L-carnitine is a molecule that is involved in lipid metabolism — that is, it helps the body burn fat. All the way back in 1983, an article in the Japanese Circulation Journal explained that L-carnitine could reduce the incidence of a heart arrhythmia after a vessel in the heart had been blocked and blood flow later reestablished, which can be dangerous because it allows a massive influx of free radicals and lipid peroxidation products to enter the weakened heart muscle.

Cardiac arrhythmias are very common after this type of occlusion of a heart blood vessel. The study on 38 dogs looked at cases where blood flow of a primary heart artery was temporarily obstructed and then reopened, imitating what happens in people who suffer a heart attack and then a return of blood flow by receiving a stent in the previously obstructed vessel. Half of the dogs were given L-carnitine and the other half saline.

The scientists found that the incidence of arrhythmias was considerably less in the animals given L-carnitine than in the controls by a measure of 26 percent vs. 5 percent. That kind of variance could mean the difference between life and death, as arrhythmias after a heart attack are the number one reason for an early death.

Levels of the energy molecule adenosine triphosphate (ATP) were much higher in the heart muscles of the animals given L-carnitine, meaning that the hearts of those dogs were getting the energy they needed. The researchers determined that this had to do with the metabolism of a fatty acid molecule in the control animals that were not given the supplement. The fatty acid was not seen in the L-carnitine group.

L-carnitine is safe and relatively inexpensive, and it protects the brain and other organs and tissues. It may also benefit arrhythmias not associated with a heart attack.