Naturally occurring nutrients with potent antioxidant and energy-generating functions

In brief

  • L-carnitine is made by the body and functions as a potent antioxidant and is essential for the breakdown of energy from fats.
  • L-carnitine can also be obtained from dietary sources, the richest being red meats but also poultry, fish and dairy foods.
  • Benefits associated with L-carnitine supplementation include
    energy production,
    promoting weight loss,
    enhancing exercise performance and recovery, and
    providing protection against several disease states
  • These benefits are associated with intakes of approximately 2 to 3 g of L-carnitine per day1-7(of which the exact dose is dependent on age, training demands, health status and habitual diet), which is most easily achieved through a combination of supplementation (providing a rich and concentrated form of L-carnitine) and a healthy balanced diet.

Background

L-carnitine is a naturally occurring conditionally essential nutrient that is made in the body from the amino acids lysine and methionine. L-carnitine is primarily made in the liver and kidneys, the majority of which (more than 90%) is stored in skeletal muscles but is also present in the brain and heart tissues1. L-carnitine is also found in dietary food sources, the richest being animal foods, particularly red meats but also poultry, fish and dairy. However, the formation of L-carnitine in the body appears to be reliant upon protein (i.e. skeletal muscle) breakdown, which then provides the primary products necessary for L-carnitine reformation1. Ensuring an adequate intake of L-carnitine through a combination of dietary and supplementary forms therefore may help to limit skeletal muscle breakdown. While L-carnitine supplementation is proposed to affect muscle metabolism, ALCAR is an acetylated form of L-carnitine that is proposed to have central effects on the brain by limiting neurological decline and enhancing cognitive function, which may have important implications for ageing populations.

The primary function of L-carnitine is for its essential role in energy production2. L-carnitine is required to transport fats into the mitochondria (“energy powerhouses”) of cells for the breakdown and release of fat for energy. L-carnitine also functions as a potent antioxidant2, which helps protect the body against harmful free radicals (i.e. reactive oxygen species; ROS) that can damage cell structures(i.e. skeletal muscles and deoxyribonucleic acid (DNA)) and increase the risk for several disease states (for more information see the article on‘Antioxidants’). Not surprisingly therefore, L-carnitine deficiency has been shown to impair muscle function3, possibly due to impaired energy production and/or increased free radical damage to skeletal muscle cells.

Due to the increased energy (fat breakdown) demands and the increased production of potentially damaging free radicals associated with exercise, exercise may increase L-carnitine requirements2. Furthermore, people following vegetarian or protein restricted diets have been shown to have significantly lower circulating L-carntine levels compared to people consuming typical Western diets1. Additionally, aging has been shown to dramatically decrease circulating L-carnitine levels3. However, supplementation with L-carnitine has been shown to increase muscle carnitine concentrations by up to 20%4,which may help maintain optimal L-carnitine levels and maximize skeletal muscle function.

What does the research say about L-Carnitine?

Recent research supports the use of L-carnitine supplementation for its ability to support:

Energy production : L-carnitine is essential for the transport of fats into mitochondria (the “energy powerhouses”of the body) for consequent breakdown and release of energy8.

Weight loss & body composition : Supplementation with L-carnitine (of 2 x 1.36 g per day for 12 weeks) helps to prevent gains in body weight (fat) associated with increased energy intake4. This maybe attributable, at least in part to the increased muscle carnitine concentrations (of up to 20%); increased energy expenditure rates (of 6%);and/or enhanced expression of genes involved in energy breakdown and storage4.

Exercise performance &recovery : L-carnitine supplementation may enhance exercise performance through a combination of different mechanisms. Co-ingestion of L-carnitine glucose (sugar) can help maximize muscle L-carnitine levels when supplementing. Consequently, this can enhance fat (energy) burning at rest and during exercise4, which  may also help spare muscle energy (sugar)stores to help fuel more intense bouts of exercise.  Supplementation with L-carnitine may also help delay the accumulation of waste products (lactate) and decrease ratings of perceived exertion (RPE)5, which may help prolong exercise by reducing feelings of fatigue.

