Supplement Forms / Alternate Names
• Acetyl-L-Carnitine (ALC); L-Acetyl-Carnitine (LAC); L-Carnitine; Propionyl L-Carnitine
Principal Proposed Uses
• Angina; Chronic Obstructive Pulmonary Disease; Congestive Heart Failure; Diabetic Peripheral Neuropathy; Heart Attack; Hyperthyroidism; Intermittent Claudication; Male Infertility; Male Sexual Dysfunction; Peyronie’s Disease
Other Proposed Uses
• Alzheimer's Disease; Attention Deficit Hyperactivity Disorder (ADHD) ; Celiac Disease; Chronic Fatigue Syndrome; Depression; Diabetes; Diabetic Cardiac Autonomic Neuropathy; Enhancing Mental Function in Seniors; Fatigue in Seniors; Fibromyalgia; High Cholesterol; HIV Support; Hyperactivity in Fragile X Syndrome; Liver Cirrhosis; Sports Performance Enhancement; Weight Loss
Carnitine is a substance used by the body uses to turn fat into energy. It is not normally considered an essential nutrient because the body can manufacture all it needs. However, supplemental carnitine could in theory improve the ability of certain tissues to produce energy. This has led to the use of carnitine for various muscle diseases as well as heart conditions.
There is no dietary requirement for carnitine. However, a few individuals have a genetic defect that hinders the body's ability to make carnitine. In addition, diseases of the liver, kidneys, or brain may inhibit carnitine production. Certain medications, especially the antiseizure drugs valproic acid (Depakene) and phenytoin (Dilantin), may reduce carnitine levels; however, whether taking extra carnitine would be helpful has not been determined. 1-11 Heart muscle tissue, because of its high energy requirements, is particularly vulnerable to carnitine deficiency.
The National Institutes of Health's Office of Dietary Supplements offers this list of foods that are high in carnitine: 114
While carnitine can be found in foods like meat and dairy products, a supplement is necessary to obtain therapeutic dosages.
Typical adult dosages for the diseases described here range from 500 mg to 1,000 mg three times daily. For children, one study used 50 mg/kg twice daily, up to a maximum of 4 g daily. 73
Carnitine is taken in three forms: L-carnitine (for heart and other conditions), propionyl-L-carnitine (for heart conditions), and acetyl-L-carnitine (for Alzheimer's disease). The dosage is the same for all three forms.
Carnitine is primarily used for heart-related conditions. Some evidence suggests that it can be used along with conventional treatment for angina to improve symptoms and reduce medication needs. 12-17 When combined with conventional therapy, it may or may not help prevent medical complications or sudden cardiac death in the months following a heart attack . 18,19,34,36,88
Lesser evidence suggests that it may be helpful for a condition called intermittent claudication (pain in the legs after walking due to narrowing of the arteries), 20-30 as well as congestive heart failure . 12,31-33 In addition, a few studies suggest that carnitine may be useful for cardiomyopathy . 27,35
Warning: You should not attempt to self-treat any of these serious medical conditions, nor should you use carnitine as a substitute for standard drugs.
Growing, if not entirely consistent, evidence suggests that L-carnitine or acetyl-L-carnitine, or their combination, may be helpful for improving sperm function and thereby provide benefits in male infertility. 58-66,71,80,86,90-92,103
Some studies have found evidence that one particular form of carnitine, acetyl-L-carnitine, might be helpful in Alzheimer's disease , 40-46 but the two most recent and largest studies found no benefit. 47,48 One review evaluated published and unpublished double-blind, placebo-controlled trials, and concluded that acetyl-L-carnitine may only be helpful for very mild Alzheimer's disease. 70
Some evidence suggests that carnitine may be useful for improving blood sugar control in people with type 2 (adult-onset) diabetes . 52,85 Better evidence suggests benefit with acetyl-L-carnitine for a major complication of diabetes, diabetic peripheral neuropathy (injury to nerves of the extremities caused by diabetes). 83 Acetyl-L-carnitine might help prevent diabetic cardiac autonomic neuropathy (injury to the nerves of the heart caused by diabetes). 53 However, one study found that carnitine supplements had an adverse effect on triglyceride levels in people with diabetes. 85
Much weaker evidence suggests possible benefits for neuropathy caused by the chemotherapy drugs cisplatin and paclitaxel. 95 Weak evidence hints that carnitine might help reduce liver and heart toxicity caused by the chemotherapy drug adriamycin . 104
One small study demonstrated a beneficial effect of L-carnitine on anemia and high cholesterol in patients on hemodialysis for chronic renal failure. 109
A genetic condition called fragile X syndrome can cause behavioral disturbances such as hyperactivity, along with intellectual disability, autism, and alterations in appearance. A preliminary study of 17 boys found that acetyl-L-carnitine might help to reduce hyperactive behavior associated with this condition. 51 Evidence for the effectiveness of L-carnitine in attention deficit and hyperactivity disorder (ADHD) has been mixed. 73,111
Celiac disease is an autoimmune disease affecting the digestive tract. Fatigue is a common symptom of the disease. One small double-blind trial found evidence that use of L-carnitine at a dose of 2 g daily might help alleviate this symptom. 107 Weak evidence hints that carnitine may help people with degeneration of the cerebellum (the structure of the brain responsible for voluntary muscular movement). 55 One very small study suggests carnitine may be helpful for reducing symptoms of chronic fatigue syndrome . 56 Another study suggests that carnitine may be of value for treating hyperthyroidism57 and for severe liver disease. 96 A substantial study marred by poor design (specifically, far too many primary endpoints) found equivocal evidence that L-carnitine, taken at dose of 500 mg three times daily, might be more effective than placebo for the treatment of fibromyalgia . 106
Other weak evidence suggests that carnitine may be helpful for decreasing the muscle toxicity of AZT (a drug used to treat HIV infection ). 67,68 Other weak evidence hints that the acetyl-L-carnitine might reduce nerve-related side effects caused by HIV drugs in general. 105
Little to no evidence supports other claimed benefits such as treating irregular heartbeat, Down's syndrome, muscular dystrophy, and alcoholic fatty liver disease. However, in a randomized trial involving 25 patients with liver cirrhosis and early brain dysfunction (hepatic encephalopathy) associated with severe forms of this condition, carnitine appeared to significantly improve the function of both the liver and the brain after 3 months of treatment. 112
What Is the Scientific Evidence for Carnitine?
