Carnitine, or L-carnitine as it's commonly referred to, is classified as a non-essential amino acid produced in the liver, brain and kidneys from the essential amino acids methionine and lysine. Amino acids are typically used by the body for protein synthesis but carnitine is different as it is mainly used to promote the transport of long-chain fatty acids into the mitochondria for energy production. The result of this process is to provide muscular energy by burning fat. Its name comes from the fact that it was first isolated from meat in 1905 ( carnivore or meat eater), and was initially termed vitamin B-t. Carnitine can also be the generic term for a number of compounds that include L-carnitine, L-acetylcarnitine, acetyl-L-carnitine, and L-propionyl carnitine, however, when the term carnitine is mentioned, most people will see it as a common fat loss ingredient that can be found in numerous and different types of fat loss products. More recently, in addition to it's primary role as a fat burner, there have been a few specialized formulas which combine different types or versions of carnitine into one product, the advantage being that this combination results in numerous benefits not obtainable with standard l-carnitine. However, most people will use this as part of their fat loss strategy.
- The primary benefit is that carnitine helps burn fat for energy, contributing towards fat loss and muscular energy.
- Research is ongoing regarding other potential benefits of carnitine, such as: heart health, brain health and infant nutrition, among others.
In these supplement guides,specifically creatine, I have talked about the energy systems of the body. As you read about carnitine and it's role in energy production, you may be wondering how it ties into the discussion regarding creatine. There is actually an additional system not talked about in the creatine guides, that fourth system is the Aerobic Glycolytic System, also called the Oxygen System. The main source of energy for this system is carbohydrates (from stores in muscles or from the blood stream) and fats (from stores). In order for this system to work there needs to be oxygen present. The waste products are carbon dioxide,which we exhale, and water. This system, if the activity is not too intense, can continue indefinitely assuming the body has glucose, fat, and oxygen. However, if the activity is too intense then glucose may run out, and the body will produce lactic acid. This is referred to as oxygen deficit.
Also, no single system works by itself. All systems are involved all the time no matter what you are doing. The duration and intensity of the activity will determine which system is the primary one, but they are all used to some degree.
Additionally, carnitine is a mainstay of various fat loss formula's, from thermogenics to those products that do not rely on caffeine at all. Numerous studies have been done on carnitine as far back as 1937, included here are two examples:
The effect of l-carnitine on fat oxidation, protein turnover, and body composition in slightly overweight subjects. Metabolism. 2004 Aug;53(8):1002-6. We used a combined tracer technique with the stable isotopes (13)C and (15)N to gain further insight into the metabolic changes that accompany supplementation of l-carnitine. The aim of the present study was to investigate whether l-carnitine supplementation can influence fat oxidation, protein turnover, body composition, and weight development in slightly overweight subjects. Twelve volunteers received an individual regular diet either without or with l-carnitine supplementation of 3 grams a day for 10 days. Body fat mass, total body water, and lean body mass were calculated by using bio-electric impedance analysis. L-carnitine supplementation led to a significant increase in protein synthesis indicating that the increased dietary fat oxidation in slightly overweight subjects was not accompanied by protein catabolism.
Caffeine, carnitine and choline supplementation of rats decreases body fat and serum leptin concentration as does exercise. J Nutr 2000 Feb;130(2):152-7 The effect of a combination of caffeine, carnitine and choline with or without exercise on changes in body weight, fat pad mass, serum leptin concentration and metabolic indices was determined in 20 male, 7-wk-old Sprague-Dawley rats. They were given free access to a nonpurified diet without or with caffeine, carnitine and choline at concentrations of 0.1, 5 and 11.5 g/kg diet, respectively. In a 2×2 factorial design, one-half of each dietary group was exercised, and the other half was sedentary. Food intake of the groups was not different, but the body weight was significantly reduced by exercise in both dietary groups. Fat pad weights and total lipids of epididymal, inguinal and perirenal regions were significantly reduced by the supplements as well as by exercise. Regardless of exercise, supplements significantly lowered triglycerides in serum but increased levels in skeletal muscle. Serum leptin concentrations were equally lowered by supplements and exercise. Serum leptin was correlated with body weight, fat pad weight and serum glucose. We conclude that the indices of body fat loss due to dietary supplements with carnitine were similar to those due to mild exercise, and there were no interactive effects of the two variables.
L-carnitine is very popular as a stand-alone product, coming in tablet, capsule and liquid forms. Potency will vary anywhere form 250mg to 1000mg on average, with 500mg being a common potency level. Timing is usually product dependent so label reading is a must. As part of formula products, L-carnitine is in a wide array of products, not only fat loss but also pre and post workout products as well. While not a overly common ingredient in “pump” based products, it is in several, so it does have a hand in the sarcoplasmic hypertrophy concept I've mentioned over the course of these guides. As to timing and dosage, you would usually purchase a formula product not for the carnitine but more for the specific purpose of the product, so take as that product suggests. The main carnitine formula product that's actually based on carnitine is manufactured by Beverly Nutrition and is a combination of 4 different versions of carnitine and claims to have 21 benefits. This is a unique product offering and at this time is pretty much the only one of it's kind in the marketplace. Finally and as always, careful label reading is a must and your use of carntine, especially in fat loss formulas, requires a complete understanding of the product you are purchasing.