Warn people about drug interactions with grapefruit
Consumer publications are starting to warn people about drug interactions with grapefruit.
A substance in grapefruit inhibits cytochrome P450 enzymes in the GI tract. This reduces presystemic metabolism of some drugs...allowing increased absorption and higher serum concentrations.
This substance hasn't been identified yet. It's thought to be a flavonoid found mainly in grapefruit. But don't swear that it's not in other citrus fruits. It MIGHT be.