Origin, Distribution and Composition
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 Purana. 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, possibly in the Iran-Pakistan region. It has been cultivated since ancient times in the Middle East and India. Its areas of cultivation indude 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.
Healing Power and Curative Properties
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.
Respiratory Diseases
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.
Tuberculosis
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.
Anaemia
Onions are noted for their easily assimilable iron content. They are, therefore, beneficial in treating anaemia.
Heart-Attack
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.1 It assists the functioning of the heart by correcting thrombosis besides reducing blood
cholesterol.