Carnitine

Carnitine can be found in food and is also synthesized in the body in the brain, liver, and kidneys, but only if necessary substances are available. Carnitine is predominately found in meat and animal products. In general, the redder the meat, the higher the carnitine content.[1] Mutton and lamb have the highest levels, while chicken and turkey contain much less. Milk and dairy then follow in carnitine content, and grains, fruits, and vegetables have almost none.[2] For the body to synthesize carnitine, certain substances are required, namely, the two essential amino acids lysine and methionine (essential meaning they must come from the diet), as well as vitamin C, niacin, vitamin B6, and iron. A deficiency in any one of these nutrients impairs carnitine production in the body.[1],[3],[4],[5]

Essential for Energy

Carnitine’s most important function is to help produce energy. In the body it is the transporter for fatty acids into the mitochondria, which are the energy furnaces of body cells. It is here that the fat is turned into energy. Most tissues, particularly the heart and skeletal muscles, depend primarily on fatty acid oxidation (metabolism) as a source of energy. Therefore, the far-reaching impact of carnitine is dramatic, not only energy for day-to-day activities but also for overall health.[2],[5],[6] Robert Crayhon, in his book The Carnitine Miracle, explains it this way: “If you give your cells the ability to make optional levels of energy, they can use it to do whatever they want: build and renew cell membranes,…maintain cell structures,…create a better defense against viruses and bacteria…In short, they can use it to make themselves work better and last longer.” Simply put, this allows the body to heal itself and produce optimal health.

Carnitine may also be useful for sports endurance. During aerobic exercise, fat normally provides approximately 50% of the energy and, during long endurance activities, 80%. Carnitine must be available for these fats to be used for energy.[7],[8] Supplementation with carnitine has resulted in significant improvements in cardiovascular function (e.g. building stamina and endurance) in response to exercise in several double-blind studies in both athletes and average exercisers.[9],[10]

Slow the Aging Process

Body levels of carnitine decline as we get older,[11] thus cells are not as energized. The more energy cells have available to help them repair and stay healthy, the more slowly they age. The best supported theory for the cause of aging and cell or tissue damage (i.e. disease) involves free radicals. These “delinquent” unstable compounds are generated by normal metabolic functions in the body as well as by exposure to pollutants, bacteria, radiation, and toxic chemicals. Accelerating the aging process is not difficult to do, considering the overabundance of free radical-generating insults we are exposed to on a daily basis, including such things as stress, cigarette smoke, pesticides, and processed foods. Thankfully, carnitine is one nutrient that can help protect the body against these damaging free radicals,[12] and thus slow aging.

Lose Some Weight

Some studies suggest that fat-burning is increased with higher carnitine levels in the body.[13] For instance, two groups of overweight teenagers were put on a healthy diet and moderate exercise program for twelve weeks. The control group experienced, on average, a weight reduction of one pound. For those who received one gram of carnitine per day with the same regimen, weight loss averaged eleven pounds.[14] Other findings suggest that carnitine is more effective for weight loss when combined with a lower carbohydrate diet, meaning limited breads, pastas, and sugars.[2]

Boost Brain Power

For brain function, the focus turns to acetyl-L-carnitine (ALC), which is a different form of carnitine. ALC is formed in the mitochondria when carnitine joins an acetyl group. The attached acetyl group makes it especially powerful at optimizing brain function, since it can more effectively cross into the brain than regular carnitine can. ALC has become a central focus in neurodegenerative disease research. The acetyl group contributes to the production of the neurotransmitter acetylcholine, a critical player in nerve/muscle communication, concentration, memory, and learning. It is also suggested that since ALC is structurally similar to acetylcholine, it may have similar actions in the nervous system.[38] Acetylcholine is so central to mental function that the leading pharmaceutical drugs used for senility are aimed at elevating its levels in the brain.[15]

