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ONION ( Allium cepa L. )
Names in Other Languages:

English Onion
French Oignon
German Zwiebel
Spanish Cebolla
Italian Cipolla
Turkish Soğan
Japanese 玉葱 Tamanegi, 分葱 Wakegi, オニオン Onion

FAMILY: Alliaceae

ORIGIN:   Onion is originated from West or Central Asia. It is cultivated in Netherlands, Italy, Poland, Spain, France, Hungary, Turkey, Israel, Egypt, South Africa, USA, Chile, Argentina, Canada, Australia, New Zealand, Tasmania. In Europe, it is known since the bronze ages.

GENERAL DESCRIPTION: The onion (bulb) is composed of a highly compressed basal plate, which gives rise to the roots, and the main shoot apex, around which the thickened onion scale leaves are arranged. These end in the onion neck, from which the above-ground shoot or peduncle emerges. The outermost scale leaves are dry and protect the onion from external influences.

USEFUL PARTS: Bulb and leaves of onions can be used raw or cooked. Onion powder is used in many dishes.

SENSORY PROPERTIES: In fresh state, onion is spicy, pungent and lachrymatory. On cooking, the flavour mellows and can become even sweet, depending on the cooking type. Dried onion has an aromatic, spicy odour and mild flavour.

MAIN CONSTITUENTS: Onions are rich in powerful sulfur-containing compounds that are responsible for their pungent odors and for many of their health-promoting effects. Onions contain allyl propyl disulphide, while garlic is rich in allicin, diallyl disulphide, diallyl trisulfide and others. In addition, onions are very rich in chromium, a trace mineral that helps cells respond to insulin, plus vitamin C, and numerous flavonoids, most notably, quercitin. [1]

Big onion per 100 gram contains:
Moisture: 86.8%
Protein: 1.2%
Fat: 0.1%
Carbohydrates: 11.6%
Calcium: 0.18%
Phosphorus: 0.005%
Iron: 0.7 mg/100 gram

Source: http://www.indianetzone.com/1/onion.htm

Composition of onion powder per 100 gram is:
Moisture: 4.6%
Protein: 10.6%
Fat: 0.8%
Fiber: 8.4%
Carbohydrates: 74.1%
Total ash: 3.5%
Calcium: 0.3%
Phosphorus: 0.29%
Sodium: 0.04%
Potassium: 1.0%
Vitamin A: 175 i.u/100 gram
Vitamin B1: 0.42 mg/100 gram
Vitamin B2: 0.06 mg/100 gram
Nicotinic acid: 0.6%
Vitamin C: 14.7 mg/100 gram
Calorific value: 370 calories/100 gram

Source: http://www.indianetzone.com/1/onion.htm

Fresh onions contain only traces (0.01%) of essential oil, which mostly consists of sulfur compounds: Ethyl and propyl disulfides, vinyl sulfide and other sulfides and thioles. The lachrymatory principle is variously identified as thiopropanal-S-oxide (CH3–CH2–C(SO)H) or its tautomer propenyl sulfenic acid (CH3–CH=CH–SOH). This substance is released from its precursor S-1-propenyl-L-cysteine sulfoxide as a reaction to cell damage that the mechanism is similar to garlic. [2]


Onions have almost no odor until they are cut, cooking the onions drives off the odoriferous compounds and converts some of them to sugars. They are available in fresh, frozen, canned, pickled, powdered, chopped, and dehydrated forms. Onions can be used, usually chopped or sliced, in almost every type of food including cooked foods and fresh salads and as a spicy garnish. They are rarely eaten on their own but usually act as accompaniment to the main course.


--> Blood Sugar-Lowering Effects

The higher the intake of onion, the lower the level of glucose found during oral or intravenous glucose tolerance tests. Experimental and clinical evidence suggests that allyl propyl disulfide is responsible for this effect and lowers blood sugar levels by increasing the amount of free insulin available. Allyl propyl disulfide does this by competing with insulin, which is also a disulphide, to occupy the sites in the liver where insulin is inactivated. This results is an increase in the amount of insulin available to usher glucose into cells causing a lowering of blood sugar.

