The clinical benefits of Acetyl-L-Carnitine

Robert Crayhon

Nutrition can play an important role in promoting brain wellness. The older we are, the more likely we are to suffer from cognitive loss. While some survive into their sixth and seventh decades with good mental function, this becomes less likely as we age further. Decline is almost universal in at least one cognitive area among those over 85. (1) Are there nutrient strategies that can slow or even prevent this decline?

Certain nutrients have also undergone examination for their role in promoting brain health in older adults. One of the most extensively researched nutrients for its role in promoting brain wellness is Acetyl-L-Carnitine (ALCAR). ALCAR has demonstrated marked positive effects on brain aging, both from a preventive and therapeutic standpoint.

ALCAR is the O-acetylated form of the fatty acyl ester L-carnitine. ALCAR benefits mitochondrial efficiency and functions as an antioxidant within the mitochondria, helping neurons maintain maximal energy levels. ALCAR increases acetylcholine levels in the brain, one of the main neurotransmitters needed for learning and memory. Acetylcholine is the main neurotransmitter deficiency that occurs with age. There is also a great deal of evidence that age-related memory loss is cholinergic in nature. Therefore, maintaining healthy acetylcholine levels must be the centerpiece of any brain antiaging strategy. ALCAR levels decline markedly as we age, even in healthy adults. (2) Restoring ALCAR levels to those seen in twenty-year olds may be desirable for older adults. Declining ALCAR levels may in fact be one of the causes of the cognitive decline seen with aging.

Optimizing Neuronal Energy

For brain longevity, it is essential that neurons maintain a constant supply of energy to protect against cell loss. ALCAR maximizes neuronal energy production, (3,4) and regenerates mitochondrial function, especially cellular respiration, mitochondrial membrane potential, and cardiolipin levels. (5)

Brain Protector

ALCAR significantly reduces the amounts of damaged fats such as lipofuscin as the brain ages, a sign that ALCAR is slowing brain aging. (6) Double-blinded studies in humans show that ALCAR also protects against such ischemia-induced free radical damage to neurons. (7,8) Brain levels of ALCAR often determine how many cells survive an ischemic event. (9) ALCAR also acts as an antioxidant through its ability to naturally raise production as well as release of the free radical scavenger melatonin. (10,11)

Antioxidant levels in the substantia nigra decline with age, (12) increasing risk of damage to the dopanergic neurons in this region of the brain. ALCAR increases levels of glutathione in the neurons of the substantia nigra, which suggests that ALCAR may help protect and be useful in the prevention and perhaps the treatment of Parkinson’s disease. (13) ALCAR has been found to protect against MPTP induced Parkinsonism in primates (14) and may protect against Parkinson’s in humans. (15)

Increasing Molecules Needed for Memory

ALCAR increases levels of nerve growth factor (NGF)–an important brain healing compound. In the central nervous system, nerve growth factor (NGF) protects cholinergic neurons. NGF helps increase levels of choline acetyltransferase (ChAT), which makes the valuable neurotransmitter acetylcholine. The aging process reduces both nerve growth factor levels and the ability of neurons to bind to this valuable cellular messenger. ALCAR ameliorates these age-related deficits, therefore demonstrating another way it naturally helps create more acetylcholine needed for neuronal transmission, learning, and recall. (16) ALCAR has been found to optimize the response of the NMDA receptors and lessen their decline in number. (17,18)

Treating Depression

Research has shown that ALCAR is one of the most valuable compounds for relieving depression, (19,20) especially in older adults. (21) The usual dose used is 3 g/day. (22)

Reversing Senility

There are over 30 studies which show that ALCAR slows or prevents age related decline in mental function. (23) 1.5 g/day of ALCAR given to 236 older adults for 45 days significantly increased the effectiveness of performance on all the measures of cognitive functioning, memory performance, and constructional thinking. (24) Twenty adults given 1.5 g of ALCAR per day showed that it reversed many of the signs of aging. Cognitive ability, depression, behavioral and self-sufficiency performances and quality of life all improved. (21) Studies of 40 senile patients given 1.5 g/day of ALCAR for 40 days (25) and of 481 subjects given 2 g for 150 days showed similar results. (26) Two g/day of ALCAR enhances learning in older adults. (27,28) ALCAR also improves directional and word memory after only a few weeks of treatment. (29)