This brain-boosting nutrient not only helps the aging brain function better, but it also prevents the degradation of the brain during stress and natural aging. Its role in supporting mental function may improve memory, attention span, and mental performance in the “average” brain as well as in those with brain impairment.[2] Several double-blind clinical trials suggest that ALC delays the progression of cognitive decline.[16],[17] In an Italian study, 236 elderly patients with mild senility were given either 1,500 mg ALC or placebo. The ALC group showed significant improvements in memory and cognition compared with controls.[18] Crayhon believes it is important to supplement with this nutrient as early as young adulthood but at least at forty for anyone who wants optimal brain health and longevity.[2]

Protect Your Heart

Essentially, carnitine helps the heart work more effectively, particularly as we age. The heart is highly dependent on fatty acid oxidation for normal functioning and, as explained, carnitine is the “key-master” for this to occur. Therefore, normal heart function relies on adequate levels of carnitine. In fact, carnitine may be one of the most important compounds for the prevention of a range of ailments that affect the heart and circulatory system. Carnitine has shown promise in individuals with irregular heartbeat, heart muscle inflammation (cardiomyopathy) and angina (pain in the chest).[19],[20],[21] Carnitine also exerts a beneficial effect on blood lipids by lowering triglycerides and total cholesterol levels while raising HDL cholesterol.[22],[23] This protective heart nutrient has also been shown to prevent the production of toxic fatty acid metabolites, which are damaging to the heart muscle.[24]

A modified form of carnitine, called propionyl-L-carnitine (PC) has been used for most congestive heart failure research. A double-blind trial using 500 mg of this unique form per day resulted in a 26% increase in exercise capacity in those with this heart condition after six months of supplementation.[25] Additional research has shown that 1.5 gram of PC is effective for increasing exercise tolerance and oxygen consumption in this group as well.[26]

Other Functions of this Supernutrient

Carnitine may increase fertility in males by boosting sperm counts and making the sperm more mobile.[27] There is some evidence that carnitine deficiency promotes liver congestion or fatty infiltration.[28] Carnitine has been used in supporting liver in the utilization and metabolism of fatty acids, which is particularly important for people with compromised livers due to the ingestion of alcohol or exposure to xenobiotics (foreign chemicals). In elderly patients, ALC may help decrease depression and improve quality of life. ALC has also been used to improve deteriorations of the nervous system associated with diabetes[29] as well as reduce the development of cataracts.[30] Lastly, a growing area of interest is carnitine’s role in carbohydrate metabolism,[31] which is not well understood. It appears that ALC may be more appropriate for maximizing this function.[32]

The Essentiality Debate

Whether carnitine is an essential nutrient or not has been on the debate table for some time. In the early investigations of this nutrient, it was assumed that an individual could synthesize adequate amounts, ingest sufficient amounts through the diet, or meet needs by a combination of both. However, more current research shows that this is not the case for some individuals, and supplementation is necessary to maintain normal energy metabolism, thus making this nutrient essential.[33] Carnitine has also been called conditionally essential, which means that in certain situations the need for carnitine exceeds production by the body and it must be taken in through the diet or a supplement. This may be particularly relevant in times of stress, higher energy needs (as in pregnancy and breastfeeding), or with a restricted, meatless diet. This is bad news for vegetarians, who take in almost no carnitine and are often deficient in lysine as well, which is a critical nutrient for carnitine synthesis in the body.[2],[34]

Which Form to Take?

Choose the L form of carnitine over the D, since it is the biologically active form found in foods and synthesized in the body.[35] The tartrate form is considered stable and pure.[2] Another more recently produced form is fumarate, which is a component in the Krebs cycle, a key energy-producing process. Because of fumarate’s role in this cycle, the fumarate form may be better utilized by the cells that are struggling for oxygen, such as with energy production or heart function.[36] When choosing L-carnitine or ALC, keep in mind that L-carnitine is useful to support energy production, weight loss, and heart muscle function, whereas ALC is the preferred form to support brain and nerve function.[2],[38] Thus, if you want to achieve both benefits, take both.

How Much?

There is substantial evidence that for optimal health, we should be getting at least 250 to 500 mg of carnitine in our daily diet.[2] However, studies indicate that the average diet only contains between 5 to 100 mg.[1] It is interesting to note, humans have been eating carnitine in significant amounts for most of history. It has been suggested that during pre-modern times, people ate at least 500 mg and up to 2,000 mg of carnitine per day.[2] Since red meat is not necessarily a staple in most diets these days, it is starting to appear that supplemental carnitine is a viable and wise choice for many people.

