by Natalie Parletta
Garlic and its relatives
been implicated in
for several cancers.
adds to evidence
Eating lots of onions,
garlic and leeks has been linked to reduced risk of
bowel cancer in a Chinese study of
more than 1600 volunteers.
The vegetables, collectively in the genus Allium (read
Fighting Cancer with Phytochemicals from
Allium Vegetables), contain several
bioactive compounds known as
phytonutrients, including sulfur-rich flavonoids, which have been
linked to anti-bacterial, anti-fungal and antioxidant outcomes in
To explore links between allium vegetables and bowel cancer, the
researchers led by Xin Wu from the First Hospital of China
Medical University in Shenyang compared the previous 12 months' food
intake of 833 patients with colorectal cancer to that of 833 people
free from the disease.
The cohorts were matched
for age, sex and residence.
Results showed eating
allium vegetables was associated
with 50% to 80% lower colorectal cancer risk after controlling for
various factors such as smoking, family history of colorectal
cancer, alcohol and diet.
The research (Allium
vegetables are associated with reduced risk of colorectal cancer - A
hospital, based matched case, control study in China) is
published in the Asia-Pacific Journal of Clinical Oncology.
Mary Flynn, research dietitian and associate professor of
medicine at Brown University, US, says the study is interesting. But
she adds that it's important to note the patients had higher family
history of colorectal cancer than controls - 5.9% versus 1.0%.
The cancer patients also smoked more, ate more calories and reported
consuming less fruit, other vegetables and milk, more alcohol, and
nearly double the amount of red meat than controls.
Although the link with allium vegetables remained after factoring
these differences into analyses, higher red meat and lower plant
food intake has previously been linked to higher bowel cancer risk.
Flynn notes a strength of the study is the number of foods assessed.
But she says the
difference in allium consumption between patients and controls was
an average daily
intake of 43.6 grams versus 58.5 grams.
The difference equates to
around three to five cloves of garlic per day.
People have enjoyed the bulbs and leaves of allium vegetables -
which also include shallots, spring onions and chives - for their
flavor and medicinal benefits for more than 4000 years.
More recently, test tube and non-human animal research has shown
that sulfer-containing allium compounds can fight tumors at each
stage of their formation by inhibiting the growth of precancerous
cells and stifling tumor-promoting micro-environments through
antioxidant and antimicrobial properties.
The compounds are released when the fresh vegetable is cut or
crushed. The effects can be reduced by cooking.
Several population-based studies with humans have linked allium
vegetables to lower risk of different cancers including,
But the findings have
Some reviews have
concluded that allium vegetables lower risk of bowel cancer, while
others found little to support the contention.
Wu and colleagues suggest inconsistencies may be attributed to
differences between studies, including,
how allium intake
vegetables are cooked or eaten raw
factors are included in analyses...