Dietary proteins are digested to their component amino acids . Aminoacids derived from dietary proteins are used as a material to build, and rebuild, the host's own proteins, and they also serve as a 'last resort' energy substrate. The body proteins are renewed at a different rate. Amino acids are contained in animal and plant proteins. Due to the different composition of animal and plant proteins, eating no animal products at all may lead to nutrient deficiencies such as these of vitamin B12, calcium, iron, and zinc. Similarly to energy requirements, protein requirements change during life cycle (Table 21.1). Increased demand for amino acids (dietary protein) is associated with pregnancy, lactation and the adolescent growth spurt.
|
|