L-carnitine is extremely safe. No significant side effects have been reported and overdose or toxicity levels are unknown. The daily dosage of L-carnitine in all of its forms is typically between 1,500 and 4,000 mg in divided doses,[37],[38] although Crayhon recommends a lower dose of ALC at 250 to 1,000 mg.[2] Consider beginning with 500 mg of L-carnitine per day and/or 250 mg per day of ALC for a few days and increase the total amount by the same dosage every few weeks until desired results are achieved. Given the safety of carnitine, it appears to be better to err on the side of taking too much rather than too little (except in patients undergoing hemodialysis).[38]

As time goes on, nutrients – including carnitine – are being lost in the shuffle of “progress”. Due to its invaluable functions, considering supplementation seems appropriate for most anyone. Whether you are looking for more brain power, heightened energy in everyday life or on the trail, heart disease protection, or just overall health maintenance, carnitine is a prime candidate.

Focus on getting carnitine from foods as well. The following foods contain the indicated milligrams per 100 g of edible weight (about 3.5 ounces): sheep (muscle) has 210 mg, lamb (muscle), 78 mg; beef (muscle), 64 mg; chicken (muscle), 8 mg; cow’s milk, 2 mg .[39]


References

[1] Borum PR. Carnitine. Ann Rev Nutr 3:233-259 1984

[2] Crayhon, Robert, M.S. The Carnitine Miracle. M Evans and Company. 1998.

[3] Bremer J. Carnitine – metabolism and function. Physiol Rev. 63: 1420-1480. 1983.

[4] Bamji MS. Nutritional and health implications of lysine carnitine relationship. Wld Rev Nutr Diet. 3: 233-259. 1983.

[5] Lieberman, Shari, PhD. The Real Vitamin and Mineral Book. 2nd Ed. Avery Publishing Group. 1997.

[6] Shigenaga, MK, Hagen TM, Ames BN. Oxidative damage and mitrochondrial decay in aging. Proceedings of the National Academy Sciences (USA) 1994; 91(23):10771-10778.

[7] Bremer J. Carnitine metabolism and function. Physiol Rev. 1983: 63: 1420-1480.

[8] Colombani P, Wenk C, Kunz I, et al. Effects of L-carnitine supplementation on physical performance and energy metabolism of endurance-trained athletes: a double blind crossover field study. Eur J Appl Physiol 1996;73:434–39.

[9] Dragan AM et al. Studies concerning some acute biological changes after exogenous administration of 1 g L-carnitine in elite athletes. Physiologie. 24:231-234. 1987.

[10] Drangan GI, Wgner W, Ploesteaunu E. Studies concerning the ergogeic value of protein supply and L-carnitine in elite junior cyclists. Physiologie. 25:129-132. 1988.

[11] Costell M, O’Connor JE, Grisolia S. Age-dependent decrease of carnitine content in muscle of mince and humans. Biochem Biophy Res Commum 161(3): 1135-1143. 1989.

[12] Tesco G et al. Protection from oxygen radical damage in human diploid fibroblasts by acetyl-L-carnitine. Dementia 3:58-60 1992.

[13] Avogaro P et al. Acute effects of L-carnitine on FFA and beta-OH-butyrate in man. Pharma Res Com. 13:443, 1981.

[14] He Zhi-Qian, Phone ZS. Body weight reduction in adolescents by a combination of measures including using L-carnitine. Acta Nutrimenta Sinica 1997;19(2)

[15] Standberry, Jill, N.D. Sustain Your Brain. Delicious 2001.

[16] Pettegrew JW, Klunk WE, Panchalingam K, et al. Clinical and neurochemical effects of acetyl-L-carnitine in Alzheimer’s disease. Neurobio Aging 1995;16:1–4.

