Protein is needed for growth because it is an essential nutrient that plays a crucial role in building and repairing tissues. It is made up of amino acids, which are the building blocks of proteins. These amino acids are necessary for the growth and development of muscles, bones, organs, and other body tissues. Protein also helps in the production of enzymes, hormones, and antibodies, which are essential for various bodily functions. Therefore, protein is an important nutrient required for growth.