Effect of high-dose vitamin C on hepatic cytochrome P450 3A4 activity.
OBJECTIVE
To investigate the effect of high-dose vitamin C on cytochrome P450 (CYP) 3A4 activity, and to evaluate possible sex-specific effects on CYP3A4 activity.


METHODS
Single-center longitudinal study.


METHODS
Tertiary- and specialty-care teaching hospital.


METHODS
Fourteen healthy Caucasian adult volunteers (seven men, seven women).


METHODS
Subjects self-administered vitamin C 500 mg twice/day for 14 days.


RESULTS
Hepatic CYP3A4 activity was measured by using the erythromycin breath test on days 1 (baseline) and 15. Overall, no significant effect of vitamin C on CYP3A4 activity was observed. Sex and baseline results were significant predictors of changes in CYP3A4 activity. In men, mean activity increased by 21.9% (95% confidence interval -3.88-47.6%). The effect in women was not consistent.


CONCLUSIONS
Sex and baseline CYP3A4 activity appeared to influence the effect of vitamin C on CYP3A4 activity.
van Heeswijk
Rolf P G
RP
Ottawa Hospital and Ottawa Health Research Institute, the University of Ottawa, Ontario, Canada. rvheesw1@tibbe.jnj.com
Cooper
Curtis L
CL
Foster
Brian C
BC
Chauhan
Bobby M
BM
Shirazi
Farshad
F
Seguin
Isabelle
I
Phillips
Elizabeth J
EJ
Mills
Ed
E
D000328:Adult; D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D004790:Enzyme Induction; D005260:Female; D006801:Humans; D008099:Liver / Q000201:enzymology*; D008137:Longitudinal Studies; D008297:Male; D012737:Sex Factors
D000975:Antioxidants; D003577:Cytochrome P-450 Enzyme System; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D001205:Ascorbic Acid