L-Carnitine - Metabolic Functions and Meaning in Humans Life

Abstract

L-Carnitine is an endogenous molecule involved in fatty acid metabolism, biosynthesized within the human body using amino acids: L-lysine and L-methionine, as substrates. L-Carnitine can also be found in many foods, but red meats, such as beef and lamb, are the best choices for adding carnitine into the diet. Good carnitine sources also include fish, poultry and milk. Essentially, L-carnitine transports the chains of fatty acids into the mitochondrial matrix, thus allowing the cells to break down fat and get energy from the stored fat reserves. Recent studies have started to shed light on the beneficial effects of L-carnitine when used in various clinical therapies. Because L-carnitine and its esters help reduce oxidative stress, they have been proposed as a treatment for many conditions, i.e. heart failure, angina and weight loss. For other conditions, such as fatigue or improving exercise performance, L-carnitine appears safe but does not seem to have a significant effect. The presented review of the literature suggests that continued studies are required before L-carnitine administration could be recommended as a routine procedure in the noted disorders. Further research is warranted in order to evaluate the biochemical, pharmacological, and physiological determinants of the response to carnitine supplementation, as well as to determine the potential benefits of carnitine supplements in selected categories of individuals who do not have fatty acid oxidation defects.

Genetic parameters for carnitine, creatine, creatinine, carnosine, and anserine concentration in longissimus muscle and their association with palatability traits in Angus cattle1

“…Oral L-carnitine supplementation has been reported to have benefi cial effects on exercise capacity in clinical populations and is considered a potential ergogenic aid for endurance athletes (Muller et al, 2002). Although dietary reference intakes for L-carnitine have not been established, beef is one of the best dietary sources of L-carnitine (Demarquoy, 2011;Pekala et al, 2011). L-carnitine content of beef steaks in our study averaged 316 mg/serving (100 g).…”

“…Carnitine, sometimes regarded as a vitamin-like substance (Pekala et al, 2011), is an essential molecule in fatty acid oxidation, mediating the transport of medium-/ long-chain fatty acids into the mithocondrial matrix (Demarquoy et al, 2004) and preventing accumulation of toxic intermediate compounds by facilitating their transport out of the mitochondria. Oral L-carnitine supplementation has been reported to have benefi cial effects on exercise capacity in clinical populations and is considered a potential ergogenic aid for endurance athletes (Muller et al, 2002).…”

The effects of graded levels of calorie restriction: IX. Global metabolomic screen reveals modulation of carnitines, sphingolipids and bile acids in the liver of C57BL/6 mice

“…We also found that all identified carnitines and carnitine derivatives were increased with CR, and this has implications for longevity, as in Drosophila L‐carnitine shows a highly significant decline with age (Hoffman et al ., 2014). L‐carnitine shuttles fatty acids across the mitochondrial membrane, where they can be processed by β‐oxidation enzymes to ultimately generate ATP (Flanagan et al ., 2010; Pekala et al ., 2011). Studies have shown that L‐carnitine supplementation has positive effects in obese and diabetic humans, as well as benefits in cats and mice (Levin et al ., 1999; Blanchard et al ., 2002; Mingorance et al ., 2012).…”

Associations between acylcarnitine to free carnitine ratio and adverse prognosis in heart failure patients with reduced or preserved ejection fraction

“…Carnitine transports long‐chain fatty acids into the mitochondria for β‐oxidation and protects the myocardium against ischaemic injury, the occurrence of angina, diastolic dysfunction, and HF 2, 3. Carnitine deficiency results in impaired mitochondrial β‐oxidation, decreased glucose oxidation, and accelerated cellular apoptosis 4, 5.…”