Allium cepa

Description

Allium cepa is the common onion. Although it is usually thought of as a vegetable, A. cepa also has a long history of medicinal use.

Onions are perennials that are cultivated for food worldwide. There are many varieties. Most onion bulbs are white, yellow, or red. The green stems and leaves are hollow and can reach 3 ft (1 m) in height. The plants bear small flowers that are usually white or purple. The fleshy bulb that grows below the ground is used medicinally as well as for food. Onions are members of the lily family.

General use

Onion has been used as a food source for almost as long as humans have been keeping written records. Their usefulness has been discovered independently by many cultures on several continents. Onions are mentioned in ancient Egyptian

writings and were known in ancient Greece. In medieval Europe, they were used unsuccessfully to ward off plague.

In North America, Native Americans used onion to treat insect stings and relieve colds. It is also used in traditional Chinese medicine . Homeopaths make a tincture of onion to treat a variety of conditions including cold, cough, diarrhea , facial paralysis, hay fever , hernia, laryngitis, pneumonia , and trauma.

Over the centuries, onion has been used for healing both internally and externally. Internally, onion has been recommended to treat colds, cough, bronchitis, whooping cough, asthma , and other respiratory problems. It is believed to help loosen congestion in the lungs and expand the airways.

Onion is also used internally to relieve excess gas and calm an upset stomach. A mixture of rue (Ruta graveolens ) and onion is used to rid the digestive system of parasites. Onion is also thought to stimulate the appetite.

Onion is believed to have a positive effect on the circulatory system. It has been used as a diuretic to reduce swelling. It is also thought to help reduce arteriosclerosis by lowering blood cholesterol levels and preventing the formation of blood clots . Onion has been used to treat diabetes and is reputed to lower blood sugar levels.

Externally, fresh onion juice is used to prevent bacterial and fungal infections . It can be applied to wounds and stings on the skin, used to remove warts , used to stimulate hair growth, and even used to reduce unwanted skin blemishes. Warm onion juice dropped in the ear is said to help relieve earache . Baked onion is used to draw pus from abscesses.

Modern scientific research supports many of the traditional uses for onion. Onion contains thiosulphinate, a compound that is effective in killing many common bacteria, including Salmonella typhi, Pseudomonas aeriginosa, and Escherichia coli. This finding supports the folk use of onion to treat wounds and skin infections and possibly its use for an upset stomach.

Even more supportive are small clinical studies on humans that show that both fresh onions and commercial onion extracts actually lower blood cholesterol levels, lower blood pressure and help prevent the formation of blood clots. Although these studies have been done on only a small number of people, they are consistently supported by additional data from animal and test-tube studies. In addition, many of these properties have been found in garlic (A. sativum ) which is a close relative to onion.

In 1990, scientists detected the presence of a compound in onion that partially blocks the development of inflammation. In addition, laboratory animals were protected against induced asthma with fresh onion juice. Humans with asthma have also shown reduced allergy-induced constriction of the airways when given an extract of onion. These findings support the traditional folk administration of onion to treat asthma and respiratory complaints.

Some test-tube and small animal studies suggest that onion oil can stop the growth of tumors. Whether these results are applicable to humans remains to be seen, but in a 1989 study done in China, people who ate large amounts of vegetables in the Allium family appeared to have a significantly reduced rate of stomach cancer .

Onion has also been shown to contain antioxidants , which are compounds that protect the body against free radicals. Free radicals are highly reactive molecules that destabilize other molecules and are associated with a number of degenerative diseases.

The German Federal Health Agency's Commission E, established in 1978 to independently review and evaluate scientific literature and case studies pertaining to herb and plant medications, has approved onion as an antibacterial agent. Although many studies are promising, more information is needed before this endorsement is extended to other uses of onion. In general, however, it appears that onion is a healthful vegetable that may confer many medical benefits.

Preparations

Onion is a common vegetable, and can be served cooked or raw. For medicinal purposes, onion is available for internal use as a capsule or tablet containing dehydrated onion or onion extract. A recent study of the antioxidant activity of onion juice indicates that it is not affected by heating or boiling. For external use, the juice of fresh onion is used. A common dose is 1/4–1 cup of raw onions daily or one teaspoon of juice three times a day. In folk medicine, a cough syrup is made of raw onion liquid and honey.

Precautions

No special precautions are needed when taking onion medicinally.

Side effects

Although no allergic reactions to the bulb of the onion are reported, some people develop an allergic rash after handling the leaves of the plant. In addition, windblown particles of onion leaves and skin have been shown to irritate the eyes of farm workers employed to harvest the onions.

Interactions

There are no studies of the interaction of onion and conventional pharmaceuticals. However, given the long and widespread use of onion as a vegetable, serious interactions appear unlikely.

Resources

BOOKS

Chevallier, Andrew. Encyclopedia of Medicinal Plants. London: Dorling Kindersley, 1996.

PDR for Herbal Medicines. Montvale, N. J.: Medical Economics Company, 1999.

Peirce, Andrea. The American Pharmaceutical Association Practical Guide to Natural Medicines New York: William Morrow and Company, 1999.

PERIODICALS

Hwang, Y. H., et al. "Suspended Onion Particles and Potential Corneal Injury in Onion Harvesters." Archives of Environmental Health 57 (January-February 2002): 78-84.

Racchi, M., et al. "Antiradical Activity of Water-Soluble Components in Common Diet Vegetables." Journal of Agricultural and Food Chemistry 50 (February 2002): 1272-1277.

