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Not to be confused with carnosine or creatine.
Clinical data
AHFS/ Micromedex Detailed Consumer Information
  • US: B (No risk in non-human studies)
Routes of
Oral, intravenous
ATC code A16AA01 (WHO) (L form)
Legal status
Legal status
Pharmacokinetic data
Bioavailability <10%
Protein binding None
Metabolism slightly
Excretion Urine (>95%)
CAS Number 541-15-1 YesY
PubChem (CID) 288
DrugBank DB00583 N
ChemSpider 282 YesY
KEGG C00318 YesY
ChEBI CHEBI:17126 YesY
Chemical and physical data
Formula C7H15NO3
Molar mass 161.199 g/mol
3D model (Jmol) Interactive image
 NYesY (what is this?)  (verify)

Carnitine(β-hydroxy-γ-N-trimethylaminobutyric acid,3-hydroxy-4-N,N,N- trimethylaminobutyrate) is a quaternary ammonium compound[1] involved in metabolism in most mammals, plants and some bacteria.[2] Carnitine may exist in two isomers, labeled D-Carnitine and L-Carnitine, as they are optically active. At room temperature, pure carnitine is a white power, and a water soluble zwitterion with low toxicity. Carnitine only exists in animals as the L enantiomer, and DL-Carnitine is toxic as it is inactive but inhibits the activity of L-Carnitine.[3] Carnitine, discovered in 1905 with a high density in muscle tissue was labeled Vitamin BT, however as carnitine is synthesized in the human body, it is not a vitamin.[2] Carnitine is involved in the oxidation of fatty acids, and involved in systemic primary carnitine deficiency. It has been researched for preventing and treating other conditions, and may be used as an athletic performance enhancer.[1]

Biosynthesis and metabolism[edit]

Many eukaryotes have the ability to synthesize carnitine, including humans. Humans synthesize carnitine from the substrate TML(6-N-Trimethyllysine), derived from the methylation of lysine. TML is then hydroxylated into HTML by TML dioxygenase, requiring the presence of ascorbic acid. HTML is then cleaved by HTML aldose, yielding 4-trimethylaminobutyraldehyde(TMABA) and glycine. TMABA is then dehydrogenated into gamma-butyrobetaine, in an NAD+ dependent reaction catalyzed by TMABA dehydrogenase. Gamma butyrobetaine is then hydroxylated by gamma butyrobetaine hydroxylase into L-Carnitine, requiring Fe2+.[4]

Carnitine is involved in transporting fatty acids across the mitochondrial membrane, by forming a long chain acetylcarnitine ester and being transported by Carnitine palmitoyltransferase I and Carnitine palmitoyltransferase II.[5] Carnitine also plays a role in stabilizing Acetyl-CoA and coenzyme A levels through the ability to receive or give an acetyl group.[6]

Physiological effects[edit]


Carnitine deficiency caused by a genetic defect in carnitine transport occurs in roughly 1 in 50,000 in the US. SPDC is characterized by various cardiological, metabolic and musculoskeletal symptoms that vary widely in age of onset and presentation. Prognosis is generally good with carnitine supplementation.[7]

Secondary carnitine deficiency may occur due to conditions such as malnutrition, poor absorption or access to only vegetables.[5]


Some research has been carried out on carnitine supplementation in athletes given its role in fatty acid metabolism, however individual responses have been significant in the 300 persons studied.[6] Carnitine has been studied in various cardiometabolic conditions, with a bit of evidence pointing towards efficacy as an adjunct in heart disease and diabetes. However there are insufficient trials to determine its efficacy.[8] Carnitine has no effect on preventing mortality associated with cardiovascular conditions.[9] Carnitine has no effect on serum lipids, except a possible effect on LDL[10] Carnitine has no effect on most parameters in end stage kidney disease, however it possibly has an effect on c-reactive protein. The effects on mortality and disease outcome are unknown.[11]



