Onion – nutrition, proven benefits, uses


The scientific name of the onion is Allium cepa L.

Scientific names Common names
Allium angolense Baker Sibuyas (Tag.)
Allium aobanum Araki Cebollas (Span.)
Allium cepa L. Cebuyas (C. Bis.)
Allium cepaeum St.-Lag. Lasona (Ilk.)
Allium commune Noronha Common onion (Engl.)
Allium esculentum Salisb. Onion (Engl.)
Allium napus Pall. ex Kunth Scallions (Engl.)
Allium pauciflorum Willd. ex Ledeb. True onion (Engl.)
Allium salota Dostal
Ascalonicum sativum P.Renault
Cepa alba P.Renault
Cepa esculenta Gray
Cepa pallens P.Renault
Cepa rubra P.Renault
Kepa esculenta Raf.
Porrum cepa (L.) Rchb.
Allium cepa L. is an accepted name
Other vernacular names
ARABIC: Bassal.
BENGALI: Piaaj, Pinaaj.
BOSNIAN: Crni luk, Crveni luk, Ljetnji luk, Luk.
BURMESE: Kyet thun ni.
CHINESE: Yuan cong, Cong tou, Yang cong.
CROATIAN: Crni luk, Crljenac, Crveni luk, Črlenec, Luk, Sijanac.
CZECH: Cibule, Cibule kuchyňská.
DUTCH: Ajuin, Ui.
FINNISH: Sipuli, Punasipuli , Ruokasipuli.
FRENCH: Oignon.
GREEK: Kremmydi.
HEBREW: Bazal, Besalim.
HINDI: Pyaaz, Pyāja sanyantra.
HUNGARIAN: Hagyma, Vöröshagyma.
ITALIAN: Cipolla
COUNTRY: Tama negi.
KHMER: Khtüm barang.
KOREAN: Yang pa.
LAOTIAN: Bwàx fàlangx, Phak bouo.
MALAY: Bawang besar (Brunei), Bawang Bombay (Indonesia).
ORIYA: Piaja.
PERSIAN: Piyaaz.
POLISH: Cebula, Cebula jadalna, Cebula zwyczajna, Czosnek cebula.
RUSSIAN: Luk repchatyi.
SANSKRIT: Palandu.
SERBIAN: Arpadžik, Crni luk , Crni lukac , Crvenac , Crveni luk, Kapula , Kromid , Kromit, Kromiti luk.
SLOVAK: Cibuľa, Cibuľa kuchynská.
SLOVENIAN: Čebul, Čebula.
SPANISH: Cebolla, Cebolla macho.
SWAHILI: Kitunguu.
SWEDISH: Lök, Vanlig lök, Vitlök.
THAI: Dton bpa ser gor, Dton hom hua yai, Hom yai, Hom huayai, Hua hom.
URDU: Pyaaz.
VIETNAMESE: Củ hành tây, Hành tây.

Onion is a low herb, with leaves shorter than the scape, cylindric, hollow, 8 millimeters in diameter, narrowing upward to a slender apex, shorter than the inflorescence. Scape is inflated, about 30 centimeters high, 1 centimeter thick in the middle, narrowed at both ends. Flowers are stellate, numerous in a dense and rounded umbel, with pedicels 5 to 7 millimeters long. Perianth segments are oblong, acuminate, 5 to 6 millimeters long. Filaments are longer than the petals.


– Cultivated as market produce.

– Originated in western Asia, from where it spread to Greece, Italy, and Egypt.


– Onion bulb yields 0.005 per cent of its weight of a dark-brown essential oil. The main portion of the oil consists of a compound, C6H12S2.

– Outer skin of the onion bulb yields a yellow coloring matter (quercetin), C15H10O7, allyl propyldisulphide, inulin, carbohydrate (6%), protein (2.4%), fat (0.1%), ash (0.3%), and vitamin C.

– Bulb constituents are reported as: essential oil (0.015%), quercetin, quercetrin, allyl disulphide, allyl

– Study isolated seven compounds from the ethanolic extract of seeds of A. cepa: tianshic acid, N-trans-feruloyl tyramine, beta-sitosterol-3 beta-glucopyranoside-6′-palmitate, sitosterol, daucosterol, tryptophane, and adenine riboside.

