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James Meschino DC, MS, ROHP

General Features
Carnitine is an amino acid made in the body that helps to facilitate the burning of fat.  It primarily functions to transport long-chain fatty acids into the mitochondria of the cell, where these fats are metabolized to produce the ATP energy required to power biological activities of the cell. A good example involves the muscle contraction of the heart which is an ATP-dependent activity. The heart muscle, in particular, requires adequate concentrations of L-Carnitine due to the heart muscle’s high reliance upon fat as an energy source from which it generates ATP energy for muscle contraction.1   In the body  L-Carnitine is produced in the liver, kidney and brain.  Its precursor is the amino acid lysine.2  Carnitine deficiency in humans was first described in 1973.3  Until then it had been assumed that individuals could synthesize adequate amounts of Carnitine, ingest adequate amounts of Carnitine from food, or meet needs by a combination of both.  The discovery that some individuals require Carnitine supplementation to maintain normal energy metabolism has prompted its use in clinical trials involving patients with cardiovascular diseases, Alzheimer’s disease, dementia, obesity, alcohol-induced fatty liver disease, low sperm counts and decreased sperm motility, and as an ergogenic aid to enhance performance in endurance athletes.4

Supplementation Studies and Clinical Application
Only L-Carnitine should be used for supplementation purposes.  D-Carnitine has been shown to interfere with Carnitine metabolism and reduces fatty acid metabolism and energy production.5,6,7

Also note, that when using L-Carnitine to prevent or treat dementia or Alzheimer’s disease, the only form that crosses the blood-brain barrier is Acetyl-L-Carnitine.8,9

  1. Cardiovascular Disease

In cases of angina, congestive heart failure and other cardiomyopathies, a daily supplementation with 1,500-4,000 mg of L-Carnitine has produced significant improvement in cardiac function in many clinical trials.  This effect appears to be due to improved fat burning capability by cardiac muscle with resulting increased production of ATP energy, which is the energy substrate required for heart muscle contraction.10-26

  1. Alzheimer’s Disease and Age-Related Dementia

Acetyl-L-Carnitine has been shown to improve cognitive function in patients with mild to moderate Alzheimer’s disease and dementia.  The usual daily dosage was 1,000-2,000 mg per day.  This effect appears to involve better fat burning by brain cells to produce more ATP energy, and the fact that Acetyl-L-carnitine can induce synthesis of the memory chemical, acetylcholine, and increase concentrations of the mitochondrial phospholipid known as cardiolipin, which is important for the transfer of electrons in the synthesis of ATP energy in brain cells.9,27-35

  1. Male Fertility

Carnitine concentrations are critical to sperm energy metabolism, affecting sperm count and sperm motility.  Studies with infertile men have demonstrated that supplementation with 3,000 mg per day of L-Carnitine can significantly increase sperm counts and sperm motility.  This effect is related to enhanced ATP energy production as well.36,37,38

  1. Endurance Performance and Fat Burning

Some preliminary trials reveal that L-Carnitine supplementation can enhance fatty acid oxidation in skeletal muscle during endurance exercise in healthy subjects and athletes.  The dosage for endurance athletes is usually 2,000 mg, two to three times per day.  However, this evidence requires much more substantiation.  Certain obese patients have been shown to have a relative deficiency in L-Carnitine that may impair their fat-burning ability, and they may thus benefit from L-Carnitine supplementation.39,40,41

  1. Protection Against Drug Toxicity

L-Carnitine can protect the heart against the damaging effects of the chemotherapy drug adriamycin.42

Dosage Range
For most applications, 1,500 mg to 4,000 mg is the daily dosage.  For brain function, only Acetyl-L-Carnitine has been shown to be effective.

Toxicity and Contraindications
L-Carnitine is extremely safe with no significant side effects reported in any human clinical studies.

Drug-Nutrient Interactions
There are no reported drug-nutrient interactions of concern for L-Carnitine.  Note that the anti-seizure drug, Valproic acid and the HIV drug, AZT (zidovudine) have been shown to deplete L-Carnitine levels in the body, and thus, supplementation with L-Carnitine may be warranted under these circumstances.43,44,45

Synergistic Interactions
L-Carnitine and co-enzyme Q10 appear to work synergistically, enhancing the bioenergetics of mitochondrial oxidative phosphorylation in muscle, nerve and other tissues.  In turn, this increases levels of ATP energy within these tissues.46

Choline supplementation appears to spare L-Carnitine and may increase intracellular Carnitine levels (20 mg of choline per kg of body weight).47

