The Anti-Cancer and Anti-Aging Effects of Onion, the Queen of Vegetables
The onion is the bulb of Allium cepa L. of the lily family (Liliaceae), also known as scallion head, ball onion, round onion, jade onion, or Dutch onion. Prized for its delicious flavor and high nutritional and health value, it is hailed as the “queen of vegetables.” Onions are rich in nutrients—potassium, vitamin C, folate, zinc, selenium and dietary fiber. In addition, onions contain two special nutrients: quercetin and prostaglandin A.
Quercetin inhibits the activity of cancer-causing substances and prevents cancer cells from growing, making onion an excellent anti-cancer food. Prostaglandin A is an unsaturated fatty acid that counteracts atherosclerosis and thrombosis; it is now used clinically to treat a variety of diseases and has some therapeutic effect in patients with hyperlipidemia and hypertension.
People who eat onions regularly have a lower risk of cancers such as gastric, colorectal, breast and esophageal cancer. The trace element selenium and the sulfur compounds in onions both have strong anti-cancer effects. Onion is therefore a highly recommended anti-cancer food; whether white or purple, it is high in nutritional and health value. Some people rarely eat onions because they pass gas afterward or because their urine and stool smell unpleasant, which is a great pity.
Of course, onions are not suitable for everyone. Onions are a strongly stimulating food; when many people cut onions, the fumes bring tears. This is because when an onion is cut and its cells rupture, a sulfur compound called “propenesulfenic acid” is produced, from which the onion's pungent odor derives. Allergy sufferers may have allergic reactions when cutting or eating onions, and patients with eye disease may find their condition worsens after cooking with or eating onions. Most other people can eat onions safely. When onions are in season, cancer patients without onion allergy may well eat them regularly; this is far more effective than various health supplements, and the onions are delicious, cheap and good value.
Onion also has good anti-aging effects, and it lubricates the intestines and promotes bowel movements, making it especially suitable for middle-aged and elderly people. Onion can raise bone density in experimental mice; eating onions regularly helps prevent osteoporosis.
As early as the Han dynasty, after Zhang Qian opened the gateway to the Western Regions, onions were introduced into China from the west. China has a long history of growing and eating onions, and TCM has long recognized their medicinal value.
Traditional TCM holds that onion is pungent and sweet in taste and warm in nature; it strengthens the stomach and regulates qi, and kills parasites, and is mainly used for poor appetite and abdominal distension. Mashing onion into a paste and applying it externally can treat wounds and ulcers; eaten cooked, it treats hypertension and hyperlipidemia and can also aid weight loss. In addition, mashing onion into a paste and applying it to the navel for 2–4 hours can treat constipation. The Fujian Annals of Medicinal Materials records that taking equal parts of onion and celery, pounding them for juice, adding an appropriate amount of vinegar to make a medicinal solution, and inserting a cotton ball dipped in the solution into the vagina before bedtime, removing it the next morning, can treat trichomonal vaginitis.
Onions can be paired with all kinds of meat and vegetable dishes, and may be eaten raw or cooked; either way, their nutritional and health value is unaffected.