Uien tegen kanker.*
Uit
laboratoriumstudies blijkt dat uien speciaal die soorten met de sterkste smaak
zoals sjalotjes goed te zijn in de bestrijding van kanker.
Strong-flavored Onions Show
Promise For Fighting Cancer
Strong-flavored onions can be
harsh on your social life, but they’re potentially great for fighting cancer.
Researchers at Cornell University have found, in preliminary lab studies, that
members of the onion family with the strongest flavor — 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’d have to eat to maximize 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,” says study
leader Rui Hai Liu, M.D., Ph.D., a chemist with Cornell’s Department of Food
Science in Ithaca, N.Y.
Researchers have known for
some time that onions may help fight cancer, but the current study is believed
to be the first to compare cancer-fighting abilities among commonly consumed
onion varieties. The new study will appear in the Nov. 3 print issue of the
Journal of Agricultural and Food Chemistry, a peer-reviewed journal of the
American Chemical Society, the world’s largest scientific society.
Liu and his associates
analyzed 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 flavor — 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, Liu says.
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 researcher says. 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.
Green onions and cocktail
onions were not tested in this study, nor did the researcher test whether
cooking made a difference in terms of cancer-fighting ability. Liu cautions that
human studies are needed before any definitive links between onion consumption
and cancer-prevention can be established.
While popular as fried
“rings,” onions are known mostly for their ability to add flavor to a
variety of food dishes, including meats, pizza, soups and salads. But they are
increasingly becoming known for their potential health benefits. Onions are rich
in a flavor compound known as quercetin, a potent antioxidant that has been
linked to protection against cataracts and heart disease as well as cancer. They
are also sodium, fat and cholesterol free.
Onions are the third-most
consumed vegetable crop in the United States, with a per capita consumption
estimated around 19 pounds per year and a retail value estimated at $3 billion
to $4 billion, according to the National Onion Association.
Onions can be part of a
healthy diet. The National Cancer Institute recommends eating at least five
servings of fruits and vegetables a day.
The New York State Department
of Agriculture and Markets provided funding for this study.
The American Chemical Society is a nonprofit organization, chartered by the U.S. Congress, with a multidisciplinary membership of more than 159,000 chemists and chemical engineers. It publishes numerous scientific journals and databases, convenes major research conferences and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.(Nov. 2004)