Amino acid

Amino acids are organic compounds comprise mainly from the elements carbon (C), hydrogen (H), oxygen (O), and nitrogen (N), although other elements are found in the side chains of certain amino acids. Because of their biological significance, amino acids are important in nutrition and are commonly used in nutritional supplements, fertilizers, and food technology. Industrial uses include the production of drugs, biodegradable plastics, and chiral catalysts.

Branched chain amino acids
The branched chain amino acids (BCAAs): (BCAAs) are leucine, isoleucine and valine.

Long neutral amino acids
The long neutral amino acids (LNNAs) are tyrosine, tryptophan, threonine, methionine, valine, isoleucine, leucine, histidine and phenylalanine.

Essential amino acids
The essential amino acids in humans are those which cannot be made by the body, and must be taken in from food (diet). The nine essential amino acids are phenylalanine, valine, tryptophan, threonine, isoleucine, methionine, histidine, leucine, and lysine.

ME/CFS
Several studies have found altered serum levels of amino acids in ME/CFS patients, including reduced branch chain amino acid intermediates (i.e., 2-Hydoxyisocaproic acid (HICA)), reduced levels of BCCAs and LNNAs during exhaustion and reduced levels of long chain amino acids (LNAAs) during recovery. One study found reduced urinary BCCA excretion.