Many people may know that, in general, grapefruits and meds are a bad combination. But probably few of us realize that a number of other foods can affect a key enzyme involved in metabolizing drugs.

The enzyme is called cytochrome P450. It’s found mainly in liver cells, but is also present in cells throughout the body. Variations of genes found in cells containing P450 can either break down a drug slowly or quickly, affecting a med’s potency.

Besides grapefruit, Seville oranges, pomelos, pomegranates, star fruit, black pepper, cranberry and grape juice, black tea, beer, kava, licorice root, wine, olive oil, broccoli, cabbage, and cauliflower can affect this enzyme and how it breaks down meds.

Because each person has a unique P450 profile, “the effect these foods have on drug metabolism varies greatly among people,” explains Denise Webb, PhD, a registered dietitian who wrote about studies that exposed a variety of these interactions.

Certainly that’s food for thought.