Archives of Toxicology

, Volume 89, Issue 11, pp 2079–2087 | Cite as

The influence of chronic l-carnitine supplementation on the formation of preneoplastic and atherosclerotic lesions in the colon and aorta of male F344 rats

  • Michael T. Empl
  • Patricia Kammeyer
  • Reiner Ulrich
  • Jan F. Joseph
  • Maria K. Parr
  • Ina Willenberg
  • Nils H. Schebb
  • Wolfgang Baumgärtner
  • Elke Röhrdanz
  • Christian Steffen
  • Pablo Steinberg
Organ Toxicity and Mechanisms


l-Carnitine, a key component of fatty acid oxidation, is nowadays being extensively used as a nutritional supplement with allegedly “fat burning” and performance-enhancing properties, although to date there are no conclusive data supporting these claims. Furthermore, there is an inverse relationship between exogenous supplementation and bioavailability, i.e., fairly high oral doses are not fully absorbed and thus a significant amount of carnitine remains in the gut. Human and rat enterobacteria can degrade unabsorbed l-carnitine to trimethylamine or trimethylamine-N-oxide, which, under certain conditions, may be transformed to the known carcinogen N-nitrosodimethylamine. Recent findings indicate that trimethylamine-N-oxide might also be involved in the development of atherosclerotic lesions. We therefore investigated whether a 1-year administration of different l-carnitine concentrations (0, 1, 2 and 5 g/l) via drinking water leads to an increased incidence of preneoplastic lesions (so-called aberrant crypt foci) in the colon of Fischer 344 rats as well as to the appearance of atherosclerotic lesions in the aorta of these animals. No significant difference between the test groups regarding the formation of lesions in the colon and aorta of the rats was observed, suggesting that, under the given experimental conditions, l-carnitine up to a concentration of 5 g/l in the drinking water does not have adverse effects on the gastrointestinal and vascular system of Fischer 344 rats.


l-Carnitine Trimethylamine Aberrant crypt foci F344 rat Atherosclerosis 



The authors wish to thank (in alphabetical order) Judith Bigalk and Nicole Brauer for excellent technical assistance and Dr. Laura C. Bartel, Maria D. Brauneis, Janine Döhring, Julia Hausmann, Anne von Keutz, Dr. Petra Nicken, Bettina Seeger and Shan Wang for valuable help in taking care of the experimental animals. The authors would also like to acknowledge the financial support of the German Federal Institute for Drugs and Medical Devices (Bonn, Germany).

Supplementary material

204_2014_1341_MOESM1_ESM.pdf (104 kb)
Supplementary material 1 (PDF 103 kb)


