Does your pee stink after eating asparagus?

If you said 'no', you're wrong!

Like about half of the population, my piss really stinks after eating asparagus. Even if I eat just one or two spears of the stuff, there will be a noticeable smell as soon as half an hour after eating. If, as I did last night, I eat an entire bunch of the stuff, the stench is overpowering. And it lasts for up to a day.

If I'm completely honest, the smell is actually fairly pleasant. Like many bodily odours, it's OK when it's your own. I'm not the only one to think this: Gabriel Garcia Marquez in "Love in the Time of Cholera" writes: "he enjoyed the immediate pleasure of smelling a secret garden in his urine that had been purified by lukewarm asparagus.". Marcel Proust wrote: "...my greatest pleasure was the asparagus, bathed in ultramarine and pink and whose spears, delicately brushed in mauve and azure, fade imperceptibly to the base of the stalk... the precious essence that I would still recognize when, all night following a dinner where I had eaten them, they played in their crude, poetic farces, like one of Shakespeare's fairies, at changing my chamberpot into a bottle of perfume."

As I say, this effect is only noticed by half of the population. I had always believed that there is a gene that some of us have, which somehow breaks down the asparagus, causing the smell. I thought this gene was called 'asparagene'.

Wrong and wrong again, it seems.

Asparagine is actually the name of an amino acid and has nothing to do with the smell. Asparagus contains several sulphur-derived amino acids which break down during digestion into Methyl Mercaptan - the stuff that makes rotten eggs and skunks stink - and a couple of other mysterious amino acids.

Latest research suggests that everybody's piss smells after eating asparagus. But not everyone can smell it.

So, yes, it is a genetic thing, but it is the ability to smell it which is controlled by the gene.

Next in this series: Think your shit doesn't stink? Think again, buddy!