Acetyl-L-Carnitine: Overview

Alternative names: Acetyl-L-carnitine.

L-Carnitine has a chemical structure similar to the amino acids but is not truly an amino acid.  It helps the body metabolize fatty acids to provide energy; promotes a healthy heart and lessens the risk of heart disease; aids in weight loss; improves muscle strength and lowers blood triglyceride levels.

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Although recognized as a B-vitamin (vitamin B-t), L-Carnitine is not a member of the B-Complex family.  It does possess one of the strong attributes of the B-complex family of vitamins, namely its water-solubility and non-toxic nature.  It is also similar to some B-complex vitamins in that it can be produced by a liver process combining two essential amino acids, Lysine and MethionineCarnitine is unique in that it is recognized both as a vitamin and also as an amino acid.

As with most other substances produced by the body, there are times when insufficient quantities of carnitine may be produced.  Also, there are times when a metabolic defect may exist, interfering with the body's ability to metabolize it.

Most dietary regimens of today do not contain the proper amounts of free amino acids, which are the building blocks of protein and other amino acids such as Carnitine.  Another reason for an inadequate supply, and the body's inability to produce it, is the consumption of protein foods which originate largely from the animal kingdom.


The 'L' in L-Carnitine indicates that it is a natural concentrated organic form of supplement designed primarily for therapeutic use.  This type of supplement can only be produced from the plant kingdom.

Natural sources include Almonds (raw), apricots, artichokes, asparagus, bananas, beans, bee pollen, beet greens, brazil nuts (raw), brewer's yeast, broccoli, Brussels sprouts, buckwheat, carob, cashew nuts (raw), chestnuts (raw), collard greens, garlic, hazel nuts (raw), kale, legumes (beans and peas), lentils, millet, mustard greens, oatmeal, okra (raw), parsley (raw), peanuts (raw-organic), pumpkin seeds (raw), rice bran, rye, sesame seed (raw), soy beans (cooked and sprouted), sunflower seeds (raw), walnuts (raw), whole wheat, wheat bran, wheat germ, yellow corn (raw).

Carnitine is also found in the following herbs: Amaranth, black walnut, burdock, chaparral, comfrey, fenugreek, ginger, horseradish, kelp, nettle, sassafras, spirulina.

Antagonists (substances that diminish its effectiveness) include: Alcoholic beverages tobacco (nicotine) cola drinks, most soft drinks (other than natural juices), coffee and tea (caffeinated and decaffeinated), chocolate (cocoa), inorganic mineral water (tap, well, spring), polluted air, refined sugar and refined sugar substitutes, overcooking foods (especially over 130°F), refined and processed foods, long-term storage of foods, freezing of foods, canning of foods, commercial synthetic fertilizers, pesticides, herbicides, fungicides, radiation exposure, synthetic estrogen, birth control pills, sulfa drugs, most all drug medications.

NOTE: Antagonists for carnitine would for the most part be the same as it would for most other water-soluble B-vitamins.

Function; Why it is Recommended

Carnitine is an essential nutrient with vitamin-like qualities.  It is considered essential in helping to transport fatty acids into mitochondria (the power plants of the cells).  A deficiency in carnitine can therefore result in an overall reduction in energy production by the cells.  It is well-known that individuals can become carnitine-deficient for a number of reasons.

Carnitine has been researched extensively, and has been found very effective in the utilization of fats and the burning of fatty acids.  It is so effective in the process of burning fatty acids that it has shown the ability to register a marked decline in the bad cholesterol (LDL) levels, and simultaneously raise the good cholesterol (HDL) levels.  It also plays a vital role in lowering blood triglycerides, which is the fat content of the blood.

Carnitine helps to balance blood sugar levels and has a direct effect on heart muscle function.

When engaging in physical exercise, muscles require higher levels of carnitine than during periods of rest; the body responds by releasing carnitine reserves stored in the liver.  These reserves are released into the bloodstream and transported to the muscles.  However, only the muscles in need of carnitine are involved.  This process is regulated by the temperature of the muscles: the higher the temperature of the muscles, the more carnitine is attracted to them, thus systematically supplying the muscles with their requirements.

Carnitine is particularly important during strenuous exercise since fat burning contributes approximately 60% of muscle energy in continuous exercise of great intensity.  The Carnitine level in muscle tissue is over 40 times that in blood plasma; the longer or more strenuous the exercise, the greater the requirement.

Carnitine utilizes unsaturated fat as a source of energy, converting muscle and liver glycogenVitamin C-complex works synergistically with carnitine for its synthesis.

L-carnitine, aside from being an incredible anti-aging nutrient, also has shown benefit for multiple medical conditions, including cardiovascular disease such as angina and congestive heart failure, liver and kidney disease, obstructive lung disease, hypoglycemia, and many others.  L-carnitine helps prevent obesity and has even shown benefit in AIDS patients.  Although it is unusual to see physicians prescribing vitamins in the hospital, acetyl-L-carnitine is routinely prescribed by kidney specialists for their patients, since the kidney is a major site of carnitine synthesis.

Carnitine may also be useful in the treatment of anorexia, impaired metabolism, high LDL cholesterol, hypoglycemia, low HDL cholesterol, poor circulation, high triglycerides.