  1. Bain MA, Fornasini G, Evans AM (2005) Trimethylamine: metabolic, pharmacokinetic and safety aspects. Curr Drug Metab 6(3):227–240CrossRefPubMedGoogle Scholar
  2. Bain MA, Milne RW, Evans AM (2006) Disposition and metabolite kinetics of oral L-carnitine in humans. J Clin Pharmacol 46(10):1163–1170CrossRefPubMedGoogle Scholar
  3. Baker JR, Chaykin S (1962) The biosynthesis of trimethylamine-N-oxide. J Biol Chem 237:1309–1313PubMedGoogle Scholar
  4. Barnett C, Costill DL, Vukovich MD et al (1994) Effect of L-carnitine supplementation on muscle and blood carnitine content and lactate accumulation during high-intensity sprint cycling. Int J Sport Nutr 4(3):280–288PubMedGoogle Scholar
  5. Bennett BJ, de Aguiar Vallim TQ, Wang Z et al (2013) Trimethylamine-N-oxide, a metabolite associated with atherosclerosis, exhibits complex genetic and dietary regulation. Cell Metab 17(1):49–60PubMedCentralCrossRefPubMedGoogle Scholar
  6. Bird RP (1995) Role of aberrant crypt foci in understanding the pathogenesis of colon cancer. Cancer Lett 93(1):55–71CrossRefPubMedGoogle Scholar
  7. Blankenship B, Skaggs H (2013) Findings in historical control Harlan RCCHan™: WIST rats from 4-, 13-, 26-week studies. Toxicol Pathol 41(3):537–547CrossRefPubMedGoogle Scholar
  8. Brass EP (2000) Supplemental carnitine and exercise. Am J Clin Nutr 72(2 Suppl):618S–623SPubMedGoogle Scholar
  9. Center for Drug Evaluation and Research (2005) Guidance for industry—estimating the maximum safe starting dose in initial clinical trials for therapeutics in adult healthy volunteers. In: Information DoD (ed). U.S. Food and Drug Administration, Rockville, MD, USAGoogle Scholar
  10. Cerretelli P, Marconi C (1990) L-carnitine supplementation in humans. The effects on physical performance. Int J Sports Med 11(1):1–14CrossRefPubMedGoogle Scholar
  11. Coleman GL, Barthold W, Osbaldiston GW, Foster SJ, Jonas AM (1977) Pathological changes during aging in barrier-reared Fischer 344 male rats. J Gerontol 32(3):258–278CrossRefPubMedGoogle Scholar
  12. Dinse GE, Peddada SD, Harris SF, Elmore SA (2010) Comparison of NTP historical control tumor incidence rates in female Harlan Sprague Dawley and fischer 344/N rats. Toxicol Pathol 38(5):765–775CrossRefPubMedGoogle Scholar
  13. Eder K (2000) L-carnitine supplementation and lipid metabolism of rats fed a hyperlipidaemic diet. J Anim Physiol Anim Nutr (Berl) 83(3):132–140CrossRefGoogle Scholar
  14. Erguven M, Yılmaz O, Koc S et al (2007) A case of early diagnosed carnitine deficiency presenting with respiratory symptoms. Ann Nutr Metab 51(4):331–334CrossRefPubMedGoogle Scholar
  15. Evans AM, Fornasini G (2003) Pharmacokinetics of L-carnitine. Clin Pharmacokinet 42(11):941–967CrossRefPubMedGoogle Scholar
  16. Flanagan JL, Simmons PA, Vehige J, Willcox MD, Garrett Q (2010) Role of carnitine in disease. Nutr Metab (Lond) 7:30CrossRefGoogle Scholar
  17. Furukawa F, Nishikawa A, Kitahori Y, Tanakamaru Z, Hirose M (2002) Spontaneous development of aberrant crypt foci in F344 rats. J Exp Clin Cancer Res 21(2):197–201PubMedGoogle Scholar
  18. Gaillard ET, Clifford CB (2000) Common diseases. In: Krinke GJ (ed) The laboratory rat. Academic Press, London, pp 99–132CrossRefGoogle Scholar
  19. Goodman DG, Ward JM, Squire RA, Chu KC, Linhart MS (1979) Neoplastic and nonneoplastic lesions in aging F344 rats. Toxicol Appl Pharmacol 48(2):237–248CrossRefPubMedGoogle Scholar
  20. Grunewald KK, Bailey RS (1993) Commercially marketed supplements for bodybuilding athletes. Sports Med 15(2):90–103CrossRefPubMedGoogle Scholar
