| Ilena Rose 2004-10-29, 7:16 pm |
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Previous page : Strong flavoured onions fight growth of liver cancer
http://www.foodnavigator.com/news/p...is.asp?id=55619
Strong flavoured onions fight growth of liver cancer cells
25/10/2004 - Stronger flavoured onions could be better cancer-fighting
foods than their mild-flavoured cousins, find researchers in the US
that analysed an array of common varieties.
Onions contain the flavonoid quercetin and a raft of recent science
has uncovered the role polyphenols, to which quercetin belongs, can
play in preventing the onset of various diseases, notably certain
cancers and cardiovascular disease, that annually kills 17 million
people in the world.
Researchers at Cornell university found, in preliminary lab studies,
that members of the onion family with the strongest flavour —
particularly New York bold, western yellow and shallots — are the best
varieties for inhibiting the growth of liver and colon cancer cells.
“No one knows yet how many daily servings of onions you would have to
eat to maximise protection against cancer, but our study suggests that
people who are more health-conscious might want to go with the
stronger onions rather than the mild ones,” said study leader Rui Hai
Liu, a chemist with Cornell’s department of food science in New York.
Liu and his associates analysed 10 common onion varieties and shallots
for total antioxidant activity and their ability to fight the growth
of cancer in human cell lines. Although shallots resemble onions, they
are actually a separate, distinctive species. Fresh, uncooked samples
were used, with extracts taken from the bulbs with the outer skin
removed.
Shallots and onion varieties with the strongest flavour — western
yellow, New York bold and northern red — had the highest total
antioxidant activity, an indication that they may have a stronger
ability to destroy charged molecules called free radicals, an excess
of which are thought to increase the risk of disease, particularly
cancer, the researcher says.
Onion varieties with the mildest flavor — empire sweet, western white,
peruvian sweet, Mexico, texas 1015, Imperial Valley Sweet and Vidalia
— had the lowest total antioxidant activity, reported Liu.
In tests against liver and colon cancer cells, onions were
significantly better at inhibiting the growth of colon cancer cells
than liver cancer cells, an indication that they are potentially
better at fighting colon cancer, the researchers commented.
The strongest cancer-fighters tested were the New York Bold variety,
Western Yellow and shallots. The sweetest tasting onions, including
the beloved Vidalia, showed relatively little cancer-fighting ability,
he notes. But at the same time cautioning that human studies are
needed before any definitive links between onion consumption and
cancer-prevention can be established.
World onion production has increased by at least 25 per cent over the
past 10 years with current production at around 44 million tonnes,
making it the second most important horticultural crop after tomatoes,
according to researchers at the department of plant genetics and
biotechnology, Horticulture Research International in the UK.
Because of their storage characteristics and durability for shipping,
onions have always been traded more widely than most vegetables.
Onions are versatile and used as an ingredient in a wide range of
dishes, accepted by almost all traditions and cultures.
Horticulture Research International claims that onion consumption is
increasing significantly, particularly in the USA, on the back of
heavy promotion that links the vegetable to flavour and health
benefits. Onions are rich in two chemical groups that have perceived
benefits to human health.
Full findings for the recent US study will appear in the November 3
print issue of the Journal of Agricultural and Food Chemistry, the
journal of the American Chemical Society.
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