RESUMO
We examined the modifying effect of freeze-dried whole-leaf Aloe arborescens Miller var. natalensis Berger (Kidachi aloe in Japan; designated as 'ALOE') on azoxymethane (AOM)-induced intestinal carcinogenesis in rats. Male F344 rats (4 weeks old) were fed basal diet or experimental diet containing 0.2% or 1% ALOE for 28 weeks. Starting two weeks later, the animals received subcutaneous injections of AOM once weekly for 10 weeks. The incidence of colorectal adenocarcinomas in the 0.2% (but not 1%) ALOE group showed a strong tendency for decrease (p = 0.056) from the control group. Further, the adenocarcinoma incidence in the entire intestine (small and large intestines) in the 0.2% ALOE group was significantly (p = 0.024) decreased compared to the control value. However, there were no significant differences in tumor multiplicities of colorectal or entire intestines among the 3 groups. In addition, we also studied the safety of long-term ingestion of ALOE as a health food or natural thickening stabilizer. Rats were fed the basal diet or 1% ALOE diet for 35 weeks without AOM treatment. Feeding with 1% ALOE did not affect most hematological and serum biochemical parameters in the rats. These results indicate that a low level of ALOE ingestion might have a mild suppressive effect on intestinal tumor growth without harmful side effects.