Dietary Carotenoid Intake, Gut Microbial Diversity, and Community Composition in Latino Emerging Adults

Carotenoids are bioactive compounds abundant in fruits and vegetables that may influence gut microbial composition through effects on the intestinal environment; however, evidence in emerging adults remains limited. This pilot study examined associations between carotenoid intake and gut microbial composition through a cross-sectional analysis of 50 Latino emerging adults (18-25 years). Dietary intake was assessed using three 24 h recalls, and carotenoid intake was modeled continuously and by tertiles. Microbial profiling was conducted using 16S rRNA gene sequencing (V3-V4 region) from stool samples. α-Diversity was analyzed using multivariable linear regression and β-diversity using PERMANOVA (9999 permutations), adjusting for relevant covariates. Participants were 20.3 ± 2.19 years old and 74.0% female. Continuous carotenoid intake was not associated with α- or β-diversity. A nominal association was observed between higher carotenoid intake tertiles and greater Chao1 richness (B = 7.06; 95% CI: 0.40, 13.7; p = 0.038); however, this association did not remain statistically significant after Benjamini-Hochberg false discovery rate correction. In sensitivity analyses additionally adjusted for dietary fiber and fruit and vegetable intake, carotenoid tertiles were associated with unweighted UniFrac (R² = 0.08; p = 0.009). Exploratory differential abundance analyses identified taxa that varied across intake groups. Although carotenoid intake was not associated with global microbial diversity, exploratory differences in richness and taxonomic composition were observed across intake levels, suggesting that carotenoids may be associated with specific features of gut microbial community structure in Latino emerging adults. These preliminary findings from this pilot study warrant confirmation in larger studies.