In this article, I'll be talking about the medicinal importance of onions, the types and their uses. Please, read through. Onion is a vegetable from the widely grown species of genus Allium. This class of vegetables are low in calories but high in vitamins and minerals. Usefulness and medicinal importance of Onions. As earlier stated, this class of veggies contain vitamins and minerals. Most of these minerals and vitamins consist of phytochemical constituents; terpenes, flavonoids, steroids, tannins and so on. These properties play important roles in the body by preventing and also curing diseases: 1. A special kind of flavonoid in onions is quercetin, which acts as an a ntioxidant (compounds that inhibit oxidation, a process that leads to cellular damage and contributes to diseases like cancer, diabetes and heart disease) that may be linked to preventing cancer. “It also might have heart health benefits, though more studies need to be done,” said Angela Lemond, a Pla