A new study from Spain has shown that L-carnitine supplementation can aid muscle damage and speed up recovery after exercise.
The researchers noted the results are especially effective for test subjects who are already deficient in L-carnitine.
The study, a review of 15 earlier studies on L-carnitine’s exercise benefits, was conducted at the University of Valladolid in Soria, Spain.
The results were published in Nutrients in May 2023.
What is L-carnitine?
L-carnitine is sometimes identified as an amino acid; however, it is really a chemical derivative that is synthesized in the human body from the amino acids lysine and methionine. This synthesizing happens primarily in the brain, liver and kidneys. The body then uses the L-carnitine to release energy from lipids or fats.
L-carnitine is also acquired through food intake and supplementing. Meat, poultry, fish, and dairy products are the richest sources of L-carnitine; however, plant-based foods rich in lysine and methionine will allow the body to readily synthesize L-carnitine naturally.
Foods rich in lysine include legumes, avocado, nuts and grains. Foods rich in methionine include seaweed, spinach, sesame seeds, nuts, oats, white beans, chickpeas and corn.
Since it is present in virtually every cell in the body, and is essential for good health, L-carnitine is also approved for medical treatments.
WebMD states: “Taking L-carnitine by mouth or by IV is effective for treating L-carnitine deficiency caused by certain genetic diseases or other disorders. It’s approved by the FDA for this use.”
Study details
The new study focused on exercise-induced muscle damage. This damage encompasses both structural and functional aspects, leading to weakened strength, fatigue, muscle pain, and cramping.
The researchers noted their new study supports earlier findings that L-carnitine can serve as an “ergogenic aid” in helping offset this damage.
Exercise is known to induce oxidative stress which is characterized by an upsurge in free radical production. This is a side effect from mitochondrial activity and an increase in muscle inflammation.
Previous studies have provided evidence supporting the potential benefits of nutritional supplements, including L-carnitine, in the treatment of muscle damage. The research showed L-carnitine is not only essential for cellular energy metabolism in the muscles, but that it also acts as an antioxidant and reduces inflammation.
According to the researchers, supplementing with L-carnitine increases its levels in the blood, promoting improved blood flow and oxygen delivery to muscles. This reduces hypoxic damage and speeds recovery after exercise-induced stress.
The study was a review of 15 earlier studies, including both human and animal models.
Researchers reviewed dozens of earlier studies that examined the efficacy of L-carnitine supplementation in the treatment of post-exercise muscular damage. They isolated the studies that were randomized, double-blind controlled studies with a parallel design.
Three database were used to review and qualify the studies: SCOPUS, Medline, and Web of Science.
Published results
Results from all the qualified studies suggested that L-carnitine supplementation did provide positive effects on exercise performance and recovery.
In their findings the researchers wrote that the supplementation was found to “improve lipid oxidation, preserve muscle glycogen, reduce inflammation, and potentially accelerate recovery from exercise-induced muscle injury.”
One study observed that L-carnitine supplementation is effective in attenuating the signs of tissue damage induced by exercise. Additionally, one dog-model study observed that the administration of L-carnitine increased muscle contractile force by 30% accompanied by an increase in blood flow.
The researchers hypothesized that L-carnitine exerts an effect on the vascular cells surrounding muscle, and thereby increases oxygen delivery.
Writing in the study summary the researchers concluded that L-carnitine supplementation shows promise in enhancing exercise recovery and performance; however, as with virtually all studies, further research is encouraged to fully understand the mechanisms involved and to ensure duplicate findings.
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Sources: Nutrients (MDPI), WebMD, University of Valladolid.