Valine serves as an excellent example of why amino acids are the building blocks of life. It is a component of many proteins and is essential to humans and many animals. Valine acts as a stimulant. It is a branched-chain amino acid (BCAA) and should be taken with leucine and isoleucine for improved muscle metabolism, tissue repair, and nitrogen balance. Valine is also involved in mental clarity and muscle coordination. Valine deficiency leads to a negative hydrogen balance in the body.
With leucine and isoleucine, valine is associated with "maple syrup urine" disease. This occurs when these three amino acids are not metabolized and are excreted through the urine, which has a smell similar to maple syrup. Afflicted infants will initially appear normal, but are unable to suck or swallow within a few days. If they survive the resulting seizures, they run the risk of severe mental retardation.