(P21-016-24) A Randomized Pilot Study of the Combined Effects of Fish Oil and Fermentable Dietary Fiber on the Gut Microbiome

Objectives: Preclinical studies show that the concurrent consumption of dietary fiber and n-3 polyunsaturated fatty acids from fish oil reduce colon tumor formation. However, no controlled dietary intervention has explored the combined effects of these two dietary components on CRC risk factors in humans. This pilot study investigated the synergistic effects of fish oil and fermentable fiber on the gut microbiome composition in adult humans.

Methods: In a randomized controlled crossover pilot study in 30 men and women ages 50-75, we tested the combined effects of supplemental fermentable fiber (35 g/d soluble corn fiber) and eicosapentaenoic acid, and docosahexaenoic acid (EPA+DHA as fish oil, 6 g/d) compared to similar doses of maltodextrin and corn oil. Blood samples were collected at baseline and end of each 30-day intervention period. Serum was used to measure phospholipid fatty acids. Participants collected stool samples at the beginning, middle, and end of each period, which were used to assess the microbiome via (16S rRNAseq) and short chain fatty acids (SCFA) via GC-MS.

Results: Serum DHA and EPA concentrations were statistically significantly higher after fish oil and fiber vs the comparison supplements (P < 0.0001), suggesting good adherence to the intervention. Microbiome analysis revealed significant differences in beta-diversity (P = 0.001). Twenty-six of 116 genera analyzed, were significantly different between the two intervention (FDR < 0.05) and are known SCFA producers. Although fecal butyrate concentrations were not statistically significant different between intervention periods (P = 0.9), the bacteria identified play a key role in fermenting dietary fiber and producing butyrate.

Conclusions: Intervention differences in the microbial ecosystem underscore the role of dietary components in modulating the gut microbiota. The insights from this study lay a foundation for future research focused on dietary interventions for CRC prevention, emphasizing the importance of diet-gut microbiome interactions.

Funding Sources: Study supported by NCI. Supplements provided by Tate & Lyle Solutions USA LLC and Omega3 Innovations