(P27-03-26) The Effect of Replacing Usual Snacks With Pecans on Gut Microbiota Assessed by Shotgun Metagenomics: An Exploratory Analysis of a Randomized Clinical Trial

Objectives: Pecans contain unsaturated fats, fiber, and polyphenols that can influence the gut microbiota; however, their specific effects on gut microbiota diversity and composition are less studied.

Methods: A single-blind, parallel-arm, 12-week randomized clinical trial was conducted in healthy adults with overweight or obesity and ≥1 feature of metabolic syndrome. In the intervention arm, participants were provided with 57 g/d of raw, unsalted pecans (∼392 kcal, 40.8 g fat, 7.9 g carbohydrates, 5.2 g protein, 5.4 g fiber) and instructed to consume these instead of their usual snacks. The comparator arm was instructed to continue consuming their habitual diet. Fecal samples were collected at baseline and 12 weeks and analyzed via shotgun metagenomic sequencing using the Illumina NovaSeq X platform. Statistical analyses were performed using R. Taxonomic and pathway abundances were determined using MetaPhlAn v4.0.6 and HUMAnN v3.9, respectively, and normalized using log2 transformation. Alpha diversity was assessed using the Shannon index and beta diversity was assessed using Bray–Curtis dissimilarity (vegan v2.6-10).

Results: The analytical sample included 130 participants (56% female, 46 ± 13 y, 29.7 ± 3.7 kg/m²) who completed the trial (pecan: n=62; usual diet: n=68). Compared to the usual diet group, the pecan group had an increase in gut microbial richness and evenness (Shannon index, between-group difference: 0.19 [95% CI: 0.09, 0.29]; p=0.0001). The change in Bray–Curtis beta diversity (distance to baseline) was greater for the pecan group relative to the usual diet group (0.03 [0.01, 0.06]; p=0.0007). Compared to the usual diet group, the pecan group had a greater relative abundance of a member of the Lachnospiraceae family (S_GGB3653_SGB4964) [log(2)-fold mean difference: 3.56; FDR q < 0.1]. Pathway differential abundance analysis revealed 32 significantly altered microbial pathways in the pecan group compared to the usual diet group, characterized by upregulation of amino acid and vitamin biosynthesis with enhanced degradation of fiber and complex glycans.

Conclusions: Replacing usual snacks with pecans was associated with beneficial shifts in gut microbiota composition and function in adults at risk for cardiometabolic disease.

Funding Sources: American Pecan Council