Carnitine is a biochemical found in nearly every cell in the human body. There are several forms of carnitine (e.g., L-Carnitine, Acetyl L-carnitine), which have been studied for their effects on the heart and brain, the aging process, energy metabolism in the cells, diabetes, infertility and other medical conditions. Our focus is on the role L-Carnitine plays in energy production and metabolism for healthy individuals.

The “power” generator of the cells in your body is the mitochondria. Carnitine has a critical role in the mitochondria’s ability to produce energy. It acts like a key that unlocks the door so long-chain fatty acids can pass into the cell and be “burned” for energy. Carnitine also removes waste products out of the cells to prevent their accumulation. It is highly concentrated in skeletal muscle tissue and the heart, both of which utilize fatty acids as fuel. For these reasons, L-Carnitine has received a lot of research attention as a supplement to help improve athletic/fitness performance, oxygen use during exercise, recovery time and also for weight loss.

In theory, a carnitine supplement should boost physical performance by enhancing the body’s ability to use oxygen or boost metabolism during exercise. However, 20 years of studies on athletic performance have not produced consistent evidence to support L-carnitine supplements can enhance athletic performance, improve body composition, or facilitate significant weight loss.

Exercise scientists also have examined the effect of L-Carnitine on recovery and muscle repair after intense sport conditioning in healthy adults (including vegans, vegetarians) and youth athletes. Overall, studies indicate 1-4 g/day of L-Carnitine enhances recovery, particularly muscle repair, from intense weight-training, sport conditioning, and endurance exercise in healthy individuals. Because of the wide variety of studies, it’s important to talk with your health practitioner to see if L-Carnitine may be a beneficial supplement for you.

The body produces sufficient carnitine for the needs of most healthy people. If your diet includes lean cuts of meat, fish, poultry, and milk, you are getting adequate Carnitine. Vegans may want to check with their health practitioner if they are concerned that their diet is not providing sufficient carnitine.

Resources
National Institutes of Health: Office of Dietary Supplements. “Carnitine: Fact Sheet for Health Professionals.” Updated Feb 11, 2016. Accessed on March 11, 2016. https://ods.od.nih.gov/factsheets/Carnitine-HealthProfessional/
Eckerson, J. M. “Weight Loss Nutritional Supplements.” In Greenwood, M. et al. (Eds). Nutritional Supplements in Sports and Exercise (2nd Ed.) (2015) pp. 167-168.
Eckerson, J. M. “Nutritional Supplements to Enhance Recovery.” In Greenwood, M. et al. (Eds). Nutritional Supplements in Sports and Exercise (2nd Ed.) (2015) pp. 290-291.
Brass, E. P. “Supplemental carnitine and exercise” Am J Clin Nutr. (2000) 72:6; 18S-23S.
Spiering BA, Kraemer WJ, et al., “Effects of L-carnitine L-tartrate supplementation on muscle oxygenation responses to resistance exercise.” J Strength Cond Res, (2008) Jul, 22(4):1130-5. Accessed on March 12, 2016. https://www.researchgate.net/publication/10604648_The_Effects_of_L-Carnitine_L-Tartrate_Supplementation_on_Hormonal_Responses_to_Resistance_Exercise_and_Recovery
Ho JY, Kraemer WJ, et al., “L-Carnitine L-tartrate supplementation favorably affects biochemical markers of recovery from physical exertion in middle-aged men and women.” Metabolism (2009, Dec). Accessed on March 12, 2016. https://www.researchgate.net/publication/40833254_L-Carnitine_L-tartrate_supplementation_favorably_affects_biochemical_markers_of_recovery_from_physical_exertion_in_middle-aged_men_and_women
Guzel, A. et al., “Effects of acute L-carnitine supplementation on nitric oxide production and oxidative stress after exhaustive exercise in young soccer players.” Jnl Sports Med & Phys Fit (2015, Jan-Feb). 55(1-2). pp. 9-15. Accessed on March 12, 2016. http://www.minervamedica.it/en/journals/sports-med-physical-fitness/article.php?cod=R40Y2015N01A0009
Marz, R. B. Medical nutrition from Marz: A textbook in clinical nutrition. (1999). Portland, Or: Omni-Press.

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