Which supplement is known to interact with many prescription medications via induction of hepatic enzymes?

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

Answer: (B)

A key idea here is how some supplements can boost the liver’s drug‑metabolizing enzymes. When hepatic enzymes are induced, they work faster, so prescription drugs are cleared from the body more quickly. That can drop drug levels enough to make a treatment less effective or fail.

St. John’s Wort is a well-known inducer of multiple drug‑metabolizing pathways, especially CYP3A4, and it also affects transporters like P‑glycoprotein. Because of this broad induction, many medications end up at much lower levels when taken with it—including oral contraceptives, some immunosuppressants, anticoagulants, and certain antivirals—potentially compromising efficacy.

The other options don’t have that same broad, clinically important enzyme‑induction effect. Garlic can interact in other ways (like increasing bleeding risk with anticoagulants) but isn’t a consistent enzyme inducer. Melatonin and black cohosh aren’t known for strong induction of hepatic enzymes.