(P18-003-25) Impact of Dietary Fiber and Protein on Intestinal Immune Functions

Objectives: Maintaining a moderate calorie count is a fundamental aspect of a healthy diet. Beyond this, balancing carbohydrates, protein, fat, and fiber is widely recognized. However, except for the distinction between saturated and unsaturated fats, nutrients within these categories are often treated as equal. Our study explored an understudied aspect of diet: digestibility as a driver of metabolism. The objective was to determine the effect of different dietary fibers and proteins on colonic tissue immune responses.

Methods: We investigated dietary polysaccharides such as inulin (IN), pectin (PN), and cellulose (CS), along with highly digestible amylopectin (AM). Additionally, we examined various proteins including free amino acids (FAA), casein (CN), whey (WY), egg (EG), soy (SY), pea (PA), fava bean (FB), and rice (RC). These were incorporated into a chow diet (10% dietary fiber and 20% protein) and fed to C57BL/6 mice for 10 days. Colon tissues were then collected and analyzed for TH17 cytokines.

Results: Our findings revealed that supplementation with fermentable fibers (IN, PN) significantly decreased IL-17A, a proinflammatory cytokine, compared to AM and CS-fed mice. Generally, animal proteins tend to be more digestible than plant proteins. IL-10, an anti-inflammatory marker, was significantly increased in RC-fed mice compared to WY-fed mice.

Conclusions: This study demonstrates that digestibility is a key feature of diet that influences the gut immune system. This could be linked to health inequalities, where more affluent populations tend to consume intact fresh foods with lower digestibility, while less privileged populations often consume processed foods with high digestibility, paradoxically contributing to metabolic and gut health issues.

Funding Sources: This project was funded by a 2023 Princeton Initiative for Collaborative Research and Innovation (PACRI) funding program.