What is the role of protein in the diet?

Protein plays a crucial role in the diet primarily because it helps build and repair tissues. This function is essential for growth and maintenance of the body's structures, such as muscles, organs, skin, and hair. Proteins are made up of amino acids, which are the building blocks necessary for synthesizing new cells and repairing damaged ones, making them vital for growth, especially in children, teenagers, and pregnant women.

In addition to tissue repair and growth, proteins support the production of enzymes and hormones, contribute to immune function, and serve as an energy source when carbohydrate and fat stores are low. Thus, the correct answer effectively highlights the fundamental role of protein in maintaining health and facilitating various bodily functions.