L-Carnitine

What Are "Star" Ratings?

a7_3star Reliable and relatively consistent scientific data showing a substantial health benefit.

a7_2star Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

a7_1star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

This supplement has been used in connection with the following health conditions:

Used for	Amount	Why
Angina	1 gram two or three times per day	Supplementing with L-carnitine may improve heart function and ease angina symptoms.
Angina 1 gram two or three times per day L-carnitine is an amino acid needed to transport fats into the mitochondria (the place in the cell where fats are turned into energy). Adequate energy production is essential for normal heart function. Several studies using 1 gram of L-carnitine two to three times per day showed an improvement in heart function and a reduction in symptoms of angina.²^{, 3}^{, 4}Coenzyme Q10 also contributes to the energy-making mechanisms of the heart. Angina patients given 150 mg of coenzyme Q10 each day have experienced greater ability to exercise without experiencing chest pain.⁵ This has been confirmed in independent investigations.⁶ Learn More

Used for	Amount	Why
Congestive Heart Failure	500 mg two to three times per day with a doctor's supervision	Supplementing with L-carnitine can improve heart function and exercise capacity and reduce heart muscle damage due to insufficient oxygen.
Congestive Heart Failure 500 mg two to three times per day with a doctor's supervision People with CHF have insufficient oxygenation of the heart, which can damage the heart muscle. Such damage may be reduced by taking L-carnitine supplements.⁷ L-carnitine is a natural substance made from the amino acids lysine and methionine. Levels of L-carnitine are low in people with CHF;⁸ therefore, many doctors recommend that those with CHF take 500 mg of L-carnitine two to three times per day. Most L-carnitine/CHF research has used a modified form of the supplement called propionyl-L-carnitine (PC). In one double-blind trial, people using 500 mg of PC per day had a 26% increase in exercise capacity after six months.⁹ In double-blind research, other indices of heart function have also improved after taking 1 gram of PC twice per day.¹⁰ It remains unclear whether propionyl-L-carnitine has unique advantages over L-carnitine, as limited research in animals and humans has also shown very promising effects of the more common L-carnitine.¹¹ Learn More

Used for	Amount	Why
Heart Attack	2 grams daily	Taking L-carnitine may help reduce damage and complications following a heart attack.
Heart Attack 2 grams daily L-carnitine is an amino acid important for transporting fats that can be turned into energy in the heart. Clinical trials have reported that taking L-carnitine (4–6 grams per day) increases the chance of surviving a heart attack.¹²^{, 13}^{, 14} In one double-blind trial, individuals with suspected heart attack were given 2 grams of L-carnitine per day for 28 days.¹⁵ At the completion of this study, infarct size, as well as the number of nonfatal heart attacks, was lower in the group receiving L-carnitine versus the placebo group. Double-blind research using L-carnitine intravenously also shows promise.¹⁶ Learn More

Used for	Amount	Why
Attention Deficit–Hyperactivity Disorder	100 mg per 2.2 lbs (1 kg) of body weight daily, up to a maximum of 4 grams per day	In a double-blind study, supplementing with L-carnitine resulted in improvement in 54% of a group of boys with ADHD, compared with a 13% response rate in the placebo group.
Attention Deficit–Hyperactivity Disorder 100 mg per 2.2 lbs (1 kg) of body weight daily, up to a maximum of 4 grams per day In a double-blind study, supplementation with L-carnitine for eight weeks resulted in clinical improvement in 54% of a group of boys with ADHD, compared with a 13% response rate in the placebo group.¹⁷ The amount of L-carnitine used in this study was 100 mg per 2.2 pounds of body weight per day, with a maximum of 4 grams per day. No adverse effects were seen, although one child developed an unpleasant body odor while taking L-carnitine. Researchers have found that this uncommon side effect of L-carnitine can be prevented by supplementing with riboflavin. Although no serious side effects were seen in this study, the safety of long-term L-carnitine supplementation in children has not been well studied. This treatment should, therefore, be monitored by a physician. Learn More

Used for	Amount	Why
Chronic Fatigue Syndrome	1 gram three times daily	L-carnitine is an important nutrient for energy production. Supplementation can make up for a possible deficiency.
Chronic Fatigue Syndrome 1 gram three times daily L-carnitine is required for energy production in the powerhouses of cells (the mitochondria). There may be a problem in the mitochondria in people with CFS. Deficiency of carnitine has been seen in some CFS sufferers.¹⁸ One gram of carnitine taken three times daily for eight weeks led to improvement in CFS symptoms in one preliminary trial.¹⁹ Supplementation with 6 grams of L-carnitine per day for four weeks also improved fatigue in a preliminary study of patients with advanced cancer.²⁰ Similar improvements were seen in another study of patients with advanced cancer given up to 3 grams of L-carnitine per day for one week.²¹ Learn More

