Macronutrients in diets differentially affect gastrointestinal cytokine and tight junction protein levels

Abstract

Western diet is known to result in intestinal inflammation and loss of barrier function. In the present work, we investigated whether other macronutrients contribute to inflammation and destabilising barrier function in mice, without using any inflammatory agents, to see the sole effects of dietary intervention. The present work was designed to determine the direct effects of diet on the intestinal barrier function and inflammation, using eight diets that differed on carbohydrate, fat, and fibre ratios for 17 weeks. At the end of the study, a distinct difference in mRNA expressions of cytokines and tight junction proteins was observed between intestinal and colon samples. Small intestinal cytokine expressions showed no difference among different diets, and tight junction protein expressions were only significant for occludin and ZO-1 in high carbohydrate diets. Colon samples had significantly different TNFα and IL-6 expressions among diets, especially in high carbohydrate diets. Tight junction protein expressions also differed significantly among diets, and low carbohydrate zero fibre diet had the lowest expression levels compared to the rest of diets. The present work reveals that not only western diet, but also diets high in carbohydrate negatively affect intestinal health, resulting in significant changes in inflammation markers. The role of carbohydrate and fiber contents are also observed in regulating tight junction protein expression. Based on these findings, adjusting macronutrient ratios can be used as a potential approach to help manage intestinal inflammation, though further research is needed.