CaffeineCAM InteractionsTurmeric

Risk of curcumin-drug interactions

Researchers at Central South University, in Hunan, China studied the effect of curcumin (turmeric) on drug metabolizing enzymes.

Their findings suggest a risk for curcumin-drug interactions.

First, the details.

  • 16 healthy Chinese men were recruited for the study.
  • There were 2 phases.
    • First phase, volunteers received 100 mg caffeine by mouth and 0- to 12-hour blood and urine samples were collected.
    • Second phase, volunteers received 1000 mg curcumin once daily for 14 continuous days, with blood and urine samples were collected on days 1 and 15.
  • Caffeine metabolites (eg 17X, 17U) in the urine were used as the indicators of the activities of 4 enzymes: cytochrome P450 enzymes (CYP1A2 and CYP2A6), N-acetyltransferase type 2 (NAT2), and xanthine oxidase (XO).
    • CYP1A2 and CYP2A6 are members of the “superfamily” of liver enzymes, which alter the rate of drug metabolism and synthesis of cholesterol, steroids and other lipids.
    • NAT2 and XO participate in detoxification of foreign substances in the body.
  • The pharmacokinetics of caffeine and its metabolites were measured using high-performance liquid chromatography.

And, the results.

  • When taking curcumin…
    • CYP1A2 activity significantly decreased 29%.
    • CYP2A6 activity significantly increased 49%.
    • The area under the concentration-time curve (a measure of how much drug is absorbed) from 0 to 12 hours of 17X significantly decreased 27%.
    • Urinary excretion of 17X and XO decreased 36% and 31%, respectively.
    • Excretion of 17U significantly increased 77%.
  • There were no significant changes for caffeine, 1-methylurate, and 5-acetylamino-6-formylamino-3-methyluracil between the 2 study phases.

The bottom line?

The authors concluded, “Curcumin inhibits CYP1A2 function but enhances CYP2A6 activity. Simultaneously, some pharmacokinetic parameters relating to 17X were affected by curcumin.”

No actual curcumin-drug interaction has been reported, but there is a risk that should be considered when patients are evaluated.

5/20/10 17:09 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.