Give me an A

“What is the difference between L-Carnitine and acetyl L-carnitine?” Asks an HSI member named Kelly. She says, “I have both and no one seems to know the difference between them.”

Two weeks ago I sent you an e-Alert about the importance of maintaining healthy mitochondria, the cellular powerplants that process nutrients and oxygen to feed the cells (“The Mighty Mite” 5/20/03). I mentioned that a supplement of acetyl L-carnitine (ALC) protects brain nerve cells from degeneration, largely because it stimulates the mitochondria.

So the quick answer to Kelly’s question is that acetyl L-carnitine is one of the types of L-carnitine (sometimes referred to as “carnitine,” or more simply LC). But as you’ll see, there’s much more than that to these very important amino acids.



What the heart wants 

Carnitine is produced in the kidneys and liver, and its main job is to carry fatty acids into the mitochondria. In addition, carnitine protects cells in the heart muscle from damage when a heart attack or spasm cuts off the oxygen supply. One study shows that patients who took 2 grams of L-carnitine a day for four weeks cut the number of complications from a heart attack (angina, heart rhythm disturbances and heart failure) in half.

L-carnitine also gives the body a boost in energy levels. The release of fat makes LC important in weight loss or exercise regimens because it helps convert body fat into fuel. It also raises levels of certain enzymes needed to metabolize sugars, starches and other carbohydrates. A supplement of L-carnitine promotes stamina when used with an exercise program, while also reducing production of lactic acid, which causes that burning feeling in the muscles.

The body rarely produces carnitine in amounts that are high enough to provide significant benefits. Dietary sources (such as meat, chicken, fish and dairy products) can provide LC, but the body only absorbs about 25 percent through diet. So for those seeking the heart healthy effects of carnitine, the recommended supplement dosage is generally 1 to 2 grams per day, with the higher dosage suggested for seniors because carnitine levels progressively decrease as we age, especially in the heart and skeletal muscles.

Clear thinking 

In the process of delivering fatty acids to the mitochondria, L-carnitine is converted to acetyl-L-carnitine, which enhances brain activity.

ALC has been shown to prevent brain-cell death and to protect nerve cells from degeneration due to aging or disease. This nutrient is one of the few that can cross the blood-brain barrier and move directly into the tissues of the brain, where it stimulates the mitochondria within the brain cells. ALC also helps stimulate acetylcholine, which is the most important neurotransmitter for memory function. In a clinical trial we told you about in the March 2000 Members Alert, Alzheimer’s disease patients who took 3 grams of ALC per day for one year showed significantly less deterioration in brain function than the control group.

In addition to enhancing cognitive abilities (such as increased alertness, longer attention span, and improved learning and memory), acetyl-L-carnitine has also been shown to effectively suppress protein glycation, which can lead to the formation of cataracts.

The recommended dosage for ALC is 250 mg to 2 grams a day, and like L-carnitine, is available in most supplement stores and through online sources.

What goes with what 

Now that we’ve had a little seminar in the difference between L-carnitine and ALC, this e-mail from HSI members Bob and Suzanne gives us a better idea of how the two supplements interact:

“Is there any reason that these substances should NOT both be taken? The goal is to help with fat metabolism AND to help ward off age-related neurological degenerative problems. We know that the LC is promoted for the former and ALC for the latter, but could ALC help toward achieving BOTH of these goals?”

There’s no real danger in taking an LC supplement with ALC, except that when LC levels get too high they can restrict the amount of ALC that reaches the brain. Meanwhile, when you take a supplement of ALC, much of it is converted into LC during metabolism, so an ALC supplement delivers both forms of this amino acid. In other words, Bob and Suzanne are on the right track when they wonder if ALC alone can provide the benefits of both fat metabolism and neurological benefits.

In the e-Alert about mitochondria, I mentioned an important note about taking ALC, which bears repeating. Research has shown that ALC can increase oxidative stress. However, combining ALC with a supplement of alpha lipoic acid not only eliminates the concerns about oxidative stress, but also magnifies ALC’s anti-aging benefits.

So when taking an ALC supplement, it’s a good idea to protect yourself with 100 to 600 mg of alpha lipoic acid daily.


To Your Good Health,

Jenny Thompson
Health Sciences Institute

“The Antiaging Effects of Acetyl-L-Carnitine New Research Yields Unexpected Benefits” Life Extension Magazine, May 2000,
“The Benefits of Acetyl-L-Carnitine Supplementation” Smart Publications,
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Journal of the American College of Cardiology, 1995.
American Journal of Cardiology, pp. 755-60, March 1990.