Broccoli and Brussels sprouts protect against bladder cancer

Mar 5 2008

An international team of researchers has found that vegetables from the cabbage family, such as broccoli, cauliflower, Brussels sprouts and watercress, can protect against bladder cancer.

The researchers led by New Zealand scientist Dr. Rex Munday discovered that an extract of broccoli sprouts can halve the incidence of bladder cancer in an animal model.

The scientists say the extract from broccoli sprouts prevents the development of bladder cancer by delivering a high dose of cancer-fighting chemicals to the organ.

Collaborating with Dr. Munday on the project were researchers from the Roswell Park Cancer Institute (USA), Johns Hopkins University (USA), Massey University and Crop & Food Research (NZ).

Broccoli sprouts are a great source of cancer-preventing chemicals known as isothiocyanates, in particular sulforaphane.

An earlier study supported by the Waikato Medical Research Foundation, found that rats fed a diet of cruciferous vegetables showed an increase in two tissue enzymes that protect against oxidants and cancer-promoting chemicals.

People lacking these two enzymes are at increased risk of bladder cancer.

In this latest study, the researchers fed broccoli sprout extract to rodents that had been given a bladder cancer-inducing chemical called BBN.

Some of the animals were fed the extract over a 12 week period and it was found that bladder cancer developed in 95.8 percent of the rats given BBN but no broccoli sprout extract.

But only 37.5 percent of the animals that were given the highest dose of broccoli sprout extract along with BBN developed the cancer.

Among the rodents given a lower dose of the extract along with BBN, 73.9 percent developed bladder cancer.

Tests showed 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.

Dr. Munday says as the greatest effect was seen in the bladder, the suggestion is that such vegetables protect against bladder cancer.

Dr. Yuesheng Zhang of Roswell Park Cancer Institute in Buffalo, New York and colleagues say the findings support research in humans that shows eating more broccoli and other cruciferous vegetables is associated with a lower risk of the disease.

Dr. Zhang says although this is an animal study, it provides potent evidence that eating vegetables is beneficial in bladder cancer prevention.