The consumption of high biological value proteins is an essential component for a healthy diet and for the optimal production of antibodies [141]. Proteins, or amino acids, deficiency is known to impair immune function and increase susceptibility to infectious diseases. In fact, some amino acids modulate both metabolism and immune functions [142]. Most reviews indicate an important role for amino acids in the immunity by regulating the activation of T lymphocytes, B lymphocytes, natural killer cells and macrophages; cellular redox state, gene expression and lymphocyte proliferation. Evidence shows that the dietary integration of specific amino acids in humans with malnutrition and infectious diseases improves the immune status, thus reducing morbidity and mortality [141]. Glutamine is the most abundant and versatile amino acid present in the body and its level in the immune cells is similar to, or even greater than, glucose in both health and disease conditions.