Monograph

Boost energy, burn fat, and build muscle. As an essential amino acid in the fat burning process, L-Carnitine moves stored body fat and triglycerides into the bloodstream to be used for energy. It is also a key nutrient for energy production in the heart and skeletal muscle. NUTRAscriptives® L-Carnitine is obtained from the finest-quality formula (L-CarniPure®) to maximize absorption and utilization.
 

Description

Produced in the United States, L-CarniPure® is NUTRAscriptives® source for an advanced L-Carnitine formula. L-Carnitine is an essential amino acid that is synthesized in the kidneys and liver by lysine and methionine, two essential amino acids. L-Carnitine resides mainly in the muscle tissue.

Research

Cardiovascular Health

Patients undergoing hemodialysis (medical process to clean the blood in the kidneys) experience a decrease in L-Carnitine levels. A twelve-month study found that supplementing with 10 mg of L-Carnitine, after each hemodialysis treatment, increased L-Carnitine serum levels and decreased left ventricular mass.[1]

L-Carnitine can improve vascular function in insulin-resistant, overweight patients. By reducing the formation of free fatty acids that cause endothelial dysfunction (function of the cells that line the inner surface of the blood vessels), L-Carnitine aids normal vessel function. A group of subjects with decreased blood flow in the legs found that L-Carnitine alleviated free fatty acid formation caused by excessive body weight. The decrease in free fatty acids and improvement in blood flow positively contributed to healthy vascular function.[2]

The role of L-Carnitine in maintaining cellular energy, along with its antioxidant activity, can aid cardiac function during various medical heart treatments. One study found L-Carnitine sustained the function of heart muscle cells during heart valve surgery.[3] Another study found L-Carnitine provides a protective role in an ischemia-reperfusion injury (process of unblocking clogged arteries).[4]

By increasing antioxidant activity, L-Carnitine supplementation decreased oxidative stress caused by blood pressure imbalances. One study found this effect offered protection to endothelium tissue in rats with high blood pressure levels.[5]

The deterioration of mitochondria function can lead to age-related health ailments. L-Carnitine can support normal cellular function by improving energy synthesis in the mitochondria. This hinders the decline of various physiological functions. One study found L-Carnitine altered the enzyme activity involved in mitochondria function in aged rats to reach similar levels found in young rats.[6]

Athletes/Energy

L-Carnitine can make exercise training more efficient by improving oxygen uptake. Aerobic processes were strengthened in moderately trained athletes by supplementing 2 g/day of L-Carnitine.[7]

A study reviewed the effects of L-Carnitine on aerobic endurance finding exercise was more sustainable with L-Carnitine supplementation.[8] Furthermore, adding L-Carnitine to an aerobic program can increase exercise tolerance in individuals with respiratory problems. Patients with respiratory ailments were recruited to take 2 g/day of L-Carnitine for 6 weeks. Through muscle training and aerobic tests, results indicated L-Carnitine improved exercise tolerance and muscle strength, as it also reduced lactate production.[9]

L-Carnitine is a beneficial nutrient for muscle fatigue, as it is a major contributor to cellular energy metabolism. A study recruited 84 elderly subjects with onset fatigue to take 2 g/ twice daily of L-Carnitine, or a placebo. These subjects participated in mild physical activity and experienced mental and physical fatigue. Findings suggested L-Carnitine improved energy levels, as well as decreased total fat mass and increased total muscle mass.[10]

Another study indicated L-Carnitine influenced muscle performance by improving aerobic metabolism. The study suggested L-Carnitine delayed muscle fatigue by reducing oxidative damage in the muscle.[11] In addition, L-Carnitine, when combined with exercise training, improved insulin levels and lipid profile levels.[12]

Individuals with gluten sensitivities often have greater fatigue, because of low L-Carnitine levels in the blood. Sixty patients with gluten-intolerance participated in a six-month study, in which patients received 2 g/day of L-Carnitine or a placebo. Results indicated L-Carnitine is a safe, effective treatment for reducing fatigue in gluten-intolerant individuals.[13]

Fat Metabolism/Weight Balance

One study observed the effects of L-CarniPure® on long-chain fatty acid oxidation in healthy adults with 1 g/t.i.d for 10 days. Results showed an increase in fat oxidation among subjects receiving L-CarniPure®; therefore, L-CarniPure® aided fat metabolism.[14]

Another study sustained these findings suggesting L-CarniPure® significantly influenced fat oxidation in overweight subjects. Subjects that received 3 g/d of L-CarniPure® for 10 days had an increase in fat oxidation, in other words the fat stored in the body was used efficiently for energy.[15]