Carnitine might be a good addition to standard therapy for angina . In one controlled study, 200 individuals with angina (the exercise-induced variety) took either 2 g daily of L-carnitine or were left untreated. All the study participants continued to take their usual medication for angina. Those taking carnitine showed improvement in several measures of heart function, including a significantly greater ability to exercise without chest pain. 12 They were also able to reduce the dosages of some of their heart medications (under medical supervision) as their symptoms decreased.
Unfortunately, the results of this study can't be fully trusted because researchers didn't use a double-blind protocol. (For more information on why double-blinding is so important, see Why Does This Database Rely on Double-blind Studies? ) Another trial did use a double-blind, placebo-controlled, design tested L-carnitine in 52 people with angina and found evidence of benefit. 16
In addition, several small studies (some of them double-blind) tested propionyl-L-carnitine for the treatment of angina, and also found evidence of benefit. 13-17
People with advanced hardening of the arteries, or atherosclerosis , often have difficulty walking due to lack of blood flow to the legs, a condition called intermittent claudication . Pain may develop after walking less than half a block. Although carnitine does not increase blood flow, it appears to improve the muscle's ability to function under difficult circumstances. 26 A 12-month, double-blind, placebo-controlled trial of 485 patients with intermittent claudication evaluated the potential benefits of propionyl-L-carnitine. 29 Participants with relatively severe disease showed a 44% improvement in walking distance as compared to placebo. However, no improvement was seen in those with mild disease. Another double-blind study followed 245 people and also found benefit. 20
Similar results have been seen in most but not all other studies of L-carnitine or propionyl-L-carnitine. 21-28,30 Propionyl-L-carnitine may be more effective for intermittent claudication than plain carnitine.
Congestive Heart Failure
Several small studies have found that carnitine, often in the form of propionyl-L-carnitine, can improve symptoms of congestive heart failure . 12,31-33 In one trial, benefits were maintained for 60 days after treatment with carnitine was stopped. 79
After a Heart Attack
L-carnitine has shown inconsistent promise for use after a heart attack .
A double-blind, placebo-controlled study that followed 101 people for 1 month after a heart attack found that use of L-carnitine, in addition to standard care, reduced the size of the infarct (dead heart tissue). 34
In the months following a severe heart attack, the left ventricle of the heart often enlarges, and the pumping action of the heart becomes less efficient. Some evidence suggests that L-carnitine can help prevent heart enlargement, but that it does not improve heart function. In a 12-month, double-blind, placebo-controlled study of 472 individuals who had just undergone a heart attack, use of carnitine at a dose of 6 g/day significantly decreased the rate of heart enlargement. 19 However, heart function was not significantly altered.
A 3-month, double-blind, placebo-controlled study of 60 individuals who had just undergone a heart attack also failed to find improvements in heart function. 36 (Heart enlargement was not studied.)
Results consistent with those of the studies above were seen in a 6-month double blind, placebo-controlled study of 2,330 people who had just had a heart attack. 98 Carnitine failed to produce significant reductions in mortality or heart failure (serious decline in heart function) over the 6-month period. However, the study did find reductions in early death. (Unfortunately, for statistical reasons, the meaningfulness of this last finding is questionable. Reduction in early death was a secondary endpoint rather than a primary one.)
Note: Carnitine is used along with conventional treatment, not as a substitute for it.
High levels of blood sugar can damage the nerves leading to the extremities, causing pain and numbness. This condition is called diabetic peripheral neuropathy . Nerve damage may also develop in the heart, a condition called cardiac autonomic neuropathy. Acetyl-L-carnitine has shown considerable promise for diabetic peripheral neuropathy and some promise for cardiac autonomic neuropathy.
