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GI highlights from the literature
  1. Mairi McLean, Education editor
  1. School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, UK
  1. Correspondence to Dr Mairi McLean, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen AB25 2ZD, UK; m.h.mclean{at}

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Basic Science

Effect of laxatives on microbiota

Tropini C, Moss EL, Merrill BD, et al. Transient osmotic perturbation causes long-term alteration to the gut microbiota. Cell 2018; 173:1742-1754

Osmotic diarrhoea is a common medical condition, precipitated by food intolerance, gut malabsorptive conditions such as coeliac and pancreatic diseases, and the use of osmotic laxatives. Over-the-counter laxative use is prevalent in industrialised countries. Despite their widespread usage, there is little known about the impact of osmotic laxatives on the gut microbiota. This recent preclinical study showed that osmotic laxatives cause disruption to the gut microbiota of mice, including extinction of key taxa and some effects are long lasting. Their data suggest that the response of the microbiota to polyethanol glycol treatment is influenced by host-related factors such as colonic mucus loss and changes in immune system function, as well as host-independent microbial growth inhibition due to altered osmolality in the microenvironment. Higher taxonomic level reporting failed to identify important microbiota changes, for example the competition between related taxa in response to gut perturbation and changes in nutrients/resources. Species reintroduction through environmental exposure allowed resilience of the gut microenvironment. This higher level of detail is clearly important as we move towards the personalised medicine era. Better understanding of the interaction between the gut microbiota and its niche will translate into better therapeutic approaches.

Gut microbiota, bile acid metabolism and anti-tumour immunity

Ma C, Han M, Heinrich B et al. Gut microbiome–mediated bile acid metabolism regulates liver cancer via NKT cells. Science 2018: May 25 360 (6391) doi: 10.1126/science.aan5931

Ma and colleagues provide an intriguing story linking gut microbiota, bile acid metabolism and cancer immunity. Building on observations that gut microbiota influence hepatic bile acid metabolism and the development of spontaneous hepatocellular carcinoma (HCC), this group used antibiotics to sterilise the murine gut in a variety of hepatic and extrahepatic cancer models. This reduced the size …

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  • Competing interests None declared.

  • Patient consent Not required.

  • Provenance and peer review Not commissioned; internally peer reviewed.