Balance Cholesterol

L-Carnitine may be an aid in maintaining normal cholesterol levels. In a six-month clinical trial of 94 patients with blood sugar and cholesterol imbalances, L-Carnitine lowered cholesterol levels in patients supplementing with this nutrient.[16] A similar study of 52 insulin resistant patients found 2 g/day of L-Carnitine normalized cholesterol levels in three months.[17]

Cognitive Function

Older individuals with low L-Carnitine levels can experience an increase in cognitive and physical fatigue. A study recruited 66 subjects, 100 to 106 years old, with physical and mental fatigue, 2 g/day of L-Carnitine supplementation significantly improved energy levels and mental function.[18]

Impotence

Various infertility clinics have used L-Carnitine to improve sperm quality. One hundred patients received 3 g/d of L-Carnitine for four months finding an increase in sperm motility.[19] A similar study observed an increase in sperm count and motility among 37 out of 47 patients taking 3 g/d of L-Carnitine for three months.[20]

The benefits of L-Carnitine, testosterone, and acetyl-l-Carnitine on impotence, fatigue, and mood were reviewed among 120 men between 60 and 74 years of age. Researchers divided the subjects into three groups to compare the effects. Results indicated L-Carnitine and acetyl-l-Carnitine were significantly more affective than testosterone in restoring erectile health. In addition, L-Carnitine and acetyl-l-Carnitine relieved symptoms of fatigue and low mood associated with male aging.[21]

Blood Sugar

High-fructose diets are largely associated with the development of insulin complications. Such diets also influence changes in cholesterol, free fatty acids, and phospholipids in the skeletal muscle, as oxidative stress and lipid peroxidation lead to insulin imbalances. Supplementing with L-Carnitine has been shown to alleviate the effects of high-fructose diets helping to normalize blood sugar and cholesterol levels in the muscle.[22]

Though high-fructose diets lead to blood sugar imbalances, normal amounts of fructose are needed to maintain red blood cell integrity. One study found L-Carnitine can aid the stabilization of low blood sugar levels in rats that were given high-fructose diets to maintain red blood cell composition.[23] Another study found L-Carnitine hinders the development of glycation (sugar molecule that binds to a protein) that augments insulin-complications.[24]

L-Carnitine may also be an aid for pregnant women with insulin-imbalances. A twelve-week study found that 2 g per day of L-Carnitine significantly moderated the increase of free fatty acids in the blood, which can be a main cause of insulin resistance in pregnant women.[25]

Additional Information – Dosage & Interactions

Suggested Use

As a dietary supplement, take one capsule, or as directed by a physician.

Dosage

Up to 2,000 mg per day in divided doses

Precautions

The maximum safe dosage of this supplement has not been determined for children, pregnant or nursing women, or those with severe liver or kidney disease. As with all supplement regimens, please consult your physician prior to use.

L-Carnitine is generally well-tolerated, although some individuals have reported mild gastrointestinal symptoms.

Drug Interactions

Consult your physician before supplementing with L-Carnitine if you are taking the following medications.
Acenocoumarol (blood thinner); valproic acid; nucleoside analogues didanosine; zalcitabine; stavudine; pivalic acid-containing antibiotics (pivampicillin, pivmecillinam, pivcephalexin).

*Statements made herein have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.

References

[1] Sakurabayashi, T, Takaesu, Y, Haginoshita, S, et al. Improvement of Myocardial Fatty Acid Metabolism through L-Carnitine Administration to Chronic Hemodialysis Patients. Am J Nephrol. 1999; 19:480-484.

[2] Shankar, SS, Mirzamohammadi, B, et al. L-Carnitine may attenuate free fatty acid-induced endothelial dysfunction. Ann NY Acad Sci. 2004 Nov; 1033:189-197.

[3] Xiang, D, Sun, Z, et al. Effect of L-Carnitine on cardiomyocyte apoptosis and cardiac function in patients undergoing heart valve replacement operation. J Huazhong Univ Sci Technolog Med Sci. 2005; 25(5):501-504.

[4] Xie, J, Zeng, Q, Wang, L. The protective effect of L-Carnitine on ischemia-reperfusion heart. J Huazhong Univ Sci Technolog Med Sci. 2006; 26(2):188-191.

[5] Gomez-Amores, L, Mate, A, Miguel-Carrasco, JL, et al. L-Carnitine attenuates oxidative stress in hypertensive rats. J Nutr Biochem. 2007 Aug; 18(8):533-540.