The highest concentrations of carnitine are found in red meat.[12][13] It can be found at significantly lower levels in many other foods including nuts and seeds (e.g. pumpkin, sunflower, sesame), legumes or pulses (beans, peas, lentils, peanuts), vegetables (artichokes, asparagus, beet greens (young leaves of the beetroot), broccoli, brussels sprouts, collard greens, garlic, mustard greens, okra, parsley, kale), fruits (apricots, bananas), cereals (buckwheat, corn, millet, oatmeal, rice bran, rye, whole wheat, wheat bran, wheat germ) and other foods (bee pollen, brewer's yeast, carob).[citation needed]

Product Quantity Carnitine
Lamb 100 g 190 mg
Beef steak 100 g 95 mg
Ground beef 100 g 94 mg
Pork 100 g 27.7 mg
Bacon 100 g 23.3 mg
Tempeh 100 g 19.5 mg
Cod fish 100 g  5.6 mg
Chicken breast 100 g  3.9 mg
American cheese 100 g  3.7 mg
Ice cream 100 mL  3.7 mg
Whole milk 100 mL  3.3 mg
Avocado one medium 2 mg[14]
Cottage cheese 100 g  1.1 mg
Whole-wheat bread 100 g  0.36 mg
Asparagus 100 g  0.195 mg
White bread 100 g  0.147 mg
Macaroni 100 g  0.126 mg
Peanut butter 100 g  0.083 mg
Rice (cooked) 100 g  0.0449 mg
Egg 100 g  0.0121 mg
Orange juice 100 mL  0.0019 mg
Lentil 100 g 2.1 mg[15]
Potato 100 g 2.4 mg[15]
Sweet Potato 100 g 1.1 mg[15]
Banana 100 g 0.2 mg[15]
Carrot 100 g 0.3 mg[15]
Apple (without skin) 100 g 0.2 mg[15]
Raisin 100 g 0.8 mg[15]

In general, 20 to 200 mg are ingested per day by those on an omnivorous diet, whereas those on a strict vegetarian or vegan diet may ingest as little as 1 mg/day.[citation needed] However, even strict vegetarians (vegans) show no signs of carnitine deficiency, despite the fact that most dietary carnitine is derived from animal sources.[12][13] No advantage appears to exist in giving an oral dose greater than 2 g at one time, since absorption studies indicate saturation at this dose.[16]

Health Canada[edit]

Other sources may be found in over-the-counter vitamins, energy drinks and various other products. Products containing L-carnitine can now be marketed as "natural health products" in Canada. As of 2012, Parliament has allowed carnitine products and supplements to be imported into Canada (Health Canada). The Canadian government did issue an amendment in December 2011 allowing the sale of L-carnitine without a prescription.[17]


Levocarnitine was approved by the U.S. Food and Drug Administration as a new molecular entity under the brand name Carnitor on December 27, 1985.[18]

See also[edit]


