L-carnitine, sometimes referred to as simply carnitine, is a nutrient manufactured from the amino acids methionine and lysine in the liver and kidneys and stored in the brain, heart, muscles tissue, and sperm. Most people produce sufficient amounts of this nutrient to stay healthy. In infancy, and in situations of high energy needs, such as pregnancy and breast-feeding, the need for L-carnitine can exceed production by the body. Therefore, L-carnitine is considered a "conditionally essential" nutrient. Certain medical disorders may also prevent carnitine biosynthesis or inhibit its distribution to tissue cells, such as intermittent claudication, heart disease, and certain genetic disorders. Some medications may also adversely affect carnitine metabolism in the body.
The primary function of L-carnitine is to convert lipids, or fats, into fuel for energy. Specifically, its role is to move fatty acids into the mitochondria of eukaryotic cells that reside within the protective membranes that surround cells. Here, the fatty acids undergo beta oxidation and break down to form acetate. This event is what kicks off the Krebs cycle, a series of complex biological reactions that are essential to provide energy for every cell in the body.
This nutrient is also known to reduce oxidative stress in tissues and organs initiated by the release of lipid peroxides and free radicals that occur as byproducts of oxygen metabolism. The "stress" results when these rogue molecules, which are highly reactive, attach to and damage cellular proteins and genetic material. Since L-carnitine demonstrates antioxidant activity, it is sometimes used as a complementary therapy in treating various conditions related to oxidative stress, most notably heart disease and angina. In fact, The American Journal of Cardiology reports that this nutrient permits angina patients to exercise more with less pain and also to reduce medication levels. A few studies indicate that carnitine may also permit heart failure patients to experience similar results.
L-carnitine also plays a role in preserving bone density. Unfortunately, this nutrient becomes less concentrated in bone along with osteocalcin, a protein secreted by osteoblasts that is involved in bone mineralization. In fact, these deficiencies are the main factors that contribute to osteoporosis in postmenopausal women. Studies have shown that this condition may be reversed with L-carnitine supplementation, which increases available levels of osteocalcin.
Other issues that L-carnitine therapy may address include enhanced glucose utilization in diabetics, reduced symptoms associated with chronic fatigue syndrome, and improved thyroid regulation in people with hyperthyroidism. There is also evidence to suggest that propionyl-L-carnitine may help to improve erectile dysfunction in men. In addition, research has shown that this nutrient improves sperm count and motility.
In the U.S., this nutrient is sold as an over-the-counter dietary supplement. It is also found in natural weight loss products. While there is little evidence that it actually induces weight loss, there is merit to the claim that it increases muscle mass. L-carnitine is also used as a food additive for sports drinks designed to increase energy and exercise performance. Canada, however, prohibits the labeling of this nutrient as a natural health product and products containing carnitine may not be imported into the country.
Red meat (particularly lamb) and dairy products are the main food sources of carnitine. It can also be found in fish, poultry, tempeh, wheat, asparagus, avocados, and peanut butter. Therefore, people who have a limited intake of meat and dairy products tend to have lower L-carnitine intakes.
As highlighted above, L-carnitine is a non-essential amino acid which is found in foods such as red meat, avocado and dairy products, with supplements also available from health food shops and pharmacies. Key health benefits of taking L-carnitine, include improved energy levels, sperm health, digestion and heart disease symptoms, while side-effects of large does may include diarrhoea and nausea.
L-carnitine supplements are used to increase L-carnitine levels in people whose natural level of L-carnitine is too low because they have a genetic disorder, are taking certain drugs (valproic acid for seizures), or because they are undergoing a medical procedure (hemodialysis for kidney disease) that uses up the body's L-carnitine. It is also used as a replacement supplement in strict vegetarians, dieters, and low-weight or premature infants.
L-carnitine is used for conditions of the heart and blood vessels including heart-related chest pain, congestive heart failure (CHF), heart complications of a disease called diphtheria, heart attack, leg pain caused by circulation problems (intermittent claudication), and high cholesterol.
