Nutrition Facts

The word protein is derived from – and the meaning of protein is “of first importance”. Proteins are indeed the most important in human nutrition. Proteins are complex organic substances containing nitrogen in its molecule. Proteins differ from carbohydrates and fats form the fact that they contain nitrogen. The nitrogen content in protein is approximately 16%. Proteins contain carbon, hydrogen, oxygen, nitrogen and sulphur in its molecule in varying amount. Some of the proteins contain phosphorus, iron (hemoglobin is classical example of protein containing iron) and sometimes other elements. Proteins are very large molecules with very high molecular weight (largest organic molecule) and made up of many smaller units called amino acids. About 20% of adult body weight is made up of protein.
Functions of Proteins:
Proteins are required for the following major functions:

1. Proteins are required for growth and building of body and proteins are body building materials. This is very important for the growing children and infants. But this is very small component of function of protein in compare to the maintenance proteins do everyday continuously.
2. Repair and maintenance of body tissue is the most important and extensive function of proteins. Proteins are required for healing of wounds, any damage of tissue. Any ware and tear is repaired by proteins which is a constant process.
3. Maintenance of plasma oncotic pressure is also function of proteins. Without normal plasma oncotic pressure there will be no perfusion and diffusion of chemicals.
4. Proteins can supply energy of 4 kcal of energy per gram if there is inadequate supply of calorie, but supply of energy (calorie) is not primary function of protein.
5. Synthesis of important substances like antibodies, immunoglobulin, hemoglobin, hormones, enzymes, plasma proteins, coagulation factors and many more. All of these are proteins. They perform very important functions. Antibodies and immunoglobulins fight with bacteria and other foreign invaders and protect body from diseases. Hemoglobin carries oxygen and supply to tissues which is vital for survival. Hormones are very important for normal functioning of humans. Enzymes are required for all the chemical reactions that take place in the body. Plasma proteins maintain oncotic pressure and also supply proteins where it is required. Coagulation factors are required for control of blood loss from injury or cut surface.

Other than the above mentioned functions, proteins also have some minor functions. The bactericidal (killing of bacteria) action of white blood cells is hampered if there is protein deficiency. Cell mediated immunity is also hampered in protein deficiency states. Both of the above conditions are seen in protein energy malnutrition (kwasiorkar and marasmas).