Dataset Information

Almond Snacking for 8 wk Increases Alpha-Diversity of the Gastrointestinal Microbiome and Decreases Bacteroides fragilis Abundance Compared with an Isocaloric Snack in College Freshmen.

ABSTRACT: Background:Changes in gut microbiota are associated with cardiometabolic disorders and are influenced by diet. Almonds are a rich source of fiber, unsaturated fats, and polyphenols, all nutrients that can favorably alter the gut microbiome. Objectives:The aim of this study was to examine the effects of 8 wk of almond snacking on the gut (fecal) microbiome diversity and abundance compared with an isocaloric snack of graham crackers in college freshmen. Methods:A randomized, controlled, parallel-arm, 8-wk intervention in 73 college freshmen (age: 18-19 y; 41 women and 32 men; BMI: 18-41 kg/m2) with no cardiometabolic disorders was conducted. Participants were randomly allocated to either an almond snack group (56.7 g/d; 364 kcal; n = 38) or graham cracker control group (77.5 g/d; 338 kcal/d; n = 35). Stool samples were collected at baseline and 8 wk after the intervention to assess primary microbiome outcomes, that is, gut microbiome diversity and abundance. Results:Almond snacking resulted in 3% greater quantitative alpha-diversity (Shannon index) and 8% greater qualitative alpha-diversity (Chao1 index) than the cracker group after the intervention (P < 0.05). Moreover, almond snacking for 8 wk decreased the abundance of the pathogenic bacterium Bacteroides fragilis by 48% (overall relative abundance, P < 0.05). Permutational multivariate ANOVA showed significant time effects for the unweighted UniFrac distance and Bray-Curtis beta-diversity methods (P < 0.05; R 2 ? 3.1%). The dietary and clinical variables that best correlated with the underlying bacterial community structure at week 8 of the intervention included dietary carbohydrate (percentage energy), dietary fiber (g), and fasting total and HDL cholesterol (model Spearman rho = 0.16; P = 0.01). Conclusions:Almond snacking for 8 wk improved alpha-diversity compared with cracker snacking. Incorporating a morning snack in the dietary regimen of predominantly breakfast-skipping college freshmen improved the diversity and composition of the gut microbiome. This trial was registered at clinicaltrials.gov as NCT03084003.

SUBMITTER: Dhillon J

PROVIDER: S-EPMC6736066 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

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Almond Snacking for 8 wk Increases Alpha-Diversity of the Gastrointestinal Microbiome and Decreases <i>Bacteroides fragilis</i> Abundance Compared with an Isocaloric Snack in College Freshmen.

Dhillon Jaapna J Li Zhaoping Z Ortiz Rudy M RM

Current developments in nutrition 20190703 8

<h4>Background</h4>Changes in gut microbiota are associated with cardiometabolic disorders and are influenced by diet. Almonds are a rich source of fiber, unsaturated fats, and polyphenols, all nutrients that can favorably alter the gut microbiome.<h4>Objectives</h4>The aim of this study was to examine the effects of 8 wk of almond snacking on the gut (fecal) microbiome diversity and abundance compared with an isocaloric snack of graham crackers in college freshmen.<h4>Methods</h4>A randomized, ...[more]

PMID: 31528836

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Project description:Abstract Objectives Almond consumption can improve cardiometabolic health. However, the mechanisms underlying those physiological changes are not well characterized. This study explored the effects of consuming a snack of almonds for 8 weeks on changes in omics profiles in young adults. Methods Newly enrolled, college students (n = 73, age: 18–19 years, BMI: 18–41 kg/m2) were randomly assigned to consume a morning snack, i.e., either almonds (2 oz./d, n = 38) or an isocaloric control snack of graham crackers (325 kcal/d, n = 35) daily for 8 weeks (Clinical trials: NCT03084003). Blood samples were collected every 4 weeks over the 8 week intervention. Metabolite abundances in the serum were quantified by hydrophilic Interaction chromatography (HILIC) quadrupole (Q) time-of-flight (TOF) mass spectrometry (MS/MS), gas chromatography time-of-flight (GCTOF) MS, and CSH-ESI (electrospray) QTOF MS/MS. Data were reported as quantitative ion peak heights and were normalized by systematic error removal using random forest (SERRF) normalization. The baseline-adjusted means of the almond and cracker groups at week 8 were analyzed using ChemRICH which is a chemical similarity enrichment analysis software for metabolomics datasets that uses medical subject headings and Tanimoto substructure chemical similarity coefficients to cluster metabolites into non-overlapping chemical groups. Statistically significant p-values for clusters were obtained by self-contained Kolmogorov–Smirnov tests. Results Out of the 5716 features detected, 857 were identified as known compounds. ChemRICH mapped 660 of the identified metabolites to 63 nonoverlapping chemical classes, of which 2 were found to be significantly different between the almond and cracker groups (false discovery rate adjusted P value (FDR) < 0.05). Almond snacking for 8 weeks was associated with altered unsaturated lipid metabolism represented by significantly increased levels of unsaturated triglycerides and unsaturated lysophosphatidylcholines compared with cracker snacking (cluster FDR < 0.05). Conclusions These findings indicate that almond and cracker snacking for 8 weeks differentially altered lipid metabolism. Funding Sources Research supported by Almond Board of California and NIH-NIMHD.

Project description:Consumption of a Western-type diet has been linked to gut-microbiota-mediated colon inflammation that constitutes a risk factor for colorectal cancer. A high salt diet (HSD) exacerbates IL-17A-induced inflammation in inflammatory bowel disease and other autoimmune diseases. Enterotoxigenic Bacteroides fragilis (ETBF) is a gut commensal bacterium and reported to be a potent initiator of colitis via secretion of the Bacteroides fragilis toxin (BFT). BFT induces ectodomain cleavage of E-cadherin in colonic epithelial cells, consequently leading to cell rounding, epithelial barrier disruption, and the secretion of IL-8, which promotes tumorigenesis in mice via IL-17A-mediated inflammation. A HSD is characteristic of the Western-type diet and can exhibit inflammatory effects. However, a HSD induces effects in ETBF-induced colitis and tumorigenesis remain unknown. In this study, we investigated HSD effects in ETBF-colonized mice with azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced tumorigenesis as well as ETBF colitis mice. Unexpectedly, ETBF-infected mice fed a HSD exhibited decreased weight loss and splenomegaly and reduction of colon inflammation. The HSD significantly decreased the expression of IL-17A and inducible nitric oxide synthase (iNOS) in the colonic tissues of ETBF-infected mice. In addition, serum levels of IL-17A and nitric oxide (NO) were also diminished. However, HT29/C1 colonic epithelial cells treated with sodium chloride showed no changes in BFT-induced cellular rounding and IL-8 expression. Furthermore, HSD did not affect ETBF colonization in mice. In conclusion, HSD decreased ETBF-induced tumorigenesis through suppression of IL-17A and iNOS expression in the colon. HSD also inhibited colonic polyp numbers in the ETBF-infected AOM/DSS mice. Taken together, these findings suggest that a HSD consumption inhibited ETBF-promoted colon carcinogenesis in mice, indicating that a HSD could have beneficial effects under certain conditions.

Dataset Information

Almond Snacking for 8 wk Increases Alpha-Diversity of the Gastrointestinal Microbiome and Decreases Bacteroides fragilis Abundance Compared with an Isocaloric Snack in College Freshmen.

Publications

Almond Snacking for 8 wk Increases Alpha-Diversity of the Gastrointestinal Microbiome and Decreases <i>Bacteroides fragilis</i> Abundance Compared with an Isocaloric Snack in College Freshmen.

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