L-Carnitine: The Wonder Nutrient

By: Mark Occhipinti, M.S.

Many nutrients have been touted as the ultimate fat burner, along with over 16,000 diets that promise weight loss. Each diet claim has been followed by another claim that guarantees quick weight loss that is permanent. The problem with all of these quick weight loss schemes is that what is lost in weight is muscle and water primarily. 1  
In addition L-Carnitine has been found to reduce delayed onset of muscular soreness in athletes involved in aerobic endurance activities. 24

Several years ago a breakthrough was in fat mobilization was researched and found to increase energy and muscular efficiency, while improving enhancing fat loss and lowering of triglycerides in the blood of both animals and humans.2  This nutrient is known as L-Carnitine, originally classified as an amino acid, and in some scientific circles remains as one of the non-essential amino acids.3  Recently some scientific studies have classified L-Carnitine as vitamin O (B11), due to its properties that closely resemble the water soluble B vitamin family, and fat soluble vitamins.4  Which ever you choose as a family name the facts are that L-Carnitine has been demonstrated to cause improvements in the heart muscle by bringing free fatty acids into the interior of the cell to be burned as fuel in the mitochondria.5   In addition L-Carnitine has demonstrated a "feel good" effect or state of mild euphoria in individuals taking this nutrient.6   During the past decade L-Carnitine has been used by endurance athletes that have been interested in increased stamina without depleting further their glycogen stores. Bodybuilders focus on maintaining as much muscle mass as possible while reducing bodyfat, a game that has not changed much during the past 30 years, have found that L-Carnitine uniquely beneficial over the traditional low carbohydrate high protein diets and exercise alone. In both these groups of athletes carnitine may be the one key element for achieving each of their goals quicker and more efficiently.

What Is L-Carnitine?

L-Carnitine is an amino acid or vitamin (depending on who you read) which is found in all living tissue. It is a water soluble nutrient that is synthesized endogenously in the liver from its amino acid precursors, the amino acids (Lysine and Methionine). Research has demonstrated that due to the fact that L-Carnitine is water soluble, losses occur easily during cooking. This could create some deficiencies in a vegetarian diets who do not supplement their diet with L-Carnitine or limit their intake of plant foods such as avocado's.7  
L-Carnitine is found in animals in the highest concentrations sheep.
 

Where Is L-Carnitine Found In The Body?

In the body L-Carnitine is found in highest concentrations in the adrenal glands, skeletal, and cardiac muscle. The levels of L-Carnitine in the skeletal & cardiac muscle are approximately 40 times the level found in the plasma.8  Smaller concentrations of L-Carnitine are found in the kidneys and brain. This pattern of L-Carnitine distribution reflects the utilization of fatty acids by the tissues as a source of energy. In the last 8 years L-Carnitine was found to be utilized more by the brain then previously believed. Scientists theorize this is due to the close resemblance that L-Carnitine has to the B-vitamin Choline.9  L-Carnitine plays a vital role in fatty acid metabolism as well as supporting the adrenal glands in their monumental task of regulating many bodily functions.10  It is a well known fact that the adrenal glands are exposed to continuous stress, not only through physical activity but also the daily "grind" of living. It is a little known fact outside of medicine that the adrenal glands play a significant role in maintaining fluid balance within the body.11  Blood sugar regulation and energy output are another important function shared by the pancreas which also has a high demand for Carnitine.

Mechanism of Action: L-Carnitine Within The Body

L-Carnitine functions as a biocatalyst, in other words L-Carnitine shuttles long and medium chain fatty acids across the cell wall and into the mitochondria (the cell's furnace). This shuttling enables the muscle cell to utilize essential fatty acids as a substrate (source) for energy metabolism. Converting triglycerides into free fatty acids (fatty acid oxidation) then liberates large amounts of energy. This release of energy provides the muscle it's major source of fuel. 8,9,10,11    For those individuals that continue to use anabolic steroids (I realize they are illegal, but there are many that continue to use them anyway) know that their serum cholesterol and triglyceride levels tend to rise sharply during their cycle. Even birth control pills have demonstrated a rise in both serum cholesterol and triglycerides, and L-Carnitine has proven it's ability to lower both cholesterol and triglycerides.12,13
 

Myocardial Considerations and L-Carnitine

The most noteworthy benefits which have been observed by the addition of L-Carnitine supplementation has been for those individuals with heart disease. L-Carnitine supplementation improved stress tolerance in patients with angina, while improving the performance of the ischemic heart (when the muscle does not receive adequate blood supply). 14  Oral L-Carnitine increases the pacing of the ischemic heart, more specifically it will assist in maintaining the integrity of the heart muscle for a longer duration as exercise loads increase.15  This has direct clinical applications for those individuals suffering from angina. Researchers have found that exercise time was improved after oral supplementation of L-Carnitine.16    Increases in the intensity of exercise was noted while the individual was able to maintain the same exercise heart rate while on L-Carnitine supplementation.17   The use of L-Carnitine has been observed to prevent the occurrence of ventricular fibrillation (a potentially deadly arrhythmia) in early phases of ischemia.18   In a related area, L-Carnitine has shown major clinical applications in lower hyperlipidemia (high cholesterol). This action is achieved by L-Carnitine selectively targeting lipoprotein receptors. Furthermore, clinical studies with the administration of L-Carnitine found that a dramatic decrease in triglyceride levels while increasing HDL serum levels.19  By improving the ratio of HDL total serum cholesterol to LDL serum cholesterol, carnitine minimizes one of the major risk factors associated with coronary heart disease.
 

