Just a few more portions of broccoli
each week may protect men from prostate cancer, British
researchers recently reported.
The researchers believe a chemical in the food sparks
hundreds of genetic changes, activating some genes that
fight cancer and switching off others that fuel tumors,
said Richard Mithen, a biologist at Britain's Institute
of Food Research.
There is plenty of evidence linking a healthy diet
rich in fruits and vegetables to reduced cancer risk.
But the study published in the Public Library of Science
journal PLoS One is the first human trial investigating
the potential biological mechanism at work, Mithen added
in a telephone interview.
"Everybody says eat your vegetables but nobody can
tell us why," said Mithen, who led the study. "Our study
shows why vegetables are good."
Prostate is the second-leading cancer killer of men
after lung cancer. Each year, some 680,000 men worldwide
are diagnosed with the disease and about 220,000 will
die from it.
Mithen and colleagues split into two groups 24 men
with pre-cancerous lesions that increase prostate cancer
risk and had them eat four extra servings of either
broccoli or peas each week for a year.
The researchers also took tissue samples over the course
of the study and found that men who ate broccoli showed
hundreds of changes in genes known to play a role in
fighting cancer.
The benefit would likely be the same in other cruciferous
vegetables that contain a compound called isothiocyanate,
including brussel sprouts, cauliflower, cabbage, rocket
or arugula, watercress and horse radish, they added.
Broccoli, however, has a particularly powerful type
of the compound called sulforaphane, which the researchers
think gives the green vegetable an extra cancer-fighting
kick, Mithen said.
"When people get cancer some genes are switched
off and some are switched on," he said. "What
broccoli seems to be doing is switching on genes which
prevent cancer developing and switching off other ones
that help it spread."
The broccoli eaters showed about 400 to 500 of the
positive genetic changes with men carrying a gene called
GSTM1 enjoying the most benefit. About half the population
have the gene, Mithen said.
The researchers did not track the men long enough to
see who got cancer but said the findings bolster the
idea that just a few more vegetable portions each week
can make a big difference.
It is also likely that these vegetables work the same
way in other parts of the body and probably protect
people against a whole range of cancers, Mithen added.
"You don't need a huge change in your diet,"
he said. "Just a few more portions makes a big
difference."
