You might not know what it is, but you know what it does. It's a substance that is apparently unique to asparagus, and when you run it through your kidneys, well . . . . Kenneth Kidd of the Toronto Star tells you all you need to know:
You won't find asparagusic acid in anything else we eat, although its close relatives turn up in everything from tropical mangroves to marine worms. Asparagusic acid, it turns out, is what young asparagus use to ward off parasites. As the plant ages, however, the concentrations decline.
We would have seen this coming, really, if anyone had first consulted Samuel Johnson's 1755 Dictionary of the English Language. Johnson quotes a slightly earlier book by Queen Anne's physician, a Scot by the name of John Arbuthnot, who wrote that asparagus "affects the urine with a foetid smell (especially if cut when they are white) and therefore have been suspected by some physicians as not friendly to the kidneys."Arbuthnot adds: "When they are older, and begin to ramify, they lose this quality; but then they are not so agreeable."
I pride myself on my knowledge of literary trivia, but I didn't know this. Of course, Pope doesn't mention it in his Epistle.
Arbuthnot is pictured above.