The abundance of GIP during the fasting state (Figure 4B) was reduced in all four groups; however, after the glucose stimulation, GLP-1 was induced in the C, BB and BB + HF + S groups (Figure 5B), indicating that butyrate produced by the RS of BB binds to GPR41, increasing GLP-1 secretion by L cells. Here, GIP is linked to hydrops fetalis.