Dietary fiber may regulate appetite through hormones in Ileum, suggests study

A recent research published in the Science Translational Medicine journal highlighted the significant role of the human ileum in regulating appetite by releasing key hormones like glucagon-like peptide-1 (GLP-1) and peptide tyrosine tyrosine (PYY), in response to food intake.

The human ileum is rich in enteroendocrine L-cells that release GLP-1 and PYY when stimulated by food. While it has been established that these hormones play a crucial role in appetite regulation, the specific influence of food structures on their release has remained unclear. Thereby, Aygul Dagbasi and team explored the impact of different dietary compositions on hormone release by administering diets varying in fiber content and food structure to healthy volunteers.

The participants consumed either a high-fiber diet with intact food structures, a high-fiber diet with disrupted food structures, or a low-fiber diet with disrupted food structures. The team utilized nasoenteric tubes to sample chyme from the intact distal ileum lumina of the participants. The samples were taken in the fasted state and every 60 minutes for 480 minutes postprandially (after eating).

The outcomes revealed a dynamic and wide-ranging molecular environment in the ileum over time. There was a substantial decrease in bacterial numbers and bacterial metabolites in the ileum following intake of food. One of the major finding was that high-fiber diets significantly increased the release of PYY when compared to a low-fiber diet during the first 240 minutes postprandially regardless of whether the food structure was intact or disrupted. This suggests that fiber content in the diet is a crucial factor in stimulating PYY release which is integral to appetite suppression.

Also, high-fiber diets were found to increase levels of stachyose in the ileum. The disrupted high-fiber diet resulted in an increase of certain amino acids within the ileum. These findings unveil the complex interactions between dietary components and the metabolic environment of the ileum. Through treating human ileal organoids with ileal fluids or a mixture of amino acids and stachyose these outcomes were further validated. The treatment stimulated PYY expression in a profile similar to blood PYY concentrations observed in the study participants which confirmed the role of ileal metabolites in release of PYY.

The findings highlighted how these diet-induced changes in the metabolite environment of the intact human ileum influence the release of appetite-regulating hormones. This study emphasize the importance of dietary fiber in promoting the release of PYY which could offer new insights into dietary strategies for appetite control and weight management.

Reference:

Dagbasi, A., Byrne, C., Blunt, D., Serrano-Contreras, J. I., Becker, G. F., Blanco, J. M., Camuzeaux, S., Chambers, E., Danckert, N., Edwards, C., Bernal, A., Garcia, M. V., Hanyaloglu, A., Holmes, E., Ma, Y., Marchesi, J., Martinez-Gili, L., Mendoza, L., Tashkova, M., … Frost, G. (2024). Diet shapes the metabolite profile in the intact human ileum, which affects PYY release. In Science Translational Medicine (Vol. 16, Issue 752). American Association for the Advancement of Science (AAAS). https://doi.org/10.1126/scitranslmed.adm8132