Used for	Amount	Why
Chronic Obstructive Pulmonary Disease	2 grams taken twice per day	Studies have shown that when L-carnitine is given to people with chronic lung disease, breathing during exercise improves.
Chronic Obstructive Pulmonary Disease 2 grams taken twice per day L-carnitine has been given to people with chronic lung disease in trials investigating how the body responds to exercise.²²^{, 23} In these double-blind trials, 2 grams of L-carnitine, taken twice daily for two to four weeks, led to positive changes in breathing response to exercise. Learn More

Used for	Amount	Why
Erectile Dysfunction (Acetyl-L-Carnitine)	2 grams of each daily	In one study, supplementing with the combination of propionyl-L-carnitine (a form of L-carnitine) and acetyl-L-carnitine significantly improved erectile function in elderly men.
Erectile Dysfunction 2 grams of each daily In a double-blind study, supplementing with the combination of propionyl-L-carnitine (a form of L-carnitine) and acetyl-L-carnitine (2 grams of each per day) for six months significantly improved erectile function in elderly men with erectile dysfunction associated with low testosterone levels. Propionyl-L-carnitine and acetyl-L-carnitine were significantly more effective than testosterone treatment.²⁴ Learn More

Used for	Amount	Why
High Triglycerides	1 to 3 grams daily	Supplementing with L-carnitine may help normalize triglyceride levels.
High Triglycerides 1 to 3 grams daily L-carnitine is another supplement that has lowered TGs in several clinical trials.²⁵^{, 26} However, the effect of carnitine is unpredictable, and some individuals have experienced an increase in triglyceride levels after receiving this supplement.²⁷ Some doctors recommend 1–3 grams of carnitine per day, in the form known as L-carnitine. Learn More

Used for	Amount	Why
Intermittent Claudication	2 grams a day of proprionyl-L-carnitine	In double-blind trials, supplementation with either L-carnitine or propionyl-L-carnitine (a form of L-carnitine) has increased walking distance in people with intermittent claudication.
Intermittent Claudication 2 grams a day of proprionyl-L-carnitine 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.²⁸ In the study using propionyl-L-carnitine, improvement occurred only in those who could not walk 250 meters to begin with. In that group, maximum walking distance increased by 78% with propionyl-L-carnitine supplementation compared with a 44% increase in the placebo group, also a statistically significant difference.²⁹ The amount of propionyl-L-carnitine used was 1 gram per day, increasing to 2 grams per day after two months, and 3 grams per day after an additional two months, if needed. The results of this trial have been confirmed in a large European trial.³⁰ Learn More

Used for	Amount	Why
Male Infertility	3 grams daily	L-carnitine appears to be necessary for normal functioning of sperm cells. Supplementing with it may improve sperm motility.
Male Infertility 3 grams daily L-carnitine is a substance made in the body and also found in supplements and some foods (such as meat). It appears to be necessary for normal functioning of sperm cells. In preliminary studies, supplementing with 3–4 grams per day for four months helped to normalize sperm motility in men with low sperm quality.³¹^{, 32} While the majority of clinical trials have used L-carnitine, one preliminary trial found that acetylcarnitine (4 grams per day) may also prove useful for treatment of male infertility caused by low quantities of immobile sperm.³³ Learn More

Used for	Amount	Why
Multiple Sclerosis and Drug-Induced Fatigue	3 to 6 grams daily	Some drugs that are used to treat MS appear to deplete carnitine. In one trial, supplementing with L-carnitine significantly improved fatigue in 63% of drug-treated MS patients.
Multiple Sclerosis and Drug-Induced Fatigue 3 to 6 grams daily Some drugs that are used to treat MS appear to deplete carnitine. In a preliminary trial, supplementation with 3 to 6 grams of L-carnitine per day significantly improved fatigue in 63% of drug-treated MS patients.³⁴

