|| L-acetylcarnitine (LAC), acetyl-L-carnitine, L-proprionyl carnitine (LPC),
L-carnitine fumarate, L-carnitine tartrate, L-carnitine magnesium
Carnitine is a nutrient responsible for the transport of long-chain fatty
acids into the energy-producing centers of the cells (known as the
mitochondria). In other words, carnitine helps the body convert fatty acids into
energy, which is used primarily for muscular activities throughout the body. The
body produces carnitine in the liver and kidneys and stores it in the skeletal
muscles, heart, brain, and sperm.
Some people have dietary deficiencies of carnitine or cannot properly absorb
this nutrient from foods that they eat. Carnitine deficiencies may be caused by
genetic disorders, liver or kidney problems, high-fat diets, certain
medications, and low dietary levels of the amino acids lysine and methionine
(substances needed to make carnitine). Carnitine deficiencies may cause symptoms
such as fatigue, chest pain, muscle pain, weakness, low blood pressure, and/or
confusion. A healthcare provider may recommend use of the supplement
levocarnitine (L-carnitine) for individuals who have a suspected or confirmed
deficiency of this nutrient.
In addition to helping those with carnitine deficiencies, L-carnitine
supplementation may benefit individuals with the following conditions:
Studies suggest that people who take L-carnitine supplements soon after
suffering a heart attack may be less likely to suffer a subsequent heart attack,
die of heart disease, experience chest pain and abnormal heart rhythms, or
develop congestive heart failure. (Congestive heart failure is a condition that
leads to a back up of blood into the lungs and legs because the heart loses its
ability to pump blood efficiently).
In addition, people with coronary artery disease who use L-carnitine along
with standard medications may be able to sustain physical activity for longer
periods of time.
Congestive Heart Failure (CHF)
In addition to reducing one's chances of developing heart failure after a
heart attack, some studies suggest that carnitine may help treat CHF once it has
set in. These studies have shown that carnitine may improve exercise capacity in
people with CHF.
In several studies, people who took L-carnitine supplements had a significant
lowering of their total cholesterol and triglycerides, and an increase in their
HDL ("good") cholesterol levels.
Decreased blood flow to the legs from atherosclerosis (plaque build up) often
causes an aching or cramping pain in the legs while walking or exercising. This
pain is called intermittent claudication and the diminished blood flow to the
legs is called peripheral vascular disease (PVD). At least one well-designed
study suggests that carnitine supplements may improve muscle function and
exercise capacity in those with PVD. In other words, people with PVD may be able
to walk farther and longer if they take carnitine, particularly
Carnitine, in theory, is thought to be helpful for improving exercise
performance. However, studies in healthy athletes have not yet proven this
Although L-carnitine has been marketed as a weight loss supplement, there is
no scientific evidence to date to show that it improves weight loss. A recent
study of moderately overweight women found that L-carnitine did not
significantly alter body weight, body fat, or lean body mass. Based on the
results of this one small study, claims that L-carnitine helps reduce weight are
not supported at this time.
Several studies suggest that amino acid levels, including carnitine, are
diminished in people with anorexia nervosa. Some experts believe that low levels
of carnitine contribute to muscle weakness frequently seen in people with this
eating disorder. However, one study of severely underweight women with anorexia
found that carnitine supplements did not raise levels of this amino acid in the
blood nor did it improve muscle weakness. If you have anorexia, your doctor will
decide if you need amino acid replacement or not.
Alcohol-related Liver Disease
Some researchers speculate that alcohol consumption reduces the ability of
carnitine to function properly in the body. This can lead to a buildup of fat in
the liver. Supplementation with carnitine has been shown to prevent and reverse
the damage caused by alcohol-induced fatty buildup in the liver of animals.
Dementia and Memory Impairment
Some studies have shown that L-acetylcarnitine (LAC), a form of L-carnitine
that readily enters the brain, may delay the progression of Alzheimer's disease,
relieve depression related to senility and other forms of dementia, and improve
memory in the elderly. Unfortunately, however, results from other studies have
been conflicting. For example, one trial suggests that this supplement may help
prevent the progression of Alzheimer's disease in its early stages, but it may
worsen symptoms in later stages of the disease. For this reason, carnitine for
Alzheimer's and other forms of dementia should only be used under the direction
and supervision of your physician.
In a study of individuals with Down syndrome, L-acetylcarnitine (LAC)
supplementation significantly improved visual memory and attention.
Kidney Disease and Hemodialysis
Given that the kidney is a major site of carnitine production, damage to this
organ can cause a significant carnitine deficiency. Many patients undergoing
hemodialysis also experience carnitine deficiencies. For these reasons,
individuals with kidney disease (with or without the need for hemodialysis) may
benefit from carnitine supplementation, if recommended by a healthcare provider.
Low sperm counts have been linked to low carnitine levels in men. Several
studies suggest that L-carnitine supplementation may increase sperm count and
Chronic Fatigue Syndrome (CFS)
Some researchers speculate that chronic fatigue syndrome may be caused by
deficiencies in a variety of nutrients, including carnitine. L-carnitine has
been compared to a medication for fatigue in a study of 30 people with CFS.
Those who took L-carnitine did much better than those who took the medication,
particularly after receiving the supplement for 4 to 8 weeks.
Carnitine (administered intravenously in the hospital) may be helpful in
treating shock from loss of blood, a sizeable heart attack, or a severe
infection of the bloodstream known as sepsis. In one study, acetyl-L-carnitine
helped improve the condition of 115 people with septic, cardiac, or traumatic
Shock is a failure of the circulatory system and is a life-threatening
medical emergency. Its key feature is inadequate blood flow to vital organs in
the body. Therefore, if carnitine were used for this condition, it would, again,
be administered in the hospital along with many other essential conventional
Peyronie's disease is characterized by a curvature of the penis that leads to
scar tissue development and pain during an erection because of blocked blood
flow. A recent study compared acetyl-L-carnitine to a medication in 48 men with
this unusual condition. Acetyl-L-carnitine worked better than the medication at
reducing pain during intercourse and minimizing the curve of the penis.
