Carnosine

Carnosine (beta-alanyl-L-histidine) is a dipeptide of the amino acids beta-alanine and histidine. It is highly concentrated in muscle and brain tissues.

A small 2002 study reported that carnosine improved on a measure of socialization and receptive vocabulary in children with autism. Improvement in this study could have been due to maturation, educational interventions, placebo effect, or other confounds that were not addressed in the study design. Supplemental carnosine may increase corticosterone levels, which can explain the hyperactivity sometimes seen in high doses. Researchers in Australia, Britain, and Russia have also shown that carnosine has a number of antioxidant properties that may be beneficial.

Carnosine has been proven to scavenge ROS (radical oxygen species) as well as alpha-beta unsaturated aldehydes formed from peroxidation of cell membrane fatty acids during oxidative stress. It can oppose glycation and it can chelate divalent metal ions.

While a small number of studies have produced evidence of beneficial effects of N-acetyl carnosine in treating cataracts of the eyes, these and other ophthamological benefits have not been proven. Britain's Royal College of Ophthamologists assert that neither safety nor efficacy have been sufficiently demonstrated to recommend its use as a topical treatment for cataracts.

Typical vegetarian diets are thought to be lacking in carnosine, but whether this has a detrimental effect on vegetarians is controversial.