  1. Bermer J. Carnitine-metabolism and function.  Physiol Rev 1983;63:1420-80.
  2. Bamji MS. Nutritional and health implications of lysine carnitine relationship.  Wld Rev Nutr Diet 1984;44:185-211.
  3. Engel AG, Angelini C. Carnitine deficiency of human skeletal muscle with associated lipid storage myopathy: A new syndrome.  Science 1973;179:899-902.
  4. Murray M. Encyclopedia of Nutritional Supplements.  Rocklin, CA: Prima Publishing; 1996.  34.
  5. Bazzato G, Mezzina C, Ciman et al. Myasthenia-like syndrome associated with carnitine in patients on long term dialysis.  Lancet 1979;I:1041-2.
  6. Paulson DJ, Shug AL. Tissue specific depletion of L-carnitine in rat heart and skeletal muscle by D-carnitine.  Life Sci 1981;28:2931-8.
  7. Watanable S, et al. Effects of L- and DL-carnitine on patients with impaired exercise tolerance.  Jap Heart J 1995;36:319-31.
  8. Bowman B. Acetyl-carnitine and Alzheimer’s disease.  Nutrition Reviews 1992;50:142-4.
  9. Carta A, et al. Acetyl-L-carnitine and Alzheimer’s disease.  Pharmacological considerations beyond the cholinergic sphere.  Ann NY Acad Sci 1993;49:1137-41.
  10. Goa KL, Brogden RN. L-carnitine – a preliminary review of its pharmacokinetics, and its therapeutic use in ischemic cardiac disease and primary and secondary carnitine deficiencies in relationship to its role in fatty acid metabolism.  Drugs 1987;34:1-24.
  11. Silverman Na, Schmitt G, Vishwanath M, et al. Effect of carnitine on myocardial function and metabolism following global ischemia.  Ann Thor Surg 1985;40:30-5.
  12. Cherchi A, Lai C, Angelino F, Trucco G, Caponnetto S, Mereto PE, et al. Effects of L-carnitine on exercise tolerance in chronic stable angina: a multicenter, double-blind, randomized, placebo controlled crossover study.  Int H Clin Pharm Ther Tox 1985;23:569-72.
  13. Orlando G, Rusconi C. Oral L-carnitine in the treatment of chronic cardiac ischemia in elderly patients.  Clin Trials 1986;23:338-44.
  14. Kamikawa T, Suzuki Y, Kobayashi A, Hayashi H, Masumura Y, Nishihara K, et al. Effects of L-carnitine on exercise tolerance in patients with stable angina pectoris.  Jap Heart J 1984:25:587-97.
  15. Kosolcharoen P, et al. Improved exercise tolerance after administration of carnitine.  Curr Ther Res 1981;30:753-64.
  16. Pola P, Savi L, Serricchio M, et al. Use of physiological substance, acetyl-carnitine, in the treatment of angiospastic syndromes.  Drugs Exp Clin Res 1984;X:213-7.
  17. Lagioia R, Scrutinio D, Mangini SG, et al. Propionyl-L-carnitine: a new compound in the metabolic approach to the treatment of effort angina.  Int J Cardiol 1992;34:167-72.
  18. Bartels GL, Remme WJ, Pillay M, Schonfeld DH, Kruijssen DA. Effects of L-propionylcarnitine on ischemia-induced myocardial dysfunction in men with angina pectoris.  Am J Cardiol 1994;74:125-30.
  19. Cacciatore L, Cerio R, Ciarimboli M, Cocozza M, Coto V, D’Alessandro A, et al. The therapeutic effect of L-carnitine in patients with exercise-induced stable angina: a controlled study.  Drugs Exp Clin Res 1991;17:225-35.
  20. Davini P, Bigalli A, Lamanna F, Boem A. Controlled study on L-carnitine therapeutic efficacy in post-infarction.  Drugs Exp Clin Res 1992;18:355-65.
  21. Iliceto S, Scrutinio D, Bruzzi P, D’Ambrosio G, Boni L, Di Biase M, et al. Effects of L-carnitine administration on left ventricular remodelling after acute anterior myocardial infarction: the L-Carnitine Ecocardiografia Digitalizzata Infarto Miocardico (CEDIM) trial.  J Am Coll Cardiol 1995;26:380-7.
  22. Mancini M, Rengo F, Lingetti M, Sorrentino GP, Nolfe G. Controlled study on the therapeutic efficacy of propionyl-L-carnitine in patients with congestive heart failure.  Arzneim Forsch 1992;42:1101-4.
  23. Pucciarelli G, Mastursi M, Latte S, Sacra C, et al. The clinical and hemodyanamic effects of propionyl-L-carnitine in the treatment of congestive heart failure.  Clin Ther  1992;141:379-84.
  24. Brevetti G, Perna S, Sabba C, et al. Comparison between the effect of L-propionylcarnitine, L-carnitine in improving walking capacity in patients with peripheral vascular disease: an acute, intravenous, double-blind, cross-over study.  Eur Heart J 1992;13:251-5.
