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Our bodies are
made up of billions of cells, which contain protein. Throughout our
lives cells wear out and are replaced. All the material for new cells
comes from food. The main nutrient involved in the building of new
cells and replacing of worn cells is protein.
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Composition
of Proteins
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Proteins are made up
of small units called amino acids. The amino acids, which the
body cannot make, are known as essential amino acids. Adults need
8 and children need 10 essential amino acids.
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Proteins are broken
down into amino acids in the digestive system. Amino acids
are smallest units of Protein. They can then be used to build
up different proteins for the formation of new cells in the body.
Amino acids are made up of the elements carbon, hydrogen, oxygen
and nitrogen.
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Classification
of Proteins
Proteins are
classified into two groups: HBV and LBV
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LBV
FOODS
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High
Biological Value
Low
Biological Value
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HBV
FOODS
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Sources
of Proteins
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The
functions of proteins are:
 Growth
of new cells such as skin hair and blood.
Repair
of damaged cells.
Production
of heat and energy.
Manufacture
of important body chemicals such as enzymes, hormones and antibodies.
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The RDA of protein
depends on your body weight. For every kilogram of body weight
one gram of protein per day is needed, e.g. if you weigh 60 kg
you need 60 g of protein per day.
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Retarded
growth in children.
Worn
out cells are not replaced. This prevents healing of wounds.
Malfunction
of various organs due to hormone / enzyme deficiency.
Susceptibility
to disease, due to lack of antibodies.
In
severe cases, as in underdeveloped countries, protein / calorie
deficiency diseases such as kwashiorkor and marasmus may occur,
particularly in children.
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ACTIVITIES
1. Weigh yourself. Calculate how much protein you
need every day.
2. What are the advantages of using plant foods as a source
of protein?
3. Check the nutrition information on a variety of groceries.
4. Find out the protein content per 100 grams for a variety
of foods.
5. What food has the highest protein content?
6. What food has the lowest protein content
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