As the different sources of protein have diverse properties and physiological effects due to significant intrinsic chemical and structural differences, it is not possible to predict the nutritional effect of protein solely on the basis of proximate measures such as total nitrogen. The true nutritional value of dietary protein, irrespective of source, is only realised after ingestion (Robinson, 1990). Amino acids are the building blocks of proteins, and are required for numerous functions within the human body. During digestion and absorption, protein molecules are denatured and broken down to these amino acids by digestive enzymes. The free amino acids are absorbed through the gastro-intestinal wall into the bloodstream, where they are either used for energy, or reassembled into the different proteins required in the human body