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L- Carnitine

Biosynthesis

The body makes L-Carnitine from iron, vitamin B-1 (thiamine), vitamin B-6 (pyridoxine or P5P) and the amino acids lysine and methionine, and requires the presence of adequate levels of vitamin C.

Function

Unlike true amino acids, carnitine is not used for protein synthesis or as a neurotransmitter. Its main function in the body is to help transport long-chain fatty aids across the mitochondrial membrane — for which it's essential.

  • Energy, detox, fat management
    • In the mitochondria, fatty acids are burned to produce NADH, a major source of energy. Carnitine thus increases the use of fat as an energy source. This prevents fatty buildup, especially in the heart, liver and skeletal muscles
    • Acetyl groups are another end product of fatty acid oxidation; most are then further oxidized in the Krebs cycle, but others produce detoxification metabolites in the cytosol — after being shuttled, by L-carnitine, back through the mitochondrial membranes to the cytosol.
    • Carnitine reduces the health risks posed by poor fat metabolism associated with autism and other developmental disorders. It has the ability to lower blood triglyceride levels, aid in weight loss and improve muscle strength in people with neuromuscular disorders.
    • There's a diagram of all this on the Carnipure site.
  • "Brain food"
    • Acetyl-L-carnitine contributes to synthesis of choline acetyl transferase, which declines with age and probably impairs brain function. Two other mechanisms also appear to protect neurofunction:
      • maintenance of cellular membrane stability
      • restoration of other membrane changes associated with aging

Sources

  • Biosynthesis:
    • main production is in liver and kidney.
    • requires lysine, methionine, vitamin C, iron, vitamin B6, and niacin.
    • involves a series of enzymatically catalyzed reactions.
    • "The requirement for all these essential nutrients implies that malnutrition has a highly negative impact on L-Carnitine biosynthesis." (Carnipure)
  • Dietary sources — Carnipure lists concentrations. The highest is lamb, then venison.
  • The proportion made endogamously is approximately 10% of the body's daily requirement.

Supplemental Forms

  • Carnitor is the patented, prescription form of L-carnitine. Unfortunately, its excipient is also Povidone/ polyvidone (a polyvinyl compound; see above).
  • Promatrix Acetyl-L-Carnitine — references on this page.
  • L-carnitine Tartrate [how is this different? is it acidic?] — mentioned on Biometric Autism
  • Carnipure — "the only commercially available L-Carnitine free from D-Carnitine" according to the 2 July 02 issue of the Healthy News newsletter. Don't see this on Carnipure's site; just the claim it's completely free of "harmful D-Carnitine" How is the mirror form harmful? [need to check out the supplements that use their product]

My experience

So far, I have been unable to tolerate the acidity of the L-Carnitine products I have tried.

For More Information

  • Acetyl-L-carnitine — a page of references, at Life Extension Foundation's site. Each is linked to an abstract.
  • L-Carnitine:B-hydroxy y-trimethylamino butyrate — uncredited author on the American Fitness Professionals and Associates site says "It appears that if you purchase carnitine in hope that it will help burn fat then you may be disappointed, but if you buy it to improve cardiovascular efficiency, exercise tolerance, and VO2, then you may be pleased with carnitine's results." References.

Please note

I am not advising anyone to do what I'm doing. Your body may react entirely differently from mine. I am not a doctor, and do not know enough about these supplements to recommend them.

copyright © 2000 and 2002 by Catherine Holmes Clark. Last updated 11 March 2002