Content provided by the Faculty of the Harvard Medical School

By the way, doctor: What's the problem with grapefruit juice and statins?

By the way, doctor

What's the problem with grapefruit juice and statins?

Q. A warning on my statin prescription tells me not to drink grapefruit juice or eat grapefruit. Does this mean I can never enjoy this delicious fruit again?

A. I can understand your disappointment at this double whammy. Here's some news I hope will at least partly cheer you up: You don't have to give up grapefruit forever as long as you (and your doctor) are willing to switch to a statin or other cholesterol-lowering agent that isn't affected by grapefruit juice.

Grapefruit juice and grapefruit itself can boost blood levels of some statins and a variety of other drugs (see table). Something in grapefruit — scientists aren't yet sure what — latches onto an enzyme in the intestines called CYP3A4. This enzyme partially breaks down some drugs, so knocking it out of action means more of the drugs get into the bloodstream. In the case of statins, abnormally high blood levels can damage muscles or the liver.

One glass of grapefruit juice is enough to suppress CYP3A4 activity by half, and the effect lasts for 12–24 hours.

You have several options:

• Switch to orange juice. It doesn't affect CYP3A4, and so won't boost blood levels of your statin.

• If you are taking only a low dose of a statin, you can probably get away with the occasional small glass of grapefruit juice or half a grapefruit. Don't do this if you are taking a high dose.

• Switch to pravastatin (Pravachol, generic), which the body breaks down via a route that doesn't involve CYP3A4. Rosuvastatin (Crestor) and fluvastatin (Lescol) are broken down by a cousin of CYP3A4, which is less affected by grapefruit. Ezetimibe (Zetia), colesevelam (WelChol), and niacin are other cholesterol-lowering options that work safely with grapefruit.

If you can't start the day without a glass of grapefruit juice or a juicy half-grapefruit, check to make sure you aren't taking other medications affected by this citrus fruit. If you are, your doctor can steer you to safer alternatives. The University of Florida has set up a Web site (www.druginteractioncenter.org) where you can see if your medications interact with grapefruit. In the lab, pomegranate juice and star-fruit juice also block CYP3AY. Whether they increase drug levels in the body isn't known.

— Thomas Lee, M.D. Editor in Chief, Harvard Heart Letter

Last updated:	September 05, 2008