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Sep 15, 2010
L-Carnitine is a naturally occurring amino acid which plays a vital role in the metabolism of fat. It functions as a transporter of fatty acids into the mitochondria, the metabolic furnace of the cell.

L-carnitine was discovered in Russia, and one year later in Germany. The proper name, Carnitine, refers to the Latin origin, (carno, caris). Its structural formula was decoded in 1927, and its physiological significance was understood by the 1960's. L-carnitine is synthesized in the liver and kidneys, from two essential amino acids, lysine and methionine. This synthesis requires the presence of vitamins niacin, B6, and iron. Most (98%) of the carnitine supply resides in the body's muscle tissue. Approximately 80% of the amino acids our bodies need is endogenously synthesized, the remaining 20% are referred to as the essential amino acids. The supply of such aminos, like l-carnitine, must be supplemented exogenously. L-carnitine is available in the following food sources: red meat, diary products, avocado, and tempeh. Although a well balanced diet can provide approximately 75% of what the body is lacking, often conditions arise that make it difficult to obtain all the carnitine one needs.

It has been established that an adequate supply of l-carnitine is necessary for the maintenance of good health. L-carnitine transports long-chain fatty acids across the mitochondrial membrane to be metabolized. L-carnitine aids in the release of stored body fat, tryglycerides, into the bloodstream for energy. Tryglycerides are the major source for the production of energy in the heart and skeletal muscles. Access to l-carnitine is believed to increase energy levels for long-term aerobic activity. L-carnitine is also responsible for muscle contraction, regulation of protein balance and maintenance of a healthy heart. Research also suggests that an adequate supply of l-carnitine could be instrumental in the treatment of diabetes, chronic fatigue syndrome, kidney and liver disease. Since its involvement in the process of burning fats is of most importance to those interested in endurance and body fitness, it is this topic that will be focused upon.

Carnitine boosts energy by stimulating the body's burning of tryglycerides as fuel, and sparing the supply of glycogen stored in the liver for heavier exertion. During exercise, the body will burn fat at a rate of 75-80% of maximum exertion, thus less glycogen from carbohydrates is burned. L-carnitine allows the body to burn more fat, save more glycogen, and ultimately boost stamina and endurance. By providing more fat to the muscles, carnitine makes accessible an otherwise unavailable energy source.


Is this the recipe for success? According to proponents of L-Carnitine, it is the essential amino acid in the optimum fat burning process. They believe that carnitine is to the human body, what a turbo mechanism is to a car: both provide optimal fuel and performance. Minus L-carnitine, fatty acids would have a difficult time permeating the walls of the mitochondria. Energy, stored in carbohydrates and fats, is required to work the muscle. Carbohydrates are converted from glucose to glycogen, to be stored in liver and muscle cells. Eventually, the body turns to fat storage for energy, and possibly, with more ease in the presence of L-carnitine. This is where L-carnitine as a supplement enters. During high energy output, the supply of L-carnitine becomes exhausted. Is it possible to compensate for this decrease solely through metabolic processes and diet? Or is an additional carnitine supplement needed for the extra boost? Judging from the variety of carnitine products now on the market, apparently many believe an additional outside source proves beneficial.

Recent research done on L-carnitine shows mixed results concerning its effectiveness. A number of journal studies involving the administration of l-carnitine to both human participants and animal subjects reveals both adverse and positive results. In Training and Nutrition, J. P. Krabbe (1996) reports that although L-carnitine is important in the correction of human carnitine deficiency, once such a deficiency is corrected, more is unnecessary. Since humans get plenty of it from meat and diary products, most healthy individuals exceed the recommended daily dosage. Krabbe writes, "Also true is that once any deficiency is corrected, that the majority will get excreted. Thus, more is not better, unless you need it." (http;//

Such a case is reported in the Journal of Clinical Neurology. A woman showed secondary carnitine deficiency as a result of anorexia nervosa and liver damage, which rendered her liver incapable of synthesizing l-carnitine (Negoro, Tsuda, Kato & Morimatsu, 1995). Her deficiency was treated with oral administration of L-carnitine.

