WHAT IS L-CARNITINE?

L-Carnitine is a naturally occurring amino acid which plays a vital role in the metabolism of fat.  It allows the body to become dramatically more efficient at burning fat in such a way that it functions as a transporter of fatty acids into the mitochondria, the metabolic furnace of the cell where it is burned and utilized as an energy source rather than accumulating in and on the body.

L-carnitine was discovered in Russia, and one year later in Germany. The proper name, Carnitine, refers to the Latin origin, (carno, caris). Its structural formula was decoded in 1927, and its physiological significance was understood by the 1960's.  L-carnitine is synthesized in the liver and kidneys, from two essential amino acids, lysine and methionine. This synthesis requires the presence of vitamins niacin, B6, and iron. Most (98%) of the carnitine supply resides in the body's muscle tissue. Approximately 80% of the amino acids our bodies need is endogenously synthesized, the remaining 20% are referred to as the essential amino acids.  The supply of such aminos, like l-carnitine, must be supplemented exogenously.  L-carnitine is available in the following food sources: red meat, diary products, avocado, and tempeh.  Although a well balanced diet can provide approximately 75% of what the body is lacking, often conditions arise that make it difficult to obtain all the carnitine one needs.

It has been established that an adequate supply of l-carnitine is necessary for the maintenance of good health.  L-carnitine transports long-chain fatty acids across the mitochondrial membrane to be metabolized. L-carnitine aids in the release of stored body fat, tryglycerides, into the bloodstream for energy.  Tryglycerides are the major source for the production of energy in the heart and skeletal muscles.  Access to l-carnitine is believed to increase energy levels for long-term aerobic activity.  L-carnitine is also responsible for muscle contraction, regulation of protein balance and maintenance of a healthy heart.  Research also suggests that an adequate supply of l-carnitine could be instrumental in the treatment of diabetes, chronic fatigue syndrome, kidney and liver disease.  Since its involvement in the process of burning fats is of most importance to those interested in endurance and body fitness, it is this topic that will be focused upon.

THE ROLE OF L-CARNITINE: HOW DOES IT WORK?

Carnitine boosts energy by stimulating the body's burning of tryglycerides as fuel, and sparing the supply of glycogen stored in the liver for heavier exertion. During exercise, the body will burn fat at a rate of 75-80% of maximum exertion, thus less glycogen from carbohydrates is burned.  L-carnitine allows the body to burn more fat, save more glycogen, and ultimately boost stamina and endurance.  By providing more fat to the muscles, carnitine makes accessible an otherwise unavailable energy source.

FAT + OXYGEN + L-CARNITINE = ENERGY

Is this the recipe for success? According to proponents of L-Carnitine, it is the essential amino acid in the optimum fat burning process. They believe that carnitine is to the human body, what a turbo mechanism is to a car: both provide optimal fuel and performance. Minus L-carnitine, fatty acids would have a difficult time permeating the walls of the mitochondria. Energy, stored in carbohydrates and fats, is required to work the muscle. Carbohydrates are converted from glucose to glycogen, to be stored in liver and muscle cells. Eventually, the body turns to fat storage for energy, and possibly, with more ease in the presence of L-carnitine. This is where L-carnitine as a supplement enters. During high energy output, the supply of L-carnitine becomes exhausted. Is it possible to compensate for this decrease solely through metabolic processes and diet? Or is an additional carnitine supplement needed for the extra boost? Judging from the variety of carnitine products now on the market, apparently many believe an additional outside source proves beneficial.

Is L-carnitine a safe and effective means of enhancing fat metabolism? The evidence presented here reports no harmful side effects. Product reports contest that l-carnitine works by transporting fatty acids to be burned for fuel, increasing both energy supply and lean muscle mass. Studies show a more skeptical look at the product. Most found that unless an individual is deficient in l-carnitine, it is an unnecessary ergogenic aid. I conclude that as with other vitamins, minerals and medications, L-carnitine is as effective as the consumer's belief in the product.

How should carnitine be taken?

The typical dosage for carnitine is 1-4 g/day.  A study on the pharmacokinetics of oral L-carnitine in human subjects found no differences in plasma carnitine after 2 g vs. 6 g, indicating that 2 g is already more than the saturable dose.  The half-life of the 2 gram dose was 6.5 hours, and this would imply that the ideal dosing schedule would be 1-2 grams 2-3 times daily, although many studies indicate beneficial effects with only .5-1.5 grams  2-3 times daily.

L-CARNITINE + CAFFEINE AND WHY IT'S SO EFFECTIVE IN BURNING FAT

The following article was writen by:  Jim Stoppani, PhD

* L-carnitine The most critical step in peeling away that layer of fat over your abs is transporting that fat to a place where it'll be burned off. That "place" would be microscopic machinery in cells called mitochondria. But fat requires the help of carnitine to get into the mitochondria. Before a workout is one of the best times to take carnitine, as research shows it can increase fat burning during exercise by almost 25%. This helps to also delay muscle fatigue, as with more fat being burned, muscle glycogen and other fuel sources are spared.

* Caffeine works on the fat loss equation from the other side--prompting more fat to leave the fat cells that blur your abs. Once the fat exits the fat cells and enters the bloodstream, it travels to muscle cells. Inside the muscle cells, carnitine carries the fat into the mitochondria, where it gets burned as fuel. In addition, caffeine mimics a molecule called adenosine; when adenosine binds to its specific receptors in the central nervous system, it makes you tired. Caffeine binds to adenosine receptors instead, thus blocking this fatigue effect. Adenosine receptors are also located on fat cells--when adenosine binds to its receptors on fat cells, it prevents fats from leaving. By binding to these fat-cell receptors instead, caffeine allows fat to leave the cells and get burned. Thus, taking caffeine with carnitine enhances the overall fat-burning effect. In fact, Korean scientists found that when trained athletes took carnitine and caffeine together before exercise, they burned more fat and lasted longer until fatigue than when carnitine or caffeine were taken alone.

* Stack it like this about one hour before workouts, take about 1.5 3 grams of carnitine (in the form of L-carnitine, acetyl-L-carntine, propionyl-L-carnitine, or L-carnitine L-tartrate) along with 200-400 milligrams of caffeine in the form of caffeine anhydrous. Do not grab a coffee for your preworkout caffeine kick.

--Jim Stoppani, PhD