Probiotics, true or false hope against digestive disorders?
The market for yogurts and food supplements for “intestinal comfort” is flourishing. These products, rich in probiotics, appear to improve digestion, but their real effects remain to be proved.
Probiotics are live microorganisms, bacteria, and yeasts, which are bought for their beneficial effects on the intestine. On the packaging of the numerous food supplements available on the market, one sometimes reads: “rebalance,” “modifies” or “modulates” the intestinal flora.
“These are false allegations,” insists Gérard Corthier, director of honorary research at INRA (National Institute for Agricultural Research). Probiotics only pass through the intestine. They do not settle in and do not replace the bacteria that naturally colonize it.
The stimulating effect of fermented milk
According to a recent study, carried out for the giant Danone agri-food, probiotics would rather have a stimulating effect. In researchers observed the intestinal flora of 28 women with irritable bowel syndrome (IBS ).
For one month, one group consumed two lactose-poor yogurts a day, while the other group took two daily pots of fermented milk – in this case, Activia. “Using a very innovative technique, we found that half a dozen bacterial species out of the 300 in the intestine at a detectable level were stimulated by fermented milk,” says Dusko Ehrlich, one of the Authors of this study. However, the impacted species produce butyrate, a short-chain fatty acid, which favors healthy intestinal functioning. It is impossible to draw any more conclusions for now.
Probiotics effective against diarrhea
Research on probiotics is promising but still insufficient. It is known that the yeast Saccharomyces boulardii of Ultra – Levure has an efficacy against diarrhea associated with the taking of antibiotics. This is what allowed him to be recognized as a drug. VSL # 3 (a complex that combines eight highly bacterial strains), available only on the internet, appears to work in some forms of chronic and post-antibiotic diarrhea.
“Some studies show that probiotics could reduce the duration of gastroenteritis or a turista. Others show an interest in irritable bowel syndrome and inflammatory bowel disease. However, these products are not all available in France and any case, their effectiveness is equivalent to the current medicines that are available, ” says Dr. Harry Sokol, a gastroenterologist at the Saint-Antoine Hospital (Paris) and Researcher at Inserm.
Pending further research, many gastroenterologists prescribe probiotics empirically. Patients do their tests. There is no risk in attempting the experiment.
“The strains most commonly found in commercial products, lactobacilli, bifids or Streptococcus thermophilus are not, a priori, pathogenic,” observes Gérard Corthier.
Yogurt or dietary supplements?
In our diet, fermented products naturally contain probiotics: yogurts, cheeses, beer, sauerkraut … To be called “yogurt,” a fermented milk must contain two species of bacteria: Streptococcus thermophilus and lactobacillus bulgaricus . “In 100 grams of yogurt, there are 108 bacteria, or 100 billion, as much as in a food supplement capsule,” says Gérard Corthier.
To be effective, these bacteria must arrive alive in the intestine. “In a capsule, the bacteria are lyophilized. It is as they are in hibernation. It takes three hours between the time they are ingested and their arrival in the colon. By the time they return to their active form, we can think that 90% of these bacteria are dead, ” explains Gérard Corthier.
Between yogurts and food supplements, this specialist gives more confidence to the first: “I prefer to consume food rather than a food supplement. At least, I take calcium, and I am the current recommendation of three dairy products per day, “he concludes.
In fact, doctors have no real concern about probiotics, regardless of their presentation. They simply regret that, in the present state of knowledge, they can not prescribe the right product to the right patient. What strain for which symptom? Meanwhile, they let everyone try the experiment.
“Probiotic,” a highly controlled claim
The legislation regards probiotics as food and not as medicines. In 2012, the European Food Safety Agency (EFSA) published a list of 222 authorized health claims on consumer products. To establish this, it was based on scientific evidence showing a beneficial effect on health. For example, state that “activated charcoal helps to reduce excess flatulence after a meal” is allowed, but marking a product as “probiotic” is prohibited. The National Syndicate of Food Supplements (Synadiet) regrets this decision and recommends its members to argue instead about “lactic bacteria.”