Carnitine, typically in the form of L-carnitine, has developed a following as a supplement for those wanting to increase muscle strength and energy, and to burn fat more efficiently. However, research is showing it may provide benefits to a much wider population swath. Studies are uncovering that L-carnitine can promote cardiovascular health and that it may prove useful in the fight against obesity.
Things chemical and biochemical
The name carnitine encompasses a group of compounds that include L-carnitine, acetyl-L-carnitine, propionyl-L-carnitine and L-carnitine L-tartrate. Carnitine (C7 H16 NO3+ ), whose precursors are the amino acids lysine and methionine, has two isomers, D and L, but only the form found in food, L-carnitine, is active in the body. It is essential in the body’s metabolic processes, playing a role in a host of metabolic pathways, including:
• Fatty-acid transport: On a cellular level, carnitine moves medium- and long-chain fatty acids across the mitochondrial membrane, so they can be metabolized into energy.
• Toxin removal: Carnitine helps transport toxins out of the mitochondria, preventing accumulation.
• Coenzyme A (CoA) buffer: Carnitine helps maintain an adequate level of free CoA by reacting with the acyl groups of acylCoA.
• Membrane repair: Carnitine might provide activated fatty acids to enzymes that remove and replace damaged fatty acids from membrane phospholipids.
Consuming carnitine
Average diets containing red meat and other animal products, including whey, provide about 60 to 180 milligrams of carnitine per day. Vegetarians consume much less, about 10 to 12 milligrams daily. Carnitine is absorbed in the intestine, with the rate depending on the dose and dietary source: 54% to 87% is absorbed from food and 14% to 18% from supplements. Daily intake over 3 grams may cause unpleasant side effects, such as nausea and abdominal cramps. The body concentrates carnitine in areas that use fatty acids as fuel, such as the skeleton and cardiac muscle. In a 155-lb. man, the total body content of carnitine is about 20 grams.
