Are probiotics good for you? Is FMT the new alternative?

June 6, 2023

Have you been taking probiotics? Two new studies out of the University of Tel Aviv have shown that probiotics may be at best ineffective and at worst harmful to your long term health. One study focused on probiotic use after a dose of antibiotics, while the other sought to find out how effective the human body is at retaining probiotic material. The results go against much of the previous praise probiotics have garnered for their health promoting ways.

In this blog I’ll go over the two studies and what they have concluded about probiotic use.

Two new studies and what they are saying

Probiotics slow down microbiome recovery

One of the studies performed on a group of human subjects tested the use of probiotics as a microbial enhancer after the use of antibiotics. Antibiotics can wipe out large populations of bacteria in the body. This study focused on the best way to rebuild the microbiome after antibiotic use. The study was split up into three groups: the first group was a control group, receiving nothing after the antibiotics, the second group received Fecal Microbiota Transplants (FMT) of their own pre-antibiotic stool and the final group received a probiotic supplement. Researchers found that individuals using a probiotic supplement took longer to return to a healthy and diverse microbiome than those doing nothing or doing FMT. Those taking probiotics took months to return to the same microbial diversity as they had before the antibiotic round, while those who had an FMT recovered in mere days. And it is not just that FMT worked quicker than the probiotics, probiotics actually seemed to slow down the process of recovery.  Those who did nothing recovered faster than those in the probiotic group.

Probiotics don’t last long in the body

The second study examined the gut microbiomes of a group of individuals using a probiotic supplement to see how much of the probiotic could actually be retained by the human gut. The study utilized the most common strains of probiotics on the market. A two month follow up was performed and compared to their baseline gut composition before the probiotics. The results showed that colonization of probiotic bacteria in the gut only occurred in half the test subjects. They called those that were successfully colonized the “persisters” and those who were not, the “resisters”.

Though this study only examined the retention of probiotics and not the potential benefits to those who did retain them, both studies do bring into question the veracity of their health benefits. If they do in fact have health benefits, those benefits are probably only accessible to half the population.

Should I take probiotics: the conclusion

The two studies in combination showed that probiotics might not be as beneficial as previously believed and in some cases might actually be harmful to the gut. Though this research is far from conclusive on probiotics as a whole, it may be the beginning of a turn away from probiotics use or in the direction of targeted probiotic use.

It is important to note that the data from these studies is not conclusive about probiotics. Probiotics may still hold a lot of health benefits but it is obvious that more research is still needed to figure out exactly how best they can be used and which ones work best for whom. If the studies point to one thing it is that,  "The benefits of the standard probiotics we all take can't be as universal as we once thought. These results highlight the role of the gut microbiome in driving very specific clinical differences between people," says Eran Segal, a computational biologist at the Weizmann Institute and author of the first study.