Two 52-week double-blind, placebo-controlled studies, involving a total of 1,257 people with diabetic peripheral neuropathy, evaluated the potential benefits of ALC taken at 500 mg or 1000 mg daily. 83 The results showed that use of ALC, especially at the higher dose, improved sensory perception and decreased pain levels. In addition, the supplement appeared to promote nerve fiber regeneration.
A small study found some potential benefits for cardiac autonomic neuropathy. 53
For more information, including full dosage and safety issues, see the full Carnitine article.
Male Sexual Function
Carnitine has shown promise for improving male sexual function . One double-blind, placebo-controlled study of 120 subjects compared a combination of propionyl-L-carnitine (2 g per day) and acetyl-L-carnitine (2 g per day) against testosterone for the treatment of male aging symptoms (sexual dysfunction, depression, and fatigue). 81 The results indicated that both testosterone and carnitine improved erectile function, mood, and fatigue, as compared to placebo. However, no improvements were seen in the placebo group. This is an unusual occurrence in studies of erectile dysfunction, so it casts some doubt on the study results.
A double-blind study of 40 men evaluated propionyl-L-carnitine (2 g per day) in diabetic men with erectile dysfunction who had not responded well to Viagra. 82 The results indicated that carnitine significantly enhanced the effectiveness of Viagra.
In another double-blind study, a combination of the propionyl and acetyl forms of carnitine enhanced the effectiveness of Viagra in men who suffered from erectile dysfunction caused by prostate surgery. 99
Growing evidence suggests that L-carnitine or acetyl-L-carnitine or their combination may be helpful for improving sperm quality and function, thereby benefiting male infertility . 58-66,71,80,100-101,103
For example, in one double-blind, placebo-controlled study of 60 men, use of combined L-carnitine (2 g per day) and acetyl-L-carnitine (also at 2 g per day) significantly improved sperm quality. 80
Chronic Obstructive Pulmonary Disease (COPD)
Evidence from three double-blind, placebo-controlled studies enrolling a total of 49 people suggests that L-carnitine can improve exercise tolerance in COPD , presumably by improving muscular efficiency in the lungs and other muscles. 37-39
Numerous double- or single-blind studies involving a total of more than 1,400 people have evaluated the potential benefits of acetyl-L-carnitine in the treatment of Alzheimer's disease and other forms of dementia. 40-48,76-78 However, while early studies found evidence of modest benefit, two large and well-designed studies failed to find acetyl-L-carnitine effective at all.
The first of these was a double-blind, placebo-controlled trial that enrolled 431 participants for 1 year. 47 Overall, acetyl-L-carnitine proved no better than placebo. However, because a close look at the data indicated that the supplement might help people who develop Alzheimer's disease at an unusually young age, researchers performed a follow-up trial. This 1-year, double-blind, placebo-controlled trial evaluated acetyl-L-carnitine in 229 patients with early onset Alzheimer's. 48 Unfortunately, no benefits were seen here either.
One review of the literature concluded that acetyl-L-carnitine may be helpful for mild cases of Alzheimer’s disease, but not more severe cases. 72
A double-blind study of 60 seniors with dysthymia (a mild form of depression ) found that treatment with 3 g of carnitine daily over a 2-month period significantly improved symptoms as compared to placebo. 49 Positive results were seen in two other studies as well, one of depression and one of dysthymia. 50,102
Enlargement of the thyroid (goiter) can be due to many causes, including cancer and iodine deficiency. In some cases, thyroid enlargement occurs without any known cause, so-called benign goiter.
Treatment of benign goiter generally consists of taking thyroid hormone pills. This causes the thyroid gland to become less active, and the goiter shrinks. However, there may be undesirable effects as well. Symptoms of hyperthyroidism (too much thyroid hormone) can develop, including heart palpitations, nervousness, weight loss, and bone breakdown.
A double-blind, placebo-controlled trial found evidence that use of L-carnitine could alleviate many of these symptoms. This 6-month study evaluated the effects of L-carnitine in 50 women who were taking thyroid hormone for benign goiter. 57 The results showed that a dose of 2 g or 4 g of carnitine daily protected participants' bones and reduced other symptoms of hyperthyroidism.
Carnitine is thought to affect thyroid hormone by blocking its action in cells. 75 This suggests a potential concern—carnitine might be harmful for people who have low or borderline thyroid levels to begin with. This possibility has not been well explored as yet.
Peyronie’s disease is an inflammatory condition of the penis that develops in stages. In the first stage, penile pain occurs with erection; next, the penis becomes curved; finally, erectile dysfunction may occur. Many medications have been tried for Peyronie’s disease, with some success. One such drug is tamoxifen, which is better known as a treatment to prevent breast cancer recurrence. A 3-month, double-blind study compared the effectiveness of acetyl-L-carnitine to the drug tamoxifen in 48 men with Peyronie's disease. 74 Acetyl-L-carnitine (at a dose of 1 g daily) reduced penile curvature while tamoxifen did not; in addition, the supplement reduced pain and slowed disease progression to a greater extent than tamoxifen.