Some people use L-carnitine for muscle disorders associated with certain AIDS medications, difficulty fathering a child (male infertility), a brain development disorder called Rett syndrome, anorexia, chronic fatigue syndrome, diabetes, overactive thyroid, attention deficit-hyperactivity disorder (ADHD), leg ulcers, Lyme disease, and to improve athletic performance and endurance.
L-carnitine is a non-essential amino acid which is highly concentrated in the cells of the heart muscle, making it important for maintaining a healthy heart. To ensure a supplement contains the ingredient L-carnitine, check to see that it has the letter "L" or "DL" on the label, with "L being the best option to choose, due to its action. In addition to taking L-carnitine nutritional supplements, levels may be increased naturally through eating avocado, dairy products and plenty of red meat.
L-carnitine is made in the liver and recognised to have multiple benefits for physical health and well-being. Its major benefit, as recognised by Lakin et al. (2006) in Healing Supplements, involves its fat metabolizing properties and the ability to lower blood fats associated with high cholesterol. In The Essential Guide to Vitamins, Minerals and Herbal Supplements, Brewer (2010) highlights key health benefits and healing properties relating to L-carnitine supplements, to include the following:
regulates fat metabolism
contains antioxidants
is an energy source for muscle cells
help weight loss
aids digestion – stimulates secretion of gastric/pancreatic juices
helps treat atherosclerosis – hardening/furring up arteries
improves poor circulation
helps fight coronary heart disease
improves exercise tolerance/duration in angina patients
reduces calf pain
minimizes diabetic neuropathy symptoms – numbness, burning, pins and needles
promotes regeneration of nerve fibres
helps elderly fatigue sufferers
improves sperm health
The evidence is mixed as to whether carnitine is useful in treating Alzheimer's disease. Several early studies showed that acetyl-L-carnitine, might help slow down the progression of Alzheimer's disease, relieve depression related to senility and other forms of dementia, and improve memory in the elderly. But larger and better-designed studies found it didn' t help at all. People should take carnitine for Alzheimer's and other forms of dementia only under the supervision of their health care provider.
Decreased blood flow to the legs from atherosclerosis or hardening of the arteries -- where plaque builds up in the arteries -- often causes an aching or cramping pain in the legs while walking or exercising. This pain is called intermittent claudication, and the reduced blood flow to the legs is called peripheral vascular disease (PVD). Several studies show that carnitine can help reduce symptoms and increase the distance that people with intermittent claudication can walk. Most studies have used propionyl-L-carnitine. Scientists don't know whether L-carnitine would work the same.
Diabetic neuropathy happens when high blood sugar levels damage nerves in the body, especially the arms, legs, and feet, causing pain and numbness. Some small preliminary studies suggest acetyl-L-carnitine may help reduce pain and increase feeling in affected nerves. It is also possible that carnitine can help nerves regenerate.
Some studies do show that oral carnitine reduces fat mass, increases muscle mass, and reduces fatigue, which may contribute to weight loss in some people.
Because the kidneys make carnitine, kidney disease could lead to low levels of carnitine in the body. If you have kidney disease, your health care provider may prescribe carnitine -- but you shouldn' t take it without medical supervision.
Low sperm counts have been linked to low carnitine levels in men. Several studies suggest that L-carnitine supplements may increase sperm count and mobility.
Preliminary studies suggest propionyl-L-carnitine may help improve erectile dysfunction.
Peyronie's disease is characterized by a curvature of the penis that leads to pain during an erection. One promising study compared acetyl-L-carnitine to the medication tamoxifen in 48 men with this condition. Acetyl-L-carnitine worked better than tamoxifen at reducing pain during marital relation and reducing the curve of the penis. Acetyl-L-carnitine also had fewer side effects than tamoxifen.
