Altered estrogen metabolism and excretion in humans following consumption of indole-3-carbinol.
Research studies have demonstrated a strong association between estrogen metabolism and the incidence of breast cancer, and we have therefore sought pharmacological means of favorably altering both metabolism and subsequent risk. Indole-3-carbinol (I3C), obtained from cruciferous vegetables (e.g., cabbage, broccoli, etc.), is a known inducer of oxidative P-450 metabolism in animals. We investigated the effects in humans of short-term oral exposure to this compound (6-7 mg/kg/day over 7 days). We used an in vivo radiometric test, which provided a highly specific and reproducible measure of estradiol 2-hydroxylation before and after exposure to I3C. In a group of 12 healthy volunteers, the average extent of reaction increased by approximately 50% during this short exposure (p less than 0.01), affecting men and women equally. We also measured the urinary excretion of two key estrogen metabolites, 2-hydroxyestrone (2OHE1) and estriol (E3). We found that the excretion of 2OHE1 relative to that of E3 was significantly increased by I3C, further confirming the ongoing induction of 2-hydroxylation. These results indicate that I3C predictably alters endogenous estrogen metabolism toward increased catechol estrogen production and may thereby provide a novel "dietary" means for reducing cancer risk.
Michnovicz
J J
JJ
Institute for Hormone Research, New York, NY 10016.
Bradlow
H L
HL
D000328:Adult; D000975:Antioxidants / Q000494:pharmacology*; D015992:Body Mass Index; D001834:Body Water / Q000737:chemistry; D004958:Estradiol / Q000032:analysis / Q000378:metabolism* / Q000652:urine; D004964:Estriol / Q000652:urine; D002393:Estrogens, Catechol / Q000652:urine; D004970:Estrone / Q000652:urine; D005260:Female; D006801:Humans; D006894:Hydroxyestrones / Q000652:urine; D006900:Hydroxylation; D007211:Indoles / Q000494:pharmacology*; D008297:Male; D014316:Tritium
D000975:Antioxidants; D002393:Estrogens, Catechol; D006894:Hydroxyestrones; D007211:Indoles; D014316:Tritium; D004970:Estrone; D004958:Estradiol; C016517:indole-3-carbinol; D004964:Estriol; C024980:2-hydroxyestrone