Grapefruits May Overdose You.

It's the time of year when citrus fruits are a Thing - at least here in Germany, they are mostly available in autumn and winter, and that's the time of year when they are best anyways. Mostly unrelated to this, we recently had a conversation about chinine and bitter lemon and from that started to wonder what chemical causes the bitter taste in grapefruit, which led to a visit to Wikipedia and... oh wow. I wasn't aware of grapefruit being such an interesting player when it comes to drug interaction!

I really like the taste of grapefruit, especially of the more mild, modern variations. I still remember that when I was a child, they were very sour and often also quite bitter, and generous amounts of sugar were added to the fruit. Which was eaten by cutting it in half, then cutting around the outer rim of the fruit with a special grapefruit knife, and then spooning out the flesh. After the addition of said generous amounts of sugar, of course. (These days I usually peel them and remove the inner skins between the segments.)

If you're taking medication, though, citrus fruits or their juice might not be the best choice - quite a lot of drugs (and caffeine) interact with the stuff. Or, more precisely, citrus fruit contents interact with enzymes and transport proteins in the body and can cause both underdosage and overdosage, depending on consumption and the type of drug. It's quite fascinating!

You can read more about the fruit on the grapefruit wikipedia page, and more about its effects on drugs on this page.