Dietary Supplements and Botanicals
Core concepts
Understand supplement regulation (in the U.S., supplements are regulated as food, not drugs-no premarket efficacy or safety approval), quality issues (contamination, adulteration, mislabeling), and the highest-yield interaction and safety facts. Know common botanicals (e.g., St. John's wort, ginkgo, turmeric/curcumin, echinacea, ginseng, valerian) and their key concerns.
Traps in questions
- St. John's wort induces CYP3A4 and P-glycoprotein; it reduces efficacy of many drugs (oral contraceptives, warfarin, cyclosporine, some antiretrovirals) and can cause serotonin syndrome with SSRIs.
- Ginkgo increases bleeding risk; caution with anticoagulants/antiplatelets and before surgery.
- Turmeric/curcumin may increase bleeding risk and interact with anticoagulants; poor bioavailability is a common claim.
- Confusing "standardized extract" (a quality marker) with proof of efficacy.
- Assuming "natural" means safe-herb-drug interactions are common.
Worked example / rule of thumb
A patient on warfarin asks about St. John's wort for mood. Rule of thumb: any supplement that induces hepatic enzymes or affects platelets is high-risk with narrow-therapeutic-index drugs. St. John's wort is contraindicated here (enzyme induction reduces warfarin effect; bleeding risk compounds). Recommend clinician-guided alternatives and document.
Safety practice
Always ask about supplements at every visit, check for interactions, and counsel on stopping certain agents before surgery. Encourage third-party–tested products (e.g., USP, NSF) when relevant.