Speeding Stroke Recovery

One-hundred sixty patients who had had a stroke a year or more ago were given 1.5 g ALCAR each day orally for eight weeks. This caused a marked degree of functional recovery, as well as improved mood and attention conditions. (30) Twenty patients with chronic cerebrovascular disease who suffered an ischemic stroke at least 6 months before were given a single 1.5 g dose of ALCAR intravenously, leading to acutely enhanced cerebral blood flow. (31)

Slowing Alzheimer’s

Thirty AD patients given 2.5-3 g/day ALCAR for 6 months achieved less mental deterioration according to a wide range of mental function tests. (32) One year treatment with ALCAR in 130 patients with AD led to a slower rate of deterioration in 13 of the 14 outcome measures. (33) Two g of ALCAR given to 20 AD patients for 24-weeks enhanced short term memory. (34)

Research shows that AD subjects under 65 may benefit the most from ALCAR. A study of 334 subjects diagnosed with AD showed that ALCAR slows the progression of AD, particularly in younger subjects. (35) Another 1-year, double-blinded study using 3 g/day of ALCAR or placebo for 12 months in 358 patients showed ALCAR slows the decline of early-onset AD patients aged 65 or younger. (38)

ALCAR has also been found useful in enhancing visual memory and attention in Down’s syndrome patients. (37) This is a group at increased risk to AD, and lifelong supplementation of ALCAR may be of particular benefit to them.

Two placebo controlled trials showed ALCAR improves mental parameters in patients with organic brain syndrome after only eight weeks. (38) Alcoholics with cognitive impairment also benefit from ALCAR. (39)

Healing Physically Damaged Neurons

Animal models of sciatic nerve injury show that ALCAR dramatically increases the speed of nerve healing and prevents loss of nerve function. (40) ALCAR should be considered in all cases where physical injury to neurons occurs, including brain injuries. (41)

In summary, ALCAR has proven itself safe and effective in ameliorating the symptoms of cognitive loss in older adults, relieving depression, speeding stroke recovery, and slowing the progression of Alzheimer’s disease. What are now needed are prospective, randomized trials of ALCAR in subjects who take it from middle age onward to see if ALCAR can prevent the cognitive loss in healthy adults.

Benefits of Acetyl-L-Carnitine

* Protects and Enhances Mitochondrial Function (16)

* Enhances Immune Function and IGF-1 levels (17)

* Protects against the loss and reduction in axonal transport of substance P (18)

* Reduces HPA axis hyperactivity (19)

* Increases hippocampal synaptic contact zones (20)

* Protects against stress-induced neuroendocrine changes (21)

* Enhances long-term memory (22)

* Increases learning capacity (23)

* Prevents age-related memory deterioration (24)

* Helps maintain a normal number of both axosomatic synapses and giant bouton vesicles (25)

* Increases membrane fluidity and counters the increase in membrane viscosity seen both in aging and in neuronal lipid peroxidation (26)

* Protects cell membranes from physical stress (27)

* Reduces lipofuscin accumulation in neurons (28)

* Helps neurons remain energetic by using alternate energy sources such as lipids and ketones (29)

* Increases the efficiency of neuronal transmission (30)

* Protects against ischemia/reperfusion induced cellular damage (31) and lowers lactic acid levels and speeds recovery from ischemic events (32)

* Protects neuronal RNA from damage (33)

* Helps maintain cholinergic transmission between neurons (34)

* Protects against DNA breakage (36)

Therapeutic Doses Suggested by Research

Stroke Victims 1.5 g/day

Memory/Learning Enhancement 2 g/day

Alzheimer’s Disease 2-3 g/day

Senility 3 g/day

Depression 3 g/day

Nerve Injury (Animal Research) 3 g/day


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(29.) Arrigo A, Casale R, Buonocore M, Clano C. Effects of acetyl-L-camitine on reaction times in patients with cerebrovascular insufficiency. Int J Clin Pharmacol Res 10(1-2): 133-7. 1990.

