Onion is native to southwestern Asia but presently is grown throughout the world, mostly in the temperate zones.Onion is among the world’s oldest cultivated vegetable and were probably knownin India, China and the Middle-East. Ancient Egyptians regarded the spherical bulb as a symbol of the universe, and its name is derived from the Latin unus, meaning “one.”
Onion was introduced by Romans to Britain and then reached to Native Americans, who added it to their stews. Onion has lots of curative powers, throughout the centuriesit has been used in folk medicine for varied ailments as colds, earaches, laryngitis, animal bites, burns, and warts.The medical documents of Charaka Samhita (way back in the 6th century BC) mention onion as a medicinal plant. A Greek physician from the 1st century AD (Dioscorides) documented the vegetable’s medicinal uses.Onions have been a part of the French Paradox –and are thought to be responsible for the low incidences of heart disease among the French despite of their high-calorie diet. The most common types of onion are yellow onion, sweet onion, white onion, red onion, green onion, leeks and shallots (known as pran in Kashmiri.)
One medium onion gives 44 calories only but provides a considerable dose of vitamins, minerals and fiber. This vegetable is particularly high in vitamin C (7.4 mg, i.e. 12% of RDA), B vitamins, including folate (19ugi.e 5 % of RDA)and pyridoxine (B6) — which play key roles in metabolism, red blood cell production and nerve function.Being a good source of potassium and magnesium (10mg),ithelps in regulating muscle and nerve function, making protein , bone and DNA. The calcium content of onion is also good (23mg i.e 2% of RDA),calcium being main nutrient for bone health makes it useful for healthy bones.
Some Swiss researchers state that a white compound present in onion called as GPCS can reduce bone loss.Onion consumption has a beneficial effect on the bone density of women older than 50 years.According to the Arthritis Foundation, quercetin in onions inhibits the activity of inflammation causing compounds namely leukotrienes, prostaglandins, and histamines in osteoarthritis and rheumatoid arthritis, hence, onion intake was also found useful in treating of joint pains.
Onions are also rich in manganese that offers protection against cold and flu. According to some American studies onion has proved useful for asthmatic patients and those who suffer from allergic rhinitis.Onion juice also helps to reduce earache,for that purpose heat up the onion at 450F for 15 minutes, until tender, cool and extract some of the juice, and pour a few drops into the infected ear(under supervision of doctor).Sulphur in onions stimulates the production of a protein named glutathione, an antioxidantthat helps to improve the health of the lens of the eye. It reduces risk of glaucoma, macular degeneration and cataracts. Some studies also reveal that onions can inhibit the growth of normal eye flora and prevent corneal haze.
Allium and allyl disulphide are two phytochemicals found in onions, which are converted into allicin after ingestion. Some studies state that Allicin, has properties to fight cancer and diabetes,it reduces the stiffness of blood vessels and lowers blood pressure. Chives, leeks, and shallots have similar benefits.Quercetin is another antioxidant present in onion that fights inflammation.Various studies, say red onion can prove helpful in destroying breast and colon cancer, because of high levels of Quercetin and anthocyanin.The flavonoids and organo-sulphur compounds in red onions can also help to keep your heart healthy. Onions, when combined with garlic, have better effects. The two, together, tend to be effective antidepressants, painkillers, anticoagulants, and anti-inflammatory.The content of thio-sulfinates make it a natural blood thinner, hence reduces the risk of heart attack and stroke.Onions also prevent the blood platelets from sticking each other, which causes clotting and eventually, heart attacks.
Onion is also rich in inulin, a fiber required for healthy gut; however thiosulphates in onion can sometimes cause harm to these friendly bacteria.Oligo fructose (a sub group of inulin) is also present in onion which is found to prevent and treat different types of diarrhea.The phytochemicals in onions cut the risk of gastric ulcers.Copper present in onion aids in better brain communication, also a sulphur compound namely, di-n-propyl trisulphide improves memory impairment. This compound gets deteriorated by heating hence for this purpose raw onion is beneficial.
We need potassium rich diet for normal cellular function, fluid balance, nerve transmission, kidney function and muscle contraction. The 100gm of onion has 146mg potassium (i.e 4% of RDA). The onion’s characteristic is due to sulfur-rich volatile oil; the release of this oil during peeling or chopping brings tears to the eyes.Raw onions have higher levels of organic sulfur compounds that offer numerous benefits. One study has found that outer layers of onion flesh has the highest concentrations of flavonoids – hence, remove as little of this part as possible while peeling the vegetable. Not only the vegetable, even the essential oil from onions has benefits. The oil has antiseptic and antibacterial properties.Last, but not least, onions promote hair growth because of a sulphur compounds and keratin required for stronger and thicker hair. These sulphur compounds stimulate collagen production which aids in production of healthy skin cells and hair growth. Applying onion to hair and scalp increases blood supply to hair follicles and enhances hair growth.
The authors are Associate professors at Division of FST, Skuast-K [email protected]