The onion (Allium cepa L., from Latin cepa "onion"), also known as the bulb onion or common onion, is a vegetable that is the most widely cultivated species of the genus Allium. They contain a number of antioxidant compounds that are very effective in neutralizing the free radicals present in the human body. They have been used for medicinal purposes for millennia.
The humble onion is found in every kitchen, but its curative powers make it an important medicinal plant too. It forms the basis of so many dishes - whether raw, sautéed, baked, steamed or boiled, that it would be difficult to imagine the cuisine of any country without it. Onions were historically as a preventative medicine during epidemics of cholera and the plague. They were apparently eaten by Roman emperor Nero as a cure for colds, and its reputation has made onions a popular component in the diets of many countries.
More than just a tasty culinary plant, the onion contains natural sugar, vitamins A, B6, C and E, minerals such as sodium, potassium, iron and dietry fibre. In addition, onions are a good source of folic acid.