The Indian, Egyptian, Chinese and Roman used the herbs from the ancient civilization for treating diseases. Recently researchers also started conducting studies in the medicinal plants. Usually the herbs have no major harmful side effects but preferably one herb at a time must be used for a particular disease.
The scientific name of onion is Allium cepa. They belong to the same family of the garlic, the Allium family. Onion is the oldest herb cultivated and used. It is mainly used in the tropical countries. The other names of onion are piyaz in Hindi and Bengali, kando in Gujarathi, eerulli in Kannada, gandah in Kashmiri, ulli in Malayalam, kanda in Marathi, piaja in Orriya, ganda in Punjabi, vengayam in Tamil, neerulli in Telungu.
Onion produces strong odour and pungent taste. It contains essential oils and organic sulphides. The principal chemical constituent in onion is the sulphur containing volatile oil, allyl propyl disulphide. This is the chemical that give onion its taste and pungent odour. This volatile oil is the main culprit in causing eye irritation and tears while preparing onion.
If uncooked onion is eaten the volatile oil is excreted through the lungs and saliva, giving a characteristic odour to the breath. This does not happen if cooked onion is eaten since this volatile oil evaporates when exposed to heat.
Onion is known for its nutritional value and for the utility as herbal medicine in our country. It has moderate amounts of protein, fat, fibre and good amounts of calcium, phosphorous and potassium. It has high content of moisture, which is 86.8 percent for 100 gms of the edible portion. The calorie content is comparatively less. 100 gm of onion gives about 50 kcal of energy. Apart from onion as such, even the stalk is edible. The stalk contains good amount of carotene and iron.
Onions and its stalks have power to prevent and treat certain illness. Onions are stimulant and mild counter irritant. Crushed raw onion can be applied on the forehead to get relief from headaches.
Red small onions can be used as an expectorant. Crushed small onions should be mixed with sugar candy and kept for some time. The juice from the onion sugar candy preparation helps to liquefy phlegm and prevent its recurrence. 3 – 4 tsp. of juice has to be taken in intervals that will relieve the cough and soothens the throat.
Eating raw onion help to reduce cholesterol levels because they increase levels of high-density lipoproteins. It is advisable to include raw onions in the salads daily. It helps in coronary heart disease, thrombosis, and blood pressure. This use of onion is controversial. There are conflicting reports are available about this property.
Onions are beneficial in the treatment of urinary disorders. For burning sensation while passing urine, boil 100 gms of onion in 600 ml of water. When the volume reduces to half, it is ready for consumption. If onion and sugar mixture is taken, it gives good relief for retention of urine.
Sulphur compounds present in onion will help to prevent the growth of cancer cells. Onions are also used in the treatment of anaemia, bleeding piles and teeth disorders.
Even the onion stalk is useful as herbal medicine. Onion stalks juice is good for the treatment of anaemia.
The disadvantages of onion are it can lead to migraine in some people and flatulence. Eating raw onion can also lead to bad breath.