Extract of broccoli sprouts may protect against bladder cancer

PhysOrg.com
Published:
06:38 EST, February 28, 2008

Extract of broccoli sprouts may protect against bladder cancer

A concentrated extract of freeze dried broccoli sprouts cut
development of bladder tumors in an animal model by more than half,
according to a report in the March 1 issue of Cancer Research, a
journal of the American Association for Cancer Research.

This finding reinforces human epidemiologic studies that have
suggested that eating cruciferous vegetables like broccoli is
associated with reduced risk for bladder cancer, according to the
study's senior investigator, Yuesheng Zhang, MD, PhD, professor of
oncology at Roswell Park Cancer Institute. "Although this is an animal
study, it provides potent evidence that eating vegetables is
beneficial in bladder cancer prevention," he said.

There is strong evidence that the protective action of cruciferous
vegetables derives at least in part from isothyiocyanates (ITCs), a
group of phytochemicals with well-known cancer preventive
activities."The bladder is particularly responsive to this group of
natural chemicals," Zhang said. "In our experiments, the broccoli
sprout ITCs after oral administration were selectively delivered to
the bladder tissues through urinary excretion."

Other cruciferous vegetables with ITCs include mature broccoli,
cabbage, kale, collard greens and others. Broccoli sprouts have
approximately 30 times more ITCs than mature broccoli, and the sprout
extract used by the researchers contains approximately 600 times as
much.

Although animals that had the most protection against development of
bladder cancer were given high doses of the extract, Zhang said humans
at increased risk for this cancer likely do not need to eat huge
amounts of broccoli sprouts in order to derive protective benefits.

"Epidemiologic studies have shown that dietary ITCs and cruciferous
vegetable intake are inversely associated with bladder cancer risk in
humans. It is possible that ITC doses much lower than those given to
the rats in this study may be adequate for bladder cancer prevention,"
he said.

Zhang and his colleagues tested the ability of the concentrate to
prevent bladder tumors in five groups of rats. The first group acted
as a control, while the second group was given only the broccoli
extract to test for safety. The remaining three groups were given a
chemical, N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) in drinking
water, which induces bladder cancer. Two of these groups were given
the broccoli extract in diet, beginning two weeks before the
carcinogenic chemical was delivered.

In the control group and the group given only the extract, no tumors
developed, and there was no toxicity from the extract in the rats.

About 96 percent of animals given only BBN developed an average of
almost two tumors each of varying sizes. By comparison, about 74
percent of animals given a low dose of the extract developed cancer,
and the number of tumors per rat was 1.39. The group given the high
dose of extract had even fewer tumors. About 38 percent of this high-
dose group developed cancer, and the average number of tumors per
animal was only .46 and, unlike the other animals, the majority were
very small in size.

Source: American Association for Cancer Research


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