Amino acids are the building blocks of proteins. Proteins form many of the structures of the body and also serve as enzymes, which catalyze biochemical reactions. Some amino acids serve as neurotransmitters or precursors to neurotransmitters. Certain amino acids are essential, meaning the body cannot manufacture them and they must therefore be obtained through diet. Other amino acids can be manufactured by the body. Amino acids analysis can be performed on blood samples but urine specimens are usually preferable. Amino acids analysis not only reveals insufficiencies of amino acids, but also identifies need for specific vitamins and minerals. Abnormalities on amino acid analysis can result from, among other things, inadequate dietary protein, maldigestion or malabsorption. Amino acids test results often shed light on impaired detoxication, yeast overgrowth, inflammatory disorders, food and chemical sensitivities, cardiovascular disease, depression, fatigue, anorexia, learning disabilities and neurological disorders.