Probiotics have been presented as a treatment for a range of conditions – from obesity to mental problems.
One of the most common uses is the replacement of intestinal flora after a cycle of antibiotics. The logic is as follows: Antibiotics destroy microbes – a community of microorganisms living in the intestines – along with bacteria that can cause infection, so that the introduction of probiotics (living microorganisms) can help restore. that.
Although it seems to be meaningful, there is little evidence that probiotics actually work if they are used in this way.
The researchers actually discovered that taking probiotics after using antibiotics delayed the recovery of intestinal health.
Are probiotics better than others?
Part of the problem is the variety of things related to the term probiotic. For scientists, it can be a live culture of microorganisms that normally inhabit healthy human intestines. But for consumers, products sold in supermarkets – such as yoghurts and supplements – do not meet this definition.
Even when researchers use living bacterial strains in their research, the cocktail varies from one laboratory to another, making it difficult to compare.
"This is a problem: there is not enough study on any particular probiotic to say it works and does not exist," says Sidne Nevberri of Rand Corporation, who conducted a comprehensive meta-analysis on the use of probiotics for the treatment of diarrhea. caused by antibiotics in 2012.
The study, which analyzed 82 studies with nearly 12,000 patients, showed the positive effect of probiotics on reducing the risk of diarrhea caused by antibiotics. But because of variations – and sometimes lack of clarity – with which bacterial strains were used, it was not possible to identify or recommend certain probiotics or cocktails that would function.
From research by Rand Corporation in 2012, evidence supporting the use of probiotics after taking antibiotics has not changed much.
"That's why it's so problematic. There are more studies than when we did a review, but not enough to finally say whether the probiotics are working or not, enough to say which one they are doing," says Nevberry.
Particularly worrying is the lack of research on the safety of probiotic use. Although generally considered harmless in healthy people, there are worrying reports of side effects – such as fungus spreading into the bloodstream – among more vulnerable patients.
Probiotics in healthy people
Probiotics – Photo: Unsplash / Disclosure
Recent research by scientists from the Veizmann Institute of Science in Israel found that even among healthy people who take probiotics after antibiotic therapy was not harmless. In fact, they hampered the processes of bowel repair, which in theory should accelerate.
The researchers, led by Eran Elinav, gave 21 people a wide-spectrum antibiotic cycle in a week. They were then subjected to colonoscopy and endoscopy of the upper gastrointestinal tract to examine the condition of the microbial.
"As expected, many important changes have occurred in relation to microbes – many have died of antibiotics," says Elinav.
The participants were then divided into three groups. In the first, there was no intervention after the antibiotic – the idea was to wait and see. The other took a regular probiotic for a month. The third had a faecal transplant – a small sample of their own feces, collected before the beginning of the use of antibiotics, was returned to the colon as soon as the treatment was completed.
It was surprising that the group that took probiotics had the worst response in terms of microbial and what took more time to restore the health of the intestines. Even at the end of the study – after five months of follow-up – this group has not yet reached the pre-antibiotic intestinal level.
"We found a potentially alarming negative effect of probiotics," says Elinav.
The good news, however, is that the group that received the faecal transplant did very well. In a few days, the participants completely reconstructed their original microbial.
"Many people are taking antibiotics around the world. We need to try to understand this potential harmful effect we have not noticed," Elinav said.
And there is growing evidence that taking probiotics when the bowel is weak is not a good idea. Another recent study has shown that probiotics do not work well for small children hospitalized with gastroenteritis. In an American experiment, 886 children with gastroenteritis from three months to four years of age took a five-day probiotic or placebo.
The rate of moderate to severe gastroenteritis continued within two weeks was slightly higher (26.1%) in the probiotic group than in the placebo group (24.7%). There was no difference between the two groups regarding the duration of diarrhea or vomiting.
Probiotic market of billionaires
Despite such evidence, demand for probiotics is huge and growing. By 2017, this market is estimated at more than $ 1.8 billion, and is expected to reach $ 66 billion by 2024.
"Bearing in mind the large involvement of industry, clear conclusions on how useful probiotics should prove," Elinav from the Veizmann Institute of Science in Israel said.
"That is why regulatory authorities, such as the US Food and Drug Administration (FDA) and European regulators, have not yet approved a probiotic for clinical use."
But that does not mean that probiotics must be completely rejected. The problem seems to be more in use than in use. Many times, probiotics are bought at a supermarket, but consumers may not know exactly what they are taking home, even if the culture is still alive.
Who needs to use probiotics?
The Veizmann Institute of Science also investigated who could benefit from probiotics. By measuring the presence of certain genes associated with the immune system, the team was able to predict who would be susceptible to probiotic bacteria to colonize the intestines, and those in which they would simply "beat" without settling.
This is very interesting and important because it indicates that our immune system also participates in interactions with bacteria [probióticas]explains the researcher Elinav.
This paves the way for the development of personalized probiotic treatments based on the genetic profile of each one. Such a system is "realistic and could develop relatively rapidly," says Elinav.
But to become reality, more research on the adaptation of probiotics and testing with more bacterial strains will be needed in larger groups of individuals.
This kind of personalization can take advantage of the potential of probiotic treatments for bowel health. Currently, the lack of consistency in findings is partly the result of the fact that probiotics are treated as conventional drugs.
When taking a tablet with paracetamol, you can be pretty sure that the active substance will fulfill its function by interacting with the receptors in the brain, by disturbing the pain. This is because the pain receptors in most people are sufficiently similar to react in the same way to the drug.
But microbial is not just a receiver – it's closer to the ecosystem. It's no wonder that it's usually compared with the rainforest because of its complexity.
Consequently, identifying and adapting probiotic treatment that will work in something as complex and individual as an internal ecosystem is not an easy task.
With this in mind, it is not surprising that living microorganisms stored on the shelves of the supermarket may not work.