1. Anti-cancer: Onions are rich in selenium, which is an antioxidant that can stimulate the immune response of human body, inhibit the division and growth of cancer cells and reduce the toxicity of carcinogens. At the same time, onion is rich in quercetin, which can inhibit the activity of cancer-causing cells and prevent their growth.

2. Protect the cardiovascular system: it is the only vegetable known to contain prostaglandin A. This element can dilate blood vessels, reduce blood viscosity, lower blood pressure, increase blood circulation, prevent thrombosis and effectively avoid cardiovascular diseases.

3, help digestion: onions have a pungent smell, which will stimulate people's lacrimal glands and make people cry. This taste is because onion contains allicin, which can stimulate gastric acid secretion, improve gastrointestinal tension and promote gastrointestinal peristalsis, thus playing an appetizing role. It has obvious effect on anorexia caused by insufficient gastric motility and dyspepsia.

4. Prevention of colds: Onions contain elements such as phytoncide and allicin, and have strong bactericidal ability, which can effectively resist influenza virus and play a role in preventing colds.