Even though a healthy body has the ability to produce carnitine, there are conditions which sometimes require the use of therapeutic supplementation.  For example, the processes and/or nutrients required to produce it in the body may perhaps be impaired or insufficient.  Or, due to improper diet and the aging process, one's ability to synthesize properly declines.

Carnitine is essential in maintaining a healthy cardiovascular system.  It has a direct and profound effect upon the heart muscle and the way it functions.  It is known to improve the energy metabolism of heart muscle cells that have been weakened by insufficient oxygen supply.  Further, it is known to reverse congestive heart failure and restore the force of heart rate contractions.  Some natural health care doctors, primarily Naturopaths, have described carnitine as the vitamin and/or the amino acid which prevents the buildup of fatty tissue in the heart muscle and therefore preventing the heart muscle from becoming 'flabby'.

Carnitine is very important in the maintenance of muscular integrity.  Therapeutic supplementation can be used successfully to treat muscular weakness and fatigue.  It prevents the atrophying of all body muscles and so is indicated for those individuals who are unable to exercise, but have a desire to avoid muscular atrophy.

Deficiency symptoms include anorexia, cardiogenic shock, congestive heart failure, chronic fatigue, damaged heart tissue, heart attack, hypoglycemia (low blood sugar), muscle disorders, muscular dystrophy, muscle weakness, myoglobinuria (high breakdown of muscle cells), obesity, poor circulation, high cholesterol (LDL), high triglycerides, low cholesterol (HDL).

NOTE: If two or more of the above symptoms are present you may need therapeutic supplementation of carnitine.


It is considered unwise for a lay person to attempt to treat themselves therapeutically.  In view of this, one should always seek the services of a doctor that is formally schooled and trained in the profession of natural health care.

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Acetyl-L-Carnitine can help with the following:



Several clinical trials have demonstrated that carnitine supplementation improves angina and heart disease.  Improvements have been noted in exercise tolerance and heart function.  In one study of patients with stable angina, oral administration of 900mg of L-carnitine increased mean exercise time and the time necessary for abnormalities to occur on a stress test.  These results indicate that carnitine may be an effective alternative to other anti-angina agents, especially in patients with chronic stable angina.

Intermittent Claudication

In double-blind trials, supplementation with either L-carnitine and propionyl-L-carnitine (a form of L-carnitine) has increased walking distance in people with intermittent claudication.  Walking distance was 75% greater after three weeks of L-carnitine supplementation (2 grams taken twice per day), than after supplementation with a placebo, a statistically significant difference. [Brevetti G, Chiariello M, Ferulano G, et al. Increases in walking distance in patients with peripheral vascular disease treated with L-carnitine: a double-blind, cross-over study. Circulation 1988;77: pp.767-73.]

Mitral Valve Prolapse

L-carnitine is an amino acid that acts as a shuttle for fat that is required for cellular metabolism and also acts to strengthen the heart.  Dosage: 500-1,000mg two to three times daily.  Acetyl-l-carnitine is a related nutrient that may be more bio-available.  Dosage: 120mg three times daily.


Dosage: 750 to 1,500mg bid.  Important in fatty acid metabolism, depleted in cardiac muscle during acute infarctions.


There is some evidence that carnitine may be useful in cardiomyopathy [J Child Neurol (Canada) 10: pp.2S45-2S51, 1995].  A deficiency of carnitine is associated with the development of some forms of cardiomyopathy.  Inherited forms of cardiomyopathy seen in children may be the most responsive to therapy with L-carnitine.  The question of whether carnitine supplementation will help the average person with cardiomyopathy remains unanswered, but some doctors recommend up to 3gm of carnitine per day for the average adult.  Carnitine is thought to work well with CoQ10, the two treatments being often combined.


Andropause/Male Menopause

The April 2004 issue of the journal Urology published the findings of Italian researchers that the amino acid carnitine was more active than testosterone in improving symptoms of aging in men, such as sexual dysfunction and depression, associated with the decline of androgenic hormones.

120 men between the ages of 60 and 74 with symptoms of low testosterone were randomized to receive 160mg orally administered testosterone undecanoate, 2gm propionyl-L-carnitine plus 2gm acetyl-L-carnitine per day, or a placebo for a six month period.

Erectile function, sexual desire, sexual satisfaction and nocturnal penile tumescence increased over the course of the study in the group receiving testosterone as well as in the group receiving carnitine.  However, the group receiving carnitine also experienced an increase in orgasm and general sexual well-being.  Erectile function and nocturnal penile tumescence were significantly more improved in this group than in those receiving testosterone.  While both treatments lowered depression scores, carnitine's effect was greater.

Predictably, treatment with testosterone increased serum total and free testosterone and decreased luteinizing hormone levels, but carnitine's effect on these hormones was not significant.  Treatment with carnitine was not associated with an increase in prostate volume as was testosterone treatment.

Fatigue was likewise improved in both groups.  As one negative effect, the men taking testosterone developed enlargement of their prostates, which did not occur in the carnitine-treated group.  Although both testosterone and carnitine improved symptoms of male aging, there was overall superior benefit to carnitine with no real side-effects.

Organ Health

Diabetes Type II

The amino acid L-carnitine improves insulin sensitivity in type 2 diabetes.

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