Some research suggests that L-carnitine may help prevent or reduce symptoms of an overactive thyroid, such as insomnia, nervousness, heart palpitations, and tremors. In fact, in one study, a small group of people with hyperthyroidism saw these symptoms improve, and their body temperature become normal, when taking carnitine. But a larger, better-designed clinical trial is needed to see if carnitine really works. In addition, researchers think carnitine may work by blocking the action of thyroid hormone, which could be dangerous for people with low thyroid levels. Don' t take carnitine for hyperthyroidism without your doctor' s supervision.
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.
Your body can produce a very small amount of L-Carnitine on a daily basis, with the highest concentrations in the heart and skeletal muscles. In certain conditions, the demand for carnitine may exceed a person's ability to synthesize it, thus making it a conditionally essential nutrient.
As said above, individuals who eat little to no meats (vegetarians) will benefit from supplementation of L-Carnitine. Although deficiencies are uncommon, muscle fatigue, cramping are some signs of possible deficiency. Generally, deficiency is categorized as primary and secondary carnitine deficiencies.
These are relatively rare hereditary disorders, such as:
Systemic deficiency
Myopathic deficiency
These deficiencies are generally characterized by low carnitine levels, poor absorption of l-carnitine from diet, muscle pain, progressive muscle weakness, etc. The myopathic deficiency is less severe than the systemic form.
This form can be hereditary, or acquired, and generally, there's is low levels of available l-carnitine. This can be characterized by:
Increased loss of carnitine
Insufficient synthesis of carnitine
Malabsorption from diet
These forms of deficiency are generally rare, and although vegetable sources contain much less (close to none) L-Carnitine, vegetarians can usually synthesize enough carnitine to prevent deficiency. However, among pre-mature infants, children, and breast-feeding women, vegetarians are more likely to be deficient.
Some symptoms of deficiency include:
Kidneys not functioning properly after exercise
Weak muscle
Muscle fatigue and muscle cramping
Heart irregularities
(keep in mind: L-Carnitine is found in highest concentrations in the heart and skeletal muscles.
If you are currently being treated with AZT, Doxorubicin, Isotretinoin, and Valproic Acid you should speak to a physician before taking any L carnitine supplements.
If you have a health condition or are on any prescription medications you should also consult with a physician before taking any L carnitine supplements.
It does not appear that L carnitine causes significant side effects, high doses of 5 or more grams per day may cause diarrhea. Other possible but rare side effects include body odor, rash, increased appetite, nausea, vomiting, stomach upset, heartburn, diarrhea, and seizures. This dietary supplement is considered safe when used as recommended.
People with the following conditions should talk to their health care provider before taking carnitine:
Peripheral vascular disease
High blood pressure
Liver disease from alcoholism (cirrhosis)
Diabetes
Kidney disease
History of seizures
The following doses have been studied in scientific research:
BY MOUTH:
For L-carnitine deficiencies in adults: 990 mg two to three times per day in tablets or as an oral solution.
For preventing side effects caused by valproic acid (Depacon, Depakene, Depakote, VPA): 50 to 100 mg/kg/day in three or four divided doses, to a maximum of 3 grams/day.
For chest pain and congestive heart failure (CHF): 1 gram twice daily.
Following heart attack: 2 to 6 grams daily.
For symptoms of overactive thyroid: 1-2 grams twice daily.
For male infertility: 2 grams of L-carnitine plus 1 gram of L-acetyl-carnitine daily.
Carnitine is available as a supplement in a variety of forms.
L-carnitine: the most widely available and least expensive
Acetyl-L-carnitine: Often used in studies for Alzheimer's disease and other brain disorders
Propionyl-L-carnitine: Often used in studies for heart disease and peripheral vascular disease
Avoid D-carnitine supplements. They interfere with the natural form of L-carnitine and may produce unwanted side effects.
In some cases, L-carnitine may be taken by prescription or given intravenously by a health care provider.
The following reviews have been selected:
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30 of 31 people found the following review helpful:
5.0 out of 5 stars Faster Recovery, Improved Strength Gains, July 22, 2009
By
Chinadoll P "Chinadoll P" (USA)
I started taking L-Carnitine originally for it's touted fat burning benefits, but instead found it more helpful for recovering from my workouts and achieving faster strength gains... My cardio endurance has really improved as well. One of the best benefits is better mental functioning and memory, which I was starting to have trouble with from a lack of sleep. This stuff is actually used to treat Alzheimers patients to improve mental functioning as well as heart attack victims to rebuild cardiac tissue. This stuff rocks, and now I won't be without it!
