Last update: 1.5.2017.
Building and maintaining the body
Proteins are building blocks of body tissue but they can also serve as a fuel source for the body. Sometimes even existing muscle tissue is converted to energy. Proteins are essential nutrients. Proteins contain energy 4 kcal per gram. Proteins are needed for growth and maintenance of the body and it is the most common molecule in the body aside from water.
From nutritional point of view we look at proteins regards to what amino acids they contain. Amino acids are divided into two groups. There are essential amino acids and nonessential amino acids. Essential amino acids need to be obtained from food.
The essential amino acids also should be obtained in certain ratios and sources of protein are usually evaluated on this need.
Not getting enough protein can lead to mental retardation among other things.