ChEMBL

Your body is just full of carefully evolved and tried and tested systems to stop you taking bad or potentially damaging things into your body - smell receptors for the amines of rotting meat, visual receptors and a fantastic pattern-matching brain to allow you to see maggots, fungus, (blue color even in food is a usually a warning sign) etc. and taste receptors to warn of potentially toxic molecules. Drugs are highly regulated, quite rightly, and careful testing needs to be done to assess the safety of drugs.

Why, oh, why then, do we sell grapefruits without regulation and a license?

Terfenadine was a drug that was withdrawn following safety concerns, these side effects were sometimes induced by grapefruit consumption. Many, many, prescribing information sheets for drugs advise that there may be side effects and drug interactions with grapefruit - due to the prevalence of CYP3A4 mediated metabolism of the majority of current small molecule drugs. There is also an active internet (and scientific) literature in the use of grapefruit (or extracts) to exploit this CYP450 inhibition activity as a way to boost or extend plasma levels, or allow the use of lower doses of potentially life-saving drugs, and even drugs in a recreational setting. There is even a biotech established to develop drugs for this effect (but despite the wonders of Google I was unable to find it today (so maybe it is not in business any more)).

It is interesting to see grapefruit pitched as variously a 'wonder food' (health food stores, alternative therapists, agricultural organisations) or a potentially dangerous foodstuff to be consumed with care (many physicians and scientists - an example). Certainly, I always tell my mother, who loves the 'devils fruit', to tell her doctor that she frequently eats grapefruit whenever she gets a new prescription. A search of google (today, shows 3,030,000 hits for 'dangerous grapefruit' and 8,110,000 hits for 'healthy grapefruit', so a lot of opinions out there).

For the UK readers out there, the Daily Mail newspaper is renown for publishing conflicting health stories - here's what they say about grapefruit.

There are a number of compounds in grapefruit that are potent CYP inhibitors, including Naringin


and Bergamottin.



Well, the Florida Department of Citrus have provided some assurance. However, I'm still a little worried, I think I'll hold off until the 'Industrial Federation of Bergamottin and Naringin Producers' tells me it's fine ;)

The cartoon at the top was harvested from www.xkcd.com which is probably a site that is not safe for work (nsfw) - unless your work involves browsing cartoons with occasional adult humor.