The Big Sleep: Glycyrhizzzzzzzz

You know those man-bites-dog stories about people who turn a mostly harmless food into a deadly poison by excessive consumption? My char-lady's aunt's cousin heard that carrots would improve his night-vision; ate nothing else for months; turned orange and died. <tsk!> should have paid attention to Apollo O'Delphi: μηδὲν ἄγαν - 'Nothing in excess'. These peculiar stories get widely propagated because of journalistic re-churning: reading each other's copy rather than getting out on the streets and finding a new[s] story.

A couple of weeks ago it was Man Tops Himself with Licorice. That was driven out into the pop sci domain by a case report in NEJM: "A 54-year-old man was evaluated at the hospital after cardiac arrest associated with ventricular fibrillation. The patient had been in a fast-food restaurant when he gasped suddenly and lost consciousness. Emergency medical services personnel arrived, and cardiopulmonary resuscitation was initiated. A diagnosis was made". Case reports are a set of puzzles presented to the readers of NEJM giving them a chance to make a [correct] diagnosis from a clatter of symptoms and thus polish their practical skills and get a wider dissemination of the wonderfully bizarre ways in which human physiology can go wrong. Getting such experience was the key argument for allowing / encouraging junior doctors to work 100 hr weeks back in the good old bad old days of sleep deprived ER decision-making.

The bedside physicians at Mass General were apparently scratching their heads until the family turned up and said that the patient, a construction-worker, had recently switched to lurrying in the licorice instead of Opal Fruits. Licorice is an acquired taste - and not to mine - and seems sweet because it is loaded with glycyrrhizic acid [structure L], a triterpene glycoside of glycyrrhetinic acid [which is the blue multi-ring structure at the top L].  That part looks a little like a steroid - from which the sex hormones, cholesterol and cortisol are all derived. And it is used pharmacologically to block various steroid processing enzymes. And one of the consequences of that is to lower circulating concentrations of potassium K, upon the delicate balance of which normal nerve and muscle function depends. It seems that this is what had done for the licoriceer; the resulting cardiac arrest and multi-organ failure had put him beyond saving.

I wanted more back-ground, so, as you do, I googled Death by Li. . . and up popped Death by Litchi which by a bizarre coincidence, I have covered before. Weirder still, the inactivating principle in both Li*** toxins is a saponin. The trouble with these molecules is that are super-sweet and so, as with licorice you can develop a taste for them. But go easy! apart from your teeth, eating 50g of licorice a day for even 2 weeks can start cardiac arrhythmia and continued consumption can stop cardiac!