Colonic bacterial composition is sex-specific in aged CD-1 mice fed diets varying in fat quality

Abstract

Evidence suggests that sex influences the effect of diet on the gut bacterial composition, yet, no studies have been performed assessing dietary fatty acid composition (i.e., fat quality) in this context. This study examined the effect of dietary fat quality on colonic bacterial composition in an aged, genetically-diverse mouse population. CD-1 mice were fed isoenergetic diets consisting of (1) control fat (CO; “Western-style” fat blend), (2) CO supplemented with 30% fish oil, (3) CO supplemented with 30% dairy fat, or (4) CO supplemented with 30% echium oil. Fecal samples were collected at mid-life and aged (reproductively senescent) time points. Overall, the abundance of Bacteroidetes was greater in mice fed echium oil compared to mice fed the control fat. Examination of colonic bacterial relative abundance also revealed sex differences, with 73 bacterial taxa being differentially expressed in males and females. Notably, results showed a strong interactive effect among the diet, sex, and age of mice which influenced colonic bacterial relative abundance and alpha diversity. In males, supplementation of the diet with dairy fat or echium oil caused the abundance of Bacteroidetes and Bacteroides to change with age. Additionally, supplementation of the diet with fish oil induced sex-dependent changes in the alpha diversity of aged mice compared to mid-life. This work supports that sex is a critical factor in colonic bacterial composition of an aged, genetically-heterogenous population. Moreover, this study establishes that the effectiveness of dietary interventions for health maintenance and disease prevention via direct or indirect manipulation of the gut microbiota is likely dependent on an individual’s sex, age, and genetic background.

Dietary fat quality impacts metabolic impairments of type 2 diabetes risk differently in male and female CD-1® mice

“…Supplementation of the BO-, EO-and FO-diet with 30 % of the respective fat source intentionally sought to represent a dietary pattern whereby an average U.S. American substitutes fat derived from dairy, echium or fish in place of a portion of their typical fat source. In-house preparation and FA analysis of the experimental fat blends (38) and a complete composition and ingredient list of the Inc. § Analysis of FAs was performed via gas-liquid chromatography as described in Unger et al (31) . Data presented as 0 g/kg of diet signify <0•5 g/kg.…”

Facility-dependent metabolic phenotype and gut bacterial composition in CD-1 mice from a single vendor: A brief report

“…In particular, the CO diet was marked by the combination of its high content of saturated fatty acids and its high n-6/n-3 fatty acid ratio; the FO diet by its high content of long-chain n-3 fatty acids, the BO diet by its high content of short-, medium-, odd-chain, and branched-chain fatty acids; and the EO diet by its high content of n-3 fatty acids and γ-linolenic acid (n-6 fatty acid). A detailed description of the experimental diets has been previously published by Unger et al [18].…”

“…Sample collection and analysis of colonic bacteria has been described previously [18]. At approximately ten months of age, following the final GTT and ITT, 24-hour fecal collection (n = 2-5/diet/sex, n = 28-31/cohort) was executed via individual metabolism cages (Techniplast, West Chester, PA, USA).…”

“…Amplicons were sent to Molecular Research DNA (Shallowater, TX, USA) for sequencing via Illumina Miseq (v.3). Colonic bacterial density was determined as reported in Unger et al [18].…”

“…Diet is considered to be a primary risk factor in the pathogenesis of metabolic diseases [28][29][30], and in particular, changes in dietary fat quality (i.e., fatty acid composition) are shown to have an influential role in the development of metabolic impairments [31]. Research indicates that one of the avenues in which dietary fat quality likely modulates disease risk is through manipulation of the gut microbiome [18,[32][33][34][35][36]. However, it would be challenging to assess long-term effects of dietary fat quality and its interaction with gut microbiota during aging in humans without interference from confounding variables, thus rationalizing the use of a mouse model.…”