Low blow: Questions over the benefits of probiotics on gut health

They may even delay a return to health after antibiotics, study says

They’re routinely recommended to counter the effects of antibiotics, but now a study finds probiotics don’t always colonise the gastrointestinal tract and could even harm a patient’s microbiome.

In a series of experiments examining DNA from the small and large intestinal mucosa, researchers found probiotics passed straight through some people without colonising the gut, and even impaired the recovery of the normal microbiome following antibiotics. 

Past studies have used stool samples to study the microbes, but this was believed to be the first to examine probiotics by directly analysing gastrointestinal mucosal samples.

Using colonoscopies and deep endoscopies, the Israeli researchers first examined the gut microbiome of 25 healthy people, sampling from all parts of the gut. 

They found the number of bacteria increased the further down the gut they looked, with most colonisation in the