L-Carnitine L-Tartrate – better form of carnitine?

Carnitine (endogenus) is a necessary component of fat oxidation in cells. L-carnitine may improve the aerobic exercise through increasing lipid peroxidation. Carnitine acts in a transport of long-chain fatty acids to the mitochondrial matrix for oxidation thus plays and important role in energy metabolism [1]. Previous studies have shown that oral L-carnitine ingestion does not increase muscle carnitine concentrations [2,3]. However, a new more promising form of carnitine emerged: L-Carnitine L-Tartrate (LCLT). A tartrate is a salt or ester of the organic compound tartaric acid and it is used in some supplements to improve absorption of another substance.

L-Carnitine L-Tartrate Benefits

We will review a few studies conducted with l-carnitine l-tartrate as an enhancer of the hormonal responses to resistance-training and a recovery promoter. However, we should tell you right away that they are all funded by Lonza Inc., a manufacturer of l-carnitine.

Reduced Muscle Damage

Two cross-over, placebo-controlled studies have shown that oral l-carnitine l-tartrate supplementation reduces the amount of exercise-induced muscle tissue damage [4,5]. Kraemer et al. [5] suspected that less muscle damage would increase the number of intact hormonal receptors. Thus making more of them available for interaction with anabolic hormones (possibly making better environment for muscle growth). Study in professional football players reported that l-carnitine (as LCLT) as well as l-carnitine and l-glutamine beneficially affect markers of muscle damage and muscle soreness [15].

A study by Barry A. Spiering and associates [6] noted seemingly contradictory finding that l-carnitine l-tartrate attenuated markers of muscle damage despite reduced tissue oxygenation. It is plausible that lower muscle tissue oxygenation was due to enhanced muscle oxygen consumption. That however, coincides with several studies which reported that carnitine supplementation increased whole-body VO₂max during exercise [7,8].

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Hormonal Interaction

Data collected by researchers from University of Connecticut [9] demonstrated subtle yet significant increase in luteinizing hormone in response to post-workout feeding and LCLT supplementation. The primary finding of this study was l-carnitine l-tartrate supplementation upregulated resting androgen receptor content; also post-exercise androgen receptor content was greater following high caloric feeding compared with placebo (water). The increase in androgen receptor and simultaneous decrease in testosterone suggests increased cellular uptake of testosterone. So, LCLT is not a testosterone booster it may enhance testosterone uptake via less muscle damage and increased availability of androgen receptor. L-Carnitine levels in the seminal plasma have also been shown to have a positive correlation with serum testosterone [13]

Results of animal study [14] showed that l-carnitine tartrate significantly increases serum testosterone levels compared to saline solution. Serum LH and FSH levels were also significantly increased. So, besides affecting sex hormones and reproduction system, it may also improve male reproductive function.

Improved Aerobic Capacity

Very recent study [12] reported that acute consumption of l-carnitine l-tartrate positively affects lipid metabolism, maximum oxygen consumption, and distance run. 3 g of l-carnitine tartrate was able to significantly elevate lipid metabolism, VO2 max, and distance run while dependent variables were unaffected in the placebo supplemented group. Blood analysis showed that performance was increased by increased lipid metabolism.

Potential for Hair Loss Treatment

Researchers from University of Hamburg [10] used l-carnitne-l-tartrate to promote hair growth in vitro. Their findings suggested that l-carnitine stimulates human scalp hair growth by supplying energy to the hair follicles.

L-Carnitine L-Tartrate Side Effects

Martyn R. Rubin and others [11] investigated the effects of 3 week L-carnipure (l-carnitine l-tartrate) ingestion. Using a balanced, placebo, cross-over design on 10 healthy men, LCLT had no adverse effects on metabolic and hematological safety variables.