Onion's zesty flavor isn't the only thing that makes chopping one worth the tears it elicits: onions contain ingredients that fight colds and flu.
The sulfur compounds that make you cry have potent anti-inflammatory properties that relieve cold- and flu-related aches and congestion. And a flavonoid called quercetin, an even more effective congestion buster in onion, works with vitamin C to stabilize the body's histamine-producing, sniffle-causing response to germs. But best of all, the flavonols that give onions their color were shown in a recent Chinese study to help prevent influenza entirely, boosting immunity to three common strains.
Choose It & Use It One of the most universal ingredients, onion is used to add flavor to just about any course except dessert. To breathe easier all winter, eat half an onion a day; for the biggest protective punch, make it a red one. Red onions contain more pigment flavonols than yellow varieties. To reduce the eye-irritation while chopping, wear goggles and use a very sharp knife.