Probiotics are mostly useless and can actually hurt you

Probiotics are living micro-organisms that are taken by millions of people to boost their microbiome or to restore their gut ecosystem after a dose of antibiotics. Yet questions remain about whether they actually work.

To find out what really goes on in the gut when people ingest probiotics, immunologist Eran Elinav of the Weizmann Institute of Science in Israel, and colleagues, sampled the microbiome of healthy volunteers directly using endoscopies and colonoscopies. Most other microbiome research relies on faecal samples as a proxy for gut microbes. Read the original scientific paper published in Cell.

Next the researchers measured what happens to the microbiome of people who take probiotics in the hope of restoring their microbiome after antibiotics. Twenty-one volunteers took an identical course of antibiotics and were then assigned to one of three groups. The microbiome of the first group was allowed to recover by itself, whereas the second group was given probiotics. The third group was treated with a dose of their own original pre-antibiotic microbiome by a faecal microbiota transplant (FMT). Results were published in this paper.

You can also read summary of the results in the original article by Alison George published in NewScientist.

George’s take home massage is that probiotics don’t always live up to their harmless reputation, and to be effective, their formula needs to be tailored to the individual.