Onions are an excellent source of heart-healthy, cancer-fighting quercetin
Onions contain more disease-fighting polyphenols than even garlic or leeks
The sulfur compounds in onions are thought to have anti-clotting properties as well as help to lower triglycerides
Flavonoid-rich foods like onions may also inhibit the growth of H. pylori, a type of bacteria responsible for most ulcers