The many benefits of L-CARNITINE

Carnitine, or L-carnitine, is a naturally occurring substance found in most cells of the body, particularly the brain, neural tissue, muscle, and heart. Carnitine, whose structure is similar to choline, is widely available in animal foods (meat, poultry, fish and dairy products), whereas plants have very small amounts. Most non-vegetarians consume about 100 to 300 mg of carnitine a day, and the body is able to synthesize this nutrient if dietary intake is inadequate. When ingested as a pill, carnitine is not able to cross the blood-brain barrier as well as its activated form acetyl-L-carnitine. Acetyl l carnitine has a more noticeable mental effect than carnitine. Acetyl l carnitine usually enhances mental clarity and focus, along with slight mood elevation. The effects of carnitine tend to be more physical than mental, in the sense that carnitine may provide physical energy whereas acetyl l carnitine provides more mental energy.

Both acetyl l carnitine and carnitine are wonderful antioxidants, although the former may be more powerful.

Another nutrient related to carnitine is acetylcarnitine. Acetylcarnitine has more of an influence on mental function and mind energy whereas carnitine has more of an influence on physical energy. Both carnitine and acetylcarnitine are sold as supplements.

Benefits of carnitine

If you have a normal diet, you are likely to get adequate amounts of carnitine, yet there are times when taking a carnitine supplement could be helpful. Several studies show carnitine, when given as a daily supplement, improves recovery after heavy exercise. In other words, people experience less fatigue. Carnitine also mproves the exercise capacity of people with peripheral arterial disease. Peripheral artery disease is a condition where the arteries that carry blood to the legs get clogged up and cause pain with walking after a short distance.
And that's not all. Carnitine fights fatigue in other medical conditions. Cancer patients receiving chemotherapy feel less tired when supplemented with carnitine. There's even talk that carnitine may be helpful in weight control and maintaining healthy cholesterol and triglyceride levels. In one trial, when carnitine was given to healthy elderly subjects, the results showed a reduction in total fat mass, an increase in total muscle mass, and a lowering of serum lipids.

How does carnitine work?
Carnitine helps to shuttle fatty acids into mitochondria for energy production. Mitochondria are those tiny structures in each cell that help metabolize fats, protein, and carbohydrates to make energy. I call them the energy factories. There are thousands of these mitochondria in each cell. Without carnitine, fatty acids cannot easily enter into mitochondria for energy production. In addition to producing energy, carnitine helps remove toxic accumulations of fatty acids from mitochondria, keeping these organelles healthy and functioning at their best.... so you can feel energetic all day long.

What's the right dosage for l carnitine?
Since each person has a unique biochemistry, dosage recommendations vary. A carnitine dosage range of 50 to 500 mg daily works for most people. Take a day or two off each week. The effects of carnitine accumulate over time, therefore your dosage may need to be reduced or you may wish to take breaks more often.

Lcarnitine benefits - see the studies listed below
This supplement has potential as a treatment in several conditions, but more research is needed to determine the appropriate dosage and interactions with various other supplements and medications.
Treatment with carnitine decreased attention problems and aggressive behavior in boys with ADHD.

Diabetes - Oral administration of L-carnitine reduces oxidized LDL cholesterol levels in patients with type 2 diabetes.

Exercise --
Carnitine improves recovery after heavy exercise. Carnitine may be of use in improving exercise capacity of people with peripheral arterial disease. Carnitine moderately improves the duration of exercise and time to recovery in patients with chronic stable angina.

Fatigue -- Carnitine may improve fatigue in certain conditions, including cancer patients receiving chemotherapy. Carnitine decreases the severity and type of fatigue induced by interferon-alpha in the treatment of patients with hepatitis C. Administration of carnitine to healthy elderly subjects results in a reduction of total fat mass, an increase of total muscle mass, and appears to exert a favorable effect on fatigue and serum lipids.

Fertility -- Carnitine and acetyl carnitine therapy are effective in increasing fertility and sperm-semen quality.

Heart Failure -- Those with heart failure may benefit from carnitine supplements.

Hyperthyroidism -- Carnitine is effective in both reversing and preventing symptoms of hyperthyroidism and has a beneficial effect on bone mineralization.
Because hyperthyroidism depletes the body deposits of carnitine and since carnitine has little toxicity, teratogenicity, contraindications and few interactions with drugs, carnitine can be of clinical use.

Kidney dialysis -- Intravenous carnitine is an accepted pharmaceutical treatment for carnitine deficiency in end-stage renal disease in patients undergoing dialysis.

