The Influence of Fiber Source on Circulating Concentration of Age-Related Metabolites and the Gut Microbial Composition in Senior Cats

Aging is characterized by increased blood concentrations of several age-related host and microbial metabolites associated with inflammation and oxidative stress. This study aimed to evaluate the effect of various fiber sources on age-related metabolites and the gut microbiome in senior cats. Forty cats between the age of 8 and 14 were fed a pretrial food for 4 weeks and then randomly assigned to receive a control or a test food for 4 weeks each. The test food contained 1.3% crude fiber mainly from oat groats, broccoli powder, pea and tomato pomace. The control food contained 1.4% crude fiber mainly from whole wheat, beet pulp, flax seed and oat fiber. Cats were given the pretrial food again as a washout for 4 weeks before the crossover was performed. Cats initially fed the test food were then switched to the control food for remaining 4 weeks. Similarly, cats fed the control food were switched to the test food for 4 weeks. Blood, urine and fecal samples were collected at the end of each 4 week period to assess changes in blood chemistry, urinalysis, plasma metabolomics and microbiome. Statistical significance (P < 0.05) between the control and test food was determined by using a paired-t test. Cats fed the test food had significantly lower plasma concentrations of the advanced glycation endproduct, pyrraline, and the markers of oxidative stress, methionine sulfone and S-methylcysteine sulfoxide. Circulating concentrations of the uremic toxins creatinine, urea, SDMA plus ADMA, and guanidinoacetate were significantly reduced after cats ate the test food. The plasma concentrations of microbial uremic toxins, including 3-indoxyl sulfate, 6-hydroxyindole sulfate and 4-ethylphenyl sulfate, were significantly reduced after cats were fed the test food compared to the control food. Fecal microbiome data showed that cats had 63% increased abundance of bacteria in the genus Bifidobacterium and reduced abundance of the genera Clostridium and Eubacterium after they were fed the test food compared to the control food. Oat groats, broccoli powder, pea and tomato pomace provide beneficial fiber that modulates the gut microbiome of senior cats and reduces concentrations of harmful metabolites linked with aging and kidney disease. The work presented in this study was funded by Hill's Pet Nutrition, Topeka, KS.