Medicinal properties of onion

– Carminative, demulcent, diuretic, emmenagogue, expectorant, rubefacient, stimulant.

– Juice is disinfectant, rejuvinative, antispasmodic.

– Oil is considered stimulant, diuretic, and expectorant; bulb is emmenagogue, externally stimulant and rubefacient.

Parts used


Edibility / Nutrition

– Onions are used as both food and condiment.

– Peeled and eaten raw, powdered, juiced, infused or decocted as tea.

Folkloric traditional medicine remedies, benefits and uses of onion

– Bulb, cooked and mixed with coconut oil, used as ointment and applied to the abdomen to promote diuresis.

– Bulb is emmenagogue, stimulant, diuretic, expectorant; externally, is rubefacient.

– Mixed with common salt, is used for fever, catarrh, chronic bronchitis.

– Juice of onion, mixed with honey, ginger juice, and ghee, used as aphrodisiac.

– Bulb applied as cooling poultice for boils, bruises, and wounds; applied to the navel in dysentery and body heat.

– Juice is used like smelling salts for faintness, in infantile convulsions, headache, epileptic and hysterical fits.

– Juice dropped warm into ears to relieve earaches; applied hot to the soles of feet for convulsive disorders.

– Juice inhaled in epistaxis; applied to the eyes in dimness of vision.

– Mixed with mustard oil in equal proportions and applied to rheumatic pains and other inflammatory swellings.

– Onions are eaten to mitigate cough in phthsis.

– Mixed with vinegar for use in sore throat; cooked in vinegar for jaundice, splenic enlargement, and dyspepsia.

– In malarial fevers, eaten twice daily with two or three black peppers.

– Eaten with jaggery to stimulate growth in children.

– Decoction of onions used for strangury.

– Roasted onion mixed with sugar candy and cow’s ghee used as soothing demulcent and stimulant.

– Juice or slices of raw onion is applied to insect bites and stings or burns.

– Juice of the bulb mixed with mustard oil or coconut oil is used for rheumatic and inflammatory swellings.

– Onion and garlic juice used for nervousness, insomnia, and rheumatism: 3 tbsp daily.

– Juices of onion, garlic carrot, radish, garlic and lemon: Used for bronchitis, asthma.

– In Mexico, bulb is used as diuretic and vermifuge.

– Bulb taken internally to stimulate peristalsis. Also used for jaundice, hemorrhoids, and anal prolapse.

– In India, the onion is more popular as a medicine, used for fever, dropsy, catarrh, and chronic bronchitis. Mixed with common salt, used as a remedy for colic and scurvy; eaten raw as diuretic and emmenagogue.

Science proven health benefits and uses of onion


The bulb of AC has yielded kaempferol, B-sitosterol, ferulic acid, myritic acid and prostaglandins. Study showed the ethanolic extract of Allium cepa to possess antifertility activity through an anti-implantation mechanism rather than antiovulatory effect.

Hypouricemic / Antioxidant:

Study showed beneficial effects of Allium cepa and its major flavonoid on hyperuricemia and oxidative stress.


Study showed protective effect of the methanolic extract of AC bulb on ischemic and reperfusion-induced cerebral injury with reduced infarct size and attenuated impairment of short-term memory and motor coordination.

Vasorelaxant / Hypotensive:

Study showed the onion peel extract showed hypotensive and vasorelaxant effects which could be due to the extract quercetin content, antioxidant activity and inhibition of vascular smooth musch cell Ca++ influx.


Study showed onion peel extract inhibits ileum contractions without involving ß-adrenoreceptor, opioid receptor, nitric oxide production and potassium channels activation. Results suggests that the quercetin in the onion peel extract induces spasmolytic effect via calcium channels.

Antiplatelet activity:

In its raw form, onion is recognized to have antiplatelet activity from its pyruvate content. Study showed the effects of heating. Heating for 46 minutes completely suppresses in vitro antiaggregatory activity, For benefits, it is better for onions to be eaten raw or only moderately cooked. Extensive heating could result in pro-aggregatory effects.

Hemolytic Anemia:

Study confirmed onion poisoning in dogs causes hemolytic anemia.


Study showed A cepa had high superoxide-dismutase (SOD) activities in leaves and high peroxidase (P-ase) activity in all investigated organs.


