L-Carnitine on Steroids Rx.com
 | L-carnitine is widely consumed by bodybuilders and athletes. The L-carnitine fad started about 20 years ago and some believe that it is a magical supplement. L-carnitine is a naturally occurring amino acid which is essential for the metabolism of fat. | |
| It also functions as a transporter of fatty acids into the mitochondria. Fats are essential for energy for many tissues in the body. For the organs to survive fats have to be transported across the membranes and this is supported by L-carnitine. |  | |
Physiology
In experimental studies L-carnitine has been shown to stimulate the burning of fats as fuel and spares glycogen. It is felt that this selective action of L-carnitine may provide endurance and stamina.
L-carnitine is normally synthesized in the liver and kidney from a combination of two other amino acids- lysine and methionine. The majority of L-carnitine is found in the muscle tissues. L-carnitine is also available from the ingestions of foods like red meat and dairy products. Despite the wide spread belief that L-carnitine deficiency is common, this is extremely rare in real life.
Some rare individuals may develop deficiency of carnitine because they 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 deficiency may cause symptoms such as fatigue, chest pain, muscle pain, weakness, low blood pressure, and/or confusion. Despite the reports, carnitine deficiency is extremely rare and requires laboratory testing. When low levels are suspected, the amino acid is best obtained from foods, rather than tablets.
Antioxidant effects
L-carnitine has anti-oxidant effects and does provide protection to the cell membranes from oxygenated products. This anti oxidant activity provides maximim protection to the heart at cellular levels and does play a role in the prevention of atherosclerosis.
Effects on diabetes
L-Carnitine has been shown to improve blood sugar control in diabetics. It has been known that supplementation of L-carnitine with insulin also leads to a lowering of blood cholesterol.
Food sources
The highest concentrations of carnitine are found in red meat and dairy products. Other sources of carnitine include:
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Uses | Body building | |||
| Except for some congenital conditions where L-carnitine deficiency is noted, there are no other absolute medical disorders which are treated with L-carnitine. In any case, L-carnitine is recommended for some medical disorders with the belief that it may be beneficial. These conditions include: |  | On the supplement market, there are literally 100s of products that contain L-carnitine. The ads always claim that L-carnitine can increase exercise performance, make the body slim and improve endurance to exercise. And the one common theme in all formulations is that L-carnitine burns fat and thus increases energy. | ||
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| Its use in sports athletes is controversial. | ||||
Despite 30 years of solid research, the data on L-carnitine are mixed. Both negative and positive results have been observed with the use of L-carnitine in human studies. The theory that more is better is simply wrong. Carnitine is readily available from meat and dairy products and the need for supplements is completely unnecessary. The amount required for physiological functioning are so small that one can easily get all the L-carnitine required by eating almost any type of food. The physiology of the body is intricately designed such that excess is simply removed. Many other studies of L-carnitine in sport athletes have found it to be ineffective. Researchers have looked at effects of L-carnitine on endurance muscle build up, loss of weight and energy release and have found no difference compared to placebo.
Weight loss
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. Many studies have shown that L-carnitine has little or no effect on the body weight. Even after consumption of L-carnitine for more than a year, no effects were seen on the waist line or loss of fat. Most experts believe that L-carnitine is an unnecessary ergogenic aid and a waste of money.
Available Forms
Carnitine is available as a supplement in a variety of forms, but only L-carnitine (alone or formulated as to acetic or propionic acid) is recommended.
- LC carnitine is the most widely available supplement and least expensive
- L-acetylcarnitine (LAC) is sold for the treatment of dementias
- L-propionylcarnitine (LPC) is sold for the treatment of heart problems and other vascular disorders
Most experts do not recommend D-carnitine supplements because of the undesirable side effects. L-carnitine is sometimes used in hospital parenteral nutrition therapies.
Dose
L-carnitine is relatively safe and the average dose varies from 500-2000 mg/day
References
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Cha YS, Choi SK, Suh H, et al. Effects of carnitine and ingested caffeine on carnitine metabolism and endurance capacity in athletes. J Nutr Sci Vitaminol (Tokyo) 2001 Dec; 47(6):378-84.
Clarkson PM. Nutrition for improved sports performance. Current issues on ergogenic aids. Sports Med 1996 Jun; 21(6):393-401.
Gatti R, De Palo CB, Spinella P, et al. Free carnitine and acetyL-carnitine plasma levels and their relationship with body muscular mass in athletes. Amino Acids 1998; 14(4):361-9.
Gomes MR, Tirapegui J. Relation of some nutritional supplements and physical performance. Arch Latinoam Nutr 2000 Dec; 50(4):317-29.
Hawley JA, Brouns F, Jeukendrup A. Strategies to enhance fat utilisation during exercise.
Sports Med 1998 Apr; 25(4):241-57.
Karlic H, Lohninger A. Supplementation of L-carnitine in athletes: does it make sense?
Nutrition 2004 Jul-Aug; 20(7-8):709-15.
Krähenbühl S. Carnitine: vitamin or doping? Ther Umsch 1995 Oct; 52(10):687-92.
Stephens FB, Constantin-Teodosiu D, Laithwaite D, et al. A threshold exists for the stimulatory effect of insulin on plasma L-carnitine clearance in humans. Am J Physiol Endocrinol Metab 2006 Oct 17.
