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Diet & Nutrition

How Important is Protein in Our Diet? The word "protein" is derived from the Greek word "proteios", which means primary or holding first place. It is the most important cell constituent. Protein is present in all cells of the body. The level of proteins varies in different tissues of the body like muscles contain about 20% of the protein where as in blood plasma it is 7%.
In the body, protein plays an important role in the biochemical, biophysical and physiological processes. Protein is required for almost all functions of the body as well as the structural integrity of the cells. The structural integrity of the cell is maintained by the protein component present in the cell wall. Gene - the basic code of life, enzyme - the catalyst used in different chemical activities in the body and hormones - the substances, that control and stimulate organs contain protein. Protein is the major component of the disease producing organisms like virus, protective substance like antibodies and treatment medications like antibiotics. Proteins are very complex nitrogenous organic compounds built up of smaller units called amino acids. There are about 21 amino acids in the body. Most of the amino acids can be synthesized in the body but few can not be synthesized and to be provided in the food. Since it is essential to be provided in food for normal functioning of the body, they are called essential amino acids. There are eight essential amino acids and they are isoleucine, leucine, lysine, methionine, phenylanine, tryptophan, threonine and valine. In infants, apart from these amino acids histidine is essential to be provided in food. It is wrong to think that since non-essential amino acids can be synthesized in the body, their inclusion in the diet has no value. Some non-essential amino acids can be synthesized only from other essential amino acids so if they are not supplied in the diet some of the essential amino acids will have to be used for their synthesis.

Functions of Protein

Proteins are necessary structural integrity of cells and growth of the body.

They are required for the formation of enzymes, digestive juices, hemoglobin and hormones.

Required for the protection of the body against infection.

Proteins help in the transport of oxygen, nutrients and drugs.

Protein is required for tissue repair.

They are needed for the production of milk proteins during lactation.

To replace the daily loss of body proteins.

Proteins are also a source of energy. Each gram of protein provides 4 kcal

There are two sources of proteins

Animal Sources - eggs, milk, mutton, fish, poultry, liver etc.
Plant sources - pulses and legumes, cereals, nuts, beans, oilseeds etc.

Class I proteins are derived from animal sources since they contain all essential amino acids needed by the body. Egg protein is considered as the reference protein because of its high biological value and digestibility. Class II is derived from pulses and legumes, cereals, vegetables, nuts and they do not contain all the essential amino acids they lack in one or more amino acids. Individually they may be lacking in one or more amino acids but combinations make it available of all amino acids. For example cereal and pulse combination is better than consuming only pulse or only cereal.

Protein Deficiency

Weakness.

Anemia.

Protein energy malnutrition - kwashiorkor and marasmus.

Delayed wound and fracture healing.

Decreased resistance to infection because antibody formation is decreased.

Sprue syndrome.