  21. Hall WC, Ganaway JR, Rao GN et al (1992) Histopathologic observations in weanling B6C3F1 mice and F344/N rats and their adult parental strains. Toxicol Pathol 20(2):146–154CrossRefPubMedGoogle Scholar
  22. Harper P, Elwin CE, Cederblad G (1988) Pharmacokinetics of intravenous and oral bolus doses of L-carnitine in healthy subjects. Eur J Clin Pharmacol 35(5):555–562CrossRefPubMedGoogle Scholar
  23. Haseman JK, Hailey JR, Morris RW (1998) Spontaneous neoplasm incidences in Fischer 344 rats and B6C3F1 mice in two-year carcinogenicity studies: a national toxicology program update. Toxicol Pathol 26(3):428–441CrossRefPubMedGoogle Scholar
  24. Hofstetter J, Suckow MA, Hickman DL (2006) Morphophysiology. In: Suckow MA, Weisbroth SH, Franklin CL (eds) The laboratory rat, 2nd edn. Academic Press, Burlington, pp 93–125CrossRefGoogle Scholar
  25. Houten SM, Wanders RJ (2010) A general introduction to the biochemistry of mitochondrial fatty acid beta-oxidation. J Inherit Metab Dis 33(5):469–477PubMedCentralCrossRefPubMedGoogle Scholar
  26. Jacoby RO, Gaertner DJ (2006) Viral disease. In: Suckow MA, Weisbroth SH, Franklin CL (eds) The laboratory rat, 2nd edn. Academic Press, Burlington, pp 423–451CrossRefGoogle Scholar
  27. Jeukendrup AE, Randell R (2011) Fat burners: nutrition supplements that increase fat metabolism. Obes Rev 12(10):841–851CrossRefPubMedGoogle Scholar
  28. Jeukendrup AE, Saris WH, Wagenmakers AJ (1998) Fat metabolism during exercise: a review—part III: effects of nutritional interventions. Int J Sports Med 19(6):371–379CrossRefPubMedGoogle Scholar
  29. Keenan KP, Soper KA, Hertzog PR et al (1995a) Diet, overfeeding, and moderate dietary restriction in control Sprague–Dawley rats: II. Effects on age-related proliferative and degenerative lesions. Toxicol Pathol 23(3):287–302CrossRefPubMedGoogle Scholar
  30. Keenan KP, Soper KA, Smith PF, Ballam GC, Clark RL (1995b) Diet, overfeeding, and moderate dietary restriction in control Sprague–Dawley rats: I. Effects on spontaneous neoplasms. Toxicol Pathol 23(3):269–286CrossRefPubMedGoogle Scholar
  31. King WW, Russell SP (2006) Metabolic, traumatic, and miscellaneous diseases. In: Suckow MA, Weisbroth SH, Franklin CL (eds) The laboratory rat, 2nd edn. Academic Press, Burlington, pp 513–546CrossRefGoogle Scholar
  32. Knekt P, Jarvinen R, Dich J, Hakulinen T (1999) Risk of colorectal and other gastro-intestinal cancers after exposure to nitrate, nitrite and N-nitroso compounds: a follow-up study. Int J Cancer 80(6):852–856CrossRefPubMedGoogle Scholar
  33. Koeth RA, Wang Z, Levison BS et al (2013) Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis. Nat Med 19(5):576–585PubMedCentralCrossRefPubMedGoogle Scholar
  34. Kraft PL, Skipper PL, Charnley G, Tannenbaum SR (1981) Urinary excretion of dimethylnitrosamine: a quantitative relationship between dose and urinary excretion. Carcinogenesis 2(7):609–612CrossRefPubMedGoogle Scholar
  35. Lahjouji K, Mitchell GA, Qureshi IA (2001) Carnitine transport by organic cation transporters and systemic carnitine deficiency. Mol Genet Metab 73(4):287–297CrossRefPubMedGoogle Scholar
  36. Li B, Lloyd ML, Gudjonsson H, Shug AL, Olsen WA (1992) The effect of enteral carnitine administration in humans. Am J Clin Nutr 55(4):838–845PubMedGoogle Scholar
  37. Lijinsky W, Keefer L, Conrad E, Van de Bogart R (1972) Nitrosation of tertiary amines and some biologic implications. J Natl Cancer Inst 49(5):1239–1249PubMedGoogle Scholar
