New Study Shows Onion Compound May Protect Colon from Cancer
New Study Adds Further Evidence of The
Roles For Antioxidants, Carotenoids,
Phytochemicals, Plant-Derived Nutrient
Extracts For Cancer Risk Reduction...
Increased intakes of the compound Quercetin, found in onions and
apples, may reduce the risk of developing cancer of the colon by
50 per cent, says a new study.
Researchers from the University of Aberdeen, Ireland's National
Cancer Registry Ireland and the University of Ottawa add that
increased intakes of flavonols in general were associated with a
40 per cent reduction in the risk of developing colorectal cancer.
Flavonoids are divided into a number of sub-classes, including
anthocyanins found in berries, flavonols from a variety of fruit
and vegetables, flavones from parsley and thyme, for example,
flavanones from citrus, isoflavones from soy, mono- and poly-meric
flavonols such as the catechins in tea, and proanthocyanidins from
berries, wine and chocolate.
A vast body of epidemiological studies has linked increased
dietary intake of antioxidants from fruits, vegetables wine,
chocolate, coffee, tea, and other foods to reduced risks of a range
of diseases including cancer, cardiovascular disease and diabetes.
In order to examine the benefits of a flavonoid-rich diet with respect
to colorectal cancer risk, the researchers performed a case-control
study involving 264 people with confirmed colorectal cancer and 408
healthy, cancer-free controls. Colorectal cancer accounts for nine
percent of new cancer cases every year worldwide. The highest
incidence rates are in the developed world, while Asia and Africa
have the lowest incidence rates.
Since tea if the main dietary source of flavonoids in the UK, the
researchers sought to distinguish between total dietary and non-tea
intake of four flavonoid subclasses - flavonol, procyanidin, flavon-3-ol,
The participants were drawn from a "tea-drinking population with
a high colorectal cancer incidence" said the researchers.
While no association between total dietary flavonoids and the
incidence of colorectal cancer was observed, when the researchers
considered only flavonoids from non-tea sources and the specific
site of the cancer, a significant protective effect was documented
for non-tea flavonols and colon, but not rectal, cancer.
"We concluded that flavonols, specifically querce tin, obtained from
non-tea components of the diet may be linked with reduced risk of
developing colon cancer," concluded the researchers. The
researchers did not study the mechanism behind the potential
beneficial effects, but an earlier study from UCLA (Cancer, 2008,
Vol. 112, pp. 2241-2248) suggested that flavonoids may act by
blocking the formation of blood vessels that tumors develop so they
can grow and spread, a process called angiogenesis. A potential
role in apoptosis, or naturally programmed cell death, may also be
Source: British Journal of Nutrition
Published online ahead of print, First View article,
"Dietary flavonoid intake and colorectal cancer: a case-control study"