Abstract MP02: Associations of Fiber-Rich Dietary Patterns with the Gut Microbiome: Finding from the Baltimore Longitudinal Study of Aging

Background: Cardio-protective dietary patterns including the Mediterranean Diet Score (MDS), Alternative Healthy Eating Index (AHEI), and Dietary Approaches to Stop Hypertension (DASH) have been associated with the gut microbiome (GMB) in cross-sectional studies, but there is limited evidence from longitudinal studies on how changes in these dietary patterns relate to GMB. Hypothesis: Better adherence to different cardio-protective dietary patterns have similar associations with GMB diversity and composition. Methods: We used 167 participants from the Baltimore Longitudinal Study of Aging (BLSA), an ongoing community-based prospective cohort. At each visit, GMB was measured via shotgun metagenomic sequencing, and dietary intake was assessed via semi-quantitative food frequency questionnaire. MDS [range: 0-9], AHEI [0-110], and the DASH score [0-9], were calculated based on the intake of 9 food components, 11 food components and nutrients, and 9 nutrients respectively. Linear mixed models evaluated associations of the 3 dietary indices and change in GMB alpha diversity metrics and the relative abundance of the 10 most common microbial species from baseline, adjusting for baseline sex, age, and education level. Results: At baseline, the mean age was 73.8±10.4y, 74.3% self-identified as white, and 56.3% female. The mean MDS = 3.9±1.6, AHEI = 54.7±8.7, and DASH score = 1.9±1.4. The average follow-up period was 3.4±1.2y. We observed weak to moderate Spearman correlations among the 3 dietary indices (R2 range: 0.31–0.57). Over follow-up, a 1-SD increase in DASH score was associated with 0.25 (95% CI: 0.09, 0.42) decrease in Faith’s phylogenetic diversity, 2.02 (0.63, 3.36) decrease in observed species, but 0.008 (0.001, 0.015) increase in GMB evenness. Comparable trends were observed for MDS and AHEI, though not statistically significant. Among the 10 most common species in the GMB, Faecalibacterium prausnitzii and Akkermansia muciniphila were significantly changed by at least 1 of the dietary patterns. Each 1-SD increase in MDS, AHEI, and DASH was associated with 0.5 (0.0, 1.4)%, 0.6 (0.1, 1.1)%, and 0.3 (-0.1, 0.8) % increase in F. prausnitzii . While MDS was associated with a 0.6 (0.1, 1.1)% decrease in A. muciniphila, other diet patterns were not. Conclusions: MDS, AHEI and DASH Score associated in similar directions with changes in GMB alpha diversity and with increases in F. prausnitzii —a key gut taxa with previously reported cardioprotective properties.