VIP and constipation disorder: Among them, the Bifidobacteria-dominated formulations BM1 and BM2 mainly showed changes in intestinal flora composition and structure; significantly decreased the relative abundance of Tyzzerella, Enterorhabdus, Faecalibaculum, Gordonibacter, and Mucispirillum; upregulated the relative abundance of Parabacteroides; increased the content of SCFAs in faeces; restored the levels of MTL and VIP; and downregulated the levels of the pro-inflammatory cytokines IL-6 and IL-8 in the serum, thus repairing the inflammatory response caused by constipation.