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L-carnitine, its effect, use and dosage. Promotes fat burning and muscle building!

 L-carnitine, its effect, use and dosage. Promotes fat burning and muscle building!

L-carnitine is primarily known as a fat burner. However, very few of us know that in studies of L-carnitine's role in bio-processes, its anabolic potential was first discovered, capable of promoting muscle development.

This is why it is interesting to remember this point and present the anabolic activities of L-carnitine.

1. L-carnitine deficiency

The synthesis of L-carnitine in the human body is not very effective, so this compound must be provided by the diet. Our body achieves full efficiency of L-carnitine synthesis after the first year of its existence, and in the first months of newborn development, the main source is breast milk. This is why premature babies and infants, who are fed a mixture of alternatives, are particularly susceptible to deficiencies. The deficiency is also caused by the following factors:

  • genetic defects (deficiencies in the proteins responsible for transporting L-carnitine),
  • insufficient diet (eg vegetarians),
  • parenteral nutrition or elimination during certain diseases (eg diabetes),

body aging process,

Chronic diarrhea, use of certain medications (such as anti-acne medications) and hemodialysis patients.


The adult human body contains approximately 20 grams of L-carnitine, 98% of which accumulates in the muscles. L-carnitine deficiency leads to myopathy, a muscle disease that manifests as weakness and atrophy. L-carnitine, as an anabolic agent, is intended primarily

 for the treatment of certain forms of myopathy and for replacement therapy in hemodialysis. It is also recommended to promote the physical development of premature infants and infants, in order to improve protein utilization and weight gain in undernourished children. It is also used in geriatrics, as it slows age-related muscle weakness and muscle loss.

2. L-Carnitine as a fat burner

Studies in athletes have confirmed that L-carnitine reduces fat. The skeletal muscles and the heart muscle derive their energy from burning fat during prolonged periods of exertion. Giving L-carnitine to athletes was supposed to increase their oxygenation capacity, their

 ability to exercise and to conserve muscle glycogen during physical work over an extended period of time. It has been observed that L-carnitine supplementation increases the level of energy intake and at the same time leads to a significant reduction in adipose tissue, without affecting overall weight loss.


3. Effect of L-carnitine

L-carnitine is primarily responsible for transporting fatty acids in the direction of the combustion processes. It also participates in the metabolism of amino acids, the production of acetylcholine and the stabilization of biological membranes (protects muscle fibers from their destruction). All this is certainly important for the course of anabolic processes, since

 the efficient burning of fatty acids provides the most enhanced part of protein synthesis from ATP. Fatty acids accumulated in unspecialized tissues (such as adipose tissue) during storage are toxic to the cells in that tissue, scientifically known as lipotoxicity. The same principle applies to muscle fibers which is why L-carnitine deficiency leads to muscle atrophy. By binding to fatty acids, L-carnitine not only introduces them into the combustion processes, but also suppresses their toxicity.

4. Anabolic activity of L-Carnitine

L-carnitine is well known and tested as a fat burner, but it is also a very effective anabolic. It causes increased absorption of proteins and their deposition in tissues. The anabolic activity of L-carnitine is confirmed first of all by the results obtained in the latest research with the participation of athletes performing bodybuilding.


For example, in studies of the effect of L-carnitine supplementation on improving parameters of strength measured in sprint tests (Jacobs, 2010), different doses of L-carnitine or cellulose were given as a placebo to men training for strength training. It turned out that the best results in improving maximal strength and average muscle strength, compared to the placebo group, were achieved with the lowest dose of L-carnitine - 1.5 g, while the 3.0 and 4.5 g doses were completely ineffective.


In another study (Stephens, 2013), amateur athletes were given either 80 grams of carbohydrates or 80 grams of carbohydrates plus 2 grams of L-carnitine twice daily. After a 12-week trial, it turned out that the athletes who ate carbohydrates gained an average of 1.8 kg of fat and lost 200 grams of lean mass, mainly muscle tissue. On the other hand, in the carbohydrate and carnitine group, fat mass did not increase, but muscle mass increased by an average of 400 grams.

The positive effects of L-carnitine on increasing muscle mass were also demonstrated in a study in which ... centenarians volunteers participated (Malaguarner, 2007). The elderly were divided into two groups, one receiving L-carnitine daily and the other a placebo. After six months of supplementation, it turned out that the placebo group experienced an increase in fat mass and lean tissue mass, while in the L-carnitine group, fat mass decreased and muscle mass increased.


5. L-Carnitine compared to anabolic and catabolic hormones


Testosterone stimulates the production of L-carnitine. Administration of testosterone leads to a linear increase in the level of L-carnitine, that is, the higher the dose of testosterone, the higher the concentration of L-carnitine. This relationship works both ways, and administration of L-carnitine leads to increased levels of testosterone.


In one study of strength training athletes (Kraemer, 2006), young amateur athletes were given 2 g of L-carnitine or a placebo daily. After three weeks of supplementation, compared to the placebo group, testosterone levels in the carnitine-treated group were higher before

 and after training, while cortisol levels were lower. It was also found that the muscles of the athletes in the carnitine group, compared to the placebo group, contained approximately 25% more androgen receptors, the concentration of which continued to increase by 25% after training. The fact that the more protein in the muscle, the faster the growth and the larger the muscle is, an important point for athletes.


Also worth noting is one of the most interesting studies on the relationship between L-carnitine and testosterone (Cavallini, 2004), which involved older men (mean age: 66). They were divided into 3 groups. The first group received starch daily for 6 months as a placebo, the second group testosterone and the third group L-carnitine. Placebo administration was clearly ineffective, while testosterone and L-carnitine significantly improved sexual function, well-being and stamina in older men, with L-carnitine having a much stronger effect on erectile parameters.



As a result of research into the relationship between L-carnitine and cortisol (Alesci and Manola, 2004), it turned out that L-carnitine, on the one hand, prevents the binding of cortisol derivatives to its receptors, and on the other hand, it binds itself to these receptors.

 The effect of bonding depends on the fabric. In the cells of the immune system, L-carnitine acts like cortisol. On the other hand, in bone cells, unlike cortisol, which reduces bone mass, carnitine has a positive effect on muscle and bone mass. Therefore, it can be assumed that L-carnitine reduces the catabolic activity of cortisol.


L-carnitine favorably affects muscle growth and development, for example by stimulating the synthesis of the most powerful tissue anabolic hormone, ie, insulin-like growth factor 1 (IGF-1). Research (Keller, 2011 and 2013) also shows that L-carnitine simultaneously inhibits competing catabolic activity responsible for muscle breakdown.


other hormones

L-carnitine increases the level of the powerful anabolic hormone i.e. nitric oxide and at the same time reduces the level of catabolic tissue hormones: IL-1 beta and TNF alfa. Based on this, it is suspected that carnitine hinders the production and inhibits the activity of myostatin, a protein responsible for limiting muscle growth in the body.


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