Furthermore, onions are a very good source of chromium, the mineral component in glucose tolerance factor, a molecule that helps cells respond appropriately to insulin. Clinical studies of diabetics have shown that chromium can decrease fasting blood glucose levels, improve glucose tolerance, lower insulin levels, and decrease total cholesterol and triglyceride levels, while increasing good HDL-cholesterol levels. One cup of raw onion contains over 20% of the Daily Value for this important trace mineral. [1]

-->  Cardiovascular Benefits

The regular consumption of onions has, been shown to lower high cholesterol levels and high blood pressure, both of which help prevent atherosclerosis and diabetic heart disease, and reduce the risk of heart attack or stroke. These beneficial effects are likely due to onions' sulfur compounds, its chromium and its vitamin B6, which helps prevent heart disease by lowering high homocysteine levels, another significant risk factor for heart attack and stroke. [1]

-->  Support Gastrointestinal Health

The regular consumption of onions, as little as two or more times per week, is associated with a significantly reduced risk of developing colon cancer. Onions contain a number of flavonoids, the most studied of which, quercitin, has been shown to halt the growth of tumors in animals and to protect colon cells from the damaging effects of certain cancer-causing substances. Cooking meats with onions may help reduce the amount of carcinogens produced when meat is cooked using high heat methods.

Quercitin, an antioxidant in onions, and curcumin, a phytonutrient found in the curry spice turmeric, reduce both the size and number of precancerous lesions in the human intestinal tract.

The use of onions in diet play a protective role agains the development of colorectal cancer.[1]

-->  Onion and Garlic Protective against Many Cancers

Consuming onion and garlic may lower the risk or several common cancers. [3]

Study participants consuming the most onions showed an 84% reduced risk for cancer of the oral cavity and pharynx, 88% reduced risk for esophageal cancer, 56% reduced risk for colorectal cancer, 83% reduced risk for laryngeal cancer, 25% reduced risk for breast cancer, 73% reduced risk for ovarian cancer, 71% reduced risk for prostate cancer, and 38% reduced risk for renal cell cancer, compared to those eating the least onions.

-->  Onions Protective against Ovarian Cancer

Research calculating flavonoid intake in women whose diets provided the most kaempferol had a 40% reduction in risk of ovarian cancer, compared to women eating the least kaempferol-rich foods.

-->  Boost Bone Health

Onions help to maintain healthy bones; and they are especially beneficial for women who are at increased risk for osteoporosis as they go through menopause. Potential negative side effects of eating onions: the smell of the onion while breathing.

-->  Anti-Inflammatory and Anti-Bacterial Activity

Several anti-inflammatory agents in onions render them helpful in reducing the severity of symptoms associated with inflammatory conditions such as the pain and swelling of osteo- and rheumatoid arthritis, the allergic inflammatory response of asthma, and the respiratory congestion associated with the common cold. Both onions and garlic contain compounds that inhibit lipoxygenase and cyclooxygenase, thus markedly reducing inflammation. Onions' anti-inflammatory effects are due to theris vitamin C and quercition and the active component called isothiocyanates. These compounds work synergistically to spell relief from inflammation. Quercitin and other flavonoids found in onions work with vitamin C to help kill harmful bacteria in that case it is thought that to add onions inside soups and stews is beneficial.

-->  Side effects and interactions

Onion is mostly can be consumed without any difficulties. Higher intakes of onion may worsen existing heartburn, though it does not seem to cause heartburn in people who do not already have it.There are also isolated reports of allergy to onion, including among people with asthma, manifesting as skin rash and red, itchy eyes.

Onion is safe for use in children and, in small amounts in food, during pregnancy (though some pregnant women may have heartburn that onions could exacerbate) and nursing. [4]


Lesley Bremness, Eyewitness Handbook HERBS, London, 1994
Picture source: www.babbonyc.com/in-myrtle.html
[1] Chiej. R. Encyclopaedia of Medicinal Plants. MacDonald 1984 ISBN 0-356-10541-5
[2] Bown. D. Encyclopaedia of Herbs and their Uses. Dorling Kindersley, London. 1995 ISBN 0-7513-020-31 A very well presented and informative book on herbs from around the globe. Plenty in it for both the casual reader and the serious student. Just one main quibble is the silly way of having two separate entries for each plant.
[3] Chevallier. A. The Encyclopedia of Medicinal Plants Dorling Kindersley. London 1996 ISBN 9-780751-303148
[4] Chopra. R. N., Nayar. S. L. and Chopra. I. C. Glossary of Indian Medicinal Plants (Including the Supplement). Council of Scientific and Industrial Research, New Delhi. 1986