Tradition says: Onions are considered cure-alls in many cultures. In Middle Eastern traditional medicine, they were prescribed for diabetes. During the early 20th century in the United States, William Boericke, MD, recommended onions for respiratory and digestive problems in his influential medical treatise, Homeopathic Materia Medica. Believing that onions would help improve athletic performance, ancient Greek Olympians scarfed them down, drank their juice, and rubbed them on their bodies before competitions.
Research proves: A stack of new studies has confirmed many old-time uses of onions. Their thiosulfinates (sulfur compounds responsible for their smell) reduce diabetes symptoms and protect against cardiovascular disease. Quercetin, a flavonoid found in onions, prevents the inflammation associated with allergies and also protects against stomach ulcers and colon, esophageal, and breast cancers. And it looks like the ancient Olympians had it right: A 2009 study in the International Journal of Sport Nutrition and Exercise Metabolism found that quercetin extract increased
Get the benefit: Onions may keep the doctor away even better than apples do. Your body absorbs quercetin from onions at least 3 times faster than it does from apples (or from tea, another top source), says a report for the Federation of European Biochemical Societies. To get the most thiosulfinates, choose red or yellow onions. “The more colorful, the better,” says Michael Havey, PhD, a USDA geneticist and University of Wisconsin professor of horticulture. Heat diminishes the thiosulfinates, so eat onions raw or lightly cooked, Havey adds. “Make them a regular part of a vegetable- and fruitfilled diet.”
