Supplementary Materials for Beneficial Microbes: Physiological responses and microbiota shifts after spermidine administration as a postbiotic on rodents fed a high-fat high-fructose diet

The consumption of a high-fat high-fructose diet partly resemble the western dietary patterns, which is closely associated with excessive body adiposity and metabolic disorders, such as obesity and type 2 diabetes. Moreover, this unhealthy regime produces unfavourable changes on the faecal microbiota, potentially interfering with microorganisms postbiotic function, such as spermidine, a natural polyamine that has been involved in the control of weight gain. The study aimed to analyse the repercussions of spermidine supplementation on somatic measurements, metabolic markers, and the faecal microbiota profile of rats fed a diet rich in fat and fructose. Indeed, Wistar males with oral administration of spermidine (20 mg/kg/day) for 6 weeks were evaluated for food and energy intake, biochemical markers, and faecal microbiota signatures. The daily use of spermidine decreased weight gain (P<0.01), reduced feed efficiency (P<0.01), and attenuated visceral fat deposition (P<0.01), although no effect on energy intake, hepatic weight, triglyceride and glucose index and atherogenic indexes. Similarly, the consumption of spermidine partially restored the presence of microbial species, notably Akkermansia muciniphila. Elevated concentrations of this species were linked to a decrease in triglycerides (P=0.04), indicating that the supplementation of spermidine might contribute to managing energy fuel homeostasis in association with an obesogenic diet.