Protein provides 4 calories per gram. It is chemically unique from fat and carbohydrate because it contains nitrogen. Plant-based proteins do contain essential amino acids but not all nine. Vegetarians, that eat strictly plant foods, should eat a large variety of plant foods daily to make sure they get all of the nine essential amino acids. Even though soy foods are plant-based foods, it is the only plant food that contains all nine essential amino acids.
Protein is important for growth and development.
It is a part of every body cell. The body needs a constant supply of protein to repair body cells as they wear out. Protein is important to the organs, muscles, nervous system, blood vessels and skeleton. Children and adolescents require protein for normal growth and development. Proteins are also part of enzymes, such as antibodies that help protect from diseases and viruses.