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Kruisbloemige groenten tegen kanker.*
Uit een studie onder 1.000 mensen blijkt dat het eten van broccoli en andere kruisbloemige groenten waaronder div. koolsoorten de kans op blaaskanker wel met 40% kan verminderen, en zelfs met 73%, vergeleken met rokers. Hiervoor hoeft men slechts drie keer in de maand deze groenten te eten weliswaar wel rauw dit komt waarschijnlijk omdat de meeste, wel 60-90% van de gezonde stoffen bij koken verloren gaan. Verder vond men dat vooral rokers een sterk vergrote kans op blaaskanker hebben doch ook bij hen kan hun kans hierop met 40% verminderen door kruisbloemige groenten te eten. Uit een andere studie door hetzelfde instituut bleken ratten, die behandeld werden om blaaskanker te krijgen, door het eten van broccoli-extracten aanzienlijk minder blaaskanker kregen.
Broccoli Three Times A Month Can Significantly Reduce Cancer Risk
If you are not keen on broccoli or cabbage be comforted with the news that you do not have to eat too much of it to reduce your chances of developing cancer. In fact, if you eat broccoli or cabbage just three times each month you could well be reducing your chances of developing bladder cancer by up to 40%, say scientists from the Roswell Park Cancer Institute in Buffalo, USA. They presented their findings at the American Association of Cancer Research Conference, Philadelphia.
In this study, the researchers looked at 1,000 people. 275 of them had bladder cancer while the rest (825) were cancer free. They were all asked about their eating habits, in particular, their consumption of such vegetables as cabbage or broccoli (cruciferous vegetables). Cruciferous vegetables are known to have large amounts of isothiocyanates (ITCs), which experts say can help reduce your risk of developing cancer. 
They found that a smoker who consumes less than three servings of cruciferous vegetables per month has the highest risk of developing bladder cancer. They also found that those who ate raw cruciferous vegetables at least three times a month had a 40% lower risk than those who consumed the raw veggies less often. The difference was also 40% when smokers who ate raw cruciferous vegetables at least three times a month were compared to smokers who ate them less often. 
However, the scientists stressed that they only observed this significant difference in bladder cancer risk with raw vegetables, not cooked vegetables. This is probably because cooking lowers the ITC content by 60-90%, they explained. 
In another study, carried out on rats by researchers also from Roswell Park Cancer Institute, the animals were induced to develop bladder cancer. They were then given freeze-dried broccoli sprout extract. The chances of developing bladder cancer were much lower if the rats ate larger quantities of the freeze dried extract: 
Researchers have found that this rich source of isothiocyanates (ITCs) -- a well-known class of cancer prevention agents -- could play a direct role in preventing bladder cancer. 
"The bladder is like a storage bag, and cancers in the bladder occurs 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," said senior author Yuesheng Zhang, M.D., Ph.D, professor of oncology at Roswell Park Cancer Institute. "The ITCs in broccoli sprout extracts after oral ingestion are selectively delivered to the bladder epithelium through urine excretion." 
Using a rat model of bladder cancer, Zhang and his colleagues found that freeze-dried aqueous extract of broccoli sprouts significantly, and dose-dependently, inhibited bladder cancer development. The incidence, multiplicity, size and progression of bladder cancer were all inhibited by the extract, while the extract itself caused no observable changes in the bladder. This protective effect of the extracts was associated with a significant increase in the bladder of several enzymes that are known to protect against oxidants and carcinogens, Zhang says. 
In the body, ITCs are metabolized to dithiocarbamates (DTCs). The researchers measured the levels of ITCs and DTCs in the blood, tissue and urine of the rats fed with the extracts. More than 70 percent of the ITCs present in the extracts were excreted into the urine as ITC equivalents (ITCs + DTCs) in 12 hours after a single oral dose, indicating high bioavailability and rapid urinary excretion. 
What is more striking, Zhang says, is that the concentrations of ITC equivalents in the urine of extracts-treated rats were two to three orders of magnitude higher than those in plasma, indicating that the bladder epithelium is most exposed to orally dosed ITCs. Indeed, tissue levels of ITC equivalents in the bladder were significantly higher than in the liver, demonstrating that the ITCs in the extracts are efficiently and selectively delivered to the bladder epithelium through urinary excretion, Zhang concludes. (December 2007)

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