Editors' ChoiceObesity

Zoning In on Obesity

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Science Translational Medicine  18 Sep 2013:
Vol. 5, Issue 203, pp. 203ec154
DOI: 10.1126/scitranslmed.3007555

The protein zonulin is known to regulate intestinal permeability by modulating intracellular tight junctions between gut epithelial cells. A recent study now reports higher circulating concentrations of zonulin in obese subjects as compared with nonobese subjects and in those with glucose intolerance as compared with those with normal glucose tolerance.

Zak-Gołąb et al. hypothesized that circulating zonulin may be a link between alterations in the composition of the gut microbiota and systemic micro-inflammation in obese subjects. They set out to measure plasma zonulin and proinflammatory cytokine (tumor necrosis factor–α and interleukin-6) concentrations in relation to composition of the gut microbiota in obese and healthy subjects.

The study recruited 50 obese and 30 normal-weight subjects without any concomitant disease. Anthropometric parameters were measured, and dietary energy and macronutrient intake were assessed. Plasma zonulin concentrations were measured with an enzyme-linked immunosorbent assay, and the composition of the gut microbiota was analyzed semiquantitatively.

Higher circulating levels of zonulin and inflammatory markers were found in obese individuals. A significant association was observed between zonulin and circulating cytokine concentrations, suggesting that zonulin may be an inflammatory marker. The authors also observed that plasma zonulin positively correlated with body mass, weight, age, fat mass, and bacterial colony count (P < 0.05). Moreover, plasma zonulin was proportional to daily energy intake and serum glucose concentrations. However, no variation in zonulin concentration was found with lipid metabolism. Last, multiple regression analysis showed a positive relationship between zonulin and total bacteria count.

This study suggests a role for circulating zonulin as a potential marker of gut microbiota-associated systemic micro-inflammation in obese subjects. However, there are limitations to the study, including the small sample size and the methodology used for gut microbiota analysis. Therefore, these findings will need to be investigated further in future studies.

A. Zak-Gołąb et al., Gut microbiota, microinflammation, metabolic profile, and zonulin concentration in obese and normal weight subjects. Int. J. Endocrinol., published online 18 July 2013 (10.1155/2013/674106). [Pub Med]

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