kind of visit to the farm. Probiotics, these living microorganisms, are everywhere.
"Friendly" bacteria (lactobacilli, bifids, streptococcus thermophilus, etc.) and yeasts that wish us well. They first hunt the "bad" bacteria nested in the colon to settle in their place. But the effect of probiotics is only temporary, because "they do not cling to the intestinal mucosa and do not multiply there, clarifies Marie-Christine Boutron, gastroenterologist and researcher at Inserm.
In fact, "they hold their role for about ten days after absorption, then they disappear."
In classic plain yogurts, in those enriched with bifidobacteria and lactobacilli (B’A, Activia, etc.), in mini-bottles of fermented milks also enriched (Actimel, Yakult, etc.). All contain probiotics.
Concern ? Gastric acids make short work of it, and it's a hecatomb during the digestive tract:classic yogurt only reaches the colon with 1% of living micro-organisms, while, stronger and especially added in massive doses in pots, about 20% of the probiotics in fortified dairy products survive. They are also found in the capsules and powders department:in food supplements and in ultralevure, a drug sold without a prescription.
Video of the day:"Atopic eczema in children represents the only form of allergy against which probiotics would have a preventive action. No study has demonstrated benefits against allergies in adults or those of food origin", warns Gérard Corthier, one of the specialists on the subject at the National Institute for Agronomic Research, where he heads the "Physiology of the digestive system, microbiology and human diet" research unit.
“Bifidobacteria seem to soothe abdominal pain, bloating, spasms, and they would reduce intestinal discomfort in general,” notes Dr. Boutron. To be sure to swallow the maximum of live probiotics, choose dairy products whose expiry date is the furthest away. "We can also do an ultralevure cure one week a month, especially if the discomfort is linked to or increased by the premenstrual syndrome", advises the gastroenterologist.
"In fact, you have to test over two or three months and see if there is any benefit, because the potential relief depends on the flora of each person. It is as different from person to person as a fingerprint. On the other hand, if you suffer from an intolerance to lactose – the sugar in milk – and your belly swells four hours after drinking milk, you replace it with yogurt. The lactose content is the same, but their bacteria aid digestion."
“It is misleading to speak of “rebalancing or active regenerating”. Today, we cannot say that we are rebalancing it, because we do not know what corresponds to a balanced flora, annoys Gérard Corthier. on the fact that after ingesting probiotics, one sometimes finds in the intestine a “good” bacterium previously absent.
From there they talk about rebalancing, but that is only 10% of the total flora. Admittedly, when probiotics improve transit, they act on the flora, but acting does not mean rebalancing. Currently, no irrefutable study proves that a probiotic rebalances the flora." And to boost sluggish transit? Dairy products containing bifidobacteria are supposed to regulate intestinal transits that are too slow, "at the rate of three or four pots a day", specifies the researcher. Conversely, we take ultralevure when traveling because it is a good remedy against turista.
"Not sure, but maybe", suggests Gérard Corthier, knowing that 70% of our immune defenses sit in the intestine. And indeed, the probiotics of Actimel, composed of "Lactobacillus casei defensis", succeeded in obtaining the green light from the French Food Safety Agency (Afssa) to carry the allegation "helps to reinforce the natural defenses ".
What is it actually? “The body defends itself slightly better, continues the scientist. If it was already the case before, you will not see any difference; if it defended itself badly, it will do a little better. A miracle product, however. At what dose to obtain an effect? A vial, according to the ad, but Fabiola Flex, a former marketing pro in the agri-food industry and author of Don't swallow just anything! (ed. Robert Laffont/Denoël), tells us that "the people tested in the studies submitted to Afssa swallowed two vials a day, and not just one".
In addition, beware of copies of mini-bottles:the mention "L casei" is not enough. It's the next word that counts - "defensis" for Actimel and "shirota" for Yakult, for example - because it corresponds to the specificity of the strain and, therefore, to its potential assets. However, the agri-food industry does not offer competition for the bacteria discovered in its laboratories and whose patents have been carefully filed.
Conclusion:inside a vial-clone sold under another brand is a cousin bacterium of the "L casei" family, whose properties are different...
"We must remain very careful, because we are at the experimental stage, warns Dr. Boutron. Animal studies would indicate a protective effect of yogurts on intestinal tumors. Lactic acid bacteria would indeed possess certain enzymes able to detoxify in the intestine, for example, elements resulting from the degradation of burnt meat.
But from animals to humans, there is a world, especially since human carcinogenesis is far more complex. Still, consuming one or two yogurts a day is nutritionally excellent.
An American study carried out at the Center for Genome Sciences at the University of Washington shows that genetically modified mice, completely devoid of intestinal flora, gain less weight and have 42% less fat mass than mice normally endowed with intestinal flora. a flora. However, the former eat three times as much.
The hypothesis? Some intestinal bacteria act directly on a protein responsible for storing fat. It remains to go from modified Minnie Mouse to... us.
"It's hard to know what works, there are still a lot of uncertainties and few reliable products containing effective probiotics. You have to test carefully, not to exceed two tablets a day. It's safe, but probiotics ferment and , at high doses, the production of gas is important, warns Gérard Corthier. Above all, tell yourself that there is nothing essential:ignoring probiotics does not mean that you will miss out on an essential that will keep you in shape."
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