  38. Loh YH, Jakszyn P, Luben RN, Mulligan AA, Mitrou PN, Khaw KT (2011) N-Nitroso compounds and cancer incidence: the European prospective investigation into cancer and nutrition (EPIC)-norfolk study. Am J Clin Nutr 93(5):1053–1061CrossRefPubMedGoogle Scholar
  39. Longo N, Amat di San Filippo C, Pasquali M (2006) Disorders of carnitine transport and the carnitine cycle. Am J Med Genet C Semin Med Genet 142C(2):77–85PubMedCentralCrossRefPubMedGoogle Scholar
  40. Maduagwu EN, Bassir O (1979) Microbial nitrosamine formation in palm wine: in vitro N-nitrosation by cell suspensions. J Environ Pathol Toxicol 2(4):1183–1194PubMedGoogle Scholar
  41. Maeda H, Gleiser CA, Masoro EJ, Murata I, McMahan CA, Yu BP (1985) Nutritional influences on aging of Fischer 344 rats: II. Pathology. J Gerontol 40(6):671–688CrossRefPubMedGoogle Scholar
  42. Melton SA, Keenan MJ, Stanciu CE et al (2005) L-carnitine supplementation does not promote weight loss in ovariectomized rats despite endurance exercise. Int J Vitam Nutr Res 75(2):156–160CrossRefPubMedGoogle Scholar
  43. Mitchell ME (1978) Carnitine metabolism in human subjects. I. Normal metabolism. Am J Clin Nutr 31(2):293–306PubMedGoogle Scholar
  44. Moghadasian MH (2002) Experimental atherosclerosis: a historical overview. Life Sci 70(8):855–865CrossRefPubMedGoogle Scholar
  45. Morawietz G, Ruehl-Fehlert C, Kittel B et al (2004) Revised guides for organ sampling and trimming in rats and mice—part 3: a joint publication of the RITA and NACAD groups. Exp Toxicol Pathol 55(6):433–449CrossRefPubMedGoogle Scholar
  46. Munch JW, Bassett MV (2004) Version 1.0; document # EPA/600/R-05/054) Determination of nitrosamines in drinking water by solid phase extraction and capillary column gas chromatography with large volume injection and chemical ionization tandem mass spectrometry (MS/MS). U.S. Environmental Protection Agency, Cincinnati, OhioGoogle Scholar
  47. Nicken P, Brauer N, Lampen A, Steinberg P (2012) Influence of a fat-rich diet, folic acid supplementation and a human-relevant concentration of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine on the induction of preneoplastic lesions in the rat colon. Arch Toxicol 86(5):815–821. doi: 10.1007/s00204-012-0819-1 CrossRefPubMedGoogle Scholar
  48. Percy DH, Barthold SW (2008) Rat pathology of laboratory rodents and rabbits. Blackwell Publishing Professional, Oxford, pp 125–177Google Scholar
  49. Percy DH, Hayes MA, Kocal TE, Wojcinski ZW (1988) Depletion of salivary gland epidermal growth factor by sialodacryoadenitis virus infection in the Wistar rat. Vet Pathol 25(3):183–192CrossRefPubMedGoogle Scholar
  50. Reagan-Shaw S, Nihal M, Ahmad N (2008) Dose translation from animal to human studies revisited. FASEB J 22(3):659–661. doi: 10.1096/fj.07-9574LSF CrossRefPubMedGoogle Scholar
  51. Rebouche CJ (2004) Kinetics, pharmacokinetics, and regulation of L-carnitine and acetyl-L-carnitine metabolism. Ann N Y Acad Sci 1033:30–41CrossRefPubMedGoogle Scholar
  52. Rebouche CJ, Chenard CA (1991) Metabolic fate of dietary carnitine in human adults: identification and quantification of urinary and fecal metabolites. J Nutr 121(4):539–546PubMedGoogle Scholar
  53. Rebouche CJ, Seim H (1998) Carnitine metabolism and its regulation in microorganisms and mammals. Annu Rev Nutr 18:39–61CrossRefPubMedGoogle Scholar
  54. Rebouche CJ, Mack DL, Edmonson PF (1984) L-Carnitine dissimilation in the gastrointestinal tract of the rat. Biochemistry 23(26):6422–6426CrossRefPubMedGoogle Scholar
