Onions are nutritious. According to the determination, every 100g of fresh onion contains about 88g of water, protein 1- 1.8g, 0.3-0.5g of fat, 5-8g of carbohydrate, 0.5g of crude fiber and 0/30 of dry coke. It also contains caffeic acid, sinapic acid, cinnamic acid, citrate, polysaccharide and various amino acids. The volatile oil is rich in allicin, mercaptan and trisulfide. Buds, pollen and anthers all contain carotene. The tear-causing component of onion is cyclic alliin, and S- propenyl -L- hemiglycine hydrosulfide contained in onion is the precursor of cyclic alliin, which can be cyclized into cyclic alliin under alkaline conditions. Proper amount of raw onion and garlic contains a kind of phytoncide, which has a strong bactericidal effect. Anti-cancer, softening blood vessels, prescription hypertension and hyperlipidemia, and slimming effect, the benefits are really many. Be sure to eat more shallots. In addition, after investigation, potatoes and shallots are the vegetables that are least easily polluted by the soil environment, and eating more is good for health. Raw onions and garlic are carriers themselves, because they are in contact with soil and fertilizer when they grow, and there are many parasitic eggs or other germs in their roots.