Nestle researchers link IBS to anxiety

According to the study, gut bacteria from irritable bowel syndrome (IBS) patients and anxiety caused similar symptoms, including behavioural changes in mice. Giada De Palma et al demonstrated that transplantation of fecal microbiota from IBS patients with diarrhea (IBS-D) and anxiety resulted in altered gut function and behaviour in mouse recipients, including faster gastrointestinal transit, low-grade inflammation, and anxiety-like behaviour. As IBS is the most common gastrointestinal disorder worldwide, affecting as many as 45 million people in the US, they recommend to evaluate microbiota-directed therapies in IBS patients.

The authors reported that administration of gut bacteria isolated from IBS patients with anxiety to mice caused the rodents to develop similar pathologies. In contrast, microbes from healthy individuals did not lead to any adverse symptoms. Even though the communities of bacteria from IBS samples and healthy controls were indistinguishable, distinct changes in gene expression and blood metabolite composition were found in animals colonised with IBS fecal microbiota vs. healthy control fecal microbiota. The scientists identified a 22 gene-signature and seven metabolites that differed depending on the source of the gut microbes.

Interestingly, most of the upregulated genes were involved in inflammation and immune function, though some were also implicated in neural development. The findings suggest a potential role for resident gut bacteria in IBS and anxiety and should inform donor-screening for fecal transplants.