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

• Published in: Toxicological sciences Vol. 131; no. 1; pp. 26 - 39
• Main Authors: Boudreau, Mary D, Mellick, Paul W, Olson, Greg R, Felton, Robert P, Thorn, Brett T, Beland, Frederick A
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 01.01.2013
• Subjects: Administration, Oral; Aloe - chemistry; Animals; Body Weight - drug effects; Carcinogenicity Tests; Dose-Response Relationship, Drug; Female; Hyperplasia; Intestinal Mucosa - drug effects; Intestinal Mucosa - pathology; Intestinal Neoplasms - chemically induced; Intestinal Neoplasms - pathology; Intestine, Large - drug effects; Intestine, Large - pathology; Male; Mice; Mice, Inbred Strains; Plant Extracts - isolation & purification; Plant Extracts - toxicity; Plant Leaves - chemistry; Rats; Rats, Inbred F344; Species Specificity; Survival Analysis
• ISSN: 1096-6080; 1096-0929
• DOI: 10.1093/toxsci/kfs275

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.