L-carnitine in its three forms appears to be quite safe. However, individuals with low or borderline-low thyroid levels should avoid carnitine because it might impair the action of thyroid hormone. 75
Individuals on dialysis should not receive this (or any other supplement) without a physician's supervision.
The maximum safe dosages for young children, pregnant or nursing women, or those with severe liver or kidney disease have not been established.
Interactions You Should Know About
If you are taking:
1. Hug C, McGraw CA, Bates SR, et al. Reduction of serum carnitine concentrations during anticonvulsant therapy with phenobarbital, valproic acid, phenytoin, and carbamazepine in children. J Pediatr. 1991;119:799-802.
2. Chung S, Choi J, Hyun T, et al. Alterations in the carnitine metabolism in epileptic children treated with valproic acid. J Korean Med Sci. 1997;12:553-558.
3. Melegh B, Trombitas K. Valproate treatment induces lipid globule accumulation with ultrastructural abnormalities of mitochondria in skeletal muscle. Neuropediatrics. 1997;28:257-261.
4. Zelnik N, Fridkis I, Gruener N. Reduced carnitine and antiepileptic drugs: cause relationship or co-existence? Acta Paediatr. 1995;84:93-95.
5. Coulter DL. Carnitine deficiency in epilepsy: risk factors and treatment. J Child Neurol. 1995;10(suppl 2):S32-S39.
6. Melegh B, Pap M, Morava E, et al. Carnitine-dependent changes of metabolic fuel consumption during long-term treatment with valproic acid. J Pediatr. 1994;125:317-321.
7. De Vivo DC, Bohan TP, Coulter DL, et al. L-carnitine supplementation in childhood epilepsy: current perspectives. Epilepsia. 1998;13:1216-1225.
8. Matsuda I, Ohtani Y. Carnitine status in Reye and Reye-like syndromes. Pediatr Neurol. 1986;2:90-94.
9. Camina MF, Rozas I, Gomez M, et al. Short-term effects of administration of anticonvulsant drugs on free carnitine and acylcarnitine in mouse serum and tissues. Br J Pharmacol. 1991;103:1179-1183.
10. Rodriguez-Segade S, de la Pena CA, Tutor JC, et al. Carnitine deficiency associated with anticonvulsant therapy. Clin Chim Acta. 1989;181:175-181.
11. Ater SB. A developmental center population treated with VPA and L-carnitine. In: Update 1993: inborn errors of metabolism in the patient with epilepsy. Sigma-Tau Pharmaceuticals; 1993.
12. Cacciatore L, Cerio R, Ciarimboli M, et al. The therapeutic effect of L-carnitine in patients with exercise-induced stable angina: a controlled study. Drugs Exp Clin Res. 1991;17:225-235.
13. Bartels GL, Remme WJ, Pillay M, et al. Effects of L-propionylcarnitine on ischemia-induced myocardial dysfunction in men with angina pectoris. Am J Cardiol. 1994;74:125-130.
14. Bartels GL, Remme WJ, den Hartog FR, et al. Additional anti-ischemic effects of long-term L-propionylcarnitine in anginal patients treated with conventional antianginal therapy. Cardiovasc Drugs Ther. 1995;9:749-753.
15. Bartels GL, Remme WJ, Holwerda KJ, et al. Anti-ischaemic efficacy of L-propionyl-carnitine—a promising novel metabolic approach to ischaemia? Eur Heart J. 1996;17:414-420.
16. Cherchi A, Lai C, Angelino F, et al. Effects of L-carnitine on exercise tolerance in chronic stable angina: a multicenter, double-blind, randomized, placebo controlled crossover study. Int J Clin Pharmacol Ther Toxicol. 1985;23:569-572.
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;34:167-172.
18. Davini P, Bigalli A, Lamanna F, et al. Controlled study on L-carnitine therapeutic efficacy in post-infarction. Drugs Exp Clin Res. 1992;18:355-365.
19. Iliceto S, Scrutinio D, Bruzzi P, et al. Effect of L-carnitine administration on left ventricular remodeling after acute anterior myocardial infarction: the L-Carnitine Ecocardiografia Digitalizzata Infarto Miocardico (CEDIM) Trial. J Am Coll Cardiol. 1995;26:380-387.
20. Brevetti G, Perna S, Sabba C, et al. Propionyl-L-carnitine in intermittent claudication: double-blind, placebo-controlled, dose titration, multicenter study. J Am Coll Cardiol. 1995;26:1411-1416.
21. Bolognesi M, Amodio P, Merkel C, et al. Effect of 8-day therapy with propionyl-L-carnitine on muscular and subcutaneous blood flow of the lower limbs in patients with peripheral arterial disease. Clin Physiol. 1995;15:417-423.
22. Brevetti G, Perna S, Sabba C, et al. Superiority of L-propionylcarnitine vs L-carnitine in improving walking capacity in patients with peripheral vascular disease: an acute, intravenous, double-blind, cross-over study. Eur Heart J. 1992;13:251-255.
