Types Of Vitamins is very important question for every doctor and science student.Vitamins play an important role in the physiological functions of the body. Most of them have been identified chemically, and many have been synthesized and produced on a large scale.Vitamins are widely distributed in plant and animal tissues, most foodstuffs containing one or more of them, but none contains them all, and few are rich in them.
Only small amounts of vitamins are needed to maintain bodily health, but the old idea that they behaved as catalysts and their presence, in however small a quantity, was satisfactory, is now known to be incorrect. A definite daily intake is required depending on the body weight, the calorie intake, and the metabolic rate of the individual, and although the daily amount needed is in some instances quite small, in others it is comparatively large.
Before the identity of the various vitamins was discovered it w;m necessary to determine their potency by animal experiments and consequently the dosage was referred to in units, but now that most of them are available as pure chemical substances it has become increasingly common to give the dose in milligrams. With vitamins A and D, however, units are still employed.
You Must Know Fat-Soluble Vitamins And Other Different Types Of Vitamins In order To Understand Their functions In Human Body
Pure Vitamin A can be obtained in the form of pale yellow-coloured crystals. It is formed from a provitamin carotene, a substance which forms the colouring matter in carrots and is present in many other vegetable tissues.
Sources. Fish liver oils are a rich source; milk, cream, cheese, butter. Carotene, which can be converted into Vitamin A in the body, is present in carrots, green leafy vegetables, also in certain fruits, such as apricots, peaches, prunes, and tomatoes. When carotene is the source of Vitamin A in the diet a greater allowance must be given, as it is less easily absorbed from the intestine than Vitamin A itself.
Physiological Action and Uses. Vitamin A plays an important part in maintaining the normal, moist condition of the delicate mucous membrane lining of the eyes, nose, mouth, respiratory tract, bladder, and genital organs, the integrity of which is believed to aid in resisting infection, hence A has been called the anti-infection vitamin. It plays an important part in the formation of the dentine and enamel of the teeth, and is also essential for the production of visual purple in the retina which is necessary for seeing properly in semi-darkness.
A deficiency leads to:
1) Retarded growth in children.
- Increased liability to respiratory diseases such as the common cold, and bronchitis as well as infection of other organs lined by epithelial tissue as mentioned above.
- Hardening of epithelium of the conjunctiva and cornea leading to xerophthalmia (dry eye), which, in severe degrees of deficiency, may lead to total blindness.
- Night blindness (defective vision in reduced illumination).
- Dryness and scaliness of the skin.
Vitamin A and carotene are stable to heat if oxidizing agents are jinl present, and ordinary cooking methods do not destroy the A present. Grilling or roasting for long periods may produce a considerable loss.
It is the antirachitic or calcifying vitamin, In concerned with the metabolism of calcium and phosphorus.various forms of Vitamin D arc known, but only two are of practical importance. Both are derivatives of sterols—-complex chemical substances occurring in vegetable and animal fats—which when exposed to (0 ultra-violet light acquire the power of preventing and rickets.
Physiological Action and Uses.
Vitamin D is essential for the absorption and retention of calcium and phosphorus, and maintaining the balance of these substances in the blood and tissues, and thus influences the formation of the bony skeleton. If the intake is deficient calcium is not deposited in the bones leading to:
- Rickets in children, the early signs of which are, profuse sweating, especially of the head; restlessness at night and general weakness. Later there is enlargement of the epiphyses- and curving of the long bones; enlargement of the ribs at the costo-chondral junction (‘ rickety rosary’) ; softening of the posterior bones of the skull (craniotabes); ‘ bossing ’ of the frontal and parietal bones (hot- cross bun head) and late closing of the fontanelle. Dentition is delayed and there is defective formation of dentine and enamel in both milk teeth and the permanent teeth.
- In adults softening of the bones (osteomalacia) in pregnant women, which frequently results in pelvic, deformity.
- Dental decay, especially in children and pregnant women.
Vitamin D has been employed in the treatment of various other conditions, such as respiratory affections, chilblains, arthritis, and skin diseases.Few common foods are rich in Vitamin D, consequently dietary supplements are frequently essential, especially during childhood and pregnancy.
The term Vitamin E is applied to a number of substances, known as tocopherols, which are present in the embryos of seeds and in green leaves, wheat germ and lettuce being good sources. Vitamin E is stable in the presence of heat, but is readily oxidized, especially by rancid fats.
Physiological Action and Uses.
In animals a deficiency of Vitamin E interferes with normal gestation, the foetus dying early in the period, and being reabsorbed. A less severe deficiency may permit, the young to proceed to term, but they develop a flaccid muscular paralysis. In the male animal there is complete loss of reproductive power.