[17] Sano M, Bell K, Cote L, et al. Double-blind parallel design pilot study of acetyl levocarnitine in patients with Alzheimer’s disease. Arch Neurol 1992;49:1137–41.

[18] La Clinica Terapeutica, 1990, vol. 132, no. 6

[19] Cherchi A, et al. Effects of L-carnitine on Exercise Tolerance in Chronic Stable Angina: A Multicenter, Double-blind, Randomized, Placebo Controlled Crossover Study. Int J Clin Pharmacol Ther Toxicol. Oct1985;23(10):569-72.

[20] Mondillo S, et al. Therapy of Arrhythmia Induced by Myocardial iIschemia. Association of L-carnitine, Propafenone and Mexiletine. Clin Ter. Dec1995;146(12):769-74.

[21] Winter S, et al. The Role of L-carnitine in Pediatric Cardiomyopathy. J Child Neurol. Nov1995;10(Suppl2):S45-51.

[22] Pola P, et al. Statistical Evaluation of Long-term L-carnitine Therapy in Hyperlipoproteinemias. Drugs Exptl Clin Res. 1983;9:925-34.

[23] Pola R. Carnitine in the therapy of hyslipidemic patients. Curr Ther Res 27:208-215. 1980.

[24] Opie LH. Role of carnitine in fatty acid metabolism of normal and ischemic myocardium. Am Heart J. 97: 336-341; 1979.

[25] Mancini M, Rengo F, Lingetti M, et al. Controlled study on the therapeutic efficacy of propionyl-L-carnitine in patients with congestive heart failure. Arzneimittelforschung 1992;42:1101-4.

[26] Anand I, Chandrashenkhan Y, De Giuli F, et al. Acute and chronic effect of propionyl-L-carnitine on the hemodynamics, exercise capacity and hormones of patients with congestive heart failure. Cardiovasc Drugs Ther 1998;12:291-9.

[27] Vitali G, et al. Carnitine Supplementation in Human Idiopathic Asthenospermia: Clinical Results. Drugs Exp Clin Res. 1995;21(4):157-59.

[28] Sachan DA and Rhew TH, and Ruark RA, Ameliorating effects of carnitine and its precursors on alcohol-induced fatty liver. Am J Clin Nutri 39, 738-744, 1984.

[29] Lowitt S, et al. Acetyl-L-carnitine Corrects the Altered Peripheral Nerve Function of Experimental Diabetes. Metabolism. May1995;44(5):677-80.

[30] Swamy-Mruthinti S, Carter AL. Acetyl- L -carnitine decreases glycation of lens proteins: in vitro studies. Exp Eye Res. Jul1999;69(1):109-15.

[31] Cederblad, G. et.al. 1976, Carnitine concentration in relation to enzyme activities and substrate utilization in human skeletal muscle, Scand. J. Clin. Lab. Invest., 36 : 547-552

[32] Sass R, Werness P. Acetylcarnitine: on the relationship between structure and function. Biochem Biophys Res Commum. 55(3): 736-742. 1973.

[33] Borum PR, Bennett SG. Carnitine as an essential nutrition. J Am Coll Nutr. 5: 177-182. 1986.

[34] Giovannini M, Agostoni C, Salari PC. Is carnitine essential in children? J Int Med Res 1991;19:88–102

[35] Watanabe, SW et al. Effects of L- and DL-carnitine on patients with impaired exercise tolerance. Japanese Heart Journal 36: 319-331; 1995.

[36] Richard A. Passwater, Ph.D. Coenzyme Q-10 and Heart Health. An interview with Dr. Stephen Sinatra: Part 3. Coenzyme Q-10 and L-carnitine are the twin pillars of heart health. Whole Foods Magazine 2004. Found at www.drpasswater.com/nutrition_library/Sinatra_3.html on February 19, 2006.

[37] Monograph—Acetyl-L-Carnitine. Altern Med Rev 1999;4:438–41 [review].

[38] Murray, Michael, N.D. Pizzorno, Joseph. Textbook of Natural Medicine. 2ed. Churchill Livingstone. 2000.

[39] Leibovitz B, et al. Carnitine. J Optimal Nut. 2:90-109 1993.