This is surprising. Bitter melon [ M. charantia ] is widely used in formulas against diabetes.

Bitter melon is a popular vegetable in Chinese cuisine, and its leaves possess blood sugar lowering effect

1.5 BILLION CHINESE….can this research be true!??

Bitter melon seed extracts shown to have male anti-fertility effectsHerbal preparations have been used since antiquity to reduce female fertility. Though male anti-fertility preparations are less common, modern research has demonstrated antispermatogenic activities of extracts from at least seven plants. In this study, various extracts (ether, benzene and alcohol) of M. charantia seeds were administered orally and intraperitoneally to male rats for 35 days. All three extracts demonstrated antispermatogenic activity, with the ethanol extract being the most potent. Antispermatogenic activity was assessed using measurements of the weight of the testes and other measures. These tests showed indirect evidence of reduced availability of pituitary gonadotrophs necessary for spermatogenesis. With intraperitoneal administration, increased cholesterol and Sudanophilic lipid levels denoted inhibited steroidogenesis, further evidence of reduced availability of gonadotrophs.

Bitter melon is a popular vegetable in Chinese cuisine, and its leaves possess blood sugar lowering effect

Naseem M, Patil S, Patil S, et al. Antispermatogenic and androgenic activities of Momordica charantia (Karela) in albino rats. J Ethnopharmacology 1998; 61: 9-16.