Broccoli Sprouts Help Block Bladder Cancer, In Rats

NEW YORK MAR 03, 2008(Reuters Health) - An extract from broccoli sprouts can prevent the development of bladder cancer by delivering a high dose of cancer-fighting chemicals to the organ, a new study in rats demonstrates.

The findings back up research in humans that shows eating more broccoli and other cruciferous vegetables is associated with a lower risk of the disease, Dr. Yuesheng Zhang of Roswell Park Cancer Institute in Buffalo, New York and colleagues note in their report in the journal Cancer Research.

"Although this is an animal study, it provides potent evidence that eating vegetables is beneficial in bladder cancer prevention," Zhang said in a press release accompanying the study.

Broccoli sprouts are rich in cancer-preventing chemicals known as isothiocyanates, in particular sulforaphane, the researchers write in their report. They had previously demonstrated that rats fed an extract of broccoli sprouts showed increased production in their bladder tissue of two enzymes crucial for protecting cells from oxidants and cancer-promoting chemicals. People lacking these enzymes are at increased risk of bladder cancer.

In the current study, the researchers fed broccoli sprout extract to rodents that had been given a bladder cancer-inducing chemical called BBN. The animals were fed the extract for 12 weeks and, starting two weeks later, BBN for 8 weeks.

Bladder cancer developed in 95.8 percent of the rats given BBN but no broccoli sprout extract, but in only 37.5 percent of the animals that were given the highest dose of broccoli sprout extract along with BBN. Among the rodents given a lower dose of the extract along with BBN, 73.9 percent developed bladder cancer.

Additional experiments demonstrated that levels of isothiocyanates in the urine of rodents given the broccoli sprout extract were hundreds or even thousands of times higher than in their blood, suggesting that the tissue lining the bladder known as the epithelium is very highly exposed to the compounds.

"Given that nearly all bladder cancers occur in the epithelium, isothiocyanate-enriched broccoli sprout extract and other cruciferous vegetables rich in isothiocyanates maybe particularly useful for prevention of bladder cancer," the researchers conclude.

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