PROTIENS

Chapter 5

                                                    PROTIENS

Now let us talk about the third important component of our diet. I.e. protein. 15 – 20% of our body is made up of proteins. It is a nutrient consisting of big molecules called amino acids. Proteins are needed for the prefect functioning of all living cells. Since our body cannot produce proteins by itself, we need a continuous supply of proteins from the food we eat. Protein is constantly being composed and decomposed in our body. It contains nitrogen and sulphur, which are essential elements of our body.

The protein in the food we eat is different from the protein used by our body. The proteins present in the food we eat are decomposed into their components, i.e. the amino acids. These amino acids pass into the walls of the intestines and are recomposed to form proteins which will be used by our body.  

There are different types of proteins depending upon the arrangements of amino acids in them. There are two types of amino acids. Those which are synthesised in our body are called non-essential amino acids. Those which are not synthesised in our body are called essential or indispensable amino acids. We have to get the essential amino acids from the food we eat. Our body needs both types of amino acids to recompose the protein needed. Hence the type of protein we eat is more important than the amount of protein. If the structure of the amino acids in the protein we eat is similar to that in our body then less amount is needed. Food stuffs that lack the essential amino acids are poor source of proteins since the body is not able to use the amino acids obtained, converting proteins into fats and carbohydrates. Hence a balance of essential amino acids is required for the total use of all proteins entering the body.

If we take in excess of proteins our body stores it in the same way as it stores fat. When there is a deficiency of fat and carbohydrates in the body, this stored protein is burnt to produce energy. One gram of protein produces 4.2 kilo calories of energy. When the muscle proteins are decomposed there is a tremendous loss of weight. Hence the stored protein is used only in case of emergence.

Role of proteins in our body:

1.                    Transport proteins:

 eg. Haemoglobin transports oxygen.

2.                    Motor proteins: Eg. Myosin in muscles causes movement of muscles

3.                    Storage proteins: eg. Ferritin stores iron.

4.                    Structural proteins: eg. Collagen in tendons and muscles gives the body firmness and dimensional stability.

5.                    Enzymes and hormones control different processes in the body.

6.                    Anti-bodies stop diseases from attacking our body.

7.                    Transmission of nerve impulses.

A deficiency in protein in the body can lead to physical and mental underdevelopment. The person is attacked by diseases easily.

Too much of protein can cause damage to kidneys and metabolism.

          If we take a balanced diet of wheat, milk, milk products, legumes, maize and pulses we can get all the essential amino acids our body needs.