Inhibition of urinary bladder carcinogenesis by broccoli sprouts.
Level 5 - mechanism / opinion, no new human data
Animal/preclinical experimental study
PubMed 18310317 · doi:10.1158/0008-5472.CAN-07-5009
What was done
Dietary freeze-dried aqueous extract of broccoli sprouts was administered to rats exposed to the carcinogen N-butyl-N-(4-hydroxybutyl) nitrosamine. The study assessed bladder cancer incidence, multiplicity, size, and progression, as well as histological changes, levels of protective enzymes (glutathione S-transferase and NAD(P)H:quinone oxidoreductase 1), and pharmacokinetic distribution of isothiocyanate equivalents across urine, plasma, bladder, and liver tissue.
What was found
The extract dose-dependently and significantly inhibited the incidence, multiplicity, size, and progression of bladder cancer without inducing adverse histological changes on its own (specific cancer incidence numbers not reported in the abstract). It significantly induced bladder glutathione S-transferase and NAD(P)H:quinone oxidoreductase 1. Over 70% of ingested isothiocyanates were excreted in urine within 12 hours of a single oral dose, yielding urine concentrations 2 to 3 orders of magnitude higher than plasma levels, with bladder tissue concentrations significantly higher than liver tissue levels.
Why it matters
It demonstrates that oral isothiocyanates from broccoli sprouts are rapidly concentrated in urine and bladder tissue, providing targeted exposure that inhibits chemically induced bladder carcinogenesis in a rodent model.
Limits
The study was conducted entirely in rats using a chemically induced cancer model, which may not replicate human bladder cancer biology or pharmacokinetics. The abstract omits sample sizes, exact cancer incidence and multiplicity rates, and enzyme induction magnitudes. Human clinical trials are required to establish efficacy, tolerability, and dosing.
Cited by
- supports Preclinical rat studies demonstrate that administration of isothiocyanates prior to chemical carcinogen exposure prevents bladder cancer development or significantly reduces tumor size.