By Jim Stoppani, Ph.D.
*Reprinted with the approval of Peter McGough, Group Editorial Director, FLEX and Muscle & Fitness
In the history of fat-burning supplements, carnitine was a known commodity long before green tea extract and synephrine were blips on the bodybuilding radar. But, today, the granddaddy of fat-burning supplements is known as much more than a one-trick pony.
Made from the amino acids lysine and methionine, as well as iron and vitamins C, B3 and B6, carnitine helps to carry fat into the portion of cells known as the mitochondria, which is the machinery that burns fat for fuel. New research from the University of Connecticut (Storrs) has found that carnitine may also help to increase blood vessel dilation, which, like nitric oxide, can help to increase blood flow to muscles, delivering more oxygen, nutrients and hormones to enhance muscle recovery and growth.
Researchers also discovered that carnitine is directly involved in muscle growth. In one study, they found that subjects supplementing with carnitine had increased levels of the anabolic factor insulinlike growth factor. IGF-I is known to enhance muscle growth. These are the same scientists who also discovered that carnitine increased testosterone concentrations after workouts and even boosted the amount of testosterone receptors, known as androgen receptors, inside muscle cells. With more receptors, more of your testosterone can bind to them and stimulate muscle growth.
In addition, studies performed in the United Kingdom concluded that carnitine, much like creatine, relies on insulin for entry into muscle cells. Carnitine has to get into muscles to be beneficial, which may be why earlier research failed to find that supplementing with carnitine had any positive effects. It was once recommended that carnitine be taken on an empty stomach; it is now suggested that it be taken with meals, particularly those higher in carbs – especially fast-burning carbs, which boost insulin levels. The obvious time to get this benefit is after workouts when you want to take in a decent dose of fast carbs.
DOSAGE: Take 1-3 grams of carnitine in the form of L-carnitine, acetyl-L-carnitine or L-carnitine L-tartrate after training, as well as a dose with breakfast and with your preworkout meal.
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