GlycoTrax™
Glycine Propionyl L-Carnitine Capsules

A look at GPLC - Glycine Propionyl-L-Carnitine

There are four main types of carnitine products often included in supplement products. These are glycine propionyl-l-carnitine (GPLC), ALCAR, LCLT, and L-carnitine, respectively. Although they all display similar functionalities, the use of some forms are favored over others for specific roles such as the support of cognitive function, the cardiovascular system and heart, athletic performance, weight control, and healthy aging. 

Glycine propionyl-l-carnitine is created through binding of the amino acids glycine and propionyl-L-carnitine (PLC). This results in a propionyl ester, in which the carnitine has an added glycine. The GPLC form is thought to have numerous antioxidant effects and may help to support the enhancement of nitric oxide (NO) levels in the blood. It is favored by people undergoing exercise regimes as it may help to enhance training without the jitteriness symptoms sometimes reported with other forms of L-carnitine, it is thought to support healthy blood flow, and it may offer support for erectile disorders in men.

One of the main advantages of GPLC over other L-carnitine types is its relatively improved bioavailability.

Energy 

GPLC plays a key role in the body’s energy production process. Propionyl-L-Carnitine is metabolized into propionyl coenzyme A and L-carnitine in the mitochondria. An organelle known as the cells energy center. Propionyl coenzyme A is further metabolized into a form that plays a role in the tricarboxylic acid cycle (TCA cycle) [1], which itself plays a key role in cellular aerobic respiration. 

The carnitine system helps to support loss of mitochondrial function [1] and is important in the creation of creatine. Propionyl-L-Carnitine is thought to be more effective at supporting healthy blood flow than the L-Carnitine form.

Many people, especially vegetarians, may have natural low levels of carnitine

There tends to be a lower level of circulating carnitine in vegetarians and vegans, older people, and during pregnancy. 

As carnitine is naturally found in meat and dairy products it is no surprise that the natural levels of this amino acid have been reported to be much lower in both adult and children vegetarians, especially vegans [2, 3].

In pregnant women, it has been reported that carnitine concentrations are lower in the plasma; this has been suggested to be because the carnitine precursors have lower bioavailability during the gestation period [4]. 

As people reach old age (above 70), there appears to be an increase in incidence of relative carnitine deficiency [5]. This decrease is correlated to lean body mass. Carnitine may help to support muscle function and to lower fatigue in the elderly [6]. 

Role in the support of enzymes with antioxidant activity

As it has an effect upon antioxidant activity, GPLC helps to protect the cells from damage from free radicals. It has been reported to support the stabilization of superoxide dismutase at the blood-brain barrier from the effects of alcohol [7].

It has also been demonstrated to support the response of two further enzymes involved in antioxidant activities: Glutathione peroxidase, and Catalase [8]. Research also suggests a role for L-carnitine in the support of antioxidant status and oxidative stress responses. 

Exercise performance and muscle growth and recovery 

GPLC may help to support exercise performance through the support of blood flow and circulation.

Glycine propionyl-l-carnitine may help to support healthier blood lipid profiles in humans [9]. It has been reported that GPLC may support healthy plasma nitrate/nitrite levels in both sedentary and resistance trained men compared to the controls and placebo [10]. The latter study revealed that short term dosage values of 3 g per day helped some men to improve NO levels in the plasma. Nitric oxide has been put forward as being associated with muscle growth, strength, and performance in numerous studies [10–13].

GPLC may help to support power output during sprinting. When resistance trained athletes were provided an acute supplement of it before performing Wingate cycle sprints there was an observable support of anaerobic work capacity, peak power production, and lactate accumulation and clearance compared to the baseline [14, 15]. The improved sporting performance, reported over several weeks of testing, appears to be dosage dependent.

