Are Probiotics Truly Healthy? This Study Says They’re “Almost Useless”

Probiotic-rich foods continue to be in high demand among millennial consumers with 25 percent of US adults claiming to seek out foods that are rich in probiotics and prebiotics. However, a recent study by a group of scientists at the Weizmann Institute of Science in Israel found that foods that are packed with this “gut-friendly” bacteria are “almost useless” to the human body.

These surprising results came from one of the most detailed studies on the effects of probiotic consumption, according to BBC. Although food companies claim that probiotics promote a healthy digestive tract and a healthy immune system, researchers found that they produce little to no effect inside the human body.

The team of scientists conducted their study on 25 healthy individuals who were given a cocktail made of 11 common probiotic bacteria, such as Lactobacillus and Bifidobacteria, for a month. Participants where then sedated and multiple samples were surgically extracted from their stomachs, small and large intestines.  The samples were then reviewed to see if the bacterial cultures colonized in any particular location and if they caused any changes in the gut.

The results of this study, which were published in the journal Cell, found that half of the cases resulted in the bacteria being eliminated. The other cases resulted in the bacteria being present in the gut for a brief period of time before being overpowered by existing human microbes.

This is no surprise considering the fact that human bodies contain more microorganisms, which include bacteria, viruses, fungi and single-celled archaea, than they do human cells. Trillions of these bacteria reside in the gut and the mix of microbial inhabitants vary between people. Certain bacterial combinations are linked to diseases such as obesity, inflammatory bowel disease, Parkinson’s and depression. So it seems that everyone’s gut bacteria has a unique ecosystem that cannot be generalized.

This is why Dr. Eran Elinav, one of the researchers involved in this study, says that consumers are wrong to expect that a general store-bought probiotic will work for everyone. He believes that probiotics need to be tailored for each individual patient.

“And in that sense just buying probiotics at the supermarket without any tailoring, without any adjustment to the host, at least in part of the population, is quite useless,” Elinav told BBC.

In addition to not influencing any notable positive changes in the body, probiotics were found to affect the gut negatively when used after a course of antibiotics. Elinav’s team conducted a trial on 46 people, which was also published in Cell, which showed that probiotics actually delayed the reformation of good bacteria in the gut after a round of antibiotics. This finding is likely surprising to many consumers as probiotics are commonly used with antibiotics in an effort to support good bacterial growth.

“Contrary to the current dogma that probiotics are harmless and benefit everyone, these results reveal a new potential adverse side effect of probiotic use with antibiotics that might even bring long-term consequences,” Elinav told BBC.

Although these study findings are surprising yet have proof behind them, there needs to be more research done in the field of probiotics in order to officially determine their effects on the body. Most studies on probiotics have been done on animals and human feces which is why Elinav’s study is so unique and detailed. However, this study has been done for a relatively short period of time on a small population, which is why other researchers claim that there needs to be further research done on this matter.

“These are very innovative studies, but they are preliminary findings that need replicating.” Dr. Trevor Lawley, a microbiome researcher at the Sanger Institute, told BBC.

Nevertheless, this study is likely to attract a lot of consumers considering the popularity of the probiotics in the health-food space. Probiotics are now found in a variety of dairy formulations and have helped the kombucha industry go mainstream. In addition, a recent study found that the bacteria can increase the shelf life of ice cream products.

So, the global probiotics industry, which is expected to reach a value of over $64 billion by 2022, is safe for now. However, as more research comes out the industry would be smart to invest in personalized nutrition.