Acetyl-L-carnitine also had fewer side effects than the medication. This study
is very encouraging and warrants more scientific testing.
Some research suggests that L-carnitine may prove useful for preventing or
diminishing the symptoms associated with an overactive thyroid. These symptoms
include insomnia, nervousness, elevated heart rate, and tremors. In fact, in one
study, a small group of people with hyperthyroidism had improvement in these
symptoms, as well as normalization of their body temperature, when taking
Red meat (particularly lamb) and dairy products are the primary sources of
carnitine. Carnitine can also be found in fish, poultry, tempeh (fermented
soybeans), wheat, asparagus, avocados, and peanut butter. Cereals, fruits, and
vegetables contain little or no carnitine.
Carnitine is available as a supplement in a variety of forms, but only the
form L-carnitine (alone or bound to either acetic or propionic acid) is
- L-carnitine (LC): the most widely available and least expensive
- L-acetylcarnitine (LAC): this form of carnitine appears to be the one
to use for Alzheimer's disease and other brain disorders
- L-propionylcarnitine (LPC): this form of carnitine appears to be most
effective for chest pain and related heart problems, as well as peripheral
vascular disease (PVD).
D-carnitine supplements should be avoided as they interfere with the natural
form of L-carnitine and may produce undesirable side effects.
Under certain medical conditions, L-carnitine is administered as a
prescription from a healthcare provider or given intravenously in a hospital
setting (such as in the case of shock as described in the
|How to Take It|
A typical daily diet contains anywhere from 5 to 100 mg of carnitine,
depending upon whether the diet is primarily plant-based or red meat-based.
If laboratory tests reveal that a child has an amino acid imbalance requiring
treatment, a healthcare provider may recommend a complete amino acid supplement
containing carnitine. For children on valproate for epilepsy, which can lead to
a deficiency of carnitine (see
Interactions section), the doctor will
likely prescribe a dose of 100 mg/kg of body weight per day, not to exceed 2,000
mg per day.
Recommended doses of L-carnitine supplements vary depending on the health
condition being treated. The following list provides guidelines for some of the
most common uses, based largely on doses used in studies for these
- Fat metabolism (conversion of fat to energy) and muscular performance:
1,000 to 2,000 mg usually divided into two doses
- Heart disease: 600 to 1,200 mg three times daily, or 750 mg twice
- Alcohol-related carnitine deficiency: 300 mg three times daily
- Male infertility: 300 to 1,000 mg three times daily
- Chronic fatigue syndrome: 500 to 1,000 mg three to four times per day
- Overactive thyroid: 2,000 to 4,000 mg per day in two to four divided
Because supplements may have side effects or interact with medications, they
should be taken only under the supervision of a knowledgeable healthcare
Although L-carnitine does not appear to cause significant side effects, high
doses (5 or more grams per day) may cause diarrhea. Other rare side effects
include increased appetite, body odor, and rash.
D-carnitine supplements should be avoided as they interfere with the natural
form of L-carnitine and may produce undesirable side effects.
Individuals taking L-carnitine as a sports supplement to improve fat
metabolism and muscular performance should stop using it at least for one week
If you are currently being treated with any of the following medications, you
should not use carnitine without first talking to your healthcare provider.
In a laboratory study, L-carnitine supplements protected
muscle tissue against toxic side effects from treatment with AZT, a medication
used to treat human immunodeficiency virus (HIV) and acquired immunodeficiency
syndrome (AIDS). Additional studies are needed to confirm whether L-carnitine
would also have this effect in people.
Treatment with L-carnitine may protect heart cells
against the toxic side effects of doxorubicin, a medication used to treat
cancer, without reducing the effectiveness of this chemotherapy agent.
Isotretinoin, a strong medication used for severe
acne, can cause abnormalities in liver function, measured by a blood test, as
well as elevations in cholesterol and muscle pain and weakness. These symptoms
are similar to those seen with carnitine deficiency. Researchers in Greece
showed that a large group of people who had side effects from isotretinoin got
better when taking L-carnitine compared to those who took a placebo.
The anticonvulsant medication valproic acid may
lower blood levels of carnitine and can cause carnitine deficiency. Taking
L-carnitine supplements may prevent deficiency and may also reduce the side
effects of valproic acid.
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|Review Date: April 2002|
|Reviewed By: Participants in the review process include: Ruth DeBusk, RD, PhD, Editor,
Nutrition in Complementary Care, Tallahassee, FL; Jacqueline A. Hart, MD,
Department of Internal Medicine, Newton-Wellesley Hospital, Harvard University
and Senior Medical Editor Integrative Medicine, Boston, MA; Gary Kracoff, RPh
(Pediatric Dosing section February 2001), Johnson Drugs, Natick, Ma; Steven
Ottariono, RPh (Pediatric Dosing section February 2001), Veteran's
Administrative Hospital, Londonderry, NH. All interaction sections have also
been reviewed by a team of experts including Joseph Lamb, MD (July 2000), The
Integrative Medicine Works, Alexandria, VA;Enrico Liva, ND, RPh (August 2000),
Vital Nutrients, Middletown, CT; Brian T Sanderoff, PD, BS in Pharmacy (March
2000), Clinical Assistant Professor, University of Maryland School of Pharmacy;
President, Your Prescription for Health, Owings Mills, MD; Ira Zunin, MD, MPH,
MBA (July 2000), President and Chairman, Hawaii State Consortium for Integrative
Medicine, Honolulu, HI.|
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