Like garlic, onion is another multidrug from the eastern Mediterranean. Powerful antioxidants, shallots, yellow and red (but not white) onions contain more quercetin than any other food. Onions possesses anticancer qualities, help thin the blood and protect from blood clots, lower total cholesterol but raise good HDL cholesterol, they can fight arteriosclerosis, asthma, chronic bronchitis, diabetes, hay fever, and a variety of infections. They have antibiotic and antiviral properties, but may produce gas and worsen heartburn.