A step closer to understanding how a diet high in simple carbohydrates may cause dysbiosis
Shrinivas Bishu, John Y. Kao
Shrinivas Bishu, John Y. Kao
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Commentary

A step closer to understanding how a diet high in simple carbohydrates may cause dysbiosis

Abstract

The gut microbiota is an integral part of the human metaorganism that is required to shape physiologic host immune responses including host defense against pathogens. Disease-associated gut dysbiosis has been characterized by blooms of pathobionts, which are bacterial species that can drive disease under certain conditions. Pathobionts like Enterobacteriaceae often bloom during flares of inflammatory bowel disease (IBD) and are causally linked with IBD in murine models. In this issue of the JCI, Hecht and colleagues investigated how simple carbohydrates are causally linked to the bloom of the gut pathobiont Klebsiella pneumoniae, which belong to the Enterobacteriaceae family. Notably, the presence of fiber reduced the dissemination of K. pneumoniae into the blood and liver in a colitis model. Their findings provide a diet-related mechanism for gut dysbiosis, which has implications in the management of IBD and other conditions in which gut dysbiosis is an underlying factor.

Authors

Shrinivas Bishu, John Y. Kao

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Figure 1

Dietary fiber regulates K. pneumoniae colonization and dissemination.

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Dietary fiber regulates K. pneumoniae colonization and dissemination. (A...
(A) The FARMM study revealed omnivores randomized to an EEN diet, which lacks fiber, were more likely to develop a K. pneumoniae bloom compared with individuals fed a standard omnivore diet that contained complex carbohydrates. The correlation suggests that the carbon-restricting condition limited K. pneumoniae growth. (B) Mice fed a low-fiber diet following antibiotic treatment show reduced commensal diversity and K. pneumoniae colonization compared with those fed a HF diet. (C) Mice exposed to DSS to induce colitis are susceptible to K. pneumoniae colonization and dissemination under low-fiber dietary conditions that include lactulose, a simple carbohydrate. In contrast, a HF diet protects mice from colitis-induced dissemination.