Further Reading

WebMD:

• (1) An overview of Propionyl-L-carnitine, its uses, side effects, interactions, and recommended dose. {http://www.webmd.com/vitamins-supplements/ingredientmono-803-propionyl-l-carnitine.aspx?activeingredientid=803&activeingredientname=propionyl-l-carnitine}

Wikipedia:

• Role as a nitric oxide (endothelium derived relaxing factor (EDRF); NO; NOX) stimulant and ergogenic aid {https://en.wikipedia.org/wiki/Glycine_propionyl-L-carnitine} 

Medicinenet: Guide to PLC

• {http://www.medicinenet.com/propionyl-l-carnitine/supplements-vitamins.htm}

Citations, Reviews, Abstract, and References

[1] Binienda et al. The Mitochondriotropic Effects of L-carnitine and its Esters in the Central Nervous System. Current Medicinal Chemistry - Central Nervous System Agents, Volume 3, Number 4, December 2003, pp. 275-282(8)

[2] Lombard et al. Carnitine status of lactoovovegetarians and strict vegetarian adults and children. Am J Clin Nutr. 1989 Aug;50(2):301-6.

[3] Krajcovicová-Kudlácková et al. Correlation of carnitine levels to methionine and lysine intake. Physiol Res. 2000;49(3):399-402.

[4] Ringseis et al. Low availability of carnitine precursors as a possible reason for the diminished plasma carnitine concentrations in pregnant women. BMC Pregnancy Childbirth. 2010 Apr 25;10:17. doi: 10.1186/1471-2393-10-17.

[5] Malaguarnera et al. L-Carnitine treatment reduces severity of physical and mental fatigue and increases cognitive functions in centenarians: a randomized and controlled clinical trial. Am J Clin Nutr. 2007 Dec;86(6):1738-44.

[6] Pistone et al. administration in elderly subjects with rapid muscle fatigue: effect on body composition, lipid profile and fatigue. Drugs Aging. 2003;20(10):761-7. 

[7] Haorah et al. Stabilization of superoxide dismutase by acetyl-l-carnitine in human brain endothelium during alcohol exposure: novel protective approach. Free Radic Biol Med. 2011 Oct 15;51(8):1601-9. doi: 10.1016/j.freeradbiomed.2011.06.020 

[8] Cao et al. Single dose administration of L-carnitine improves antioxidant activities in healthy subjects. Tohoku J Exp Med. 2011;224(3):209-13. doi: 10.1620/tjem.224.209.

[9] Bloomer et al. Glycine propionyl-L-carnitine modulates lipid peroxidation and nitric oxide in human subjects. International Journal of Vitamin and Nutrition Research. 2009 May;79(3):131-41. doi: 10.1024/0300-9831.79.3.131.

[10] Stamler et al. Physiology of nitric oxide in skeletal muscle. Physiol Rev. 2001 Jan;81(1):209-237.

[11] Bescós et al. The effect of nitric-oxide-related supplements on human performance. Sports Med. 2012 Feb 1;42(2):99-117. doi: 10.2165/11596860-000000000-00000. 

[12] Rovere-Querini et al. Nitric oxide and muscle repair: multiple actions converging on therapeutic efficacy. Eur J Pharmacol. 2014 May 5;730:181-5. doi: 10.1016/j.ejphar.2013.11.006.

[13] Smiljić et al. Modulatory role of nitric oxide in cardiac performance. Med Pregl. 2014 Sep-Oct;67(9-10):345-52. Review. 

[14] Jacobs et al. Long-term glycine propionyl-l-carnitine supplemention and paradoxical effects on repeated anaerobic sprint performance. J Int Soc Sports Nutr. 2010 Oct 28;7:35. doi: 10.1186/1550-2783-7-35. 

[15] Jacobs et al. Glycine propionyl-L-carnitine produces enhanced anaerobic work capacity with reduced lactate accumulation in resistance trained males. J Int Soc Sports Nutr. 2009 Apr 2;6:9. doi: 10.1186/1550-2783-6-9. 

[16] Alvarez de Sotomayor et al. Effect of L-carnitine and propionyl-L-carnitine on endothelial function of small mesenteric arteries from SHR. J Vasc Res. 2007;44(5):354-6