IIT JEE Vitamins | JEE Vitamin a Structure and Function

Definition of Vitamins

The organic compounds needed for the function of normal metabolic process and for the growth and health of human beings and animals. These compounds, though required in very small amounts, are very vital to the life process are termed as Vitamins.

Vitamins may be defined as a group of biomolecules (except fats, carbohydrates and proteins) most of which cannot be produced by the body and must be supplied in small amounts in diet to perform the specific biological function for the life, growth and health of humans beings and animal organisms.

Example: Vitamin A, Vitamin K, Vitamin B etc.
 

Importance of Vitamins

Vitamins plays an important role in keeping good health of human beings. But vitamins neither supply energy nor help in building tissue of the cell but their deficiency in the body can cause serious diseases.

As we know that vitamins cannot be synthesized by our body, therefore, it must be supplied through food. Plants can synthesize all vitamins but animals can synthesize very few vitamins. Some vitamins are present in the nature also, like vitamin D which is either supplied by food or may be produced in the skin by the irradiation of ergosterol with ultraviolet light.

Human body can also synthesize some vitamin A from carotenes, some components of vitamin B complex and vitamin K are synthesized by microorganisms present in the intestinal tract.
 

Sources of Vitamins

The main sources of vitamins are our food which consists of milk, butter, green vegetables, meat, eggs etc. Vitamins are also synthesized in the laboratory and are available in the form of tablets, capsules, which can be taken orally or as with injection as prescribed in the case of vitamin deficiency.

Classification of Vitamins

Vitamins are complex organic molecules. There are about 25 vitamins known  till today. They are broadly classified into the following two categories: Water soluble and Fat Soluble

• Water Soluble Vitamins: These vitamins are water soluble. These vitamins must be supplied regularly in diet because they are regularly excreted in urine and cannot be stored in our body.

Some important water soluble vitamins and their characteristics, sources and their deficiency diseases are given below:

1. Vitamin B₁: Its chemical name is Thiamine, and commonly called as Aneurin or Antineuritic Vitamin.

Characteristics: It is insoluble in oils and fats, and can be destroyed by heat above 313 K.

Source: It is found in pulses, nut, whole cereals, rise polishing, yeast, egg yolk, milk, green vegetables and in fruits.

Deficiency Diseases: Their deficiencies cause Beriberi disease, in which legs get paralysed and cause loss of appetite.

Fig. structure of Vitamin B1 (Thiamine)

2.  Vitamin B6: Its chemical name is as Adermin or Pyridoxine. In fact it is a mixture of pyridoxine, pyridoxal and pyridoxamine.

Characteristics: It is also insoluble in oil and fats.

Source: It is found in rice bran, yeast, molasses, meat, fish etc.

Deficiency Disease: It causes specific dermatitis in rats, pellagra and anaemia in human beings, affects central nervous system, causes general weakness, convulsions, weakness, nervousness, insomnia and irritability.

Fig. Structure of vitamin B6

3.  Vitamin B12: Its chemical name is as cyanocobalamin. It contains cobalt.

Characteristics: It is insoluble in oils and fat.

Source: It is found in milk, eggs and liver of ox, sheep, pig etc.

Deficiency Disease: It causes pernicious anaemia, inflammation of tongue and mouth.

Fig. Structural detail of Vitamin B12

4.  Vitamin C: Its chemical name is Ascorbic acid and commonly called as Antiscorbutic vitamin.

Characteristics: It is destroyed by cooking and prolonged exposure to air. To avoid the loss, vegetables riches in vitamin C must be cooked in closed pan and pressure cooker. Vitamin c increases resistance of the body towards diseases, maintains healthy skin and helps cuts and abrasion to heal properly.

Source: It is found in citrus fruits, lemons, leafy vegetables, chillies, sprouted pulses and germinated grains.

Deficiency Disease: It causes scurvy, pyorrhoea.

Fig. Structural detail of Vitamin C

5.  Vitamin B2: Its chemical name is Riboflavin or Lactoflavin.

Characteristics: It is sensitive to light but stable to heat. It is essential for growth and health of animals.

Sources: It is found in milk, yeast, green vegetables, meat, liver, kidney etc.

Deficiency Diseases: Its deficiency retards growth, and cause general inflammation of tongue, dermatitis and cheilosis.

Fig. Structural detail of Vitamin B2

• Fat Soluble Vitamins: These vitamins are the oily substance and not readily soluble in water, however they are soluble in fat. Excess intake of these vitamins is harmful for health and may cause hypervitaminoses.

Some important fat soluble vitamins and their characteristics, sources and disease caused by their deficiency is given below:

1. Vitamin A: Its chemical name is Retinol and also called as Bright Eye Vitamin. Carotenoids are precursors of vitamin A.

Characteristics: It is stable to heat. It promotes growth and vision in animals and increase resistance to diseases.

Sources: It is present in milk, butter, eggs, fish liver oil, rice polishing, green vegetables etc.

Deficiency Disease: Its deficiency causes Xerophthalamia, night blindness and xerosis.

Fig. Structure of vitamin A or Retinol

2. Vitamin D: Its chemical name is ergocalciferol and commonly called as Antirachitc Vitamin or Sunshine Vitamin.

Characteristics: It is also stable to heat and resistant to oxidation. It controls calcium and phosphorus metabolism.

Sources: It is present in fish liver oils, butter, milk, eggs, liver and meat. Daily dose of vitamin D in human body is about 0.025 mg.

Deficiency Diseases: Its deficiency causes rickets in children and oestromalacia in adults.

Fig. Structure of Vitamin D or Ergoclciferol

3. Vitamin E: It is a mixture of four vitamins called α, β, ϒ, ᵟ- tocopherols.

Characteristics: It is stable to heat and oxidation.

Sources:  Its sources are vegetable oils (like wheat germ oil, cotton seed oil, soybean oil, peanut oil etc.), eggs, milk etc. Its daily dose to human body is about 5mg.

Deficiency Disease: Its deficiency causes sterility, increased fragility of RBCs and molecular weakness.

​Fig. Vitamin E structure.

4. Vitamin K: Its chemical name is phylloquinone and commonly called as Antihaemorrhagic Vitamin. And it is a mixture of two vitamins called K1 and K2.

Characteristics: It is sensitive to light and alkali.

Sources: Vitamin K1- alfalfa, leafy vegetables and spinach. Vitamin K2- occurs mainly in bacteria.

Deficiency Disease: Its deficiency cause haemorrhage, it lengthens the time of blood clotting.

Some vitamins are neither water soluble nor fat soluble. Example of such a vitamin is Vitamin H (biotin) . It is found in liver, yest, kidney and milk and its deficiency causes Dermatitis, loss of hair and paralysis.

Lack of particular vitamin cause a specific deficiency disease. Multiple deficiencies caused by lack of more than one vitamin are called Avitaminoses. It is quite common in human beings.
 

Q1. What are the vitamins for skin and for the control of loss of hair?

Sol. Vitamin H is used to prevent the loss of hair and to prevent skin from getting dried and from disease Vitamin A is used.
 

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