[Proteins and amino acids: features and fulfillment of requirements with Latin American diets]

Diets must supply enough nitrogen and essential amino acids to satisfy human needs. A diet's protein quality is associated to its digestibility, amino acid composition, protein concentration and dietary and preparation factors that enhance or reduce essential amino acid and protein bioavailability. Dietary energy intake also affects the utilization efficiency of dietary proteins. Protein quality of Latin American diets varies between countries and between socioeconomic groups in a given country. Most poor and lower-middle income persons consume diets with strong predominance of vegetable proteins. These diets are usually bulky, with relatively low protein concentration and energy density, and sometimes do not provide enough of one or more essential amino acids. In some countries and in some population groups, over 50% of the dietary proteins are of animal origin. This may be a risk factor of cardiovascular disease. Protein quality of Latin American diets, however, can be improved by modifying the proportions of some foods in order to achieve amino acid complementation, increase protein concentration and, in some instances, increase digestibility. Examples of diets that are satisfactory for preschool children and adults are given. Nevertheless, improvement of the overall nutritional quality of the diets is of foremost importance, so that they may provide the energy and all essential nutrients required for humans.