RESUMO
Background In both human and animals, especially in food and companion animal breeding farms, infertility is normally a challenge of great concern. Males have been found to be solely responsible for about 20-30% of infertility cases. Allium cepa (Onion), being one of the highly consumed spices worldwide, is usually overlooked as a possible reproductive toxicant. Most research on A. cepa document its medicinal effects. This study focused on toxicity potential of A. cepa to the male reproductive system. Spermatozoa morphological characteristics and testicular histopathology of male Wistar rats were accessed following administration of A. cepa methanol extract for 14 and 28 days. Methods The rats (55) were divided into groups A, B and C of 25, 25 and 5 rats, respectively. Group C served as the control and was administered distilled water (10 ml/kg), while groups A and B were subdivided into five groups of five rats each. Group A and B were administered A. cepa extract at various graded doses for 14 days and 28 days, respectively. Results The results revealed significantly increased (p < 0.05) percentage spermatozoa abnormalities, with significantly lower spermatozoa concentration, mass activity and percentage sperm motility when compared with the control group. Conclusions Conclusively, excessive (>100 mg/kg) and prolonged (>7 days) consumption or administration of Allium cepa (onion), including nutraceutical preparations of A. cepa has spermatotoxic effect and may damage germinal epithelial cells of the testicles. Toxicity of A. cepa is dose-dependent and beneficial effects may be maximized at doses ≤100 mg/kg for ≤7 consecutive days.