Liver cirrhosis --
Treatment of patients with liver cirrhosis with signs of liver insufficiency is complex and seldom satisfactory. Carnitine is involved in liver lipid metabolism and thus might be a potentially effective nutrient. One study shows L carnitine lowers serum ammonia concentration and improves lipid metabolism in patients with liver cirrhosis. Carnitine may also play a beneficial role in the treatment of mild or moderate hepatic encephalopathy, and perhaps liver cancer.

Sexual health
-- Apparently l carnitine is helpful in sexual enhancement. Acetyl-l-carnitine is also helpful in this regard.

Thalassemia --
Lcarnitine may be an effective substance for improving the cardiac status of thalassemic patients.

Weight Loss -- The combination of l carnitine, choline, and caffeine has a mild effect on weight loss.

L carnitine side effects
It seems l carnitine is a relatively safe nutrient in doses ranging from 50 to 500 mg. Higher doses of carnitine may lead to excess energy, restlessness, perhaps insomnia. Long term side effects of high dose carnitine use are not fully known.

L Carnitine benefit for fatigue
L carnitine supplements may benefit certain patients with fatigue if there are no obvious causes for the fatigue, such iron deficiency anemia, a serious medical condition, etc.

Even a hundred year old may benefit from carnitine supplements. Italian researchers at the University of Catania gave sixty-six centenarians 2 grams l carnitine daily for six months. At the end of the study period, the l carnitine treated centenarians showed significant improvements in total fat mass and total muscle mass. They were also less likely to have physical and mental fatigue. LDL-cholesterol levels fell among the individuals taking the supplement. L-carnitine takers gained 3.8 kilograms (8.4 pounds) of muscle mass, on average, and lost 1.8 kg (4 pounds) of fat mass. People given L-carnitine were also able to walk 4 meters  further during a 6-minute walking test after treatment than those given placebo.
   Comments: This study shows how much we still can learn about the benefits of supplements in the aged. My preference would be to use a lower amount of carnitine, such as 250 mg or 500 mg. Sometimes when high dosages of energy enhancing pills are taken for prolonged periods, they can accumulate and interfere with sleep.

L-Carnitine treatment reduces severity of physical and mental fatigue and increases cognitive functions in centenarians: a randomized and controlled clinical trial
American Journal of Clinical Nutrition, Vol. 86, No. 6, 1738-1744, December 2007. Mariano Malaguarnera, Lisa Cammalleri, Maria Pia Gargante, Marco Vacante, Valentina Colonna and Massimo Motta. From the Department of Senescence, Urological, and Neurological Sciences, University of Catania, Catania, Italy
Sixty-six centenarians with onset of fatigue after even slight physical activity were recruited to the study. The 2 groups received either 2 grams l carnitine once daily or placebo. Efficacy measures included changes in total fat mass, total muscle mass, serum triacylglycerol, total cholesterol, HDL cholesterol, LDL cholesterol. The l carnitine treated centenarians, compared with the placebo group, showed significant improvements in total fat mass, total muscle mass, and plasma concentrations of total carnitine. Significant differences were also found in physical fatigue and mental fatigue. Our study indicates that oral administration of l carnitine produces a reduction of total fat mass, increases total muscular mass, and facilitates an increased capacity for physical and cognitive activity by reducing fatigue and improving cognitive functions.

L carnitine administration in elderly subjects with rapid muscle fatigue: effect on body composition, lipid profile and fatigue.
Drugs Aging. 2003;20(10):761-7.
L carnitine is an important contributor to cellular energy metabolism. This study aims to evaluate the effects of carnitine supplementation on body composition, lipid profile and fatigue in elderly subjects with rapid muscle fatigue.  Eighty-four elderly subjects with onset of fatigue following slight physical activity were recruited to the study. One group received carnitine 2g twice daily and the other placebo. At the end of the study, compared with placebo, the carnitine-treated patients showed significant improvements in the following parameters: total fat mass, total muscle mass, total cholesterol, LDL-C, HDL-C, triglycerides, apoA1, and apoB. There was improvement in physical fatigue and mental fatigue. Administration of carnitine to healthy elderly subjects resulted in a reduction of total fat mass, an increase of total muscle mass, and appeared to exert a favourable effect on fatigue and serum lipids.

Does carnitine help with weight loss?

L carnitine may be an effective supplement for weight loss by itself, but when combined with other nutrients it is even more effective.

The effect of l-carnitine on fat oxidation, protein turnover, and body composition in slightly overweight subjects.
Metabolism. 2004 Aug;53(8):1002-6.

