They sound similar and they share some of the same uses, but carnosine and carnitine have different compositions and functions. Carnosine and carnitine are available as supplements and carnitine is sometimes prescribed by physicians for some medical conditions. Consult with your health care provider before taking either as a supplement because they may interact with medications or cause side effects.
Carnitine and carnosine are both composed of amino acids, but from different ones. Carnitine is synthesized from lysine and methionine, while carnosine is made from alanine and histidine. The best sources for carnitine and carnosine are meat, dairy, poultry and fish, but they’re also available as supplements.
Carnitine burns fat by transporting fatty acids into the mitochondria inside cells, where the fats are converted into energy. It also transports toxic wastes out of the mitochondria. Large concentrations of carnitine are found in skeletal and cardiac muscle. Carnitine may help lower the pain associated with diabetic neuropathy and reduce the symptoms of an overactive thyroid.
Carnosine functions as an antioxidant in the brain, nervous system and skeletal muscle. While they don't know the exact way it works, it's also a chelating agent that removes excess amounts of zinc and copper from the body. Studies suggest is helps cataracts and improves wound healing.
Carnitine and carnosine may help slow the progression of age-related memory loss and Alzheimer’s disease. A study in the March 2011 edition of "PLoS One" by Carlo Corona et al. indicates that carnosine reduces the accumulation of amyloid tangles that cause Alzheimer’s. Carnitine slows the progression of memory loss by enhancing memory-related proteins, according to researched published by Xia Jiang et al. in the June 2011 edition of the "Journal of Neurochemistry." They also provide cardiovascular benefits, but in different ways. Evidence suggests that carnosine reduces the risk of atherosclerosis and lowers cholesterol, while carnitine relieves symptoms of angina and peripheral vascular disease.
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After eight weeks on carnosine, children with autism demonstrated significant improvements in behavior and communication, according to research conducted by Michael Chez, M.D., et al. and published in the November 2002 issue of the "Journal of Child Neurology." Dan Rossignol, M.D., reviewed previous research into the effectiveness of alternative and off-label treatments for autism. His results, published in the October 2009 edition of the "Annals of Clinical Psychiatry," gave carnitine a grade “B” and carnosine a grade of “C.” These grades indicate that both substances may improve symptoms related to autism, but the studies supporting carnitine were better designed and more reliable.
Even though carnitine and carnosine are both marketed as supplements to improve sports performance, there is no evidence that it works, according to the University of Maryland Medical Center. Carnitine is available in several forms, but you should avoid D-carnitine because it interferes with the natural form of L-carnitine.