Which supplement is known to induce hepatic enzymes and interact with many drugs?

• A. Garlic
• B. St. John's Wort
• C. Melatonin
• D. Black cohosh

Answer: (B)

Hepatic enzyme induction speeds up the metabolism of many drugs, lowering their blood levels and potentially making them less effective. St. John’s Wort is a well-known potent inducer of hepatic enzymes, especially the cytochrome P450 system (notably CYP3A4) and P-glycoprotein. By activating the pregnane X receptor, it increases the production of these enzymes, so a wide range of medications are cleared more quickly when this supplement is taken. This leads to interactions with many drugs, including birth control pills, immunosuppressants, anticoagulants, and various antidepressants, among others. The induction develops over days to weeks and can persist after stopping for a while, so the interactions can be clinically significant for both starting and stopping the supplement. Other supplements listed don’t produce this broad, consistent enzyme-inducing effect to the same extent; they may have some interactions but not the same pervasive impact on drug metabolism.