Amino Acid Score

The Amino Acid Score (PDCAAS) evaluates protein quality by comparing essential amino acids in a food source to a reference protein. It factors in protein digestibility and identifies the limiting amino acid, the one present in lower quantities than required by the reference. This metric is vital for assessing the nutritional efficiency of both plant and animal proteins.

The formula calculates the percentage of the limiting amino acid relative to the reference protein, multiplied by the protein's digestibility. For example, if soybeans have 85% of the required tryptophan per gram of protein and 100% digestibility, their PDCAAS would be 0.85. A maximum score of 1.0 indicates a complete protein with ideal amino acid proportions.

This tool is useful for nutritionists, food industries, and researchers classifying foods or designing balanced diets. It also supports nutritional labeling and supplement analysis. Caution: results depend on accurate amino acid data and correct reference protein selection.

Note that PDCAAS has limitations, such as underestimating high-quality proteins. For low-digestibility foods (e.g., certain plants), consider using DIAAS (Digestible Indispensable Amino Acid Score), which evaluates each amino acid's absorption individually.