Furthermore, L-carnitine may help promote blood flow to muscles assisting in the elimination of waste products and promoting the delivery of oxygen and nutrients to muscles to help facilitate recovery9. Indeed, supplementation with L-carnitine (of 2to 3 g per day for 3 weeks) decreased markers of muscle damage (creatine kinase(CK), myoglobin and also MRI scan images) by up to 45%6,7; decreased markers of oxidative damage (malonaldehyde; MDA)6; and also reduced muscle soreness levels7. Therefore L-carnitine may help promote post-exercise recovery rates and enhanced exercise performance during consequent training sessions.

Health maintenance &disease protection : L-carnitine may help protect against and treat a variety of disease states, including the ability to alleviate the decline in cognitive health associated with Alzheimer’s disease and general cognitive decline in elderly individuals. This is possibly mediated by L-carnitine’s potent antioxidant capacity and ability to cross the blood-brain barrier2,13. Furthermore,L-carnitine has also been shown to enhance mood and have possible anti-depressant effects in elderly individuals10. Finally, L-carnitine supplementation may also help to treat and reduce the risk of mortality due to cardiovascular disease(CVD)11. Supplementation with L-carnitine (2 g per day for 24 weeks)has been shown to significantly reduce blood pressure and also enhance insulin sensitivity (important for controlling blood sugar levels) in individuals with increased CVD risk12. However, further research is warranted to investigate the effects of L-carnitine supplementation on blood glucose (sugar)handling as blood sugar responses have been shown to vary in lean versus their overweight/obese counterparts13.

What does this mean in practice?

To this end, consuming L-carnitine form provides a concentrated source of L-carnitine and as an adjunct to a healthy, whole foods-based diet is likely to offer the following benefits:

  • Endurance training: may help to enhance energy (fat) breakdown and release (and potentially spare muscle energy (sugar) stores), prolonging time to fatigue and promoting the ability to train for longer or at a greater intensity
  • Team-sport athletes / Gym-based training: may help speed up post-exercise recovery rates, supporting the capacity to perform at a greater intensity during consequent sessions
  • Recovery: may help reduce the extent of muscle damage and speed up post-exercise recovery rates
  • Health promotion and disease protection: supplementation may help support healthy brain functioning and manage disease states such as diabetes and CVD

Previous studies have shown muscle saturation limits (i.e. maximal muscle uptake levels) to occur when taking large bolus doses of L-carnitine (of 1 x 2 g per day)14. Therefore to help maximize the uptake of L-carnitine by skeletal muscle cells, ROS Nutrition recommends that ALCAR supplements should be consumed in smaller (500 mg to 1 g)doses at regular intervals throughout the day in combination with a source of carbohydrate (i.e. take at mealtimes or with a glass of juice, which further promotes uptake of L-carnitine by muscle cells)4. However the exact recommended dose depends on health status, age (recommended dose increases with advancing age), training demands (increase dose with increased training demands), and dietary intake (vegetarians and people following low-protein diets warrant increased L-carnitine dosages).

L-carnitine supplementation at ROS Nutrition

ROS Nutrition provides the highest quality form of carnitine, namely L-carnitine L-tartrate (a salt form of L-carnitine that helps to aid it’s absorption) and N-acetyl L-carnitine (ALCAR). Whereas L-carnitine is essential for the breakdown and release of energy from fats8, ALCAR enters the brain more efficiently and has more potent antioxidant activity compared to the more readily available supplement form, L-carnitine15. RecoverAce® Strength and RecoverAce® Endurance both contain a specialized carntine matrix, which provides a combination of both L-carnitine L-tartrate and ALCAR and importantly at a dose shown to be effective for many of the benefits described above.

Find ALCAR at ROS Nutrition

    • Supplement
    • L-carnitine content
    • Benefit

ALCAR

Take 1 to 3 serves daily. Per serve: 500 mg – 1 g ALCAR*
  • Essential for energy production
    Promotes weight loss
  • May enhance sports performance and exercise recoveryrates
  • Promotes health and protects against disease

RecoverAce® Strength

Take 1 to 2 servings after strength training**.Per 80 g serving: 2.5 g ALCAR matrix
  • Promotes energy production
  • Mayenhance exercise recovery rates

RecoverAce® Endurance

Take 1 to 2 servings after endurance training**.Per 100 g serving: 3.0 g ALCAR matrix
  • Promotes energy production
  • May enhance exercise recovery rates

     

*EU recommended daily allowance (RDA): 0.5 g/day; consume with water, juice or beverage of choice. **Serving size recommendations are based on a 70 kg individual. One serving should be taken immediately after training, followed by another serving two hours later if a quality food source is not readily available. Each serving, for both RecoverAce®Strength and Endurance should be mixed with 500 ml of water (note: the formulation contains a source of sugar so there is no need to mix with fruit juice).