We used a combined tracer technique with the stable isotopes (13)C and (15)N to gain further insight into the metabolic changes that accompany supplementation of l-carnitine. The aim of the present study was to investigate whether l-carnitine supplementation can influence fat oxidation, protein turnover, body composition, and weight development in slightly overweight subjects. Twelve volunteers received an individual regular diet either without or with l-carnitine supplementation of 3 grams a day for 10 days. Body fat mass, total body water, and lean body mass were calculated by using bioelectric impedance analysis. L-carnitine supplementation led to a significant increase in protein synthesis indicating that the increased dietary fat oxidation in slightly overweight subjects was not accompanied by protein catabolism.

Caffeine, carnitine and choline supplementation of rats decreases body fat and serum leptin concentration as does exercise.
J Nutr 2000 Feb;130(2):152-7

The effect of a combination of caffeine, carnitine and choline with or without exercise on changes in body weight, fat pad mass, serum leptin concentration and metabolic indices was determined in 20 male, 7-wk-old Sprague-Dawley rats. They were given free access to a nonpurified diet without or with caffeine, carnitine and choline at concentrations of 0.1, 5 and 11.5 g/kg diet, respectively. In a 2x2 factorial design, one-half of each dietary group was exercised, and the other half was sedentary. Food intake of the groups was not different, but the body weight was significantly reduced by exercise in both dietary groups. Fat pad weights and total lipids of epididymal, inguinal and perirenal regions were significantly reduced by the supplements as well as by exercise. Regardless of exercise, supplements significantly lowered triglycerides in serum but increased levels in skeletal muscle. Serum leptin concentrations were equally lowered by supplements and exercise. Serum leptin was correlated with body weight, fat pad weight  and serum glucose. We conclude that the indices of body fat loss due to dietary supplements with carnitine were similar to those due to mild exercise, and there were no interactive effects of the two variables.

L carnitine benefit for fertility and sperm health

Combined treatment with L-carnitine, a popular dietary supplement, and acetyl-carnitine, a related chemical, appears to improve sperm motility in men with fertility problems, according to a new study. In the study, 60 infertile men between the ages of 20 and 40 years were randomly selected to take a combination of L-carnitine and L-acetyl-carnitine or an inactive "placebo" for 6 months. In the medical journal Fertility and Sterility, researchers at the University of Rome led by Dr. Andrea Lenzi report that 2 months after the completion of therapy, men who took L-carnitine and acetyl carnitine had increases in sperm concentration, forward movement, and total movement. The most significant improvements in sperm motility, both forward and total, were observed in men who had the lowest levels of moving sperm when the study began. The researchers note that four spontaneous pregnancies were achieved during the study by men who had taken the combination therapy.

Placebo-controlled double-blind randomized trial on the use of L-carnitine, L-acetyl carnitine, or combined L-carnitine and L-acetyl carnitine in men with idiopathic asthenozoospermia.
Fertility & Sterility 2005 Sep;84(3):662-71. Andrology unit, Department of Internal Medicine, Polytechnic University of Marche, Italy.

We evaluated the effectiveness of L-carnitine or acetyl carnitine or combined carnitine and acetyl carnitine treatment in improving semen kinetic parameters. Sixty infertile men, ages 20 to 40 years, with the following baseline sperm selection criteria: concentration > 20 x 10(6)/mL, sperm forward motility < 50%, and normal sperm morphology > 30%. Patients underwent a double-blind therapy of carnitine 3 grams a day, acetyl carntine 3 grams a day, a combination of carnitine 2 g/d and acetyl carnitine 1 g/d, or placebo for a period of six months. Sperm cell motility increased in patients to whom acetyl carnitine was administered both alone or in combination with carnitine; combined carnitine + acetyl l carnitine therapy led to a significant improvement of straight progressive velocity. The administration of carnitine and acetyl carnitine is effective in increasing sperm kinetic features in patients affected by idiopathic asthenozoospemia and improves the total antioxidant status of the seminal fluid.

L carnitine for liver health
L-carnitine inhibits hepatocarcinogenesis via protection of mitochondria.
Int J Cancer. 2004 Oct 21

Hepatocellular carcinoma is usually preceded by chronic inflammation. Recently, we reported that mitochondrial dysfunction plays an important role in hepatocarcinogenesis via the production of free radicals. Furthermore, we proved that L-carnitine effectively protects mitochondrial function in vivo. Therefore, we investigated whether long-term administration of L carnitine could prevent hepatitis and subsequent hepatocellular carcinoma in Long-Evans Cinnamon rats that are often analyzed as a model of hepatocarcinogenesis. The results indicated that oxidative stress elicited from abnormally accumulated copper increased the amount of free fatty acids, thereby inducing mitochondrial dysfunction, resulting in cell death and enhanced secondary generation of reactive oxygen species, which were significantly inhibited by carnitine treatment. Mitochondrial injury plays an essential role in the development of hepatocarcinogenesis and the clinical use of carnitine may have therapeutic potential in individuals with chronic hepatitis.