Tish Davidson

Rebecca J. Frey, PhD

onion plant of the family Liliaceae ( lily family), of the same genus ( Allium ) as the chive ( A. schoenoprasum ), garlic ( A. sativum ), leek ( A. porrum ), and shallot ( A. ascalonium ). These plants are characterized by an edible bulb composed of food-storage leaves that are rich in sugar and a pungent oil, the source of its strong taste. The above-ground green leaves, typically long and tubular, are also eaten. All these species are believed to be native to SW Asia and are known to have been cultivated since ancient times. The onion ( A. cepa ), no longer found wild, is a biennial now grown in many varieties throughout the world as a table vegetable. Common varieties include the strong-flavored red onion, the milder yellow onion, and the bland white onion. Pearl onions are small white onions used for pickling. The large Spanish and Bermuda onions have a delicate flavor. The onion was grown extensively by the ancient Egyptians, in whose writings it is mentioned, and was later spread by the Spanish colonists. The more pungent garlic, a perennial, has a bulb consisting of small bulbils called cloves. This part is most often used in cooking, chiefly as flavoring; garlic is especially popular in the Mediterranean region and East Asia. Used as a folk remedy for thousands of years, scientific investigation is confirming garlic's usefulness as a blood thinner, antioxidant, and cancer preventive. The shallot (supposedly introduced to Europe from Ascalon, or Ashqelon, by the Crusaders, hence the botanical name) is a perennial with clusters of small onionlike bulbs. It and the more familiar leek, a biennial with a small single bulb, are both commonly used fresh in salads, as asparaguslike cooked vegetables, and in soups and stews. The leek, cultivated in ancient Egypt and probably introduced to England by the Romans, is the floral emblem of the Welsh, who adorn their hats with its leaves on St. David's Day. Scallion is a popular term for any edible Allium with a reduced bulb, especially the leek and shallot. The Welsh onion ( A. fistulosum ) is a leeklike plant popular in Asia. The chive, today found wild in Italy and Greece, is a hardy perennial sometimes used as an ornamental border plant. For flavoring, its leaves are the most desirable portion. Several species of Allium are native to North America, chiefly in the West, where the edible types were collected by Native Americans. Because of the disagreeable odor and taste imparted to the milk of cows that feed upon them, some species are considered weeds, especially the common wild garlic, A. vineale, naturalized from Europe. Onion is classified in the division Magnoliophyta , class Liliopsida, order Liliales, family Liliaceae.

Onion

The onion was regarded as a symbol of the universe by the ancient Egyptians, and many beliefs were associated with it. It was believed that it attracted and absorbed infectious matters and was usually hung in rooms to prevent illness. This belief in the absorptive power of the onion is still prevalent.

British folklorist James Napier noted: "When a youth, I remember the following story being told, and implicitly believed by all. There was once a certain king or nobleman who was in want of a physician, and two celebrated doctors applied. As both could not obtain the situation, they agreed among themselves that the one was to try to poison the other, and he who succeeded in overcoming the poison would thus be left free to fill the situation. They drew lots as to who should first take the poison. The first dose given was a stewed toad, but the party who took it immediately applied a poultice of peeled onions over his stomach, and thus abstracted all the poison of the toad. Two days after, the other doctor was given the onions to eat. He ate them, and died. It was generally believed that the poultice of peeled onions laid on the stomach, or underneath the armpits, would cure anyone who had taken poison."

ONIONS

ONIONS, apparently native to Asia, were unknown to the American Indians. Early colonists first brought them to America. Wethersfield, Connecticut, soon became a noted onion-growing center. Records show that Wethersfield was shipping onions as early as 1710. A century later it was sending out a million bunches annually. Nonetheless, as onion culture spread to all parts of the country, Wethersfield lost its preeminence. Soon after 1900 extensive production of Bermuda onions began in Texas, California, and Louisiana. By 2002 Idaho, Oregon, Washington, and California had come to lead the United States in onion production. In that year the American onion crop was worth between $3 billion and $4 billion retail.

BIBLIOGRAPHY

Benes, Peter. Two Towns, Concord and Wethersfield: A Comparative Exhibition of Regional Culture, 1635–1850. Concord, Mass.: Concord Antiquarian Museum, 1982.

Main, Jackson Turner. Society and Economy in Colonial Connecticut. Princeton, N.J.: Princeton University Press, 1985.

Alvin F.Harlow/a. e.

See alsoAgriculture ; Food and Cuisines .

on·ion / ˈənyən/ • n. 1. an edible bulb with a pungent taste and smell, composed of several concentric layers, used in cooking. 2. the plant (Allium cepa) of the lily family that produces this bulb, with long rolled or straplike leaves and spherical heads of greenish-white flowers. PHRASES: know one's onions inf. be very knowledgeable about something.DERIVATIVES: on·ion·y adj.

onion know one's onions be very knowledgeable about something.
not the only onion in the stew not the only person or thing to be considered.
onion dome a dome which bulges in the middle and rises to a point, used especially in Russian church architecture.

onion Hardy, bulb-forming, biennial plant of the lily family, native to central Asia, and cultivated worldwide for its strong-smelling, edible bulb. It has hollow leaves, white or lilac flowers. Height: to 130cm (50in). Family Alliaceae/Liliaceae.

onion Bulb of Allium cepa; there are many varieties with white, brown, and red (purple) skins. A 60–g portion, raw, supplies 20 kcal (80 kJ); boiled onions supply half of this.

onion XIV. ME. unyon, oyn(y)on — AN. union, (O)F. oignon, L. uniōnem, nom. uniō.

onion (Allium See LILIACEAE.

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