Bitter Melon Powder Enhances Antioxidant Capacity, Muscle Nutrition, and Glucolipid Metabolic Homeostasis in Cyprinus...

Carbohydrates in aquaculture feeds can induce metabolic disturbance when exceeding fish utilization capacity, leading to lipid accumulation and insulin resistance. Bitter melon (BM; Momordica charantia), rich in saponins, flavonoids, and polysaccharides, shows potential as a functional feed additive for glycemic control and lipid metabolism modulation. This investigation systematically assessed the effects of BM powder (BMP) supplementation (at 0.5%, 1%, and 1.5%) in high-starch (HG) diets for Cyprinus carpio. Compared to the HG group, BMP supplementation significantly reduced serum glucose (GLU) and triglycerides (TGs), while elevating total cholesterol (TC) and high-density lipoprotein cholesterol (HDL-C). The BMP group exhibited reduced malondialdehyde (MDA), enhanced antioxidation ability, and mitigated hepatopancreatic and intestinal histopathological damage from carbohydrate overload. Meanwhile, BMP restored muscle C20:3n-6 and C22:6n-3 (DHA) levels decreased by HG diets. Notably, 1.5% BMP decreased hepatopancreatic and muscular glycogen/lipid deposition, induced by a high-carbohydrate diet. Gene expression analysis revealed BMP upregulated glycolysis-related genes (glucokinase [gk], pyruvate kinase [pk], and pfk) across tissues (hepatopancreas, muscle, intestine, and adipose tissue), while suppressing glycogen synthesis (gys) and gluconeogenesis (g6pase) genes. Besides, lipid biosynthesis genes were downregulated, corroborating reduced ectopic lipid storage. Taken together, these findings demonstrate that BMP supplementation significantly improves glycemic control, lipid metabolism, and antioxidant capacity in common carp. This suggests that BMP could serve as a natural, sustainable aquafeed additive to counter metabolic syndrome in intensively farmed fish.