Can We Define Dietary Requirements of Dispensable Amino Acids?

• Published in: The Journal of nutrition Vol. 151; no. 2; pp. 275 - 276
• Main Author: Matthews, Dwight E
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2021; American Institute of Nutrition
• Subjects: Amino acids; Amino Acids - administration & dosage; Amino Acids - biosynthesis; Diet; Dietary Proteins - metabolism; Fatty acids; High protein diet; Hogs; Humans; Nitrogen; Nutritional Requirements; Proteins; Synthesis; IAA; IAAO; DAA; UNU; EAR
• ISSN: 0022-3166; 1541-6100; 1541-6100
• DOI: 10.1093/jn/nxaa363

All of us in nutritional sciences learn early on that there are amino acids that can be synthesized de novo in our bodies, the dispensable amino acids (DAAs), and there are indispensable amino acids (IAAs) that we cannot synthesize and, thus, must consume in adequate amounts in our diet. The nitrogen (N) balance technique was initially used to define the estimated average requirement (EAR) and provide the RDA both for total protein and for individual IAAs. The EAR for protein was determined by placing test subjects on diets of high-quality protein where intakes ranged from deficient to surfeit, and N balance was measured. The EAR is the breakpoint where increasing protein intake causes N balance to go from negative to zero or positive. The EARs for individual IAAs can also be determined in the same manner, but in this case, subjects are placed on diets of crystalline amino acids where the test IAA's intake is varied from low to high.