Karnitin

Karnitin, commonly known as carnitine, is a naturally occurring quaternary ammonium compound that plays a key role in energy metabolism. It exists mainly as L-carnitine, with related derivatives such as acetyl-L-carnitine and propionyl-L-carnitine. The body can synthesize carnitine in the liver and kidneys from the amino acids lysine and methionine, with the process requiring vitamins C and B6 and iron; it is also obtained from the diet, particularly from meat and dairy products.

Biologically, L-carnitine transports long-chain fatty acids into the mitochondria, where they are oxidized to produce energy. It also participates in the removal of certain acyl groups from mitochondria and supports overall mitochondrial function. Tissues with high energy demands, such as skeletal muscle and the heart, rely on carnitine for efficient fatty acid oxidation. In addition to L-carnitine, acetyl-L-carnitine can donate acetyl groups and may have distinct effects on the brain and metabolism.

Clinical use and evidence: Carnitine deficiency disorders, including primary carnitine deficiency and some inherited metabolic conditions, can be treated with supplementation. It is also used in certain dialysis patients and other specific medical situations. For healthy individuals, evidence for routine benefits of carnitine supplementation on athletic performance, weight loss, or general energy is limited and inconclusive.

Safety and regulation: Carntine supplements are generally well tolerated, with possible side effects such as gastrointestinal symptoms and a fishy body odor due to gut bacteria. High doses may cause adverse effects in susceptible individuals, and medical supervision is advised when used therapeutically.