Topical Area: Nutritional Microbiology, Nutrient-Gene Interactions
Objectives : Polylactose is a novel dietary fiber, synthesized by extrusion of lactose. To evaluate its potential as a prebiotic, we determined its fermentability, effect on the microbiome, and its effects on adiposity, fatty liver, and liver cholesterol in a diet-induced obesity animal model.
72 male Wistar rats were fed normal fat (NF) or high fat (HF, 51% fat by kcal) diets containing various fibers (6% fiber of interest and 3% cellulose, by weight); including cellulose (NFC and HFC), polylactose (HFPL), matched lactose (HFML), matched to the residual lactose in the HFPL diet, and two established prebiotic fibers, polydextrose (HFPD) and fructooligosaccharides (HFFOS). After 10 weeks on experimental diets, organs were harvested and cecal contents collected for analysis.
There were no significant differences in final body weights among the groups, nor did average daily food intake differ significantly among the HF-fed groups. HFPL animals had greater cecal weight (empty) and lower cecal contents pH when compared to all other groups, suggesting that polylactose is much more vigorously fermented than the other prebiotic fibers. This was also indicated by an increase in taxonomical abundance of probiotic species in the cecum. Epididymal fat pad weight was significantly decreased in the HFPL animals compared to all other HF groups (p < 0.05) and did not differ from the normal fat control (NFC). Liver lipids and cholesterol were significantly reduced in HFPL fed animals when compared to HFC fed animals and were numerically lower than all other HF groups. Transcriptome analysis of the liver revealed increased lipid oxidation and decrease lipid synthesis pathway expression, providing insights into mechanisms of reduction of lipid accumulation in the liver.
Conclusions : Polylactose is a vigorously fermentable fiber and elicits a beneficial change in the gut microbiome. We also demonstrate that consuming polylactose, in the context of a high fat diet, prevents the accumulation of body fat normally seen with this diet, as well as reduced lipid and cholesterol accumulation in the liver. As these effects of polylactose were greater than those of two established prebiotics, fructooligosaccharides and polydextrose, this suggests that polylactose is a potent prebiotic.
Funding Sources : Midwest Dairy Association