Clear evidence of carcinogenic activity by a whole-leaf extract of Aloe barbadensis miller (aloe vera) in F344/N rats

摘要

Aloe barbadensis Miller (Aloe vera) is an herbal remedy promoted to treat a variety of illnesses; however, only limited data are available on the safety of this dietary supplement. Drinking water exposure of F344/N rats and B6C3F1 mice to an Aloe vera whole-leaf extract (1, 2, and 3) for 13 weeks resulted in goblet cell hyperplasia of the large intestine in both species. Based upon this observation, 2-year drinking water studies were conducted to assess the carcinogenic potential of an Aloe vera whole-leaf extract when administered to F344/N rats (48 per sex per group) at 0.5, 1, and 1.5, and B6C3F1 mice (48 per sex per group) at 1, 2, and 3. Compared with controls, survival was decreased in the 1.5 dose group of female rats. Treatment-related neoplasms and nonneoplastic lesions in both species were confined primarily to the large intestine. Incidences of adenomas and/or carcinomas of the ileo-cecal and cecal-colic junction, cecum, and ascending and transverse colon were significantly higher than controls in male and female rats in the 1 and 1.5 dose groups. There were no neoplasms of the large intestine in mice or in the 0 or 0.5 dose groups of rats. Increased incidences of mucosa hyperplasia of the large intestine were observed in F344/N rats, and increased incidences of goblet cell hyperplasia of the large intestine occurred in B6C3F1 mice. These results indicate that Aloe vera whole-leaf extract is an intestinal irritant in F344/N rats and B6C3F1 mice and a carcinogen of the large intestine in F344/N rats.