L-carnitine, also known as L-carnitine and vitamin BT, has the chemical formula C7H15NO3, and the chemical name is (R) -3-carboxy-2-hydroxy-N,N, N-trimethylpropyl ammonium hydroxide internal salt, representing the drug l-carnitine [3]. It is a kind of amino acid like that promotes the conversion of fat into energy. The pure product is white lens or white transparent fine powder [1], easily soluble in water, ethanol, methanol, slightly soluble in acetone, insoluble in ether, benzene, trichloromethane, ethyl acetate. L-carnitine is easy to absorb moisture, has good water solubility and water absorption, can withstand high temperature above 200℃. Red meat is the main source of l-carnitine, and the human body can also be synthesized to meet physiological needs. Not really a vitamin, but a vitamin-like substance [4]. It has many physiological functions such as fat oxidation decomposition, weight loss, anti-fatigue and so on [42]. As a food additive, it is widely used in infant food, weight loss food, athlete food, nutritional supplement for middle-aged and elderly people, nutritional fortifier for vegetarians [41] and animal feed additive, etc.

Appearance for white lens or white transparent fine powder, slightly special smell. It is very soluble in water, ethanol, methanol, slightly soluble in acetone, insoluble in ether, benzene, chloroform, ethyl acetate [4]. Easy to absorb moisture, exposure to air will deliquescence and may even liquefied. It can be placed in solution of pH 3 ~ 6 for more than 1 year, and can withstand high temperature of more than 200℃. Its combination bond and bond group have good water solubility and water absorption

L-carnitine can promote the activity of pyruvate dehydrogenase in cells, thus promoting the oxidation of glucose, which is conducive to delaying the occurrence of fatigue during exercise. Excessive lactic acid production during exercise will increase the acidity of blood tissue fluid, reduce the generation of ATP, leading to fatigue. Supplementation of l-carnitine can remove excessive lactic acid, improve exercise ability, and promote the recovery of exercise fatigue.

In addition, it can also be used as a biological antioxidant to remove free radicals and promote urea circulation. Ammonia is a product of protein degradation, and is also one of the identification signs of exercise fatigue. Even low ammonia content will have greater toxicity. L-carnitine detoxifies ammonia by degrading it to urea.

L-carnitine protects the stability of cell membrane, improves the immunity of human body, avoids the invasion of some diseases, and plays a certain preventive role in the prevention and treatment of sub-health.