Need a performance boost? Try Carnitine to improve fat burning and reduce muscle fatigue
Every time you exercise to a maximum, without sufficient carnitine, you can put your body into a state of muscle weakness, high blood lipid levels, unable to use fat efficiently for energy & can accumulate body fat easily.
How does Carnitine work?
When you think of Carnitine you should think of muscles, as your muscles need adequate amounts of carnitine to produce energy. Basic nutritional principles tell us that glycogen is the premium fuel our muscles need during exercise. Unless you supplement with this, your body will run out of this very quickly.
Nevertheless, fats still provide about 50% of your energy during aerobic exercise and 80% of your energy towards the end of long endurance events. But you have to be able to use these fats freely.
Carnitine controls fat use because it forms the transport system that moves the fatty acid molecules into the mitochondria (furnaces) of the cell where they are burned for fuel.
Carnitine also helps with the oxidation (burning) of pyruvate and branched chain amino acids in the energy cycle. It also prevents the build-up of fatty complexes called acylcoenzyme A, which destabilizes muscle membranes.
Carnitine is also essential for helping to inhibit the build-up of lactic acid in the muscle, one of the main causes of fatigue. In one recent study, patients with angina were supplemented with L-carnitine. The build-up of lactic acid during their moderate exercise routine was reduced by half and exercise duration was significantly increased.
Because of all these functions, the amount of free carnitine in your muscles plays a major role in their efficiency. It also places a limit on the amount of energy they can supply.
The standard textbook answer to this problem is that the human body makes carnitine from the essential amino acids lysine and methionine (plus vitamin C, niacin, pyridoxine and iron). So a sedentary person on a good diet does not need to take carnitine.
So what about athletes?
But athletes are different. During training, they put their bodies into a state of stress that uses a tonne of carnitine. Their demand for carnitine can easily exceed the body's ability to make it. Even moderate exercise, such as cycling on an ergometer bicycle at only 55% of VO2max, causes a 20% drop in muscle carnitine. Maximal exercise causes a much greater drop, putting athletes into the same carnitine status as patients with carnitine deficiency diseases.
These patients can hardly use any fat for energy, they have high levels of blood lipids, they suffer extreme muscle weakness, they accumulate body fat from the smell of a bacon cheeseburger and their heart function sounds like someone torturing a cat. Every time you exercise to a maximum, without sufficient carnitine, you put your body into this detrimental condition.
Carnitine deficiency is easily corrected by oral L-carnitine. There is no doubt that increased carnitine intake increases the serum level of free carnitine. Because of its involvement in normal heart function, oral L-carnitine has been used extensively to treat patients with angina. Because of its involvement with pyruvate metabolism, which regulates oxygen availability to muscle, it has also been used to treat patients with respiratory insufficiency.
Oral L-carnitine is so successful in medicine that three US pharmaceutical companies now make prescription tablets.
Five well-controlled recent studies show that L-carnitine increases exercise tolerance and endurance performance in patients with angina and patients with respiratory disorders.
Does L-Carnitine boost performance?
What does carnitine do for athletes? Plenty! Physiological studies show that carnitine supplements inhibit the decline in free carnitine in muscle caused by maximal exercise and completely prevent the decline in free carnitine during endurance exercise.
Carnitine also increases maximum use of oxygen in athletes. This effect was first observed by Dr Brian Liebovitz at the University of California, Davis. It has recently been confirmed by two Italian studies. Both gave athletes 4 grams of L-carnitine daily. The supplement significantly increased VO2max.
Supplementation also reduces the build-up of acids and metabolic wastes during maximal exercise. In a recent study, Dr Noris Siliprandi and colleagues at the University of Padua, Italy, gave athletes 2 grams of L-carnitine or a placebo, one hour before post-exercise levels of lactate and pyruvate, and significantly increased maximal work output.
In another similar Italian study, normal subjects who were not athletes, were given L-carnitine supplements or a placebo and tested for sub- maximal exercise on the ergometer bicycle. The carnitine trials showed a significant improvement in endurance. So there is evidence that L-carnitine can boost both anaerobic and aerobic performance.
As carnitine has proved essential in the transportation of fats into the mitochondria, supplementing your muscles with carnitine makes sense. The higher the level of carnitine in muscle, the more body fat is transported into cells for oxidation. Studies indicate that supplements of L-carnitine raise muscle carnitine levels, therefore they also help to lose body fat.
A dose of 2-4 grams taken for 2 weeks, one hour before exercise appears to be effective. That is many times the dietary intake in America, which runs about 100-300 mg per day. But even at 4 grams daily, L-carnitine shows no toxicity.
DL-Carnitine IS toxic
Real L-carnitine is expensive. That is why numerous sports supplements contain only a negligible few milligrams. Other supplements contain gram amounts, but it is cheap DL-carnitine or racemic carnitine, a very different compound than L-carnitine.
DL-carnitine contains about 50% of the dextro or right-handed molecule of carnitine. This substance does not occur in normal foods, so during evolution, the human body does not develop the mechanisms to deal with it. The body cannot use DL-carnitine, and its presence inhibits the use of L-carnitine, the levo or left-handed molecule. DL-carnitine is therefore a toxin that causes carnitine deficiency and all its detrimental consequences.
In 1984 the Food and Drug Administration issued a health warning about DL-carnitine, but it still appears in the marketplace. Be especially wary of supplements labelled on the marketplace. Be especially wary of supplements labelled on the front, "L-carnitine" in big letters. On the back, you may find in the tiniest print that is still legal, "in a base of racemic carnitine". They are all DL-carnitine.
In one case reported by Dr Robert Keith of Auburn University, Alabama, a 35-year-old runner took only 500 mg of DL-carnitine daily for two days before a race. His quadriceps became so weak, he had to miss the race and could not train for the next three weeks.
Ideal Health supplies only L-carnitine and not the toxic DL-carnitine
Extracts taken from "Optimum Sports Nutrition" by Dr Michael Colgan.