Onion is a good natural anti-cancer food, the laboratory confirmed, onion and garlic similar, contain "the allicin" and selenium sulfide, can inhibit the synthesis of nitrosamine carcinogenic substance, and promote the function of phagocyte destroy the cancer cells. Onion also contained oak PiHuang element, glutathione, cancer prevention and fighting against cancer also play an important role. Onions contain yellow urine butyric acid, can make the cells to make better use of sugar, reducing blood sugar. Onions contain prostaglandin A, can expand blood vessel, reduce the peripheral vascular resistance, to promote the excretion of sodium, make higher blood pressure drop. Onion also contained diallyl sulfide, have prevent vascular sclerosis, reduce blood fat function. In in the onion can also detect including quercitin kind material, in the yellow alcohol ketone under induced by the formation of the glycoside have diuretic detumescence effect, such as obesity, high blood fat, atherosclerosis and other disease prevention good, this and the Chinese medicine theory says Onions have dry wet detoxification function is similar place.