Besides the flavor they add to foods, what are the health benefits of onions?
From a health promotion standpoint, the most pungent (smelliest) onions are the best for you. In one test of the flavonoid content of onions, shallots had six times the amount found in Vidalia onions. Shallots also had the most antioxidant activity. Western yellow onions had the most flavonoids – eleven times the amount found in Western white onions, the type with the lowest flavonoids content. All types of onions are good additions to your diet, but choose the stronger tasting ones for the most powerful nutritional boost.
Onions contain as many as 150 phytochemicals. The flavonoid quercetin, a key antioxidant found in onions, helps eliminate free radicals in the body. Other sources of quercetin are tea and apples, but research shows that absorption of quercetin from onions is twice that from tea and more than three times that from apples.
Another big plus is that onions are low in calories yet add abundant flavor to a wide variety of foods. With only 45 calories per serving, onions are fat and cholesterol free, very low in sodium, high in vitamin C, and a good source of fiber.
To get the most health benefits from onions, let them sit for 5 – 10 minutes after cutting and before cooking. The healthy compounds that are released when the onion is sliced will intensify before heating.