Expression of Cytochrome P450 Enzymes Is Induced by Flaxseed Enterolignans

Objectives The major flaxseed lignan, secoisolariciresinol diglucoside (SDG), is metabolized to bioactive enterolignans in the intestine and liver. Once formed, enterolignans are subject to hepatic conjugation, similar to cytochrome P450 (CYP)-mediated conjugation of many drugs. CYPs also metabolize food-derived phytochemicals; therefore, adding flaxseed to the diet may promote drug-nutrient interactions affecting the potency of medications. Clinical trials have shown blood pressure-lowering effects of flaxseed in hypertensive patients; however, it is unknown if this stems from direct actions of flaxseed bioactives or indirectly from increased circulating levels of anti-hypertensive (AH) medications resulting from competition for CYP-mediated conjugation and inactivation. Our objective was to determine if enterolignans produced from flaxseed SDG affect expression or activity of CYP enzymes that metabolize metoprolol (MET), a commonly-prescribed AH medication.