Harvard Heart Letter

Ask the doctor: Does pomelo juice affect drugs the same way grapefruit juice does?

Q. I avoid grapefruit juice because my doctor says it affects how my body handles the Lipitor I take for my cholesterol. Should I also stay away from pomelo?

A. The pomelo (also called shaddock, pumelo, pommelo, and Chinese grapefruit) is the largest citrus fruit, ranging from the size of a cantaloupe to that of a large watermelon. Botanists believe that crosses between pomelo and wild orange created grapefruit. Pomelo mixes the sweet taste of orange with the tang of lemon. Its lineage means that pomelo contains many of the same compounds as grapefruit.

One or more substances in grapefruit and grapefruit juice block the action of an enzyme called cytochrome P-450 3A4 (CYP3A4). This enzyme breaks down a wide array of medications, including atorvastatin (Lipitor). (For an extensive list of drugs affected by grapefruit juice, visit health.harvard.edu/165.) Knocking CYP3A4 out of action means higher blood levels of these medications. One glass of grapefruit juice, or eating half a grapefruit, is enough to suppress CYP3A4 activity by half, and the effect lasts up to 24 hours. The accumulation of active statin in the bloodstream could cause muscle or liver problems.

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