23. Greco AV, Mingrone G, Bianchi M, et al. Effect of propionyl-L-carnitine in the treatment of diabetic angiopathy: Controlled double blind trial versus placebo. Drugs Exp Clin Res. 1992;18:69-80.
24. Brevetti G, Chiariello M, Ferulano G, et al. Increases in walking distance in patients with peripheral vascular disease treated with L-carnitine: a double-blind, cross-over study. Circulation. 1988;77:767-773.
25. Deckert J. Propionyl-L-carnitine for intermittent claudication. J Fam Pract. 1997;44:533-534.
26. Sabba C, Berardi E, Antonica G, 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;15:1348-1352.
27. Pepine CJ. The therapeutic potential of carnitine in cardiovascular disorders. Clin Ther. 1991;13:2-21.
28. Brevetti G, Attisano T, Perna S, et al. Effect of L-carnitine on the reactive hyperemia in patients affected by peripheral vascular disease: a double-blind, crossover study. Angiology. 1989;40:857-862.
29. Brevetti G, Diehm C, Lambert D. European multicenter study on propionyl-L-carnitine in intermittent claudication. J Am Coll Cardiol. 1999;34:1618-1624.
30. Hiatt WR, Regensteiner JG, Creager MA, et al. Propionyl-L-carnitine improves exercise performance and functional status in patients with claudication. Am J Med. 2001;110:616-622.
31. Caponnetto S, Canale C, Masperone MA, et al. Efficacy of L-propionylcarnitine treatment in patients with left ventricular dysfunction. Eur Heart J. 1994;15:1267-1273.
32. Mancini M, Rengo F, Lingetti M, et al. Controlled study on the therapeutic efficacy of propionyl-L-carnitine in patients with congestive heart failure. Arzneimittelforschung. 1992;42:1101-1104.
33. Pucciarelli G, Mastursi M, Latte S, et al. The clinical and hemodynamic effects of propionyl-L-carnitine in the treatment of congestive heart failure [in Italian; English abstract]. Clin Ter. 1992;141:379-384.
34. Singh RB, Niaz MA, Agarwal P, et al. A randomised, double-blind, placebo-controlled trial of L-carnitine in suspected acute myocardial infarction. Postgrad Med J. 1996;72:45-50.
35. Winter S, Jue K, Prochazka J, et al. The role of L-carnitine in pediatric cardiomyopathy. J Child Neurol. 1995;10(suppl 2):S45-S51.
36. Iyer R, Gupta A, Khan A, et al. Does left ventricular function improve with L-carnitine after acute myocardial infarction? J Postgrad Med. 1999;45:38-41.
37. Dal Negro R, Pomari G, Zoccatelli O, et al. L-carnitine and rehabilitative respiratory physiokinesitherapy: metabolic and ventilatory response in chronic respiratory insufficiency. Int J Clin Pharmacol. 1986;24:453-456.
38. Dal Negro R, Turco P, Pomari C, et al. Effects of L-carnitine on physical performance in chronic respiratory insufficiency. Int J Clin Pharmacol. 1988;26:269-272.
39. Dal Negro R, Zoccatelli D, Pomari C, et al. L-carnitine and physiokinesiotherapy in chronic respiratory insufficiency. Preliminary results. Clin Trials J. 1985;22:353-360.
40. Passeri M, Cucinotta D, Bonati PA, et al. Acetyl-L-carnitine in the treatment of mildly demented elderly patients. Int J Clin Pharmacol Res. 1990;10:75-79.
41. Calvani M, Carta A, Caruso G, et al. Action of acetyl-L-carnitine in neurodegeneration and Alzheimer's disease. Ann N Y Acad Sci. 1992;663:483-486.
42. Sano M, Bell K, Cote L, et al. Double-blind parallel design pilot study of acetyl levocarnitine in patients with Alzheimer's disease. Arch Neurol. 1992;49:1137-1141.
43. Spagnoli A, Lucca U, Menasce G, et al. Long-term acetyl-L-carnitine treatment in Alzheimer's disease. Neurology. 1991;41:1726-1732.
44. Campi N, Todeschini GP, Scarzella L. Selegiline versus L-acetylcarnitine in the treatment of Alzheimer-type dementia. Clin Ther. 1990;12:306-314.
45. 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;(suppl 2):159-168.
46. Bonavita E. Study of the efficacy and tolerability of L-acetylcarnitine therapy in the senile brain. Int J Clin Pharmacol Ther Toxicol. 1986;24:511-516.
47. Thal LJ, Carta A, Clarke WR, et al. A 1-year multicenter placebo-controlled study of acetyl-L-carnitine in patients with Alzheimer's disease. Neurology. 1996;47:705-711.
48. Thal LJ, Calvani M, Amato A, et al. A 1-year controlled trial of acetyl-l-carnitine in early-onset AD. Neurology. 2000;55:805-810.
49. Bella R, Biondi R, Raffaele R, et al. Effect of acetyl-L-carnitine on geriatric patients suffering from dysthymic disorders. Int J Clin Pharmacol Res. 1990;10:355-360.
