Amino acids are molecules that play a central role as the building blocks of proteins. Twenty amino acids exist in nature, and when they bind together they form long chains and the complex three-dimensional structures of proteins. However, when amino acids bind together to form shorter chains they become something more than the sum of their parts but something less than fully formed proteins. L-carnosine is one such small chain, and though more recently discovered it may hold some significance for the human body.
Features
L-carnosine --- the L in the name derives from the fact that the molecule is in a "left-handed" configuration --- is a combination of two main amino acids -- beta-alanine and histidine. These amino acids are chained together by what is known as a peptide bond. Beta-alanine is a nonessential amino acid, meaning that it's manufactured within the body, but you can consume histidine from animal protein and dairy. You can also take fully formed carnosine as a supplement. In the body carnosine is highly concentrated in the muscles, kidneys, heart, skin and brain tissue. The exact biological role of carnosine isn't completely understood yet, but it may have something to do with overall cell health and functionality.
Antioxidants
Carnosine is a natural antioxidant, meaning it is a molecule capable of inhibiting the effects of an oxidation reaction. The metabolic process by which the cells convert sugar and fatty acids into a usable form of energy is one kind of oxidative reaction. This process can produce free radicals that start a chain reaction that ultimately causes damage or death in the cells. Carnosine may have free radical scavenging abilities and also protects enzyme activity in the tissue.
Neurological Effects
Carnosine is widely used as a dietary supplement --- taken 500 mg a day --- and has potentially positive neurological effects. Various studies have tested whether carnosine can assist in the treatment of several neurological conditions, including Alzheimer's disease, autism, brain ischemia, Parkinson's disease, Down's syndrome and epilepsy. Carnosine may work by improving functionality and responsiveness in patients --- for example, by reducing cognitive deterioration associated with Down's syndrome --- but these results are preliminary and must survive further testing before they become significant. Many effects may prove weaker in subsequent studies.
Aging
In fibroblasts --- a type of cell found in the connective tissue of animals --- carnosine can reduce telomere damage. A telomere is a sequence of repetitive DNA at the end of a chromosome that protects the chromosome from deterioration or from fusion with neighboring chromosomes. During chromosome replication, the telomeres progressively shorten over time. Carnosine reduces this shortening by delaying cell senescence, which is the aging of cells. For this reason some researchers think that carnosine may contribute to the extension of life.
