August 8, 2005
Researchers have isolated
compounds from the vegetable broccoli that they believe may help
prevent or slow the progress of bladder cancer.
The current work builds on a major
study conducted six years ago by Harvard and Ohio State
universities that found that men who ate two or more half-cup
servings of broccoli per week had a 44 percent lower incidence
of bladder cancer compared to men who ate less than one serving
“We're starting to look at
which compounds in broccoli could inhibit or decrease the growth
of cancerous cells,” said
Steven Schwartz, a study co-author and a professor of
food science and technology at
Ohio State University .
“Knowing that could help us
create functional foods that benefit health beyond providing
just basic nutrition.”
Some 63,000 people will be
diagnosed with bladder cancer this year, according to the
Cancer Society. And more than 13,000 with the disease will
“Cruciferous veggies have
an effect on other types of cancer, too. We already know
that they contain compounds that help detoxify
carcinogens. We're thinking more along the lines of
progression and proliferation, such as once cancer
starts, is there a way to slow it down?”
The researchers isolated
compounds called glucosinolates from broccoli sprouts. During
chopping, chewing and digestion, these phytochemicals morph into
nutritional powerhouses called
isothiocyanates – compounds that the scientists believed
play a role in inhibiting cancer.
Their hunch was right, at least
in the laboratory experiments. There, isothiocyanates hindered
the growth of bladder cancer cells. And the most profound effect
was on the most aggressive form of bladder cancer they studied.
The researchers presented their
findings on July 18 in New Orleans at the annual
Institute of Food
They first extracted and
measured the levels of glucosinolates from broccoli sprouts.
They then used a process that uses enzymes to convert the
glucosinolates to isothiocyanates.
While young sprouts naturally
have higher concentrations of these phytochemicals than
full-grown broccoli spears, eating the spears also provides
health benefits, Schwartz said.
He and his colleagues treated
two human bladder cancer cell lines and one mouse cell line with
varying amounts of glucosinolates and isothiocyanates. Even
though glucosinolates are converted to isothiocyanates, the
researchers wanted to know if the former would have any effect
on controlling the growth of cancer cells.
However, the isothiocyanates
decreased proliferation in all three cell lines. The strongest
effect was on the most aggressive of these lines – human
invasive transitional cell carcinoma.
The researchers aren't sure
what caused this effect, or exactly how these compounds keep
cancer cells from proliferating. But they are looking into it.
“There's no reason to believe
that this is the only compound in broccoli that has an
anti-cancer effect,” said
Clinton, a study co-author and an associate professor of
hematology and oncology
at Ohio State. “There are at least a dozen interesting
compounds in the vegetable.
“We're now studying more of
those compounds to determine if they work together or
independently, and what kind of effects they have on cancer
cells,” he added.
Broccoli isn't the only
cruciferous veggie with health benefits, the researchers say.
The plant's kin, which include cabbage, cauliflower, Brussels
sprouts and kale, may all contain similar disease-fighting
It's too early to suggest just
how much broccoli or other cruciferous vegetables should be
eaten to stave off or slow down the progression of bladder
cancer. Still, they are an important part of the diet.
“Cruciferous veggies have an
effect on other types of cancer, too,” Schwartz said. “We
already know that they contain compounds that help detoxify
carcinogens. We're thinking more along the lines of progression
and proliferation, such as once cancer starts, is there a way to
slow it down?”
He and Clinton conducted the
study with Ohio State colleagues Robin Rosselot, a graduate
student in food science and technology and Qingguo Tian, a
research associate also in food science and technology.