50. Garzya G, Corallo D, Fiore A, et al. Evaluation of the effects of L-acetylcarnitine on senile patients suffering from depression. Drugs Exp Clin Res. 1990;16:101-106.
51. Torrioli MG, Vernacotola S, Mariotti P, et al. Double-blind, placebo-controlled study of L-acetylcarnitine for the treatment of hyperactive behavior in fragile X syndrome. Am J Med Genet. 1999;87:366-368.
52. Mingrone G, Greco AV, Capristo E, et al. L-carnitine improves glucose disposal in type 2 diabetic patients. J Am Coll Nutr. 1999;18:77-82.
53. Turpeinen AK, Kuikka JT, Vanninen E, et al. Long-term effect of acetyl-L-carnitine on myocardial 123I-MIBG uptake in patients with diabetes. Clin Auton Res. 2000;10:13-16.
54. Cavallini G, Biagiotti G, Koverech A, et al. Oral propionyl-l-carnitine and intraplaque verapamil in the therapy of advanced and resistant Peyronie's disease. BJU Int. 2002;89:895-900.
55. Sorbi S, Forleo P, Fani C, et al. Double-blind, crossover, placebo-controlled clinical trial with L-acetylcarnitine in patients with degenerative cerebellar ataxia. Clin Neuropharmacol. 2000;23:114-118.
56. Plioplys AV, Plioplys S. Amantadine and L-carnitine treatment of chronic fatigue syndrome. Neuropsychobiology. 1997;35:16-23.
57. Benvenga S, Ruggeri RM, Russo A, et al. Usefulness of l-carnitine, a naturally occurring peripheral antagonist of thyroid hormone action, in iatrogenic hyperthyroidism: a randomized, double-blind, placebo-controlled clinical trial. J Clin Endocrinol Metab. 2001;86:3579-3594.
58. Loumbakis P, Anezinis P, Evangeliou A, et al. Effect of L-carnitine in patients with asthenospermia [abstract]. Eur Urol. 1996;30(suppl 2):255.
59. Muller-Tyl E, Lohninger A, Fischl F, et al. The effect of carnitine on sperm count and sperm motility [translated from German]. Fertilitat. 1988;4:1-4.
60. Micic S, Lalic N, Nale DJ, et al. Effects of L-carnitine on sperm motility and number in infertile men [abstract]. Fertil Steril. 1998;70(3 suppl 1):S12.
61. Vicari E. Effectiveness of a short-term anti-oxidative high-dose therapy on IVF program outcome in infertile male patients with previous excessive sperm. In: International Meeting on Infertility and Assisted Reproductive Technology; Porto Cervo, Italy; June 11-14, 1997.
62. Vicari E, Cerri L, Cataldo T, et al. Effectiveness of single and combined antioxidant therapy in patients with astheno-necrozoospermia from non-bacterial epididymitis: effects after acetyl-carnitine or carnitine-acetyl-carnitine. Presented at: 12th National Conference, Italian Andrology Association; June 9-12, 1999; Copanello, Italy.
63. Campaniello E, Petrarolo N, Meriggiola MC, et al. Carnitine administration in asthenospermia. Presented at: 4th International Congress of Andrology; May 14-18, 1989; Florence, Italy.
64. Costa M, Canale D, Filicori M, et al. L-carnitine in idiopathic asthenozoospermia: a multicenter study. Andrologia. 1994;26:155-159.
65. Vitali G, Parente R, Melotti C. Carnitine supplementation in human idiopathic asthenospermia: clinical results. Drugs Exp Clin Res. 1995;21:157-159.
66. Moncada ML, Vicari E, Cimino C, et al. Effect of acetylcarnitine treatment in oligoasthenospermic patients. Acta Eur Fertil. 1992;23:221-224.
67. Semino-Mora MC, Leon-Monzon ME, Dalakas MC. Effect of L-carnitine on the zidovudine-induced destruction of human myotubes. Part I: L-carnitine prevents the myotoxicity of AZT in vitro. Lab Invest. 1994;71:102-112.
68. Dalakas MC, Leon-Monzon ME, Bernardini I, et al. Zidovudine-induced mitochondrial myopathy is associated with muscle carnitine deficiency and lipid storage. Ann Neurol. 1994;35:482-487.
69. Heinonen OJ. Carnitine and physical exercise. Sports Med. 1996;22:109-132.
70. Montgomery SA, Thal LJ, Amrein R. Meta-analysis of double blind randomized controlled clinical trials of acetyl-L-carnitine versus placebo in the treatment of mild cognitive impairment and mild Alzheimer's disease. Int Clin Psychopharmacol. 2003;18:61-71
71. Lenzi A, Lombardo F, Sgro P, et al. Use of carnitine therapy in selected cases of male factor infertility: a double-blind crossover trial. Fertil Steril. 2003;79:292-300.
72. Montgomery SA, Thal LJ, Amrein R. Meta-analysis of double blind randomized controlled clinical trials of acetyl-L-carnitine versus placebo in the treatment of mild cognitive impairment and mild Alzheimer's disease. Int Clin Psychopharmacol. 2003;18:61-71.