Used for	Amount	Why
Sickle Cell Anemia	50 mg per 2.2 lbs (1 kg) of body weight daily	In a study of children with sickle cell anemia, supplementing with L-carnitine reduced the number of painful crises and improved abnormal heart function and pulmonary hypertension.
Sickle Cell Anemia 50 mg per 2.2 lbs (1 kg) of body weight daily In a preliminary study of children with sickle cell anemia, supplementing with L-carnitine (50 mg per 2.2 pounds of body weight per day for six months) significantly reduced the number of painful crises and significantly improved the abnormal heart function (diastolic dysfunction) that was present in most of the children. L-carnitine supplementation also significantly improved pulmonary hypertension in the children who had this abnormality prior to treatment.³⁵ Learn More

Used for	Amount	Why
Sprains and Strains and Exercise-Related Muscle Injury	3 grams per day	One trial showed that people who take L-carnitine for three weeks before engaging in an exercise regimen are less likely to experience muscle soreness.
Sprains and Strains and Exercise-Related Muscle Injury 3 grams per day One controlled trial showed that people who supplement with 3 grams per day L-carnitine for three weeks before engaging in an exercise regimen are less likely to experience muscle soreness.³⁶

Used for	Amount	Why
Thalassemia	50 to 100 mg per 2.2 lbs (1 kg) of body weight daily	Studies have shown that propionyl-L-carnitine (a form of L-carnitine) protects red blood cells of people with thalassemia against free radical damage. Supplementing with it may reduce the need for blood transfusions.
Thalassemia 50 to 100 mg per 2.2 lbs (1 kg) of body weight daily Test tube studies have shown that propionyl-L-carnitine (a form of L-carnitine) protects red blood cells of people with thalassemia against free radical damage.³⁷ In a preliminary study, children with beta thalassemia major who took 100 mg of L-carnitine per 2.2 pounds of body weight per day for three months had a significantly decreased need for blood transfusions.³⁸ Some studies have found people with thalassemia to be frequently deficient in folic acid, vitamin B12,³⁹ and zinc.⁴⁰ ^{, 41} Researchers have reported improved growth rates in zinc-deficient thalassemic children who were given zinc supplements of 22.5 to 90 mg per day, depending on age.⁴² ^{, 43} Magnesium has been reported to be low in thalassemia patients in some,⁴⁴ ^{, 45} but not all,⁴⁶ studies. A small, preliminary study reported that oral supplements of magnesium, 7.2 mg per 2.2 pounds of body weight per day, improved some red blood cell abnormalities in thalassemia patients.⁴⁷

Used for	Amount	Why
Type 1 Diabetes	0.25 mg per 2.2 lbs (1 kg) of body weight	Supplementing with L-carnitine may reduce cholesterol and triglyceride levels in people with diabetes.
Type 1 Diabetes 0.25 mg per 2.2 lbs (1 kg) of body weight L-carnitine is an amino acid needed to properly utilize fat for energy. When people with diabetes were given L-carnitine (0.5 mg per 2.2 pounds of body weight), high blood levels of fats—both cholesterol and triglycerides—dropped 25 to 39% in just ten days in one trial.⁴⁸ Learn More

Used for	Amount	Why
Type 2 Diabetes	0.25 mg per 2.2 lbs (1 kg) of body weight	Supplementing with L-carnitine may reduce cholesterol and triglyceride levels in people with diabetes.
Type 2 Diabetes 0.25 mg per 2.2 lbs (1 kg) of body weight L-carnitine is an amino acid needed to properly utilize fat for energy. When people with diabetes were given DL-carnitine (0.5 mg per 2.2 pounds of body weight), high blood levels of fats—both cholesterol and triglycerides—dropped 25 to 39% in just ten days in one trial.⁴⁹ Learn More

Used for	Amount	Why
Athletic Performance	Refer to label instructions	L-carnitine has been popular as a potential aid in improving athletic performance because of its role in converting fat to energy. Some studies have found that it improves certain measures of muscle physiology.
Athletic Performance L-carnitine, which is normally manufactured by the human body, has been popular as a potential ergogenic aid (i.e., having the ability to increase work capacity), because of its role in the conversion of fat to energy.⁵⁰ However, while some studies have found that L-carnitine improves certain measures of muscle physiology, research on the effects of 2 to 4 grams of L-carnitine per day on performance have produced inconsistent results.⁵¹ L-carnitine may be effective in certain intense exercise activities leading to exhaustion,⁵² but recent studies have reported that L-carnitine supplementation does not benefit non-exhaustive or even marathon-level endurance exercise,⁵³^{, 54} anaerobic performance,⁵⁵ or lean body mass in weight lifters.⁵⁶ Learn More