Although its value in the human being has not been definitely established, there is evidence to show that it is of value in the treatment of certain types of abortion, in various neuromuscular disorders, such as amyotrophic lateral sclerosis and muscular dystrophies. It is usually administered either in the form of wheat-gorm oil or the more concentrated a-tocopheryl acetate. The hum.111 requirements of Vitamin E are not completely known.
Vitamin K is also described as the anti-haemorrhage vitamin, and represents a number of natural and synthetic substances, which, are derivatives of naphthoquinone. The human requirements are not definitely known Sources. Most green leaves contain Vitamin K, alfalfa (lucerne) and spinach being especially rich sources.
Physiological Action and Uses.
Although the exact action of Vitamin K has not yet been fully demonstrated it is known to be associated with the normal function of the liver and with the formation of prothrombin, essential for the coagulation of the blood. Bile salts are necessary for the absorption of Vitamin K, hence in obstructive jaundice absorption is deficient. Certain water-soluble derivatives are actively absorbed in the absence of bile.
As a deficiency of Vitamin K causes a low prothrombin level in the blood there will be a lengthened clotting time and a tendency to prolonged bleeding following injury. A dietary deficiency of Kt s rare, the common cause being imperfect absorption from the intestine due to deficiency of bile or to rapid passage of the contents. It may also occur following diseases of the liver when function is impaired. The therapeutic administration of Vitamin K is employed to prevent bleeding associated with a low prothrombin level such as occur in hepatic disease, obstructive jaundice, and in haemorrhage of the newborn.
The Water-soluble Vitamins Are Also Best Types Of Vitamins
Vitamin B1, the antineuritic vitamin, plays an important part in the functions of the body cells, and especially those of the central nervous system. Its chemical name is aneurin or thiamin; it can he isolated from rice polishings or yeast, but is now prepared synthetically. It is fairly stable, but is destroyed by long heating, or Seating above 120° C. and by the presence of alkali.It is present in the outer coating and germ of cereals, yeast, egg yolk, pork, liver, pulses, and nuts.
Physiological Action and Uses.
A large intake of carbohydrates increases the need for B1( whilst fat reduces the need for it. A raised metabolic rate increases the need for B1, as also do pregnancy and lactation. B1 is needed for the last stages of carbohydrate metabolism as it prevents the accumulation of lactic and pyruvic acids which interfere with tissue respiration.
Nicotinic Acid also has an important part in enzyme formation to assist tissue respiration. It is a white crystalline substance, stable to heat. Deficiency leads to a disease known as pellagra, characterized by a skin rash, especially in those parts exposed to light, wrists, ankles, and neck. Early symptoms of deficiency are weakness, loss of appetite, indigestion. Later the mouth is ul-. cerated, the tongue sore and scarlet in colour, the characteristic dermatitis is followed by derangements of the nervous system leading to paralysis and mental changes leading to insanity. In addition to the treatment of these symptoms, nicotinic acid has been used for Vincent’s infection of the mouth.
Vitamin C or ascorbic acid is a colourless crystalline substance which occurs in green vegetables and fruits. It is rapidly oxidized, particularly in the presence of heat, consequently the prolonged cooking of fruits and vegetables leads to considerable loss.
Physiological Actions and Uses. Vitamin C is another important factor in tissue respiration. As a prolonged deficiency leads to scurvy it is often known as the antiscorbutic vitamin. Early signs of scurvy are weakness and lassitude, pain in the joints, swollen and tender gums followed later by ulceration and bleeding of the gums, loosening of the teeth, and haemorrhage under the skin and into internal organs. Mild deficiencies lead to swollen and tender gums, decreased resistance to infection, and delayed healing of wounds and fractures.
Vitamin C is widely used in the treatment of various affections. There is an increased demand during pregnancy and lactation, also in the presence of infection such as tuberculosis, typhoid, pneumonia, whooping cough, rheumatic fever, etc. Large doses are beneficial in rheumatism, in the healing of wounds and fractures, skin affections, especially those caused by the toxic effects of heavy metals, such as gold, bismuth, arsenic, and mercury. It also counteracts the toxic symptoms following such drugs as cinchophen and the sulphonamides, and plays a part in the treatment of certain haemorrhagic affections. Vitamin C helps in the formation of red- blood corpuscles, and has been used in the treatment of anaemias.
(citrin or hesperidin) is closely associated with Vitamin C, and is found in citrus fruits, and appears to be a factor in maintaining the resistance of the capillary walls. It is not yet decided what its exact function is, some maintaining that it has a specific effect, others claiming that it acts in conjunction with Vitamin C, It has been used for the treatment of certain haemorrhagic diseases, the purpuras, but its true role has yet to be evaluated.