Onion has the function of calming the liver and moistening the intestines, and its volatile oil contains diallyl disulfide, a substance that lowers cholesterol. It is the only prostaglandin-like substance and the active ingredient that can activate fibrinolysis. These substances have a strong ability to relax blood vessels and coronary arteries, and can also promote the excretion of sodium salts, thereby lowering blood pressure and preventing thrombosis.

Modern medical research also shows that onion contains trace element selenium. Selenium is an antioxidant. Its special function is to produce a large amount of glutathione. The physiological function of glutathione is to transport oxygen for cell respiration. With the increase of human selenium content, the incidence of cancer will be greatly reduced. Therefore, onion is a healthy food.

Onion also has hypoglycemic effect, because it contains organic substances similar to metsulfuron, which can produce dermatan with strong diuretic effect in human body. Eating 25 ~ 50g onion per meal for diabetic patients can play a better role in lowering blood sugar and diuresis.

Phytoncide in onion can not only stimulate appetite and help digestion, but also stimulate secretion of tube wall when it is excreted through respiratory tract, urinary tract and sweat gland, so it also has the functions of eliminating phlegm, diuresis, sweating, preventing colds, inhibiting bacteria and preserving corrosion.

In addition, there is the "vegetable queen-onion", which is good for health and can also lose weight.

The above is what I know, and I hope I can give you some help.