Onion is rich in potassium, folic acid, vitamin C, zinc, selenium, cellulose and other ingredients, which can scavenge free radicals in the body, promote metabolism and prevent osteoporosis. Onion contains phytoncide, which has expectorant, diuretic, sweating and cold prevention effects. Allicin is contained in onion, which can stimulate gastric acid secretion and stimulate appetite, and has obvious effect on anorexia caused by atrophic gastritis and dyspepsia. Onion is also an antioxidant, which can activate the human immune system and inhibit the growth and division of cancer cells.