Protein quality refers to the bioavailability, digestibility, and amino acid composition. It can be quantified based on the amount and profile of essential amino acids (EAAs) and the true ileal digestibility of the EAAs in the protein. In evaluating the quality, the protein density (the number of total calories ingested to achieve an intake of the daily requirement of all EAAs) should be taken in account, and the non-protein components (the amount and nature of fat carbohydrate and fiber), as well as the content of micronutrients. Meat proteins have better quality and, like all animal-based protein foods, occupy an important place in a healthy eating pattern.
The recent IAAO method in determining protein and amino acid requirements in humans suggests these values: 1.2 g/kg in adults, 1.6 g/kg in children, 1.7-1.8 g/kg in pregnant women, 1.2-1.3 g/kg in older women, 1.7-2.2 g/kg for young bodybuilders, 1.8 and 1.5 g/kg for active male and female adolescents, 1.7-1.9 g/kg for lactating women and up to 2.0 g/kg/d or more in the case of acute or chronic disease. This recent application is novel and has significant implications for dietary protein intake recommendations globally.
As a more pertinent recommendation than minimum RDA, an acceptable macronutrient distribution range (AMDR) for protein has been set at 10-35% on daily energy intake. For healthy adults with ideal body weights, the recommended protein intake based on macronutrient considerations has thus been set at 1.4-2.0 g/kg/d.