  25. Sabba C, Berardi E, Antonica G, Ferraioli G, Buonamico P, Godi L, et al. Comparison between the effect of L-propionylcarnitine, L-acetylcarnitine and nitroglycerin in chronic peripheral arterial disease: a haemodynamic double blind echo-Doppler study.  Eur Heart J 1994;15:1348-52.
  26. Brevetti G, Chiariello M, Ferulano G, Policicchio A, Nevola E, Rossini A, et al. Increases in walking distance in patients with peripheral vascular disease treated with L-carnitine: a double-blind, cross-over study.  Circulation 1988;77:767-73.
  27. Calvani M, Carta A, Caruso G, Bendetti N, Iannuccelli M. Action of acetyl-L-carnitine in neurodegeneration and Alzheimer’s disease.  Ann NY Acad Sci 1993;663:483-6.
  28. Pettegrew JW, Klunk WE, Panchalingam K, Kanfer JN, McClure RJ. Clinical and neurochemical effects of acetyl-L-carnitine in Alzheimer’s disease.  Neurobiol Agin 1995;16:1-4.
  29. Sano M, Bell K, Cote L, Dooneief G, Lawton A, Legler L, et al. Double-blind parallel design pilot study of acetyl levocarnitine in patients with Alzheimer’s disease.  Arch Neurol 1995;49:1137-41.
  30. Spagnoli A, Lucca U, Menasce G, Bandera L, Cizza G, Forloni G, et al. Long-term acetyl-L-carnitine treatment in Alzheimer’s disease.  Neurology 1991;41:1726-32.
  31. Vecchi GP, Chiari G, Cipolli C, et al. Acetyl-L-carnitine treatment of mental impairment in the elderly:  evidence from a multicenter study.  Arch Gerontol Geriatr 1991;2(Suppl):159S-68S.
  32. Savioli G, Neri M. L-acetylcarnitine treatment of mental decline in the elderly.  Drugs Exp Clin Res 1994;20:169-76.
  33. Cipolli C, Chiari G. Effects of L-acetylcarnitine on mental deterioration in the aged:  initial results.  Clin Ther 1990;132:479-510.
  34. Garzya G, Corallo D, Fiore A, Lecciso G, Tetrelli G, Zotti C. Evaluation of the effects of the L-acetylcarnitine on senile patients suffering from depression.  Drugs Exp Clin Res 1990;16(2):101-6.
  35. Tempesta E, Casella L, Pirrongelli C, Janiri L, Calvani M, Ancona L. L-acetylcarnitine in depressed elderly subjects.  A cross-over study vs. placebo.  Drugs Exp Clin Res 1987;8:417-23.
  36. Bornman MS, et al. Seminal carnitine, epididymal function and spermatozoal motility.  S Afr Med J 1989;75:20,21.
  37. Mechini Fabris GF, et al. Free L-carnitine in human semen: its variability in different andologic pathologies.  Feril Steril 1984;42:263-7.
  38. Costa M, Canale D, Filicori M, D’Lddio S, Lenzi A. L-carnitine in idiopathic asthenozoospermia: a multicenter study.  Andrologia 1994;26:155-9.
  39. Dragan AM, Vasiliu D, Eremia NM, Georgescu E. Studies concerning some acute biological changes after exogenous administration of 1 g L-carnitine in elite athletes.  Physiologie 1987;24:231-4.
  40. Dragan GI, Vasiliu A, Georgescu E, Dumas I. Studies concerning acute and chronic effects of L-carnitine on some biological parameters.  Physiologie 1987;24:23-8.
  41. Dragan DI, Wagner W, Ploesteaunu E. Studies concerning the ergogenic value of protein supply and L-carnitine in elite junior cyclists.  Physiologie 1988;25:129-32.
  42. Furitano G, et al. Polygraphic evaluation of effects of carnitine in patients on Adriamycin treatment.  Drugs Exp Clin Res 1984;10:107-11.
  43. Murray M, editor. Encyclopedia of Nutritional Supplements.  Rocklin, CA: Prima Publishing 1996.  294-5.
  44. Van Wouwe JP. Carnitine deficiency during valporic acid treatment.  Int J Vitamin Nutr Res 1995;65(3):211-4.
  45. Dalakas MC, Leon-Monzon ME, Bernardini I, Gahl WA. Zidovudine-induced mitochondrial myopathy is associated with muscle carnitine deficiency and lipid storage.  Ann Neurol 1994;35(4):482-7.
  46. Bertelli A, Ronca F, Ronca G, Palmieri L, Zucchi R. L-carnitine and coenzyme Q10 protective action against ischaemia and reperfusion of working rat heart.  Drugs Exp Xlin Res 1992;18:431-6.
  47. Daily JW III, Sachan DS. Choline supplementation alters carnitine homeostasis in humans and guinea pigs.  J Nutr 1995;125:1938-44.
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