Rich in sulphur

Onions are rich in sulphur, fibers, potassium, vitamin B, vitamin C and they are low in fat, cholesterol and sodium.onions is much higher than many people expect. (Polyphenols are one of the largest categories of phytonutrients in food. This category includes all flavonoids as well as tannins.) The total polyphenol content of onion is not only higher than its fellow allium vegetables, garlic and leeks, but also higher than tomatoes, carrots, and red bell pepper.