(30.) Patti F, Marano P. Cappello S. Effects of L-Acetylcarnitine on functional recovery of hemiplegic patients. Clin Trials J 25 (Supp 1): 87-101, 1988.

(31.) Postiglione A, Soricelli A, Cicerano U, Mansi L, De Chiara S. Gallotta G, Schettini G, Salvatore M. Effect of acute administration of L-acetyl carnitine on cerebral blood flow in patients with chronic cerebral infarct. Pharmacol Res 23(3): 241-6, 1991.

(32.) Sano M, Bell K, Cole L, Dooneief G, Lawton A, Legler L, Marder K, Naini A, Stern Y, Mayenux R. Double-blind parallel design pilot study of acetyl levocarnitine in patients with Alzheimer’s disease. Arch Neurol 49 (11): 1137-41,1992.

(33.) Spagnoli A, Lucca U, Menasce G, Bandera L. Cizza G, Forloni G, Tettamanti M, Frattura L, Tiraboschi P, Comelli M, et al. Long-term acetyl-L-carnitine treatment in Alzheimer’s disease. Neurology 41(11): 1726-32, 1991.

(34.) Rai G, Wright G, Scott L, Beston B, Rest J, Exton-Smith AN. Double-blind, placebo controlled study of acetyl-l-camitine in patients with Alzheimer’s dementia. Cur Med Res Opin 11(10): 638-47. 1990.

(35.) Brooks JO, 3rd, Yesavage JA, Cans A, Bract C. Acetyl L-carnitine slows decline in younger patients with Alzheimer’s disease: a reanalysis of a double-blind, placebo-controlled study using the bilinear approach. Int Psychogeriatr 10(2):193-293, 1998.

(36.) ThaI LJ, Carla A, Clarke WR, Ferris SH, Friedland RP, Petersen RC, Pettegrew JW, Pleiffer E, Raskind MA, Sano M. Tuszynski MH, Woolson RF. A 1-year multicenter placebo-controlled study of acetyl-L-carnitine in patients with Alzheimer’s disease. Neurology 47(3):705-11, 1996.

(37.) De Falco PA, D’Angelo E, Grimaldi G, Scafuro F, Sachez F, Caruso G. [Effect of the chronic treatment with L-acetyl-carnitine In Down’s syndrome]. Clin Ter 144 (2): 123-7, 1994.

(38.) Herrmann WM, Dietrich B, Hiersemenzel R. Phermaco-electroencephalographic and clinical effects of the cholinergic substance acetyl-L-carnitine — in patients with organic brain syndrome. Int J Clin Pharmacol Res 10(1-2): 81-4. 1990.

(39.) Tempesta E, Troncon R, Janiri L, Colusso L, Riscica P. Saraceni G, Gesmundo E, Calvani M, Benedetti N, Pole P. Role of acetyl-L-carnitine in the treatment of cognitive deficit in chronic alcoholism. Int J Clin Pharmacol Res 10(1-2): 101-7, 1990.

(40.) De Angelis C, Scarfo C, FalcineIII M, Ferns E, Reda E, Ramacci MT. Angelucci L. Acetyl-L-carnitine prevents age dependent structural alterations in ref peripheral nerves end promotes regeneration following sciatic nerve injury in young end senescent rats. Exp Neurol 128 (1): 103-14, 1994.

(41.) De Angelis C, Scarfo C, Falcinelli M, Reda E, Ramacci MT. Angelucci L. Levocamitine acetyl stimulates peripheral nerve regeneration and neuromuscular junction remodelling following sciatic nerve injury. Int J Clin Pharmacol Res 12(56):269-79, 1992.


Robert Crayhon, MS

Designs for Health Institute, Inc.

5345 Arapahoe Ave #3 Boulder, Colorado 80303 USA


COPYRIGHT 2002 The Townsend Letter Group

COPYRIGHT 2002 Gale Group

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