[6] Kumuran, S, Subathra, M, et al. Supplementation of L-Carnitine improves mitochondrial enzymes in heart and skeletal muscle of aged rats. Exp Aging Res. 2005; 31(1):55-67.

[7] Vecchiet, L, Di, LF, Pieralisi, G, et al. Influence of L-Carnitine administration on maximal physical exercise. Eur J Appl Physiol Occup Physiol. 1990; 61(5-6):486-490.

[8] Panjwani, U, Thakur, L, Anand, JP, et al. Effect of L-Carnitine supplementation on endurance exercise in normobaric/normoxic and hypobaric/hypoxic conditions. Wilderness Environ Med. 2007; 18(3):169-176.

[9] Borghi-Silva, A, Baldissera, V, et al. L-Carnitine as an ergogenic aid for patients with chronic obstructive pulmonary disease submitted to whole-body and respiratory muscle training programs. Braz J Med Biol Res. 2006 Apr; 39(4):465-474.

[10] Pistone, G, Marino, A, et al. LevoCarnitine administration in elderly subjects with rapid muscle fatigue: effect on body composition, lipid profile and fatigue. Drugs Aging. 2003; 20(10):761-767.

[11] Dutta, A, Ray, K, Singh, VK, et al. L-Carnitine Supplementation Attenuates Intermittent Hypoxia Induced Oxidative Stress and Delays Muscle Fatigue in Rats. Exp Physiol. 2008 Jun 20.

[12] Cha, YS. Effects of L-Carnitine on obesity, diabetes, and as an ergogenic aid. Asia Pac J ClinNutr. 2008; 17(1):306-308.

[13] Ciacci, C, Peluso, G, Iannoni, E, et al. L-Carnitine in the treatment of fatigue in adult celiac disease patients: a pilot study. Dig Liver Dis. 2007 Oct; 39(10):922-928.

[14] Muller, DM, Seim, W, Kiess, HL, Richter, T. Effects of L-Carnitine supplementation on in vivo long-chain fatty acid oxidation in healthy adults. Metabolism. 2002; 51(11):1389-1391.

[15] Wutzke, H, Lorenz, H. The effect of L-Carnitine on fat oxidation, protein turnover, and body composition in slightly overweight subjects. Metabolism. 2004 Aug; 53(8):1002-1006.

[16] Derosa, G, Cicero, AF, et al. The effect of L-Carnitine on plasma lipoprotein(a) levels in hypercholesterolemic patients with type 2 diabetes mellitus. Clin Ther. 2003 May; 25(5):1429-1439.

[17] Solfrizzi, V, Capurso, C, et al. Efficacy and tolerability of combined treatment with L-Carnitine and simvastatin in lowering lipoprotein(a) serum levels in patients with type 2 diabetes mellitus. Atherosclerosis. 2006 Oct; 188(2):455-461.

[18] Malaguarnera, M, Cammalleri, L, Gargante, MP, Vacante, M, Colonna, V, Motta, M. L-Carnitine treatment reduces severity of physical and mental fatigue and increases cognitive functions in centenarians: a randomized and controlled clinical trial. Am J Clin Nutr. 2007 Dec; 86(6):1738-1744.

[19] Costa, M, Canale, D, et al. L-Carnitine in idiopathic asthenozoospermia: a multicenter study. Italian Study Group on Carnitine and Male Infertility. Andrologia. 1994; 26(3):155-159.

[20] Vitali, G, Parente, R, Melotti, C. Carnitine supplementation in human idiopathic asthenospermia: clinical results. Drugs Exp Clin Res. 1995; 21(4):157-159.

[21] Cavallini, G, Caracciolo, S, et al. Carnitine versus androgen administration in the treatment of sexual dysfunction, depressed mood, and fatigue associated with male aging. Urology. 2004 Apr; 63(4):641-646.

[22] Rajasekar, P, Anuradha, CV. Effect of L-Carnitine on skeletal muscle lipids and oxidative stress in rats fed high-fructose diet. Exp Diabetes Res. 2007; 2007:72741.

[23] Rajasekar, P, Balasaraswathi, K, Anuradha, CV. Effects of L-Carnitine on RBC membrane composition and function in hyperinsulinemic rats. Ital J Biochem. 2007 Mar; 56(1):53-60.

[24] Rajasekar, P, Anuradha, CV. L-Carnitine inhibits protein glycation in vitro and in vivo: evidence for a role in diabetic management. Acta Diabetol. 2007 Jun; 44(2):83-90.

[25] Lohninger, A, Karlic, H, Lohninger, S, et al. Carnitine in Pregnancy. Chemical Monthly. 2005; 136(8):1523-1533.