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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.
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Functions of Protein
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Proteins are necessary
structural integrity of cells and growth of the body.
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They are required for the
formation of enzymes, digestive juices, hemoglobin and
hormones.
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Required for the protection of
the body against infection.
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Proteins help in the transport
of oxygen, nutrients and drugs.
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Protein is required for tissue
repair.
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They are needed for the
production of milk proteins during lactation.
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To replace the daily loss of
body proteins.
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Proteins are also a source of
energy. Each gram of protein provides 4 kcal
There are two sources of
proteins
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Animal Sources
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eggs, milk, mutton, fish, poultry, liver
etc.
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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.
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Protein
Deficiency
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Weakness.
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Anemia.
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Protein energy malnutrition -
kwashiorkor and marasmus.
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Delayed wound and fracture
healing.
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Decreased resistance to
infection because antibody formation is decreased.
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Sprue syndrome.
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