L-Carnitine and Toxicity

Due to the high concentration of L-Carnitine in skeletal muscle, serum levels and urinary excretion have led to extensive investigations by researchers. Patients with muscular weakness have been treated successfully with L-Carnitine. 20   The anti-fatigue effects of oral ingestion of L-Carnitine have been studies in healthy individuals who suffer from physiological Hypoxia ( a condition of inadequate oxygen supply to meet the demand which causes increased respiration and heart rate).21 
This condition can also occur during prolonged extreme muscular effort such as a marathon or iron man/women competition. One of the major benefits of L-Carnitine administration in both healthy and disease is the lack of toxicity. There are no changes in bowel habits, no associated nausea, or vomiting. The only side effect noted with L-Carnitine has been a modest state of euphoria, which will could all benefit from time to time to improve our state of mind.

The other type of Carnitine, DL-Carnitine, a synthetic analogue should only be used in a clinical setting under the care of a physician due to the possibility of serious side effects that are associated with it's use.22

Application and Dosage Recommendations of L-Carnitine

Athletes preparing for endurance events using L-Carnitine have experienced greater stamina than unsupplemented athletes. L-Carnitine has a broad application in health as well as disease states, while aiding the body in utilization of essential fatty acids for nutrient starved muscle cells. A minimum daily dosage of 500 mgs. of L-Carnitine is necessary to initiate any changes on blood lipid levels.23 The average dose that has demonstrated good results in a range of 1-1,500 mgs per day for visible changes in triglycerides and serum HDL concentrations. Excellent results have been noted using L-Carnitine with bodybuilders and endurance athletes. In a group of 40 men and women athletes, a dose of 2-2,500 mgs distributed throughout the day produced excellent results. An example would be to take 500-750 mg. 25 minutes before aerobic or weight training.7
Dr. Giamberadino's study DOMS (delayed onset of muscular soreness) was reduced and physical performance increased in a group of untrained individuals that were exercising 3-4 or more days per week. 24  

The implication of this study should help in the reduction of pain and damage inevitably linked to efforts performed after inactivity, while accelerating the times of recovery for optimal physical performance.*

References

 

1.  Bremer, J. "Carnitine, Metabolism and Functions" Physiology Review. 63:1420-1480, 1983
2.  Consumer Report, January 1988
3.  Fritz, I.B. " Carnitine and its Role in Fatty Acid Metabolism" Adv. Lipid Research. 1:285-334, 1963
4.  Karlsson, J. Antioxidants and Exercise 1997 pp 13, 113 Human Kinetics Publications
5.  Rebouche, C.J. et al. "Carnitine Metabolism and Deficiency Syndrome" Mayo Clinic Proc. 58:533-540, 1983
6.  Bohmer, T. et al. "Carnitine levels in Humans Serum In Health and Disease", Clinical Chim Acta.. 57:55-61, 1963
7.  Occhipinti, M & Tyson, D. "The Effects of Carnitine on a Group of 40 Men and Women Bodybuilders",      Findings, 1987
8.  Angelini, C. et al. "Carnitine Deficiency of Skeletal Muscle, Report of Treated Cases", Neurology, 1987.
9.  Maebashi, M. et al. "Urinary Excretion of Carnitine in Progressive Muscular Dystrophy", Nature, 249:173-174,      1974.
10. Issacs, H. et al. "Weakness Associated with Pathological Presence of Lipid in Skeletal Muscle, A Detailed       Study of a Patient with Cardiac Deficiency ". Journal of Neurology 39:1114-1123, 1987
11. O'Connor, J.E. et al. "Prevention of Ammonia Toxicity By L-Carnitine", nuerochemical Research. 9(4) 563-570,       1984.
12. Goodman,B., MD Death In The Locker Room, 1992
13. Guyton, A., Textbook of Medical Physiology, Section on Endocrinology, 1994
14. Guyton, A. 1994
15. Opie, L.H. "Role of Carnitine in Fatty Acid Metabolism of Normal and Ischemic Myocardium", Am. Heart       Journal, 3: 375-377, 1974.
16. Kamikawa, T. et al. "Effects of L-Carnitine on Exercise Tolerance in Patients with Stable Angina", Japan Heart       Journal. 25: 587--597, 1984.
17. Tripp, M.E. et al. "Plasma Carnitine Concentrations in Cardiomyopathy Patients" Biochem. Med. 32:199-206,       1984
18. Ferrari, R. et al. "The metabolic Effects of L-Carnitine in Angina Pectoris", Int. Journal of Cardiology,
      5:  213-2165, 1984
19. Bellinghier, A. et al. "Correlations Between Increased Serum and Tissue L-Carnitine levels and Improved       Muscle Symptoms in Hemodilyzed Patients" Lancet 762-764, October 11, 1984.
20. Rebouche, C.J. et al. "Tissue Distribution of Carnitine Biosynthesis Enzymes in Man", Biochem. Biophy.       Acta.   630:22-29, 1980.
21. Bazzato, G. et al. "Myasthenia-like Syndrome after DL- but not L-Carnitine" Lancet, 1207-1209, 1981.
22. Maebashi, M. "Lipid-Lowering Effects of L-Carnitine in Patients with Type IV Hyper-lipoproteinemia" Lancet,       1: 805-809,1978.
23. Colgan, M., Optimum Sports Nutrition, 1997
24. Giamberardino, M,MD, "Effects of Prolonged L-Carnitine Administration on Delayed Muscle Pain and CR       Release After Eccentric Effort", International Journal of Sports Medicine, 1996;17:320-324

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