L-carnitine, L-carnitine, also known as L-carnitine, vitamin BT, chemical name β- hydroxyl γ- Trimethylammonium butyric acid is a white lens or white transparent fine powder. The research on carnitine began in the early 20th century. In 1905, Russian gulewitsch and krimberg found L-carnitine from meat extract. Since then, scientists from various countries have conducted in-depth research. In the early research, L-carnitine was found to be a kind of vitamin nutrient and named it vitamin BT. In fact, the chemical structure of alkali is similar to choline and amino acid; In addition, because some animals can synthesize by themselves to meet the needs of carnitine, it is considered that carnitine is not a vitamin, but it is still customarily called vitamin BT. Experiments show that carnitine is an essential nutrient. L-carnitine was designated as "multifunctional nutrient" at the international nutrition academic conference held in Chicago in 1985

　　L-carnitine is easy to absorb moisture and has good stability. It can be placed in pH 3 ~ 6 solution for more than 1 year, can withstand high temperature above 200 ℃, and has good water solubility and water absorption. L-carnitine in diet mainly comes from animals, and the content in plants is very small; Rich sources include lean meat, liver, heart, yeast, chicken, rabbit meat, milk and whey; Good sources include avocado, casein and malt. People such as fasting, vegetarianism, strenuous exercise, obesity, pregnancy, male infertility, and infants who eat formula without fortified carnitine are prone to carnitine deficiency. Low levels of lysine, vitamins and iron in the diet also lead to carnitine deficiency. Many patients, such as heart disease, hyperlipidemia, kidney disease, liver cirrhosis, malnutrition, hypothyroidism and some muscle and neurological diseases, generally have low carnitine levels. L-carnitine mainly depends on exogenous supplement, and the importance of carnitine supplement is no less than that of vitamins and mineral elements.

　　Muscle movement depends on your body's ability to convert fatty acids into energy. L-carnitine is an essential amino acid to achieve this transformation. Different types of diet already contain 5 - 100 mg of L-carnitine. L-carnitine is produced in the human liver and kidney and stored in muscle, semen, brain and heart. Some people do not get enough L-carnitine from their diet properly, resulting in a lack of this nutrient. As a result, they may slowly develop heart disease, muscle weakness or hypoglycemia.