(P27-05-26) Dietary Fiber and Gut Microbial and Viral Features Associated With Laxative Use in Puerto Rican Older Adults

Objectives: Laxatives, used to manage constipation, influence the gut microbiome. Dietary fiber may regulate bowel movement, reducing the need for laxatives while also providing substrates that support beneficial gut bacteria. US Hispanic and Latino older adults have unique dietary characteristics and remain underrepresented in microbiome research. Here, we examined the association between dietary fiber intake and laxative use, and identified gut bacterial species, functional pathways and viral features associated with laxative use in the Boston Puerto Rican Health Study (BPRHS).

Methods: The BPRHS is a prospective cohort of Boston-area Puerto Rican older adults. Laxative use was self-reported (yes/no), and included over-the-counter stimulants, oral osmotic, and bulk-forming laxatives. Fiber intake (g/day) was assessed by the food frequency questionnaire. Linear regression, adjusted for age, sex and BMI, was used to examine the association between fiber and laxative use. Gut bacterial, functional, and viral profiling were performed using MetaPhlAN4, HUMAnN4, and BAQLaVa0.5, respectively. Overall microbial composition was assessed by the Bray-Curtis (BC) index. Multivariate linear models (MaAsLin3), adjusted for age, sex, BMI, fiber and sequencing depth, were used to identify feature-wise associations with laxative use. FDR correction for multiple hypothesis testing was applied (q).

Results: Among 312 participants, the mean age was 69y, 76% were female, mean fiber intake was 18g/day and 14.7% self-reported laxative use. Fiber intake was not associated with laxative use (β=0.87, P=0.52). No difference in overall microbial composition was observed. In MaAsLin3, we observed a depletion of Enterocloster aldenensis (β=-1.74, q=0.08), and enrichment of valproate metabolism pathways (β=0.89, q=0.17), and a Caudoviricetes viral genome bin VGB22894 (β=1.42, q=0.07) in participants who used laxatives.

Conclusions: Dietary fiber intake was not associated with laxative use in this cohort. Our results suggest a depletion of indole-3-propionate producing taxa, such as E.aldenensis, and an enrichment of microbial pathways related to valproate metabolism associated with laxative use. Gut viral variations may further influence gut bacteria associated with laxative use.

Funding Sources: P50 HL105185, P01 AG023394, R01 AG055948, R01 NS097723, RF1 AG075922