The Function of L-Carnitine and Its Application in the Food Industry
2026-01-16
L-carnitine, also known as L-carnitine or vitamin BT, has the chemical name 3-hydroxy-4-trimethylamino butyric acid lactone. It is a type of amino acid-like substance widely present in human tissues. Since it was discovered by scientists from meat extracts in the early 20th century, L-carnitine has undergone a transformation from a growth factor to a necessary nutrient, and then to a globally widely used functional component.
The scientific discovery history of L-carnitine spans an entire century, witnessing the continuous deepening of human understanding of trace nutrients. As early as the beginning of the 20th century, Russian scientists Gulewitsch and Krimberg isolated this component from meat extracts, laying the foundation for its research. However, the true revelation of its physiological function came decades later. In 1948, Fraenkel discovered that the growth of yellow mealworm larvae required a specific factor and named it vitamin BT. In 1958, Fritz's research made a breakthrough, he found that L-carnitine could accelerate the rate of fat metabolism, thus establishing its core position in human fatty acid oxidation.
In the 1980s, L-carnitine began to be marketed as a commercial raw material and quickly gained recognition from international authoritative institutions. In 1985, at the International Nutrition Conference held in Chicago, L-carnitine was officially listed as a necessary nutrient under specific conditions. Subsequently, European countries such as France successively approved it as a nutritional fortifier and a multi-purpose nutritional supplement. In 1993, the expert committee of the US Food and Drug Administration (FDA) conducted a strict assessment and concluded that L-carnitine is a recognized safe and non-toxic substance.
In China, the management of the application of L-carnitine has also become increasingly standardized. In 2014, the National Health and Family Planning Commission issued the "Reply on Issues Concerning L-Carnitine", clearly stating that in accordance with the national food safety standard "Use Standard for Food Nutritional Fortifiers" (GB14880-2012), L-carnitine (L-carnitine) is a permitted food nutritional fortifier. The establishment of this regulation provides a solid policy guarantee for the legal and compliant use of L-carnitine in health food and ordinary food in China, and also marks that its application in China's food industry has entered a new stage of standardized development.
2.The core physiological function of L-carnitine
01.The core carrier for fat transportation and energy production
The most fundamental and important function of L-carnitine is to serve as a carrier for long-chain fatty acids to enter the mitochondria for β-oxidation. The main site for fatty acid energy production is within the mitochondria, but long-chain fatty acids cannot directly penetrate the inner mitochondrial membrane. Under the catalysis of carnitine acyltransferase I and II, L-carnitine combines with acyl-CoA to form acyl-carnitine, thereby transporting fatty acids from the outer mitochondrial membrane to the matrix.
This process directly promotes the β-oxidation of fatty acids, efficiently generating energy while reducing the levels of serum cholesterol and triglycerides. Studies have confirmed that high concentrations of acylcarnitines in the body can significantly increase the rate of fat oxidation and improve the utilization rate of fat energy. This is the fundamental mechanism underlying its application in weight loss and sports nutrition products.
02. Mitochondrial Homeostasis and Detoxification Regulation
The ratio of acyl-CoA to sulfhydryl-CoA in the mitochondrial matrix is crucial for energy metabolism. L-carnitine regulates this ratio, maintaining the activity of pyruvate kinase and ensuring the normal operation of energy metabolism. Additionally, during fatty acid metabolism, some toxic esterified-CoA substances are produced, such as propionyl-CoA, methylmalonyl-CoA, etc. These substances can inhibit key enzyme activities and cause cellular toxicity. L-carnitine can combine with these toxic acyl groups to form complexes, transporting them out of the mitochondria, thereby exerting detoxification effects. At the same time, it can also promote the oxidation of acetoacetic acid, playing an important role in the elimination and utilization of ketone bodies.
03. Cell Membrane Protection and Antioxidant Function
L-carnitine also plays a positive role in maintaining the stability of biological membranes. It can remove the excessive accumulation of long-chain fatty acyl groups on the mitochondrial membrane, preventing membrane damage. As an antioxidant, L-carnitine captures free radicals by preventing the formation of iron chelates, thereby reducing the damage to cells caused by oxidative stress.
When the primary antioxidant defense barrier is insufficient to completely eliminate free radicals, L-carnitine also participates in the deacylation-reacylation process of membrane phospholipids, assisting in the repair of damaged cell membranes and maintaining the integrity of cells.
04. Amino Acid Metabolism and Protein Conservation Effect
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