73. Van Oudheusden L, Scholte H. Efficacy of carnitine in the treatment of children with attention-deficit hyperactivity disorder. Prostaglandins Leukot Essent Fatty Acids. 2002;67:33.
74. Biagiotti G, Cavallini G. Acetyl-L-carnitine vs tamoxifen in the oral therapy of Peyronie's disease: a preliminary report. BJU Int. 2001;88:63-67.
75. Benvenga S, Lakshmanan M, Trimarchi F. Carnitine is a naturally occurring inhibitor of thyroid hormone nuclear uptake. Thyroid. 2000;10:1043-1050.
76. Rai G, Wright G, Scott L, et al. Double-blind, placebo controlled study of acetyl-l-carnitine in patients with Alzheimer's dementia. Curr Med Res Opin. 1990;11:638-647.
77. Salvioli G, Neri M. L-acetylcarnitine treatment of mental decline in the elderly. Drugs Exp Clin Res. 1994;20:169-176.
78. Cipolli C, Chiari G. Effects of L-acetylcarnitine on mental deterioration in the aged: initial results [in Italian; English abstract]. Clin Ter. 1990;132:479-510.
79. Loster H, Miehe K, Punzel M, et al. Prolonged oral L-carnitine substitution increases bicycle ergometer performance in patients with severe, ischemically induced cardiac insufficiency. Cardiovasc Drugs Ther. 1999;13:537-546.
80. Lenzi A, Sgro P, Salacone P, et al. A placebo-controlled double-blind randomized trial of the use of combined L-carnitine and L-acetyl-carnitine treatment in men with asthenozoospermia. Fertil Steril. 2004;81:1578-1584.
81. Cavallini G, Caracciolo S, Vitali G, et al. Carnitine versus androgen administration in the treatment of sexual dysfunction, depressed mood, and fatigue associated with male aging. Urology. 2004;63:641-646.
82. Gentile V, Vicini P, Prigiotti G, et al. Preliminary observations on the use of propionyl-L-carnitine in combination with sildenafil in patients with erectile dysfunction and diabetes. Curr Med Res Opin. 2004;20:1377-1384.
83. Sima AA, Calvani M, Mehra M, et al. Acetyl-L-carnitine improves pain, nerve regeneration, and vibratory perception in patients with chronic diabetic neuropathy: an analysis of two randomized placebo-controlled trials. Diabetes Care. 2004;28:89-94.
84. Pistone G, Marino A, Leotta C, et al. Levocarnitine administration in elderly subjects with rapid muscle fatigue: effect on body composition, lipid profile and fatigue. Drugs Aging. 2003;20:761-767.
85. Rahbar AR, Shakerhosseini R, Saadat N, et al. Effect of L-carnitine on plasma glycemic and lipidemic profile in patients with type II diabetes mellitus. Eur J Clin Nutr. 2005 Mar 2. [Epub ahead of print]
86. Cavallini G, Ferraretti AP, Gianaroli L, et al. Cinnoxicam and L-carnitine/acetyl-L-carnitine treatment for idiopathic and varicocele-associated oligoasthenospermia. J Androl. 2004;25:761-770; discussion 771-772.
87. Pistone G, Marino A, Leotta C, et al. Levocarnitine administration in elderly subjects with rapid muscle fatigue: effect on body composition, lipid profile and fatigue. Drugs Aging. 2003;20:761-767.
88. Villani RG, Gannon J, Self M, et al. L-Carnitine supplementation combined with aerobic training does not promote weight loss in moderately obese women. Int J Sport Nutr Exerc Metab. 2000;10:199-207.
89. Tarantini G, Scrutinio D, Bruzzi P, et al. Metabolic Treatment with L-Carnitine in Acute Anterior ST Segment Elevation Myocardial Infarction. A Randomized Controlled Trial. Cardiology. 2006 May 9. [Epub ahead of print]
90. Garolla A, Maiorino M, Roverato A, et al. Oral carnitine supplementation increases sperm motility in asthenozoospermic men with normal sperm phospholipid hydroperoxide glutathione peroxidase levels. Fertil Steril. 2005;83:355-361.
91. Balercia G, Regoli F, Armeni T, et al. Placebo-controlled double-blind randomized trial on the use of L-carnitine, L-acetylcarnitine, or combined L-carnitine and L-acetylcarnitine in men with idiopathic asthenozoospermia. Fertil Steril. 2005;84:662-671.
92. Sigman M, Glass S, Campagnone J, et al. Carnitine for the treatment of idiopathic asthenospermia: a randomized, double-blind, placebo-controlled trial. Fertil Steril. 2006 Apr 4. [Epub ahead of print]
93. Cavallini G, Modenini F, Vitali G, et al. Acetyl-L-carnitine plus propionyl-L-carnitine improve efficacy of sildenafil in treatment of erectile dysfunction after bilateral nerve-sparing radical retropubic prostatectomy. Urology. 2005;66:1080-1085.
