Just three servings a month of raw broccoli or cabbage can reduce the risk of bladder cancer by as much as 40 per cent, researchers have found.

The scientists surveyed 275 people who had bladder cancer and 825 people without cancer. They asked especially about cruciferous vegetables such as broccoli and cabbage.

These foods are rich in compounds called isothiocyanates, which are known to lower cancer risk.
The effects were most striking in nonsmokers according to the researchers from the Roswell Park Cancer Institute in New York.

Compared to smokers who ate fewer than three servings of raw cruciferous vegetables, nonsmokers who ate at least three servings a month were almost 73 per cent less likely to be in the bladder cancer group, they found.
 

Among both smokers and nonsmokers, those who ate this minimal amount of raw veggies had a 40 per cent lower risk. But the team did not find the same effect for cooked vegetables.

"Cooking can reduce 60 to 90 per cent of ITCs, (isothiocyanates)," Dr. Li Tang, who led the study, said in a statement.

A second team of researchers from Roswell Park tested broccoli sprouts in rats. They used rats engineered to develop bladder cancer and fed some of them a freeze-dried extract of broccoli sprouts.

The more they ate, the less likely they were to develop bladder cancer, said Dr. Yuesheng Zhang, who led the research.

They found the compounds were processed and excreted within 12 hours of feeding. That suggests the idea that compounds are protecting the bladder from the inside, said Zhang.

"The bladder is like a storage bag, and cancers in the bladder occur almost entirely along the inner surface, the epithelium, that faces the urine, presumably because this tissue is assaulted all the time by noxious materials in the urine," Zhang said.