Vanguard Neurologist

By David Perlmutter, MD, FACN, ABIHM

L-Carnitine is truly a mind-body nutrient. Found in all cells of the body and brain, L-carnitine has three main functions. First it transports long chain fatty acids across the inner membrane of the mitochondria. There the fats enter the citric acid cycle to be converted to ATP, the “energy molecule” needed by every cell to carry out its myriad activities. Muscle cells, heart cells and liver cells have very high numbers of mitochondria and correspondingly high amounts of carnitine.(1)

Second, L-carnitine acts as an antioxidant to protect cells from damage by free-radicals in the body and brain. In doing this, L-carnitine reduces the metabolic waste products that damage cells over time. Third, acetyl-L-carnitine donates its acetyl group to a choline molecule in a process that produces the neurotransmitter acetylcholine, which is actively involved in learning and memory.
Here’s a bit about different names for carnitine. Like many molecules in nature, carnitine is found in two stereoisomer forms, literally a “right-handed” shape (D-form) and a “left-handed” shape (L-form). Only the L-form, L-carnitine — also known as levocarnitine — is active. Much current research is done with the activated form, acetyl-L-carnitine, also called ALC or ALCAR.(1) Activated forms of substances in the body are the final molecules needed to carry out any specific activity.

Sources of L-carnitine include biosynthesis in the body, foods, and supplements. Made in the liver and kidney from the amino acids lysine and methionine, the biosynthesis of carnitine requires iron and vitamins C, B-6, and niacin. Acetyl-L-carnitine is made in small amounts naturally in the body, but, as is true of so many substances in the body, its production begins to decline in midlife.(2)

Carnitine is found primarily in animal foods. A 3.5 ounce portion of beef steak, pork, cod, and chicken breast contain 95 mg, 28 mg, 6 mg, and 4 mg respectively. Other sources of L-carnitine include over-the-counter vitamins, energy drinks, and various other products. Interestingly products containing L-carnitine cannot be marketed as “natural health products” in Canada and are not allowed to be imported into Canada.(3)

Because of L-carnitine’s vital roles in energy production and anti-oxidant capabilities, it has beneficial effects on a wide variety of health conditions. Clinical applications of L-carnitine include: diabetes (4); weight loss; enhanced male fertility; enhanced physical performance; and cognitive functioning.

A study done in Italy evaluated the efficacy of L-carnitine on physical and mental fatigue, and on cognitive functions of 66 centenarians. Thirty-two received 2,000 mg levocarnitine daily and 34 received a placebo for 6 months. Changes were monitored in total fat mass, total muscle mass, serum triacylglycerol, total cholesterol, HDL cholesterol, LDL cholesterol, Mini-Mental State Examination (MMSE), Activities of Daily Living, and a 6-min walking corridor test. Researchers concluded that “oral administration of levocarnitine reduces total fat mass, increases total muscular mass, and facilitates an increased capacity for physical and cognitive activity by reducing fatigue and improving cognitive functions.”(5)

In a recent study involving 12 institutionalized patients with moderate-to-late stage Alzheimer’s disease, supplementation with a vitamin/nutriceutical supplement containing folate, vitamin B6, alpha-tocopherol, S-adenosyl methionine [SAMe], N-acetylcysteine, and acetyl-L-carnitine, was found to significantly delay the decline in Dementia Rating Scale and clock-drawing text, as compared to subjects who received a placebo. According to institutional caregivers, those patients who received the nutriceutical supplementation were found to have a 30% improvement in the Neuropsychiatric Inventory and maintenance of performance in the Alzheimer’s Disease Cooperative Study-Activities of Daily Living. The authors conclude, “This formulation holds promise for delaying the decline in cognition, mood, and daily function that accompanies the progression of Alzheimer’s disease, and may be particularly useful as a supplement for pharmacological approaches during later stages of this disorder. A larger trial is warranted.”(6)

References:
1.
2. Gropper S. et.al. Advanced Nutrition and Human Metabolism, 2005, 4th edition, pp.190, 265
3. Carnitine not allowed in Canada
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4. Evans, JD et.al. “Role of acetyl-L-carnitine in the treatment of diabetic peripheral neuropathy”, Annals of Pharmacotherapy, 2008, 42(11):1686-91 < http://www.theannals.com/cgi/content/abstract/42/11/1686 >
5. Malaguarnera, M. et. al. “L-Carnitine treatment reduces severity of physical and mental fatigue and increases cognitive functions in centenarians: a randomized and controlled clinical trial”, American Journal of Clinical Nutrition, December 2007, Vol. 86, pp. 1738-1744.
6. Remington, R. et.al. “Efficacy of a Vitamin/nutriceutical Formulation for Moderate-stage to Later-stage Alzheimer’s Disease: A Placebo-controlled Pilot Study”, American Journal of Alzheimer’s Disease and Other Dementias, Dec. 2008.