Monosodium glutamate is associated with dose-dependent reproductive toxicity and sperm dysfunction in male wistar rats.

Objective: Monosodium glutamate (E621) is widely used as a flavor enhancer and is added to many processed foods, often concealed by the label E621. Controversies exist regarding its safety, as most studies use high doses that are challenging to translate to human relevance. This study investigated the effects of chronic low-dose MSG administration, mimicking average daily human usage, on male Wistar rats' reproductive function.

Methods: Thirty rats were divided into five groups (n=6): Group A (control, 1 ml distilled water) and Groups B, C, D, and E, receiving MSG doses of 30 mg/kg, 100 mg/kg, 300 mg/kg, and 1000 mg/kg body weight, respectively, for 30 days. Parameters measured included body weight, testicular weight, and semen analysis (sperm concentration, morphology, and motility).

Results: Body weight increased significantly in MSG-treated groups, particularly at higher doses (240±20 g for 300 mg/kg and 260±25 g for 1000 mg/kg). Gonadosomatic Index (GSI) rose dose-dependently, while testicular weight declined in higher-dose groups (1.2±0.1g at 1000 mg/kg). Sperm concentration reduced from 80±5 million/ml (control) to 30±2 million/ml (1000 mg/kg), and normal sperm morphology dropped from 76% to 58%. Defects in sperm head, neck, and tail increased with dose, and motility showed a marked decline, with fast progressive sperm decreasing to 39% (1000 mg/kg) and non-motile sperm rising to 51%.

Conclusions: These findings suggest that chronic low-dose MSG exposure negatively impacts male reproductive health, emphasizing the need to assess dietary MSG's long-term risks.