Many foods contain protein (say: PRO-teen), but the best sources are beef, poultry, fish, eggs, dairy products, nuts, seeds, and legumes like black beans and lentils. Protein builds, maintains, and replaces the tissues in your body. (Not the tissues you blow your nose in!
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One of the biggest misconceptions about protein is how much of it the body needs. Many weight trainers believe that they need 1 to 2 g per pound of body weight. This is much higher than the average recommendation. For an average person, 0.8 to 1 g per kilogram of body weight is optimal. (Kilograms can be figured out by dividing your weight by 2.2). It is true that athletes need more protein when exercising at intense levels for long periods of time, but it should still be in the 1.2 to 1.8 g/kg range.
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Protein is found throughout the body—in muscle, bone, skin, hair, and virtually every other body part or tissue. It makes up the enzymes that power many chemical reactions and the hemoglobin that carries oxygen in your blood. At least 10,000 different proteins make you what you are and keep you that way. The Institute of Medicine recommends that adults get a minimum of 0.8 grams of protein for every kilogram of body weight per day (or 8 grams of protein for every 20 pounds of body weight).
https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/protein/
A few amino acids (known as the essential amino acids) must come from food. 1  Animal sources of protein tend to deliver all the amino acids we need.  Other protein sources, such as fruits, vegetables, grains, nuts and seeds, lack one or more essential amino acids.
https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/protein/
When you eat foods that contain protein, the digestive juices in your stomach and intestine go to work. They break down the protein in food into basic units, called amino (say: uh-MEE-no) acids. The amino acids then can be reused to make the proteins your body needs to maintain muscles, bones, blood, and body organs.
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Likewise, red beans won't give you everything you need, but red beans and rice will do the trick. The good news is that you don't have to eat all the essential amino acids in every meal. As long as you have a variety of protein sources throughout the day, your body will grab what it needs from each meal.
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Protein is one of the three main macronutrients, which also include fat and carbohydrates. Macronutrients are nutrients that the body uses in large amounts. They are all-important, and have specific purposes.
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Protein is built from building blocks called amino acids. Our bodies make amino acids in two different ways: Either from scratch, or by modifying others. A few amino acids (known as the essential amino acids) must come from food. Animal sources of protein tend to deliver all the amino acids we need.
https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/protein/
Your body uses the protein you eat to make lots of specialized protein molecules that have specific jobs. For instance, your body uses protein to make hemoglobin (say: HEE-muh-glow-bin), the part of red blood cells that carries oxygen to every part of your body.
http://kidshealth.org/en/kids/protein.html
Protein is used by the body for many different reasons, but one of the most important ones is its function as the building blocks for muscle. This fact leads many weightlifters and athletes eating huge amounts of it every day.
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what does protein do to our body
Protein makes up the enzymes that power many chemical reactions and the hemoglobin that carries oxygen in your blood.