Proteins build, maintain and replace your body tissues. Your muscles, organs and immune system are composed mainly of proteins.
Proteins are made up of long chains of basic units called amino acids. There are 22 different amino acids. 13 of these can be synthesized within your body. The remaining 9 amino acids cannot be produced within your body. You have to include them in your diet. Hence, these are called as essential amino acids.
The protein that you eat is processed by your body into a variety of specialized protein molecules like cardiac muscles, hemoglobin, etc. The best sources of protein are poultry, beef, eggs, fish, dairy products, seeds, nuts and legumes.
Proteins from animal sources, like milk and meat, are called complete proteins. This is because all nine essential amino acids are present in these. Most vegetable proteins are called incomplete proteins as one or more of the essential amino acids are lacking in these. Vegetarians should therefore consume a range of protein-rich vegetable foods.
Children need to intake approximately 1 gram of protein for every kilogram of their body weight. As they grow up, their protein requirement will keep on increasing till they reach adulthood.
Content Source: http://kidshealth.org/en/kids/protein.
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