94. Zanardi R, Smeraldi E. A double-blind, randomised, controlled clinical trial of acetyl-l-carnitine vs. amisulpride in the treatment of dysthymia. Eur Neuropsychopharmacol. 2005 Nov 25. [Epub ahead of print]
95. Maestri A, De Pasquale Ceratti A, Cundari S, et al. A pilot study on the effect of acetyl-L-carnitine in paclitaxel- and cisplatin-induced peripheral neuropathy. Tumori. 2005;91:135-138.
96. Malaguarnera M, Pistone G, Elvira R, et al. Effects of L-carnitine in patients with hepatic encephalopathy. World J Gastroenterol. 2006;11:7197-202.
97. Stuessi C, Hofer P, Meier C, et al. L: -Carnitine and the recovery from exhaustive endurance exercise: a randomised, double-blind, placebo-controlled trial. Eur J Appl Physiol. 2005 Sep 29. [Epub ahead of print]
98. Tarantini G, Scrutinio D, Bruzzi P, et al. Metabolic Treatment with L-Carnitine in Acute Anterior ST Segment Elevation Myocardial Infarction. A Randomized Controlled Trial. Cardiology. 2006 May 9. [Epub ahead of print]
99. Cavallini G, Modenini F, Vitali G, et al. Acetyl-L-carnitine plus propionyl-L-carnitine improve efficacy of sildenafil in treatment of erectile dysfunction after bilateral nerve-sparing radical retropubic prostatectomy. Urology. 2005;66:1080-1085.
100. Garolla A, Maiorino M, Roverato A, et al. Oral carnitine supplementation increases sperm motility in asthenozoospermic men with normal sperm phospholipid hydroperoxide glutathione peroxidase levels. Fertil Steril. 2005;83:355-361.
101. Balercia G, Regoli F, Armeni T, et al. Placebo-controlled double-blind randomized trial on the use of L-carnitine, L-acetylcarnitine, or combined L-carnitine and L-acetylcarnitine in men with idiopathic asthenozoospermia. Fertil Steril. 2005;84:662-671.
102. Zanardi R, Smeraldi E. A double-blind, randomised, controlled clinical trial of acetyl-l-carnitine vs. amisulpride in the treatment of dysthymia. Eur Neuropsychopharmacol. 2005 Nov 25. [Epub ahead of print]
103. Zhou X, Liu F, Zhai S. Effect of L-carnitine and/or L-acetyl-carnitine in nutrition treatment for male infertility: a systematic review. Asia Pac J Clin Nutr. 2007;16(suppl):383-390.
104. Strauss M, Porras N. Differential expression of HSP70 and ultrastructure of heart and liver tissues of rats treated with adriamycin: protective role of L-carnitine. Invest Clin. 2007;48:33-43.
105. Youle M, Osio M. A double-blind, parallel-group, placebo-controlled, multicentre study of acetyl l-carnitine in the symptomatic treatment of antiretroviral toxic neuropathy in patients with HIV-1 infection. HIV Med. 2007;8:241-250.
106. Rossini M, Di Munno O, Valentini G, et al. Double-blind, multicenter trial comparing acetyl l-carnitine with placebo in the treatment of fibromyalgia patients. Clin Exp Rheumatol. 2007;25:182-188.
107. Ciacci C, Peluso G, Iannoni E, et al. L-Carnitine in the treatment of fatigue in adult celiac disease patients A pilot study. Dig Liver Dis. 2007 Aug 9. [Epub ahead of print]
108. Malaguarnera M, Cammalleri L, Gargante MP, et al. L-Carnitine treatment reduces severity of physical and mental fatigue and increases cognitive functions in centenarians: a randomized and controlled clinical trial. Am J Clin Nutr. 2007;86:1738-44.
109. Mitwalli AH, Al-Wakeel JS, Alam A, et al. L-carnitine supplementation in hemodialysis patients. Saudi J Kidney Dis Transpl. 2005;16:17-22.
110. Smith WA, Fry AC, Tschume LC, et al. Effect of glycine propionyl-L-carnitine on aerobic and anaerobic exercise performance. Int J Sport Nutr Exerc Metab. 2008;18:19-36.
111. Arnold LE, Amato A, Bozzolo H, et al. Acetyl-L-carnitine (ALC) in attention-deficit/hyperactivity disorder: a multi-site, placebo-controlled pilot trial. J Child Adolesc Psychopharmacol. 2007;17:791-802.
112. Malaguarnera M, Gargante MP, Cristaldi E, et al. Acetyl-L:-carnitine treatment in minimal hepatic encephalopathy. Dig Dis Sci. 2008 Mar 21.
113. Malaguarnera M, Gargante MP, Russo C, et al. L-carnitine supplementation to diet: a new tool in treatment of nonalcoholic steatohepatitis—a randomized and controlled clinical trial. Am J Gastroenterol. 2010;105(6):1338-1345.
114. Dietary supplement fact sheet: carnitine. Office of Dietary Supplements website. Available at: http://ods.od.nih.gov/factsheets/Carnitine-HealthProfessional/ . Accessed September 7, 2012.
Last reviewed August 2013 by EBSCO CAM Review Board
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
Copyright (C) 2011 EBSCO Publishing. All rights reserved.