Health Vitamins and Minerals Guide

Aspartic acid, also known as L-aspartate, is thought to help promote a robust metabolism, and is sometimes used to treat fatigue and depression. Aspartic acid plays an important role in the citric acid cycle, or Krebs cycle, during which other amino acids and biochemicals, such as asparagine, arginine, lysine, methionine, threonine, and isoleucine, are synthesized.

As its name indicates, aspartic acid is the carboxylic acid analog of asparagine. It is non-essential in mammals, and might serve as an excitatory neurotransmitter in the brain. Note that aspartic acid has an a-keto homolog, oxaloacetate, just as pyruvate is the a-keto homolog of alanine.

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Biological Value (%) is calculated as retained nitrogen/ absorbed nitrogen X 100. To illustrate how this provides an evaluation of protein quality, consider a scenario in which all amino acids in a protein are used for protein synthesis. Here, retained and absorbed nitrogen would be equal and the biological value would equal 100%.

Conversely, if some indispensable amino acids are not available in the protein source, protein synthesis is impaired and some unused nitrogen is excreted from the body, retained nitrogen decreases relative to absorbed and the biological value drops below 100%. Consequently, some foods such as complete protein foods (e.g., milk) have high biological values (95%), while incomplete protein foods are much lower (Le., corn [60%1). (more…)