According to the British nutrition foundation, protein is necessary for the growth and repair of the body cells. Proteins provide structure to the cells and are important in the maintenance of cells within the body.
Proteins are the source of energy, like fats and carbohydrates. They are the constituents of hormones, enzymes and antibodies. Once an individual has reached adulthood, proteins are mainly involved in the repair and replacement of worn-out, or damaged, tissues.
According to Raw Food Explained, there is a relationship between the protein in the milk of lactating animals and the rate of growth of their infants. The percentage of protein content is higher in the milk during the early stages of development, and decreases over time.