Heart Attack and Carnitine

The amino acid L-carnitine (carnitine) has shown potential value during the first few weeks after a heart attack. Supplementing with carnitine offers potential benefits such as improved heart function and reduced rate of heart enlargement.

Carnitine may have a few effects on the heart after a heart attack, including helping to improve heart function and decreasing the enlargement that often follows an attack.

Read more details about Carnitine.

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 (area of dead heart tissue).⁵ Other complications of heart attack were reduced, as well. Similar benefits were also seen in a 1-year, controlled study of 160 people who had just experienced a heart attack; however, because this study was not double-blind, its results are not reliable.⁶

In the months following a severe heart attack, the heart often enlarges and loses function. L-carnitine has shown some potential for helping the first of these complications, but not the second. In a 12-month, double-blind, placebo-controlled study of 472 people who had just experienced a heart attack, use of carnitine at a dose of 6 g per day significantly decreased the rate of heart enlargement.³ However, heart function was not improved. A 3-month, double-blind, placebo-controlled study of 60 people who had just undergone a heart attack also failed to find improvements in heart function with L-carnitine.⁴ (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.¹⁶ Carnitine failed to produce significant reductions in mortality or heart failure (serious decline in heart function) over the 6-month period. However, it did find reductions in early death.

Typical adult dosages of carnitine range from 500 mg to 1,000 mg three times daily. In one of the studies mentioned here, the daily dose was 6 g.

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.

• Integrative MD
• Naturopathic doctor
• Clinical nutritionist or registered dietitian

Safety Issues

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. ¹ 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:

• Antiseizure medications, particularly valproic acid (Depakote, Depakene) but also phenytoin (Dilantin) : You may need extra carnitine.

• Thyroid medication: Do not take carnitine except under a physician's supervision.

1. Benvenga S, Lakshmanan M, Trimarchi F. Carnitine is a naturally occurring inhibitor of thyroid hormone nuclear uptake. Thyroid. 10(12):1043-50.

3. 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.
4. 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.
5. 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.
6. 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.
16. 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]