L-carnosine, not to be confused with L-carnitine , is a substance manufactured in the human body, made by combining the amino acids alanine and histidine. The highest levels of carnosine are found in the brain and nervous system, the lens of the eye, and skeletal muscle tissue. Its exact function in the body is not known.


The body manufactures carnosine from common dietary proteins, and for this reason there is no daily requirement of this substance.

Therapeutic Dosages

Among advocates of carnosine, there is a controversy regarding whether the proper dose is 50–150 mg per day or nearer to 1,000 mg daily. However, until carnosine has actually been shown to have any medical benefits, this argument cannot be settled.

Therapeutic Uses

Carnosine is widely marketed as an anti-aging nutrient. However, while there are a large number of studies that hint carnosine might help slow various aspects of aging, the quality of these studies is as yet far too low to provide any reliable evidence for benefit. 1-20

There is some actual evidence that carnosine may be helpful for children with autistic spectrum disorders . 21 In a double-blind, placebo-controlled trial , 31 children with autism were given either carnosine (400 mg twice daily) or placebo for a period of 8 weeks. The results showed that children given carnosine showed significant improvements compared to those given placebo. While this was too small a trial to allow definitive conclusions, it is definitely promising.

Like numerous other substances, carnosine has antioxidant properties , meaning that it neutralizes dangerous, naturally occurring substances called free radicals. 22,23

Free radicals are thought to play a role in many illnesses, and on this basis many antioxidant substances have been studied for potential health-promoting properties. The best evaluated are beta-carotene , vitamin E , and vitamin C . However, despite massive amounts of research, these supplements have yet to live up to their apparent promise. Some websites claim that carnosine acts as an antioxidant in a unique way, fighting the “second wave” effects that follow attacks by free radicals. However, there is no meaningful evidence to support this theory or the hypothesis that such an effect, if it truly exists, would provide any health benefits.

Other weak evidence hints that oral carnosine might be helpful for cataracts , 24-29wound healing , 30Alzheimer’s disease and other forms of dementia, 31-50 diseases of the digestive tract, 53 and various forms of heart disease. 51,52

It has been hypothesized that taking supplements of the amino acid alanine can raise carnosine levels in muscle, and, in turn, enhance sports performance . However, the one published study where this was tried failed to report benefit. 54

Safety Issues

The use of carnosine has not been associated with any significant side effects. However, the body deploys a range of enzymes, called carnosinases, to break down carnosine. There may be a reason for the presence of these enzymes, and overcoming them by providing large amounts of supplemental carnosine could conceivably cause harm in some as-yet unrecognized way. Maximum safe doses in young children, pregnant or nursing women, or people with severe liver or kidney disease have not been established.