Study showed a herbal fraction (ALC-O) from A cepa bulb inhibited histamine release and attenuated intracellular calcium levels Compound 48/80-induced rat peritoneal mast cells. The results show a promising anti-allergic profile that could be attributed to potential antihistaminic, anti-inflammatory and antioxidant activities.

Androgenic Activity:

Study showed freshly prepared onion juice significantly affected the sperm number, percentage of viability and motility.

Hypoglycemic Activity:

Study showed crude Allium cepa produced hypoglycemic effects, and can be used as a dietary supplement in the management of type 1 or type 2 diabetes mellitus.

Hair Growth / Alopecia Areata:

Study was done testing the effectiveness of topical crude onion juice in the treatment of patchy alopecia areata in comparison to tap water. Results showed the use of crude onion juice gave significantly higher results re hair re-growth than tap water. Results suggest it might be an effective topical therapy for patchy alopecia areata.

Nephroprotective / Cadmium-Induced Renal Dysfunction:

Study showed exposure to heavy metal Cd causes renal dysfunction and oral administration of onion could prevent cadmium’s adverse effects on renal functions.

Antimicrobial / Crude Juices:

Study evaluated the antimicrobial activity of crude juices of Allium ascalonicum, Allium cepa, and Allium sativum. Results showed strong antibiotic properties, and the complete absence of development of resistance from juices of Allium species merit consideration.

Natural Corrosion Inhibitor:

One major problem with industrial chill wastewater system is corrosion. Study evaluated the potential of using Allium cepa (onion) as a natural corrosion inhibitor. There was a reduction in weight loss for iron, nickel and copper, 92%, 88%, and 46%, respectively. Results demonstrate A. cepa as an effective corrosion inhibitor, primarily for iron.

Anti-Cancer / Anti-MDR (Multidrug Resistance) Action:

Study evaluated crude onion extracts and onion compounds (quercetin and propyl disulfide) in MDR human erythroleukemic and K562 parental cell line. There was a significant increase of apoptosis in the K562 cells while the cells experienced an increase in necrosis. The OE capacity to overcome MDR phenotype suggests anti-MDR action.

Antiproliferative / Effect on Adipocytes Via Fatty Acid Synthase Inhibition:

Study showed an ethyl acetate extract of onion had potent inhibitory effects on animal fatty acid synthase and could induce apoptosis in FAS over-expressing human breast cancer MDA-MB-231 cells. Since obesity is closely related to breast cancer, results suggest onion might be useful in preventing obesity-related malignancy.

Renal Protective on Cd-induced Renal Dysfunction:

Study on Wistar rats showed cadmium-induced renal dysfunction. Allium cepa prevented renal dysfunction, possibly as a results of its antioxidant properties with reduction of activity of ROS.


Study showed the protective role of raw Nigelia sativa, garlic, and onion against ethanol-induced gastric ulcers and gastric acid secretion. Raw or boiled Nigella sativa, garlic or onion significantly inhibited histamine stimulated acid secretion. Raw Nigella sativa and garlic showed a decrease in ulcer index. Boiling reduced the potency of garlic and onion.

Effect on Serum Testosterone / Seeds:

Study of seed extract showed increased serum testosterone levels in rats.

Antibacterial Against Staphylococcus aureus / Bulbs:

Various concentrations of methanol and aqueous suspensions of dried Allium cepa bulbs was screened against gram-positive Staphylococcus aureus. All suspensions showed inhibitory activity; the highest zone of inhibition was noted with the highest concentration of methanolic suspension.

Hypolipidemic / Benefits of Combination with Zinc Sulfate:

Study evaluated the hypolipidemic effect of onion extract in rats. Results showed hypolipidemic effects. The combined use of onion and zinc sulfate showed better effect than when used alone.

Immunomodulatory / Anti-Asthmatic / Allium cepa and Quercetin:

Study evaluated the effect of Allium cepa extract (AcE) and quercetin (Qt) on cytokine and on smooth muscle contraction in vitro and its therapeutic potential in a murine model of asthma. Results showed AcE and Qt have potential as antiasthmatic drugs, as they possess both immunomodulatory and bronchodilatory properties.

Antidiabetic/ Antilipidemic:

Study of Allium cepa in streptozotocin induced diabetic male Wistar rats demonstrated significant antidiabetic and antilipidemic activities. However, the mechanism of actions needs to be established.


Cultivated market produce.

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