L carnitine help for thalassemia
Effect of L-carnitine on the physical fitness of thalassemic patients.
Ann Hematol. 2007 January. El-Beshlawy A, El Accaoui R, Abd El-Sattar M, Gamal El-Deen MH, Youssry I, Shaheen N, Hamdy M, El-Ghamrawy M, Taher A. Department of Pediatrics, New Children Hospital, Cairo University, Cairo, Egypt.

Poor physical fitness is a common problem among patients with thalassemia. The main objective of this study is to assess the effect of the administration of oral L-carnitine on exercise tolerance and physical fitness in patients with thalassemia major. Thirty patients followed up at the New Cairo University Children Hospital were included in this study. Clinical, laboratory, and cardiopulmonary exercise testing were performed before and after 6 months of oral L-carnitine therapy (50 mg per kg per day). The oxygen consumption, cardiac output, and oxygen pulse at maximal exercise significantly increased after L-carnitine therapy. However, there was no significant change in minute ventilation and ventilatory equivalent of carbon dioxide. There was also significant increase in the blood transfusion intervals after L-carnitine administration. However, there was no significant change in hemoglobin concentration. L-Carnitine seems to be a safe and effective adjunctive therapeutic approach in thalassemic patients. It improves their cardiac performance and physical fitness. The younger the patients are, the higher is the degree of improvement in their exercise parameters.

   Comments: For long term use we suggest using a much lower dosage of 5 to 10 mg per kilogram body weight.

How does L carnitine work?
Carnitine and acetyl-l carnitine play several important roles in the human body, particularly in energy metabolism. These nutrients shuttle acetyl groups and fatty acids into mitochondria for energy production. Without carnitine, fatty acids cannot easily enter into mitochondria. The acetyl group of acetyl-l carnitine is used to form acetyl-CoA, the most important intermediary in the generation of energy from amino acids, fats, and carbohydrates. Therefore, acetyl-l carnitine serves as an energy reservoir of acetyl groups and both acetyl-l carnitine and carnitine help improve energy production. Those who take carnitine pills often notice an increase in energy levels.   

Carnitine and acetyl l carnitine as anti-aging supplements?
In addition to producing energy, these two nutrients remove toxic accumulations of fatty acids from mitochondria, keeping these organelles healthy and functioning at their best. Energy production in mitochondria is not a perfect process and toxic metabolites do accumulate. Accumulation of these toxic metabolites and the resulting oxidative damage is likely to contribute to aging of cells. A waste substance called lipofuscin accumulates in cells as we age and perhaps adequate acetyl-l carnitine intake can help minimize this accumulation. A study in rats providing acetyl-l carnitine from youth showed this nutrient to decrease lipofuscin levels in their brain as they got old. Therefore, it is theoretically possible that supplementation with carnitine or acetyl-l-carnitine can slow the aging process.

Deficiency of l carnitine
Carnitine is comprised of two amino acids, lysne and methionine. Its role is to transport long-chain fatty acids across the cell's inner mitochrondial membrane. Mitochrondia use fatty acids and glucose to produce energy. Secondary carnitine deficiency is a rare metabolic disorder usually diagnosed at birth. However, primary carnitine deficiency, which is due to decreased synthesis of carnitine in the body or altered transport of carnitine across the cellular membrane, can occur in people of all ages. Carnitine levels decrease with age.

Carnitine metabolism
Carnitine, the L-beta-hydroxy-gamma-N-trimethylaminobutyric acid, is synthesized primarily in the liver and kidneys from lysine and methionine. Carnitine covers an important role in lipid metabolism, acting as an obligatory cofactor for beta-oxidation of fatty acids by facilitating the transport of long-chain fatty acids across the mitochondrial membrane as acylcarnitine esters. Furthermore, since carnitine behaves as a shuttle for acetyl groups from inside to outside the mitochondrial membrane, it covers a key role in glucose metabolism and assists in fuel-sensing. A reduction of the fatty acid transport inside the mitochondria results in the cytosolic accumulation of triglycerides, which is implicated in the pathogenesis of insulin resistance.




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