Used for	Amount	Why
High Cholesterol	Refer to label instructions	Some preliminary trials report that L-carnitine reduces serum cholesterol and raises HDL cholesterol.
High Cholesterol L-carnitine is needed by heart muscle to utilize fat for energy. Some,⁵⁷^{, 58} but not all, preliminary trials report that carnitine reduces serum cholesterol.⁵⁹ HDL cholesterol has also increased in response to carnitine supplementation.⁶⁰^{, 61} People have been reported in controlled research to stand a greater chance of surviving a heart attack if they are given L-carnitine supplements.⁶² Most trials have used 1 to 4 grams of carnitine per day. Learn More

Used for	Amount	Why
Inherited Cardiomyopathy in Children	Refer to label instructions	Inherited forms of cardiomyopathy seen in children may be responsive to L-carnitine.
Inherited Cardiomyopathy in Children Deficiency of L-carnitine, an amino acid, is associated with the development of some forms of cardiomyopathy.⁶³ Inherited forms of cardiomyopathy seen in children may be the most responsive to therapy with L-carnitine.⁶⁴ ^{, 65} Whether carnitine supplementation helps the average person with cardiomyopathy remains unknown. Nonetheless, some doctors recommend 1 to 3 grams of carnitine per day for adults of average weight.

Used for	Amount	Why
Liver Cirrhosis	Refer to label instructions	L-carnitine injections have been used to improve circulation to the liver in people with cirrhosis.
Liver Cirrhosis L-carnitine injections have been used to improve circulation to the liver in people with cirrhosis,⁶⁶ but trials of the oral supplement are lacking. Learn More

Used for	Amount	Why
Mitral Valve Prolapse	Refer to label instructions	In one report, deficient levels of L-carnitine were found in five people with MVP. One person was given L-carnitine and experienced a complete resolution of MVP symptoms.
Mitral Valve Prolapse In one report, deficient levels of L-carnitine were found in five consecutive people with MVP.⁶⁷ One of these people was given L-carnitine (1 gram three times per day for four months) and experienced a complete resolution of the symptoms associated with MVP. Learn More

Used for	Amount	Why
Obesity	Refer to label instructions	The amino acid L-carnitine is thought to be potentially helpful for weight loss because of its role in fat metabolism.
Obesity The amino acid L-carnitine is thought to be potentially helpful for weight loss because of its role in fat metabolism. In a preliminary study of overweight adolescents participating in a diet and exercise program, those who took 1,000mg of L-carnitine per day for three months lost significantly more weight than those who took a placebo.⁶⁸ A weakness of this trial, however, was the fact that the average starting body weight differed considerably between the two groups. A double-blind trial found that adding 4,000 mg of L-carnitine per day to an exercise program did not result in weight loss in overweight women.⁶⁹ Learn More

Used for	Amount	Why
Raynaud’s Disease	Refer to label instructions	In one study, people with Raynaud’s disease who were given L-carnitine showed less blood-vessel spasm in their fingers in response to cold exposure.
Raynaud’s Disease In one study, 12 people with Raynaud’s disease were given L-carnitine (1 gram three times a day) for 20 days.⁷⁰ After receiving L-carnitine, these people showed less blood-vessel spasm in their fingers in response to cold exposure. Learn More

Also indexed as:

L-carnitine

About this treatment

How to Use It

Most people do not need carnitine supplements. For therapeutic use, typical amounts are 1–3 grams per day.

It remains unclear whether the propionyl-L-carnitine form of carnitine used in congestive heart failure research has greater benefits than the L-carnitine form, since limited research in both animals and humans with the more common L-carnitine has also shown very promising effects.

Where to Find It

Dairy and red meat contain the greatest amounts of carnitine. Therefore, people who have a limited intake of meat and dairy products tend to have lower L-carnitine intakes.

Possible Deficiencies

Carnitine deficiencies are rare, even in strict vegetarians, because the body produces carnitine relatively easily.

Rare genetic diseases can cause a carnitine deficiency. Also, deficiencies are occasionally associated with other diseases, such as diabetes and cirrhosis. Among people with diabetes, carnitine deficiency is more likely to be found in persons experiencing complications of diabetes (such as retinopathy, hyperlipidemia, or neuropathy), suggesting that carnitine deficiency may play a role in the development of these complications. A carnitine deficiency can also result from oxygen deprivation which can occur in some heart conditions. In Italy, L-carnitine is prescribed for heart failure, heart arrhythmias, angina, and lack of oxygen to the heart.

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Last Review: 05-11-2011

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The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2011.

© 1995-2011 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated. This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.

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