Classification of Vitamins

A living being or system is made up of different complex biomolecules like proteins, carbohydrates, nucleic acid, lipids, etc. Carbohydrates and proteins are essential and important constituents of our food. These molecules interact with each other to formulate the molecular logic of life processes. Additionally, simple molecules like vitamins and mineral salts also play an extremely important role in the functions of organisms. 

Vitamins

Vitamins are basically the accessory food factors that are required in our diet. These vitamins are certain organic compounds that are required in small amounts but their absence or deficiency can lead to specific diseases. Most of the vitamins that are required are not synthesized in our bodies. Plants can synthesize almost all the vitamins, hence the term essential food factors. Nevertheless, there are some bacteria in the gut that can produce some required vitamins. 

The term vitamin was previously taken from ‘Vitamine’. This was derived from the combination of vital + amine due to the early identification of amino groups in compounds. However, over time, it was observed that most of the compounds did not have amino groups, and hence the letter ‘e’ was dropped and the term ‘vitamin’ came to into usage.

All required vitamins are generally available in our diet. Distinct vitamins belong to various different chemical classes. Thus, it is tough to define all vitamins on the basis of their structure. We generally regard them as organic compounds essential to be present in the diet to perform specific biological functions. These functions are important for the normal maintenance and optimal growth and health of an individual organism. 

Vitamins are categorized by alphabets A, B, C, D, E, etc. Some of these are further named into sub-groups, for example, Vitamin B₁, B₂, B₆, etc. 

Classification of Vitamins

Vitamins can be classified into two groups. This classification is on the basis of the vitamins solubility in water or fat.

• Fat-Soluble Vitamins

These are the vitamins that are soluble in fat and oils but are completely insoluble in water. Examples of these vitamins are Vitamins A, D, E, and K. These are stored in the liver and fat-storing adipose tissues. 

• Water-Soluble Vitamins

These are the vitamins that are soluble in water but are insoluble in oils and fat. B group vitamins and Vitamin C are soluble in water. These vitamins must be supplied regularly in the diet as they get excreted through urine. Except for Vitamin B₁₂, water-soluble vitamins cannot be stored in our bodies. 

Note: Vitamin H or biotin is neither soluble in water nor in fat.

Important Vitamins, their Sources, and their Deficiency Diseases

Sr. No.	Name of the Vitamin	Sources	Deficiency Diseases	Solubility
1	Vitamin A	Milk, fish liver oil, carrots, and butter	Night Blindness, Xerophthalmia (hardening of the cornea of the eye)	Fat
2	Vitamin B1 (Thiamine)	Green vegetables, yeast, milk, and cereals	Beri beri (loss of appetite, retarded growth)	Water
3	Vitamin B2 (Riboflavin)	Milk, egg-whites, liver, kidney	Digestive disorders, burning sensation of skin and Cheilosis (they are the fissuring at the corners of the mouth and lips)	Water
4	Vitamin B3 (Niacin)	Milk products, fish, meat, eggs, cereals, mushroom, guava, etc.	Pellagra, diarrhoea	Water
5	Vitamin B6 (Pyridoxine)	Yeast, milk, egg yolk, cereals, and grams	Convulsions	Water
6	Vitamin B12	Meat, fish, egg, and curd	Pernicious anemia (RBC deficient in hemoglobin)	Water
7	Vitamin C (Ascorbic acid)	Citrus fruits, green leafy vegetables, and amla	Scurvy (bleeding gums)	Water
8	Vitamin D	Exposure to sunlight, egg yolk, and fish	Osteomalacia (soft bones and joint pain in adults) and Rickets (bone deformities in children)	Fat
9	Vitamin E	Vegetable oils like sunflower oil, wheat germ oil, etc.	Muscular weakness and Increased fragility of RBCs	Fat
10	Vitamin K	Green leafy vegetables	Increased blood clotting time	Fat

Sample Problems

Question 1: What are vitamins? Give examples.

Answer: 

Vitamins are basically the accessory food factors that are required in our diet. These vitamins are certain organic compounds that are required in small amounts but their absence or deficiency can lead to specific diseases. For example, Vitamin A, C, D, E, etc. 

Question 2: How are vitamins classified?

Answer:

Vitamins are classified on the basis of their solubility in water or fat.

Fat-Soluble Vitamins are soluble in fat and oils but are completely insoluble in water. Examples of these vitamins are Vitamins A, D, E and K. These are stored in the liver and fat-storing adipose tissues.

Water-Soluble Vitamins are soluble in water but are insoluble in oils and fat. B group vitamins and Vitamin C are soluble in water. These vitamins must be supplied regularly in the diet as they get excreted through urine. Except for Vitamin B₁₂, water-soluble vitamins cannot be stored in our bodies. 

Question 3: Note down all the deficiency diseases caused by the B group vitamins.

Answer:

Name of the vitamin	Deficiency Diseases
Vitamin B1 (Thiamine)	Beri beri (loss of appetite, retarded growth)
Vitamin B2 (Riboflavin)	Digestive disorders, burning sensation of skin and Cheilosis (they are the fissuring at the corners of the mouth and lips)
Vitamin B3 (Niacin)	Pellagra, diarrhoea
Vitamin B6 (Pyridoxine)	Convulsions
Vitamin B12	Pernicious anaemia (RBC deficient in haemoglobin)

Question 4: Which Vitamin is not soluble in water or oil?

Answer:

Vitamin H or biotin is neither soluble in water nor in fat.

Question 5: Which vitamin is responsible for the coagulation of blood? Mention its sources. 

Answer: 

The vitamin responsible for the coagulation of blood is Vitamin K. It can be found in green leafy vegetables. 

Question 6: The deficiency of which vitamin causes night blindness. What must be included in the diet to avoid it?

Answer:

Deficiency of Vitamin A causes night blindness. Milk, fish liver oil, carrots and butter should be included in the diet to avoid it.

Question 7: Which vitamin do you get by exposure to sunlight? Note down the deficiency diseases of this vitamin.

Answer:

You get Vitamin D by exposure to sunlight. The deficiency diseases of this vitamin are Osteomalacia (soft bones and joint pain in adults) and Rickets (bone deformities in children).