  55. Ruehl-Fehlert C, Kittel B, Morawietz G et al (2003) Revised guides for organ sampling and trimming in rats and mice—part 1: a joint publication of the RITA and NACAD groups. Exp Toxicol Pathol 55(2–3):91–106CrossRefPubMedGoogle Scholar
  56. Sahajwalla CG, Helton ED, Purich ED, Hoppel CL, Cabana BE (1995) Multiple-dose pharmacokinetics and bioequivalence of L-carnitine 330-mg tablet versus 1-g chewable tablet versus enteral solution in healthy adult male volunteers. J Pharm Sci 84(5):627–633CrossRefPubMedGoogle Scholar
  57. Saldanha Aoki M, Rodriguez Amaral Almeida AL, Navarro F, Bicudo Pereira Costa-Rosa LF, Pereira Bacurau RF (2004) Carnitine supplementation fails to maximize fat mass loss induced by endurance training in rats. Ann Nutr Metab 48(2):90–94CrossRefPubMedGoogle Scholar
  58. Solleveld HA, Haseman JK, McConnell EE (1984) Natural history of body weight gain, survival, and neoplasia in the F344 rat. J Natl Cancer Inst 72(4):929–940PubMedGoogle Scholar
  59. Tamai I (2013) Pharmacological and pathophysiological roles of carnitine/organic cation transporters (OCTNs: SLC22A4, SLC22A5 and Slc22a21). Biopharm Drug Dispos 34(1):29–44CrossRefPubMedGoogle Scholar
  60. Tanakamaru Z, Mori I, Nishikawa A, Furukawa F, Takahashi M, Mori H (2001) Essential similarities between spontaneous and MeIQx-promoted aberrant crypt foci in the F344 rat colon. Cancer Lett 172(2):143–149CrossRefPubMedGoogle Scholar
  61. Thoolen B, Maronpot RR, Harada T et al (2010) Proliferative and nonproliferative lesions of the rat and mouse hepatobiliary system. Toxicol Pathol 38(7 Suppl.):5S–81SCrossRefPubMedGoogle Scholar
  62. Tricker AR, Preussmann R (1991) Carcinogenic N-nitrosamines in the diet: occurrence, formation, mechanisms and carcinogenic potential. Mutat Res 259(3–4):277–289CrossRefPubMedGoogle Scholar
  63. Vermeer IT, Pachen DM, Dallinga JW, Kleinjans JC, van Maanen JM (1998) Volatile N-nitrosamine formation after intake of nitrate at the ADI level in combination with an amine-rich diet. Environ Health Perspect 106(8):459–463PubMedCentralCrossRefPubMedGoogle Scholar
  64. Violante S, Ijlst L, Te Brinke H et al (2013) Peroxisomes contribute to the acylcarnitine production when the carnitine shuttle is deficient. Biochim Biophys Acta 1831(9):1467–1474CrossRefPubMedGoogle Scholar
  65. Vukovich MD, Costill DL, Fink WJ (1994) Carnitine supplementation: effect on muscle carnitine and glycogen content during exercise. Med Sci Sports Exerc 26(9):1122–1129CrossRefPubMedGoogle Scholar
  66. Zhang AQ, Mitchell SC, Smith RL (1999) Dietary precursors of trimethylamine in man: a pilot study. Food Chem Toxicol 37(5):515–520CrossRefPubMedGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Michael T. Empl
    • 1
  • Patricia Kammeyer
    • 2
  • Reiner Ulrich
    • 2
  • Jan F. Joseph
    • 4
  • Maria K. Parr
    • 4
  • Ina Willenberg
    • 1
  • Nils H. Schebb
    • 1
  • Wolfgang Baumgärtner
    • 2
  • Elke Röhrdanz
    • 3
  • Christian Steffen
    • 3
  • Pablo Steinberg
    • 1
  1. 1.Institute for Food Toxicology and Analytical ChemistryUniversity of Veterinary Medicine HannoverHannoverGermany
  2. 2.Department of PathologyUniversity of Veterinary Medicine HannoverHannoverGermany
  3. 3.Federal Institute for Drugs and Medical DevicesBonnGermany
  4. 4.Institute of PharmacyFree University of BerlinBerlinGermany

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