  1. ^ a b Karlic, Heidrun; Lohninger, Alfred (1 July 2004). "Supplementation of l-carnitine in athletes: does it make sense?". Nutrition. 20 (7-8): 709–715. doi:10.1016/j.nut.2004.04.003. ISSN 0899-9007. 
  2. ^ a b Bremer, J. (1 October 1983). "Carnitine--metabolism and functions". Physiological Reviews. 63 (4): 1420–1480. ISSN 0031-9333. 
  3. ^ Harmeyer, J. "THE PHYSIOLOGICAL ROLE OF L-CARNITINE" (PDF). Lohmann Information. 
  4. ^ Strijbis, Karin; Vaz, Frédéric M.; Distel, Ben (1 May 2010). "Enzymology of the carnitine biosynthesis pathway". IUBMB Life. 62 (5): 357–362. doi:10.1002/iub.323. ISSN 1521-6551. 
  5. ^ a b Flanagan, Judith L; Simmons, Peter A; Vehige, Joseph; Willcox, Mark DP; Garrett, Qian (16 April 2010). "Role of carnitine in disease". Nutrition & Metabolism. 7: 30. doi:10.1186/1743-7075-7-30. ISSN 1743-7075. 
  6. ^ a b Cite error: The named reference sport was invoked but never defined (see the help page).
  7. ^ Magoulas, Pilar L.; El-Hattab, Ayman W. (1 January 2012). "Systemic primary carnitine deficiency: an overview of clinical manifestations, diagnosis, and management". Orphanet Journal of Rare Diseases. 7: 68. doi:10.1186/1750-1172-7-68. ISSN 1750-1172. 
  8. ^ Mingorance, Carmen; Rodríguez-Rodríguez, Rosalía; Justo, María Luisa; Álvarez de Sotomayor, María; Herrera, María Dolores (1 January 2011). "Critical update for the clinical use of L-carnitine analogs in cardiometabolic disorders". Vascular Health and Risk Management. 7: 169–176. doi:10.2147/VHRM.S14356. ISSN 1176-6344. 
  9. ^ Shang, Ruiping; Sun, Zhiqi; Li, Hui (21 July 2014). "Effective dosing of L-carnitine in the secondary prevention of cardiovascular disease: a systematic review and meta-analysis". BMC cardiovascular disorders. 14: 88. doi:10.1186/1471-2261-14-88. ISSN 1471-2261. 
  10. ^ Huang, Haohai; Song, Lijun; Zhang, Hua; Zhang, Hanbin; Zhang, Jiping; Zhao, Wenchang (1 January 2013). "Influence of L-carnitine supplementation on serum lipid profile in hemodialysis patients: a systematic review and meta-analysis". Kidney & Blood Pressure Research. 38 (1): 31–41. doi:10.1159/000355751. ISSN 1423-0143. 
  11. ^ Chen, Yizhi; Abbate, Manuela; Tang, Li; Cai, Guangyan; Gong, Zhixiang; Wei, Ribao; Zhou, Jianhui; Chen, Xiangmei (1 February 2014). "L-Carnitine supplementation for adults with end-stage kidney disease requiring maintenance hemodialysis: a systematic review and meta-analysis". The American Journal of Clinical Nutrition. 99 (2): 408–422. doi:10.3945/ajcn.113.062802. ISSN 1938-3207. 
  12. ^ a b "L-Carnitine – Linus Pauling Institute – Oregon State University". 
  13. ^ a b Lombard, K. A.; Olson, A. L.; Nelson, S. E.; Rebouche, C. J. (1989-08-01). "Carnitine status of lactoovovegetarians and strict vegetarian adults and children". The American Journal of Clinical Nutrition. 50 (2): 301–306. ISSN 0002-9165. PMID 2756917. 
  14. ^ Rebouche CJ. Carnitine. In: Shils ME, Olson JA, Shike M, Ross AC, eds. Modern Nutrition in Health and Disease. 9th ed. Philadelphia: Lippincott, Williams & Wilkins; 1999:505-512. Cited by Jane Higdon (2002), see Oregon State U, accessed 12 January 2016
  15. ^ a b c d e f g Demarquoy, Jean; Georges, Béatrice; Rigault, Caroline; Royer, Marie-Charlotte; Clairet, Amélie; Soty, Maud; Lekounoungou, Serge; Le Borgne, Françoise (2004-06-01). "Radioisotopic determination of l-carnitine content in foods commonly eaten in Western countries". Food Chemistry. 86 (1): 137–142. doi:10.1016/j.foodchem.2003.09.023. 
  16. ^ Bain, Marcus A.; Milne, Robert W.; Evans, Allan M. (2006-10-01). "Disposition and metabolite kinetics of oral L-carnitine in humans". Journal of Clinical Pharmacology. 46 (10): 1163–1170. doi:10.1177/0091270006292851. ISSN 0091-2700. PMID 16988205. 
  17. ^ "Regulations Amending the Food and Drug Regulations". 
  18. ^ FDA approval letter

Further reading[edit]

The following are good secondary sources on the subject of this article.

External links[edit]