Pesco-vegetarian food components synergistically promote ferrroptosis in colonocytes to reduce colon cancer risk [scRNA-seq]

To assess the utility of diet modulation as a promising avenue to modulate ferroptosis in the colon, we examined the combinatorial effect of n-3 vs. n-6 polyunsaturated fatty acids (PUFA) and highly fermentable vs. poorly fermentable fiber on ferroptosis induction in preclinical models and healthy human adults. In vitro treatment of immortalized mouse colonocytes with docosahexaenoic acid, a n-3 PUFA enriched in fish oil, and butyrate, a short chain fatty acid generated by colonic microbial fermentation of fiber, reduced cell viability and interactively (P < 0.05) increased lipid peroxidation, a key biomarker for ferroptosis, compared to counterpart treatments. Addition of the ferroptosis inhibitor, ferrostatin-1, significantly blocked the combined effects of docosahexaenoic acid and butyrate on colonocyte lipid oxidation and cell death in vitro. In vivo treatment of mice fed fish oil and highly fermentable fiber (pectin) vs. control, corn oil (contains n-6 PUFA) and poorly fermentable fiber (cellulose) significantly (P < 0.05) promoted lipid peroxidation and the induction of ferroptosis transcriptional networks exclusively in colonic epithelial cells. In addition, as part of a randomized controlled crossover pilot study in humans, supplemental fermentable fiber (35 g/d soluble corn fiber) and fish oil (6 g/d n-3 PUFA) upregulated intestinal ferroptosis related gene expression, as compared to similar doses of maltodextrin plus corn oil. Our findings demonstrate that dietary fish oil and fermentable fiber act synergistically to induce ferroptosis in colonocytes. These important and often overlooked interactions between diet and the gut microbiome help to explain the anti-cancer benefit of the pesco-vegetarian diet.