A controlled safety study of diindolylmethane in the immature rat model.

Objectives/hypothesis: Diindolylmethane (DIM), a natural product from cruciferous vegetables, has been shown to be a dietary component that has inhibitory effects on some tumors (e.g., laryngeal papilloma). However, current evidence to support its safety is based on adult humans or mature animals. There is little to show on its safety in children. This study is designed to assess safety in the young rat model.

Study Design: Prospective controlled animal study.

Methods: Forty rats were separated into four treatment groups of 10 rats each, based on the amount of study drug they received in their daily food: 1) immature rats fed a low dose of DIM, (0.6 mg/kg/day); 2) immature rats fed a high dose of DIM (6.0 mg/kg/day); 3) immature rats fed no DIM (control); and 4) adult rats fed a high dose of DIM (6.0 mg/kg/day). At the conclusion of the study we collected blood to compare serum chemistries and vitamin D levels, and harvested organs to observe for any gross or histological changes among the groups. Statistical methods involved one-way analysis of variance and pairwise comparisons with Tukey multiple comparison adjustment.

Results: Although our numbers do not allow for statistical significance, there was no appreciable difference in rat weights among the immature groups, nor was there appreciable difference in serum chemistries, or gross or histological examination of liver, kidney, and bone.

Conclusions: Diindolylmethane seems to have no adverse affects on the rat even when given in doses 3x what we propose to be therapeutic. This adds evidence to the safety of this drug in the pediatric population as a treatment option for recurrent respiratory papilloma.