Abstract
OBJECTIVES: Not all dietary fibers are equal in effect. Fiber may entrap bioactive polyphenols (PP), enabling them to bypass digestion and arrive in the colon. We documented effects of fiber combinations on stool firmness and fecal metabolomics in dogs fed a hydrolyzed meat diet, hypothesizing that fiber-bound PP would deliver these bioactives to the colon, improve stool firmness and alter the fecal metabolome. METHODS: Dogs were group housed, provided daily exercise in outdoor grassy runs, had access to natural light that varied with season and were fed to healthy body weight. Health was monitored through clinical and physical indices. Fecal collections were under IACUC protocols. Fibers were measured by AOAC and PP by Folin-Ciocalteu methods. Nine foods using a base of hydrolyzed chicken and cornstarch together allowed parsing of the effects of fiber-bound PP-containing food ingredients (active blend; AB). Control food had cellulose as a fiber source, AB added pecan, citrus, beet, flax and cranberry. Cellulose, psyllium and pumpkin were explored as supplements to AB. Additionally, other fiber sources were tried alone and in combination: pea fiber, tomato pomace, maize dextrin, silica dioxide inulin, fructooligosaccharide. Dogs (n = 6) offered a diet for 10 days, with daily stool scoring on day 6–10 for firmness on an ordinal scale. A sample for fecal metabolomics by LC-MS was frozen within one hour of defecation on day 10. Linear Mixed Modeling was used to examine diet effects. RESULTS: The AB was 65% fiber and 20% PP by weight, with PP mostly in bound form. Stool firmness was highest from dogs fed the AB-containing foods; inclusion of cellulose was not required for maximal stool score. AB-containing foods increased fecal fiber-derived sugars, PP and microbial products of PP metabolism; this was not apparent from foods devoid of PP sources. Across foods, inclusion of whole flax increased fecal levels of long chain 2-acylglycerol endocannabinoids while decreasing levels of very long chain acylethanolamide endocannabinoids. Colonic microbial lipolysis may have contributed to the appearance of 1-acyl and 2-acylglycerols. CONCLUSIONS: It would appear that provision of microbiome-nourishing fibers, along with fiber-bound PP, may differentially alter acylglycerol and ethanolamide endocannabinoid levels and increase stool firmness. FUNDING SOURCES: Hill's Pet Nutrition.