Safflower dietary fiber alleviates functional constipation in rats via regulating gut microbiota and metabolism

A functional constipation rat model was established by loperamide hydrochloride (LOP), and then safflower dietary fiber (SDF) was supplemented to constipated rats. The results revealed that SDF increased the serum levels of excitatory gastrointestinal active peptides such as motilin (MTL), gastrin (GAS), and substance P (SP), while concurrently decreasing the levels of inhibitory peptides like somatostatin (SS) and vasoactive intestinal peptide (VIP). SDF restored the ratio of Firmicutes/Bacteriodetes (F/B), upregulated the relative abundance of Lactobacillus and Clostridium, and downregulated the relative abundance of Oscillopira, Ruminococcus, Coprococcus, and Akkermansia; analysis of metabolites revealed that the levels of bile acid, deoxycholic acid, chenodeoxycholic acid, and taurocholic acid were notably elevated after SDF treatment, while the levels of indole-3lactic acid, putrescine, and L-arginine were significantly decreased. Pathway enrichment analysis found that SDF regulates Taurine and hypotaurine metabolism, Primary bile acid biosynthesis, and Bile secretion. Correlation analysis between gut microbiota and metabolites revealed that Fusibacter and Actinomyces may contribute to alleviating constipation by regulating the level of bile acid in the intestine. SDF intervention increased the mRNA expressions of FABP1 and SLC1A5 in constipated rats. Furthermore, SDF exhibited notable abilities in retaining water and undergoing swelling. The above results showed that SDF helped the intestine lock water and promoted intestinal peristalsis by increasing friction. On the other hand, SDF supplementation increased the relative abundance of Lactobacillus and Clostridium, decreased the relative abundance of Oscillopira, increased the levels of various bile acids such as deoxycholic acid and chenodeoxycholic acid, further regulated intestinal lipid metabolism, up-regulated FABP1 mRNA expression, promoted intestinal cell proliferation, restored intestinal homeostasis, and thus alleviated constipation.