Vitamins are a group of organic compounds that are required by the body in very small amounts for normal growth, development, and maintenance of health. They are essential nutrients because they help regulate many physiological and biochemical processes occurring in the body. Although vitamins do not provide energy like carbohydrates and fats, they are necessary for the proper utilization of these nutrients.
Classification of Vitamins
Vitamins are classified on the basis of their solubility in water or fats. Depending on their solubility, vitamins are divided into two major groups: fat-soluble vitamins and water-soluble vitamins.
1. Fat-Soluble Vitamins
Fat-soluble vitamins dissolve in fats and oils and are absorbed along with dietary fats in the intestine. These vitamins can be stored in the liver and fatty tissues of the body for long periods.
- Since they are stored, they do not need to be consumed every day.
- The fat-soluble vitamins include Vitamin A, Vitamin D, Vitamin E, and Vitamin K.
- These vitamins perform several important functions such as maintaining healthy vision, supporting bone growth, protecting cells from damage, and helping in blood clotting.
a) Vitamin A (Retinol): Vitamin A is essential for maintaining normal vision, especially in dim light. It also helps keep the skin and epithelial tissues healthy and supports the immune system.
Sources: Carrot, spinach, milk, butter, egg yolk, fish liver oil.
Deficiency Disease: Night blindness.
b) Vitamin D (Calciferol): Vitamin D helps the body absorb calcium and phosphorus, which are necessary for the development and maintenance of strong bones and teeth.
Sources: Sunlight, fish liver oil, egg yolk, fortified milk.
Deficiency Disease: Rickets in children and osteomalacia in adults.
c) Vitamin E (Tocopherol): Vitamin E acts as an antioxidant and protects body cells from damage caused by free radicals. It also contributes to the proper functioning of muscles and the reproductive system.
Sources: Vegetable oils, nuts, seeds, green leafy vegetables.
Deficiency Disease: Muscular weakness and nerve disorders (rare).
d) Vitamin K (Phylloquinone): Vitamin K plays an important role in blood clotting. It helps produce proteins required for the coagulation of blood and prevents excessive bleeding from injuries.
Sources: Green leafy vegetables, cabbage, broccoli, spinach.
Deficiency Disease: Delayed blood clotting and excessive bleeding.
2. Water-Soluble Vitamins
Water-soluble vitamins dissolve readily in water and are not stored in significant amounts in the body. Any excess amount is usually excreted through urine.
- The water-soluble vitamins include the Vitamin B-complex group and Vitamin C.
- These vitamins are mainly involved in energy metabolism, nervous system function, red blood cell formation, and maintenance of healthy tissues.
a) Vitamin B Complex: The Vitamin B group consists of several vitamins that work together in various metabolic processes. They help the body convert food into energy and support the proper functioning of the nervous system.
Sources: Whole grains, cereals, legumes, nuts.
Deficiency Disease: Beriberi.(B12 )
b) Vitamin C (Ascorbic Acid): Vitamin C is essential for the formation of collagen, a protein that helps maintain healthy skin, gums, blood vessels, and connective tissues. It also promotes wound healing and increases resistance to infections.
Sources: Orange, lemon, amla, guava, tomato.
Deficiency Disease: Scurvy.
Functions of Vitamins
Vitamins perform a wide variety of functions in living organisms. Although required in small amounts, they are involved in numerous biological activities that are essential for maintaining life and health.
1. Regulation of Metabolism: Many vitamins act as coenzymes or components of coenzymes that assist enzymes in carrying out biochemical reactions. They help regulate metabolic pathways involved in the breakdown and utilization of carbohydrates, proteins, and fats.
2. Growth and Development: Vitamins are necessary for normal growth and development of bones, teeth, muscles, and body tissues. They ensure proper physical development, particularly during childhood and adolescence.
3. Maintenance of Vision: Vitamin A is essential for healthy eyesight. It forms part of the visual pigments present in the retina and enables the eyes to adapt to changes in light intensity.
4. Formation of Blood Cells: Certain vitamins, particularly Vitamin B₁₂ and folic acid, are required for the production and maturation of red blood cells. Their deficiency may lead to anaemia.
5. Strengthening the Immune System: Several vitamins help the body defend itself against infections and diseases. They support the immune system by promoting the production and activity of protective cells.