M. H. Williams (1992) researched the use of ergogenic aids among endurance athletes, and found L-carnitine to be ineffective. Factors that did in fact enhance performance were genetic endowment, proper training and nutrition, and an adequate supply of fluids and carbohydrates. Conversely, McCarty (1995) found that carnitine may promote weight loss in exercise regimens by enhancing glucose homeostasis in the liver. At the Nestle Research Centre, researchers studied the effect of L-carnitine on exercise metabolism after depletion of muscle glycogen. Nine healthy male subjects received L-carnitine or a placebo and then were submitted to 60 minutes of exercise after an overnight fast. It was concluded that metabolism was not influenced by carnitine supplementation (Decombaz, Deriaz, Acheson, Gmuender & Jequier, 1993). A similar study found that during submaximal exercise, carnitine supplementation did not result in increased lipid oxidation or muscle carnitine content, indicating that the administered carnitine was not absorbed by the body (Vukovich, Costill & Fink, 1994).

Is L-carnitine a safe and effective means of enhancing fat metabolism? The evidence presented here reports no harmful side effects. Product reports contest that l-carnitine works by transporting fatty acids to be burned for fuel, increasing both energy supply and lean muscle mass. Studies show a more skeptical look at the product. Most found that unless an individual is deficient in l-carnitine, it is an unnecessary ergogenic aid. I conclude that as with other vitamins, minerals and medications, L-carnitine is as effective as the consumer's belief in the product.

1. Decombaz J., Deriaz O., Acheson K., Gmuender B., & Jequier E. (1993). Effect of L-carnitine on submaximal exercise metabolism after depletion of muscle glycogen. Medicine & Science in Sports & Exercise, 25 (6): 733-40.

2. Fukusako T., Negoro K., Tsuda N., Kato M., & Morimatsu M. (1995). A case of secondary L-carnitine deficiency due to anorexia nervosa and severe liver damage. Clinical Neurology, 35 (1): 34-7.

3. Krabbe J. P., (1996). L-Carnitine. Training- Nutrition, 332.

4. McCarty M. F., (1995). Inhibition of citrate lyase may aid aerobic endurance. Medical Hypotheses, 45 (3): 247-54.

5. Vukovich M. D., Costill D. L., Fink W. J., (1994). Carnitine supplementation: effect on muscle carnitine and glycogen content during exercise. Medicine & Science in Sports & Exercise, 26 (9): 1122-9.

6. Williams M H., (1992). Ergogenic & ergolytic substances. Medicine & Sports in Sports & Exercise, 2 (suppl 9): S344-8.


Staff Member
Aug 11, 2010
Very good post hugec2. My Wife uses L-Carnitine everyday and has for years.


Sep 15, 2010
If you have never tried the homemade injectable version i HIGHLY recomend it...


Oct 19, 2010
I use AAEFX's liquid L-carnitine at 1000 mg twice per day before cardio and training and feel I get increased fat burning results from it.
Number LL

Number LL

VIP Member
Dec 4, 2010
Thanks for reminding me about this supplement. My doctor had me on it and I stopped because something had to give because of financial reasons. I need to take it up again with my cut.
mike ross

mike ross

Dec 18, 2010
If you have never tried the homemade injectable version i HIGHLY recomend it...
yes. this is by far the best results for L-carnitine usage. I like acetyl l-carnitine pills...they work well and help with mental attention/focus as well

the dbol pumps thing is 100% false....
Mini Forklift Ⓥ

Mini Forklift Ⓥ

The Veganator
Dec 23, 2012
Here's my 2c FWIW...

Basically L-Carnitine is needed to carry long chain fatty acids into the mitochondria (the components of cells that produce energy),this is then able to be metaboilsed into energy. The heart is a primary organ where this takes place, hence L-Carnitine's importance for being useful in treating heart conditions such as arrhythmia, congestive heart failure, angina etc (this is because fatty acids are the primary source of fuel for the heart). If someone has a deficiency of essential amino acids, is deficient in the co factors iron, Vitamin C, Vitamin B3 and B6),eats a high fat diet or has poor digestive function/health then that will likely lead to the person also being deficient in L-Carnitine even though it is able to naturally be synthesised in the body.

It's usefulness in terms of bodybuilding tends to be due to the fact that it is lipolytic, it has the ability to improve CV functioning and it can cause an increase in energy producing enzymes.