In vivo effects of Aspalathus linearis (rooibos) on male rat reproductive functions

Aspalathus linearis (rooibos tea) may improve sperm function owing to its antioxidant properties. To test this hypothesis, male rats were given 2% or 5% rooibos tea for 52 days. No significant alterations were observed in body and reproductive organs weight, serum antioxidant capacity and testosterone level. Seminiferous tubules displayed complete spermatogenesis. However, a significant (P < 0.05) decrease in tubule diameter and germinal epithelial height was observed. Epithelial height of caput epididymides showed a significant increase. Unfermented rooibos significantly enhanced sperm concentration, viability and motility. Fermented rooibos also significantly improved sperm vitality (P < 0.01), but caused a significant increase in spontaneous acrosome reaction (P < 0.05), whereas unfermented did not. Creatinine was significantly enhanced in all treated rats, consistent with significant higher kidney weights. Rooibos significantly reduced alanine transaminase level, while 2% fermented rooibos significantly decreased aspartate transaminase level (P < 0.01). In conclusion, treatment with rooibos improved sperm concentration, viability and motility, which might be attributed to its high level of antioxidants. However, prolonged exposure of rooibos might result in subtle structural changes in the male reproductive system and may induce acrosome reaction, which can impair fertility. Intake of large amounts of rooibos may also harm liver and kidney function.