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Last Updated: Apr 20, 2011 - 9:38:09 AM |
SUNDAY DEC 9, 2007 (Foodconsumer.org) -- Broccoli sprouts and its related vegetables have already been known to have protection against a number of cancers. A new study now found this special vegetable could also play a direct role in preventing bladder cancer.
In the rat model study, Yuesheng Zhang, M.D., Ph. D, professor of oncology at Roswell Park Cancer Institute and colleagues found that the freeze-dried aqueous extract of broccoli sprouts, which is full of bioactive compounds known as isothiocyanates (ITCs), inhibited development of bladder cancer in a dose-dependent manner.
The broccoli sprouts extract inhibited the incidence, multiplicity, size and progression of bladder cancer while it did not cause any observable changes in the bladder, according to the researchers.
Zhang said the protective effect was associated with a significant increase in several enzymes produced in the bladder, which are known to protect against oxidants and carcinogens.
ITCs are highly bio-available and easy to be metabolized to dithiocarbamates (DTCs), and discharged in the urine, according to the researchers who found more than 70 percent of ITCs are excreted after 12 hours of oral administration.
The levels of these compounds were much higher in the bladder and the urine than in the liver and the blood, meaning it is delivered selectively to the bladder epithelium through urinary excretion, Zhang concluded.
Another study by Li Tang, M.D., Ph.D. lead research also at the Roswell Park Cancer Institute and colleagues found that eating three or more servings a month of raw, but not cooked cruciferous vegetables like broccoli, cabbage and cauliflower, may reduce bladder cancer risk by approximately 40 percent.
The finding was based on dietary data from 275 people with incident, primary bladder cancer and 825 people without cancer.
Non-smokers who ate at least three servings a month were 73 percent less like to have bladder cancer than smokers who ate less than three servings a month, the researchers found.
Early studies are inconsistent when it comes to the effect of cruciferous vegetables on the risk of cancer. The researchers suggested that the discrepancy may be due to the fact that cooking significantly reduces the availability of ITCs for absorption into the body.
"Cooking can reduce 60 to 90 percent of ITCs," says Li Tang, M.D., Ph.D. of Roswell Park Cancer Institute and lead researcher on this study.
"Heating destroys the enzyme that converts the precursor glucosinolates into ITCs, and also destroys ITCs already formed, which is why you need to eat raw cruciferous vegetables to receive the food’s maximum benefit."
An estimated 67,160 new cases of bladder cancer will be diagnosed in the United States and 67,160 will die because of the disease in 2007, according to the National Cancer Institute.
These two studies were presented at the American Association for Cancer Research’s Sixth Annual International Conference on Frontiers in Cancer Prevention Research, being held from December 5 to 8 in Philadelphia, Pennsylvania.
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