I know this was discussed just a few days ago, there was an article in O,
the Oprah Magazine about it, by David L Katz, MD:

 

Q:  A friend told me I should avoid grapefruit because I'm on blood pressure
medication.  Why?  And if that's true, should I be worried about all citrus?
--Carol Weirmier, Delhi, Ontario

A:  Depending on what medication you're taking, grapefruit can cause your
body to absorb that drug much faster.  Grapefruit-along with Seville (sour)
oranges-contains a family of compounds called furanocoumarins that experts
believe interfere with certain metabolic enzymes.  When furanocoumarins
latch onto the enzymes, drugs are able to flood the bloodstream, dangerously
increasing the dosage.

Among the drugs affected are some of the popular blood pressure-lowering
agents known as calcium channel blockers.  You have plenty of other options,
so if you like grapefruit, talk to your doctor about switching medications.
(Other citrus isn't a concern.)

Statins, tranquilizers, and antidepressants may also be metabolized faster
due to furanocoumarins.  Visit
www.securepharmacy.pharmacytimes.com/lessons/200303-02.asp for a complete
list of medications.  For guidance about a variety of potential food and
drug interactions, try this guide from MD Anderson Cancer Center:
www.mdanderson.org/departments/nutrition/ (click on Food-Drug Interactions).

 

Jessica