The onion is a biennial herb, usually grown as an annual. All parts of onion produce a strong odour when crushed. It has a superficial root system, a very short flattened stem at the base, which increases in diametre as it grows. Leaves. are long. linear and hollow. A bulb is formed by the thickening of the leaf base when the plant reaches a critical stage. The fruit is a spherical capsule.
Onion is one of the oldest cultivated herbs. It was a popular food in ancient Egypt, where it is depicted on tombs as early as 3200 B.C. The Sanskrit word for onion is palandu which has been mentioned in the Garuda Puraoo. The great Indian sage Maharishi Atreya and Lord Dhanwantri have described the use of onions in great detail.
Onion is believed to have originated in Central Asia, possily in the Iran-Pakistan region. It has been cultivated since ancient times in the Middle East and India. Its areas of cultivation include India, Malaysia, Indonesia, Burma, the Philippines, China, Egypt, West and East Africa, tropical South and Central America and the Caribbean.
Onion has been used as a herbal remedy from time immemorial. The physicians of ancient Egypt prescribed onions in various diseases. Dioscoredes in the first century A.D. attributed many herbal remedies to them. In 1835, the onion and milk diet was advocated for dropsy. In 1912, a French physician, Dr. Dalache published a comprehensive article on onion cure.
It is high in food value, moderate in protein content and rich in calcium and riboflavin. There is considerable variation in the composition between different varieties, it also varies with the stage of maturity and the length of storage. Matured onions approximately contain moisture 86.6 per cent, protein 1.2 per cent, fat 0.1 per cent, fibre 0.6 per cent, minerals 0.4 per cent and carbohydrate 11.1 per cent, per 100 grams of edible portion. The carbohydrate is principally in the form of sugars. Its mineral and vitamin contents are calcium, phosphorus, iron, carotene, thiamine, riboflavin, niacin and vitamin C. Its calorific value is 51.
Onions contain an essential oil and organic sulphides. The scales of onion contain catechol and protocatechuic acid. The odour in onion is due to organic sulphur compounds, and is produced only when the tissues are cut or injured by enzyme action on a water-soluble amino acid. Heat or freeze-drying prevents the enzyme action, so that cooking produces a different odour, flavour and pungency.
Onions have great therapeutic value. They are stimulants and a mild counter-irritant. They have diuretic properties and promote the removal of catarrhal matter and phelgm from the bronchial tubes.
Onion has the property to liquify phlegm and prevent its recurrence. It has been used as a herbal remedy for centuries in colds, coughs, bronchitis and influenza. Three to four teaspoons of onion juice and honey, mixed in equal proportion can be taken daily in treatment of these conditions. It is one of the safest preventive medicines against common cold during winter.
Though it has been known for many years that onion possessed some germicidal properties, recently two Italian doctors, E. Cuboin and C. Moriandi found that the injection of its juice prevented the development of tuberculosis in animals in whom germs of tuberculosis were injected. Patients of tuberculosis have improved following adequate consumption of onions.
Onions are noted for their easily assimilable iron content. They are, therefore, beneficial in treating anaemia.
Recent researches in the West have established onion as an effective preventive edible against heart-attack. This benefit is due to the presence of its essential oil, aliypropyl disulphide, catechol, protocatechuic acid, thiopropiono aldehyde, thiocyanate, minerals and vitamins.
Dr. N. Radhakrishnan, Principal of the Trivandrum Medical College, and Dr. K. Madhavan Kutty have established, after seven years of research, that to get rid of the disorders due to coronary disease or blood pressure, one should take 100 grams of onion per day.! It assists the functioning of the heart by correcting thrombosis besides reducing blood cholesterol.
Onion is an effective remedy for cholera. About 30 grams of onion and seven black peppers can be finely pounded and given to the patient. It allays thirst, restlessness and also lessens vomiting and diarrhoea immediately. The addition of a little sugar to the recipe will increase its effectiveness.
Onions are highly beneficial in the treatment of the disorders of the urinary system. For burning sensation while passing urine, 6 grams of onion should be boiled in 500 grams of water. When the water is reduced to half, it should be cooled, strained and given to the patient. This relieves the burning sensation. Onion grated with water on a stone slab and mixed with 60 grams of sugar, is effective in treating retention of urine; it brings about free urination within a short time.
Onions are very effective in bleeding piles. About 30 grams of onions should be finely ground on a slab with water and 60 grams of sugar added to it. Taken twice daily this brings relief within a few days.
Latest research by Russian doctors have confirmed the bactericidal properties of onion. According to these findings, a person consuming at least one raw onion every day after thorough mastication, is protected from a host of teeth disorders. Chewing raw onion for 3 minutes is sufficient to kill all germs in the mouth. Toothache is often alleviated by placing a small piece of onion on the affected tooth or gum.
Onion is irritating to the skin and stimulates the circulation of blood in the mucous membranes. Warts sometimes disappear when rubbed with cut onions.
Cotton wool dipped in onion juice and put into the ear is a popular Russian remedy for noises in the ears. Heated juice dropped in the ear relieves earache.
Precautions: White onion is preferable to the red and yellow varieties. Onions should be taken with meals preferably raw, as fried or cooked onions are comparatively difficult to digest. For therapeutic purposes, it is advisable to use onion juice instead of the whole onion. Its being a stimulating and irritating food, one should avoid excess consumption.
Aphrodisiac: Onion is one of the most important aphrodisiac foods, second only to garlic. It increases libido and strengthens the reproductory organs. The white variety of onion should be peeled off, crushed and fried in pure butter. This mixture acts as an excellent aphrodisiac tonic if taken regularly with a spoon of honey on an empty stomach.
The immature and mature bulbs are either eaten raw or cooked. They are used in soups and sauces and for seasoning many foods. Small white leaf bases-before the bulbs are formed -are eaten raw, by themselves or in salads.