L-carnitine is a naturally occurring quaternary ammonium compound found in meats and dairy products. It is important for fat-burning since it transports long-chain fatty acids into mitochondria. Hence, most "supplement gurus" claim that L-carnitine L-tartrate, the most common supplemental form of L-carnitine, is an effective weight-loss agent.
However, there are several forms of L-carnitine, each with distinct applications. Depending on when you take L-carnitine and your goals, the appropriate dosage and form will vary.
This article will dive into the benefits of L-carnitine supplements and how to decide which is best for you.
L-carnitine is an important molecular chaperone for transporting fatty acids, particularly long-chain fatty acids, across the outer mitochondrial membrane. Mitochondria are cellular organelles that break down fatty acids to produce chemical energy (e.g., adenosine triphosphate/ATP). As such, mitochondria are veritable "power generators" within cells. The more dense the mitochondria are in your cells, the more energy you burn (i.e., your metabolic rate increases as mitochondria increase).
But L-carnitine supplementation is a bit more complicated than you might presume. The following section explains why the type of L-carnitine supplement you use and when you take it can make all the difference.
Not surprisingly, there are conflicting results regarding the effects of L-carnitine supplements on exercise performance and weight loss [3, 4]. The current data is riddled with methodology and practicality issues. Studies that did find a beneficial effect on VO2 max and respiratory quotient could not be replicated/supported by further research, reducing the confidence that the previous results were not anomalous or biased.
L-carnitine may be effective for improving body composition and muscle fat metabolism during exercise. The weight-loss benefits of supplementing with L-carnitine L-tartrate orally and without an ancillary to increase carnitine transport into mitochondria are most apparent in individuals with carnitine deficiencies. In healthy individuals, such benefits of L-carnitine are likely negligible.
Now, that's not to say that the tartrate form of carnitine is "bunk" or useless. There are ways to improve the absorption and uptake of this type of carnitine supplement, and it does appear to be useful for muscle recovery, exercise performance, and nutrient partitioning when taken before meals (and post-workout) [5].
However, there are several forms of L-carnitine, each with distinct applications. Depending on when you take L-carnitine and your goals, the appropriate dosage and form will vary.
This article will dive into the benefits of L-carnitine supplements and how to decide which is best for you.
L-Carnitine Supplementation: The Basics
L-carnitine is often mischaracterized as an amino acid, when in fact, it is a charged molecule known as a "quat" (short for quaternary ammonium compound). The body naturally produces L-carnitine from the essential amino acids lysine and methionine, which likely explains why people commonly mistake carnitine for an amino acid. The average adult male stores roughly 20 to 25 grams of L-carnitine, most of which (~95%) reside in skeletal muscle tissue and the heart [1].L-carnitine is an important molecular chaperone for transporting fatty acids, particularly long-chain fatty acids, across the outer mitochondrial membrane. Mitochondria are cellular organelles that break down fatty acids to produce chemical energy (e.g., adenosine triphosphate/ATP). As such, mitochondria are veritable "power generators" within cells. The more dense the mitochondria are in your cells, the more energy you burn (i.e., your metabolic rate increases as mitochondria increase).
Taking L-Carnitine Supplements: Which Form Is Best?
A typical Western diet contains roughly 100 mg to 300 mg of L-carnitine per day, mostly from red meat and dairy. In vegan diets, L-carnitine content may be as low as a few milligrams per day. At dietarily relevant intakes, L-carnitine won't produce ergogenic effects or lead to greater weight loss. As such, you'll need to take L-carnitine as a supplement for best results.But L-carnitine supplementation is a bit more complicated than you might presume. The following section explains why the type of L-carnitine supplement you use and when you take it can make all the difference.
L-CARNITINE L-TARTRATE
L-carnitine L-tartrate is the carnitine salt of tartaric acid, a naturally occurring substance found in many fruits. Supplement companies often claim that L-carnitine L-tartrate enhances exercise performance, cognitive function, and fat burning/weight loss. Yet, there isn’t much compelling evidence that's the case with this particular type of L-carnitine supplement.Moreover, intravenous administration does not help increase muscle carnitine stores; a series of I.V. infusion studies discuss how this method of administration, similarly to oral supplementation, fails to increase muscle carnitine stores [2].
Not surprisingly, there are conflicting results regarding the effects of L-carnitine supplements on exercise performance and weight loss [3, 4]. The current data is riddled with methodology and practicality issues. Studies that did find a beneficial effect on VO2 max and respiratory quotient could not be replicated/supported by further research, reducing the confidence that the previous results were not anomalous or biased.
L-carnitine may be effective for improving body composition and muscle fat metabolism during exercise. The weight-loss benefits of supplementing with L-carnitine L-tartrate orally and without an ancillary to increase carnitine transport into mitochondria are most apparent in individuals with carnitine deficiencies. In healthy individuals, such benefits of L-carnitine are likely negligible.
Now, that's not to say that the tartrate form of carnitine is "bunk" or useless. There are ways to improve the absorption and uptake of this type of carnitine supplement, and it does appear to be useful for muscle recovery, exercise performance, and nutrient partitioning when taken before meals (and post-workout) [5].
