However , carnitine supplementation at dosages of ≤ 1000 mg/day ( p = 0.035 ) or equal to 2000 mg/day ( p = 0.013 ) result ed in significant reduction in ALT level , while doses more than 2000 mg/day did not change ALT  significantly .
Carnitine exerts its reducing effect on serum ALT and AST levels only when these aminotransferases are raised or when the duration of supplementation lasts at least 3 months .
Results of the current meta- analysis showed that carnitine supplementation can decrease serum AST and ALT levels significantly , especially when supplementation lasts 3 months or more in patients with elevated serum aminotransferase levels
The effect of L-carnitine and acetyl-L-carnitine on the disappearance of DNA single-strand breaks in human peripheral blood lymphocytes.
DNA single-str and breaks ( SSBs ) and their disappearance during repair incubation were determined by alkaline filter elution in freshly isolated human peripheral blood lymphocytes ( PBLs ) after in vitro treatment with either the oxygen radical-generating system of xanthine oxidase ( XOD ) plus hypoxanthine ( HYP ) or the alkylating agent N-ethyl-N'-nitrosourea ( ENU ) . The elution curves obtained with DNA from PBLs treated with XOD/HYP were markedly nonlinear , possibly as a result of a nonr and om induction of SSBs along the DNA str and s. The disappearance of XOD/HYP-induced  SSBs during the initial repair period was quite slow ; only 20 + /- 7 % ( n = 6 ) of the induced SSBs had disappeared after a 2 1/2 h repair incubation . However , by 24 h the elution curves obtained with DNA from treated PBLs were indistinguishable from those obtained with DNA from nontreated control cells , indicating complete repair . Treatment of PBLs with ENU result ed in linear elution curves . Approximately 50 % of the total amount of  ENU-induced SSBs had disappeared within 1 h in PBLs from most donors ; the additional SSBs were found to be persistent ( Beorrigter , M.E.T.I. , Mullaart , E. , Berends , F. , and Vijg , J. ( 1991 ) Induction and disappearance of DNA str and breaks and /or alkali-labile sites in human lymphocytes exposed to  N-ethyl-N'-nitrosoureas . Carcinogenesis , 12 , 77 - 82 ) . Preincubation of PBLs with 5 mM L-carnitine , a trans-mitochondrial carrier of acetyl and long-chain acyl groups , or 5 mM acetyl-L-Carnitine , result ed in a more rapid disappearance of XOD/HYP-induced SSBs ( 48 + /- 23 % and 48 + /- 30 % respectively ) . Preincubation of PBLs with different doses of L-carnitine , before exposure to 0.5 mM ENU , increased SSB disappearance dependent on the dose and donor PBLs . In conclusion , these studies suggest that treatment with L-carnitine accelerates the disappearance of SSBs induced by oxygen radicals and alkylating agents
However , carnitine supplementation at dosages of ≤ 1000 mg/day ( p = 0.035 ) or equal to 2000 mg/day ( p = 0.013 ) result ed in significant reduction in ALT level , while doses more than 2000 mg/day did not change ALT  significantly .
Carnitine exerts its reducing effect on serum ALT and AST levels only when these aminotransferases are raised or when the duration of supplementation lasts at least 3 months .
Results of the current meta- analysis showed that carnitine supplementation can decrease serum AST and ALT levels significantly , especially when supplementation lasts 3 months or more in patients with elevated serum aminotransferase levels