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.

Types
Branched-chain amino acids (BCAAs): leucine, isoleucine and valine

Long neutral amino acids (LNNAs): tyrosine, tryptophan, threonine, methionine, valine, isoleucine, leucine, histidine and phenylalanine

ME/CFS
Several studios have 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.