L-carnitine and its role in biochemistry have been well studied for a long time. An organic nitrogenous compound, carnitine, was isolated by Russian scientists Gulevich and Krimberg in 1905 from Liebig’s meat extract, which was a popular food supplement in those years. Actually, the name came from here: from the Latin carnis – “meat”. However, research on carnitine, like many other biological compounds discovered at the beginning of the century, was suspended for quite a long time. And only in 1947, thanks to the research of famous scientists Frenkel and Blevet, this unique substance again became the subject of interest of scientific and applied medicine. In the 1970s and 1980s, it was rigorously proven that L-carnitine accelerates the transport of activated fatty acids in the form of acylcarnitine across the mitochondrial membrane.
The content of carnitine in the body. L-carnitine is widely distributed in the tissues of all organs of almost all organisms. Its concentration in plants is usually low, but in animal tissues, especially in muscles, the content is much higher. L-carnitine is synthesized in the body and comes from food. After absorption in the intestine, it enters the blood in a free or acylated form. The concentration of L-carnitine 10-100 times higher in tissues than in extracellular fluid indicates that it is actively transported into cells. The decrease in the level of L-carnitine in the body is mainly through renal excretion, and to a lesser extent through its degradation.
metabolic function
To meet energy needs, the body mainly utilizes fatty acids and carbohydrates. The inclusion of fatty acids already in the cell cytoplasm in energy metabolism is possible only after the transfer of fatty acids to mitochondria. The most significant role of carnitine in metabolism is to ensure the transport of long-chain fatty acids to the site of oxidation.
Transport is accelerated by the work of two carnitine acetyltransferases located on the outer and inner membranes of mitochondria. Transport is preceded by activation of fatty acids with coenzyme A (CoA) by acyl-CoA synthetase while still in the cytoplasm. After penetration into the lumen of the double membrane of mitochondria, transferase the inner side of the outer membrane catalyzes the formation of long-chain acylcarnitine. Translocase transports long chain acylcarnitines into the mitochondrial matrix.
A transferase on the inner membrane catalyzes the reverse reaction and regenerates long chain acyl-CoA in the mitochondrial matrix. oxidation degrades long-chain acyl-CoA to acetyl-CoA, which is mainly supplied to the tricarboxylic acid cycle for oxidation to CO2. Working like a shuttle, L-carnitine is an indispensable component involved in fatty acid oxidation and energy production at the cellular level.
Its unique feature is that it increases the permeability of cell membranes to fatty acids. Without increasing the rate of breakdown of adipose tissue, carnitine increases the utilization of lipids in order to provide energy and, as a result, slows down the rate of synthesis of fat molecules in the subcutaneous fat depots. Thus, with the start of taking carnitine, a persistent loss of adipose tissue begins, while the efficiency of fat oxidation in the body sharply increases, since fatty acids no longer produce toxic free radicals, but energy stored in the form of ATP.
A remarkable property of carnitine is its ability to reduce the content of cholesterol in the body and slow down the formation of vascular atherosclerotic plaques. Under its influence, the formation of lecithin in the liver increases, and since lecithin “washes out” cholesterol from atherosclerotic plaques, we can say that carnitine is one of the few compounds whose use allows you to achieve active longevity.
In addition, it is absolutely indispensable in sports, for the ability to optimize physical effort. By participating in the energy processes occurring in the “energy stations” of cells – mitochondria, carnitine increases physical endurance and the body’s ability to recover. L-carnitine plays an important role in the metabolism of myocardial and skeletal muscle cells; it regulates the metabolism of fatty acids, thereby preventing the accumulation of lipids in cells.
L-carnitine is necessary to increase general and special endurance in aerobic sports. The maximum increase in energy resources can be achieved by combining the intake of carnitine with an increased amount of fat in the diet, which will avoid weight loss during training.
L-carnitine enhances the detoxification function of the liver, protein and glycogen synthesis, more active breakdown of lactic and pyruvic acids, which are “fatigue toxins”. Carnitine helps to increase endurance in anaerobic sports, such as bodybuilding, powerlifting, which require a lot of effort from the athlete. L-carnitine successfully helps the body cope with overtraining and fatigue, the main reason for which is the drop in the energy potential of the nerve centers that provide movement.
As a result of studies on the use of carnitine in sports medicine, the following conclusions were made:
L-carnitine promotes the accumulation of energy in myocytes;
training increases the content of L-carnitine in the muscles;
physical exercises, including bodybuilding, accelerate the metabolism of L-carnitine;
the use of L-carnitine increases the threshold of submaximal physical effort;
the addition of L-carnitine to the diet activates the exchange of oxygen in the muscles and reduces the consumption of glycogen during prolonged physical effort;
L-carnitine increases the peak speed capabilities of marathon runners, VO2max in cyclists and in race walking over long distances.
Without a doubt, big sport is not only about spectacle and achieving results. Overload, stress – all this separately and taken together is the cause of numerous diseases. In mild forms of thyrotoxicosis, carnitine normalizes basal metabolism, reduces heart rate and eliminates nervous excitability.
Supporting the energy of the heart
Most people don’t realize that 70% of the energy the heart receives from the breakdown of fats. And since L-carnitine is directly involved in energy metabolism and actively affects the process of splitting fatty acids, it becomes absolutely indispensable in the work of the heart muscle. Scientific confirmation of the positive effect of this substance on the state of the cardiovascular system has been found. Clinical data indicate that L-carnitine has a positive effect on the functional parameters of the myocardium, significantly increases the viability of the heart muscle, and contributes to the maintenance of normal levels of cholesterol and triglycerides.
In pursuit of normal weight
So, L-carnitine is a vitamin-like substance that has a therapeutic and preventive effect on the body. Carnitine is successfully used in many areas of medicine, including sports medicine, as a non-doping anabolic agent in anaerobic sports, as a means for reducing adipose tissue and developing muscles, for treating physical overload and chronic overwork conditions.
Like many other biologically active molecules, L-carnitine exists in two forms: L-carnitine and D-carnitine. They, like a mirror, reflect each other’s actions. However, only L-carnitine is a physiologically active substance that is present in natural sources, while D-carnitine only inhibits the functions of L-carnitine. The percentage of the L-form should be considered when choosing a drug.
Overweight and obesity is an acute problem of the population of the entire globe. Based on body mass index (BMI), 50% of American adults are obese. Numerous studies have shown that L-carnitine has a positive effect on weight control. When used in conjunction with a low-calorie diet and moderate exercise, it leads to even more significant results: lowering low-density lipoprotein levels and blood pressure.
Practice has shown that athletes need L-carnitine in relatively large doses, the minimum daily dose should be from 3g, and the optimal working dose is 8-12g before the competition. At the same time, the minimum dose must be selected independently by experience, adjusting it depending on the dynamics of achieving a particular result. In case of overwork or severe stress, it is recommended to take 0.5-1 g.