L-carnitine is an amino acid needed to transport fats into the mitochondria (the place in the cell where fats are turned into energy). Adequate energy production is essential for normal heart function. Several studies using 1 gram of L-carnitine two to three times per day showed an improvement in heart function and a reduction in symptoms of angina.^2,3,4Coenzyme Q10 also contributes to the energy-making mechanisms of the heart. Angina patients given 150 mg of coenzyme Q10 each day have experienced greater ability to exercise without experiencing chest pain.⁵ This has been confirmed in independent investigations.⁶

 

People with CHF have insufficient oxygenation of the heart, which can damage the heart muscle. Such damage may be reduced by taking L-carnitine supplements.⁷ L-carnitine is a natural substance made from the amino acids lysine and methionine. Levels of L-carnitine are low in people with CHF;⁸ therefore, many doctors recommend that those with CHF take 500 mg of L-carnitine two to three times per day.

Most L-carnitine/CHF research has used a modified form of the supplement called propionyl-L-carnitine (PC). In one double-blind trial, people using 500 mg of PC per day had a 26% increase in exercise capacity after six months.⁹ In double-blind research, other indices of heart function have also improved after taking 1 gram of PC twice per day.¹⁰ It remains unclear whether propionyl-L-carnitine has unique advantages over L-carnitine, as limited research in animals and humans has also shown very promising effects of the more common L-carnitine.¹¹

L-carnitine is an amino acid important for transporting fats that can be turned into energy in the heart. Clinical trials have reported that taking L-carnitine (4–6 grams per day) increases the chance of surviving a heart attack.^12,13,14 In one double-blind trial, individuals with suspected heart attack were given 2 grams of L-carnitine per day for 28 days.¹⁵ At the completion of this study, infarct size, as well as the number of nonfatal heart attacks, was lower in the group receiving L-carnitine versus the placebo group. Double-blind research using L-carnitine intravenously also shows promise.¹⁶

The amino acid L-carnitine is thought to be potentially helpful for weight loss because of its role in fat metabolism. L-carnitine has been found to reduce fatigue and hunger and improve weight loss effects of fasting.^17,18 Multiple controlled trials and three meta-analyses have shown that supplementing with L-carnitine can lead to small reductions in body weight in people with overweight and obesity.^19,20,21 In a placebo-controlled trial that included 60 overweight women with polycystic ovary syndrome, taking 250 mg of L-carnitine daily for 12 weeks resulted in weight loss, waist circumference reduction, and improved glucose regulation and insulin sensitivity.²²