To note: If you are currently taking other medications please consult your healthcare professional before commencing supplementation to avoid any possible interference with other medications.

Further reading

  • 1. Rebouche CJ (1992) Carnitine function and requirements during the life cycle. Fed Amer Soc Exper Biol , 6,3379-3386.
  • 2. Ribas GS, Vargas CR & Wajner M (epub ahead of print) L-carnitine supplementation as a potential antioxidant therapy for inherited neurometabolic disorders. Gene.
  • 3. Costell M, O’Connor JE &Grisolía S (1989) Age-dependent decrease of carnitine content in muscle of mice and humans. Biochem Biophys Res Comm, 161(3), 1135-1143.
  • 4. Stephens FB, Wall BT, Marimuthu K, Shannon CE, Constantin-Teodosiu D, Macdonald IA & Greenhaff PL (2013) Skeletal muscle carnitine loading increases energy expenditure, modulates fuel metabolism gene networks and prevents body fat accumulation in humans. J Physiol, 591 (18), 4655-4666.
  • 5. Gamze EO & Nevin AG (epub ahead of print) The effects of acute l-carnitine supplementation on endurance performance of athletes. J Strength Cond Res.
  • 6. Volek JS, Kraemer WJ, Rubin MR, Gómez AL, Ratamess NA & Gaynor P(2002) L-carnitine l-tartrate supplementation favourably affects markers of recovery from exercise stress. Am J Physiol Endocrinol Metab, 282, E474-482.
  • 7. Giamberardino MA, Dragani L, Valente R, Di Lisa F, Saggin R & Vecchiet L (1996) Effects of prolonged l-carnitine administration on delayed muscle pain and CK release after eccentric effort. IntJ Sports Med, 17 (5), 320-324.
  • 8. Longo N, di San Filippo CA & Pasquali M (2006) Disorders of carnitine transport and the carnitine cycle. Am J Med Genet C Semin Med Genet, 142C (2), 77-85.
  • 9. Huang A & Owen K (2012) Role of supplementary l-carnitine in exercise and exercise recovery. Med Sport Sci, 59, 135-142.
  • 10. Soczynska JK, Kennedy SH, Chow CSM, Woldeyohannes HO, Konarski JZ & McIntyre RS (2008) Acetyl-l-carnitine and α-lipoic acid: possible neurotherapeutic agents for mood disorders? Expert Opin Invest Drugs, 17 (6), 827-843.
  • 11. DiNicolantonio JJ, Lavie CJ, Fares H, Menezes AR & O’Keefe JH (2013)L-carnitine in the secondary prevention of cardiovascular disease: systematic review and meta-analysis. Mayo Clin Proc, I88 (6), 544-551.
  • 12. Ruggenenti P, Cattaneo D, Loriga G, Ledda F, Motterlini N, Gherardi G, Orisio S & Remuzzi R (2009) Ameliorating hypertension and insulin resistance in subjects at increased cardiovascular risk: Effects of acetyl-l-carnitine therapy. Hypertension, 54, 567-574.
  • 13. Galloway SD, Craig TP & Cleland SJ (2011) Effects of or all-carnitine supplementation on insulin sensitivity indices in response to glucose feeding in lean and overweight/obese males. Amino Acids, 41 (2), 507-515.
  • 14. Harper P, Elwin CE & Cederblad G (1988) Pharmacokinetics of bolus intravenous and oral doses of l-carnitine in healthy subjects. Eur J Clin Pharm, 35 (1), 69-75.
  • 15. Liu J, Head E, Kuratsune H, Cotman CW & Ames BN (2004)Comparison of the effects of L-carnitine and acetyl-l-carnitine on carnitine levels, ambulatory activity, and oxidative stress biomarkers in the brain of old rats. Ann New York Acad Sci, 1033,117-131.