Nutrition: Bad Breath but Good Health
By ERIC NAGOURNEY
he stronger an onion tastes, the more likely it is to help fight cancer and other diseases, scientists at Cornell have found.
The researchers, who looked at 10 kinds of onions as well as shallots, found broad differences in the concentrations of phenolics and flavonoids, compounds that can help reduce the risk of medical problems like heart disease, cancer and diabetes.
Their report appears in The Journal of Agricultural and Food Chemistry. There is a wrinkle, however. The more powerful the concentration of the compounds in onions, the more powerful the flavor - and the smell. So there could be some social fallout. "It's not good for your friends, but it is good for your health," said the lead researcher, Dr. Rui Hai Liu, a chemist in the university's department of food science.
Unfortunately, the study said, "consumer buying trends have increasingly been toward less pungent, milder onion varieties."
Among the more popular onions, for example, is the Vidalia, favored for its sweetness. Shallots had six times as much phenolic content as the Vidalia. The western yellow onion, meanwhile, had flavonoid levels 11 times as high as the western white.
It is unclear how many onions someone would have to eat to reap a benefit.
Other agricultural products contain similar disease-fighting compounds, if not in the same concentration, and health authorities generally advise people to eat a good variety of all kinds of fruits and vegetables every day. It is also unclear whether cooking onions affects their nutritional value.
Dr. Liu noted that cooking tomatoes actually increased their effectiveness.
To test the onions, the researchers measured their concentrations of phenolics and flavonoids and then did tests to see how well they fought cancer cells in the lab.
Over all, the study said, shallots had the highest antioxidant value. Other winners were the western yellow, New York bold and northern red.