Carnosine has become the latest craze in supplements - long used by bodybuilders seeking to increase strength and size, the nutraceutical also is used by people looking to stave off dementia and visible signs of aging.
The U.S. government has even funded clinical trials that examine how the supplement affects people with bipolar disorder, schizophrenia and Gulf War illness.
Carnosine consists of two attached peptides - beta-alanine plus histidine - and is found in abundance in muscle and brains.
Sellers retail the supplement as a way to increase muscle, burn fat, rid the body of DNA-damaging free radicals and boost cognition.
Scientists debate whether supplementing with carnosine provides any true health benefits, since most of it is broken down soon after you swallow it, Jerry Brainum wrote in Iron Man Magazine in 2008.
Carnosine in supplements does reach muscle, according to a study published in August from Nestle, one of the world's largest food and beverage companies.
The placebo-controlled double blind clinical study included 31 men who were fed carnosine supplements daily for eight weeks. The men didn't take the supplement for the next eight weeks and the researchers found increased carnosine in the men's muscles. The total amount of carnosine, rather than a daily dose, predicted how much of the substance made it into muscles.
The researchers did not test any effects on the increased carnosine in muscle in the paper published in the journal Amino Acids.
Carnosine increases in boys as they reach puberty, though the dipeptide is also found in girls, according to research from Ghent University, Belgium.
Carnosine also plateaus in young adulthood, decreases in middle age, but remains stable through old age, the researchers concluded.
The survey included 263 volunteers who ranged in ages from 9 to 83 years old along with 25 identical and 22 fraternal twin pairs.
The research appeared in the journal Amino Acids in December.
Researchers are also interested in how carnosine affects brain function. Researchers in Georgetown University are currently recruiting veterans who have Gulf War Syndrome, a complex chronic disorder suffered by nearly a quarter of a million people who served in the 1991 Gulf War.
Researchers previously found that carnosine could protect against multiple neurological conditions including children with autism.