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Published on: March 28, 2017
Effect of high-dose vitamin C on hepatic cytochrome P450 3A4 activity
Rolf P G van Heeswijk1, Curtis L Cooper, Brian C Foster
1Ottawa Hospital and Ottawa Health Research Institute, the University of Ottawa, Ontario, Canada. rvheesw1@tibbe.jnj.com
Study Objectives:
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.
Design:
Single-center longitudinal study.
Setting:
Tertiary- and specialty-care teaching hospital.
Subjects:
Fourteen healthy Caucasian adult volunteers (seven men, seven women).
Intervention:
Subjects self-administered vitamin C 500 mg twice/day for 14 days.
Measurements And Main 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.
Conclusion:
Sex and baseline CYP3A4 activity appeared to influence the effect of vitamin C on CYP3A4 activity.
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