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Reason for taking: Fatigue
12/6/2011 10:12:13 AM
Comment:
3 years ago, I went from running 6 mi/day at 6:30 min/mi with little effort to not being able to run 1 mi. At 1 mi my muscles would fatigue/cramp & I'd have to quit. Recovery was 5-7days! L Carnitine has been [wonderful]! My neurologist prescribed 1000mg/day divided into 4-250mg doses. No fatigue/cramping. No problems recovering from runs!
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11 of 14 people found the following review helpful:
5.0 out of 5 stars l-carnitine is the bomb!, June 14, 2010
By
L. Rodriguez "lr" (Carmel, CA USA)
I am a nutritionist and i advise many of my clients to take 2000 mg of l-carnitine once or twice daily for assistance with burning fat and building muscle. everyone loves it!
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Reason for taking: Fatigue
Reviewer: l-canatine 1500 mg., 35-44 Female, 10/31/2011 9:38:10 AM
Comment:
this is [great] for me. i am always so tired. at 43 years old my body is always low on energy. energy drinks and pills make me too jitter. l-carnatine gives me that non jittery steady energy all day. iseem to feel better thru the day. i take one tablespoon every morning on an empty stomach. it is the best thing i have tried.
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1 of 1 people found the following review helpful:
4.0 out of 5 stars Excellent supplement, November 17, 2011
By
Rosedwsn
I've been using pure L-Carnitine for more than 2 years now and it really helped me lose weight, burn the fat. An excellent complement to diet and exercise. It gives me that boost of energy for my workouts!
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Reason for taking: General Health & Wellness
Reviewer: 35-44 Male, 9/27/2011 5:57:45 AM
Comment:
I have been taking L-Carnitine now for 3 months and have found that it has assisted me in losing +- 6 kgs in weight and I really battled to lose weight before. I believe in this supplement if you are trying to lose weight or even doing gym alot and need more energy give it a try. Good luck...
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23 of 24 people found the following review helpful:
5.0 out of 5 stars Liquid calorie burner in a bottle!, August 26, 2008
By
Felisha D. Mason (Benton, AR)
I have researched and read multiple articles about the benefits of taking L-Carnitine prior to a workout. You experience a bigger calorie burn when you take it prior and this an excellent product because in its liquid form will work immediately and you do not have to take it 30 minutes before your workout like a pill form. I take a Tbs prior to every workout and have noticed an increased weight loss and increased calorie burn.
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Reason for taking: Fatigue
Reviewer: 45-54 Female, 8/27/2011 5:07:51 PM
Comment:
I have taken l-carnitine for 15 years to help combat fatigue related to fibromyalgia (FMS) and it has helped significantly. I am up and around more than lying down! It has been a lifesaver for me. Before I started taking it I was practically bedridden from overwhelming pain and fatigue and now I am able to be more active. I would highly recommend this therapy for anyone struggling with chronic fatigue or fibro pain!
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14 of 14 people found the following review helpful:
5.0 out of 5 stars No negatives, will reorder, April 10, 2011
By
A. Dent "Aragorn" (Minas Anor, GD)
I am not going to write a lot about what L-Carnitine does to me because people react differently to dietary supplements. Speaking for myself only, I do seem to respond to taking on tablespoon prior to my near-daily few miles run on the treadmill. For the 'science' there is good Wikipedia article discussing its positive effects as an antioxidant, on weight loss, aging, diabetes, heart, kidneys and so forth. WebMD states that "L-carnitine helps the body produce energy. It is important for heart and brain function, muscle movement and many other body processes." ...
A few weeks of use show no negative side effects. The product goes down easy, tastes great and running feels good after taking it. I will reorder when I'm done with this bottle.
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