Topical Area: Nutritional Microbiology, Nutrient-Gene Interactions
Objectives : Dietary fiber consists of indigestible carbohydrate. A distinction in fiber classification is “soluble” (SOL) vs “insoluble” (INSOL). Fiber is not absorbed in the small intestine, but arrives intact to the colon where it is metabolized by microbiota. Metabolomics screening determined the impact of foods with SOL vs INSOL fiber on microbiome metabolites and bioactive lipids in feces from cats.
Methods : Healthy cats were housed in environments promoting social interaction with other cats and people, had access to natural light varying with season, opportunity to exercise and were fed to maintain body weight. Collections under IACUC approved protocols. Two foods produced: SOL (5.2% crude fiber analyzed) and INSOL (10.1% crude fiber analyzed). SOL had citrus & beet pulps, oat bran and barley. INSOL had pea & tomato fiber, and cellulose. Randomized design, with cats assigned SOL (n=15), INSOL (n=16). Cats fed for 12 weeks. Metabolomics by LC-MS, short chain fatty acids (SCFA) by GC-FID (feces). Data analyzed by mixed model, paired t-test, Hotelling’s T2 test and correlation. Significant when p < 0.05.
Results : SOL increased flavonoids in the feces, likely from fiber-bound sources; these were metabolized by gut microbiota to postbiotics. Only SOL increased SCFA acetate and propionate but not butyrate. INSOL decreased, and SOL increased putrefactive branched SCFA. Polyamine putrefaction products were decreased by INSOL relative to SOL; fecal polyamine levels predicted serum levels. Fecal microbial metabolites of resistant starch, polyphenols and redox congeners were all correlated to fecal taurine across both foods. INSOL significantly decreased the N-acyl classes of fecal endocannabinoids while leaving the O-acyl class unchanged. SOL increased the O-acyl class. Fecal anti-inflammatory fatty acid esters of hydroxystearate (FAHSA; linoleic, oleic and palmitic) were significantly increased by INSOL relative to SOL. Fecal 9/13 hydroxyoctadecadienoates (HODE) were increased by INSOL relative to SOL, but the 9-10/12-13 dihydroxyoctadecaenoates (DiHOME) were not affected.
There are apparent microbiome benefits to both SOL and INSOL fibers. The results here increase awareness of the importance of fiber for felines and further the effort to optimize fiber type and quantity in foods for cats.
Funding Sources :
Hill’s Pet Nutrition