Spice and quantity of life

Although not necessarily renowned as authoritative dispensers of health style advice, it seems that the Spice Girls (UK-based, fin-de-millennium, all-female vocal group) really were on to something in their 1997 hit ‘Spice up your life’.

Research by Jun Lv et al. shows that habitual consumption of spicy foods – in particular those containing chilli peppers – ‘was inversely associated with total and certain cause specific mortality, independent of other risk factors of death’. More specifically, of the cohort (or prospective) study of approximately half a million Chinese participants, those who ate foods containing chilli peppers at least twice a week had a 10 % reduced mortality rate, whilst those who consumed such foods 6 to 7 days a week had a 14 % reduction*.

As the investigators cautiously conclude, ‘given the observational nature of this study, it is not possible to make a causal inference. Further prospective studies in other populations would be essential to demonstrate generalizability of these findings. More evidence will lead to updated dietary recommendations and development of functional foods, such as herbal supplements’.

Whilst it is acknowledged that many people don’t like the heat of chillies, maybe this study’s outcome will be enough to encourage lifestyle coaches/nutritionalists, etc. to ‘educate’ the palates of the populace to appreciate these flavours for their greater long-term (literally!) benefits. And this work may be viewed as part of a general trend to raise awareness of the important role that taste and flavour have in a nutritional context.

Understandably, this story has caught the imagination of newspapers around the world and has generated some rather intriguing statements (which raise important questions about the accuracy of populist reporting of science…). My two favourite lines about this work are from Nicholas Bakalar in the New York Times who states that ‘Eating spicy food is associated with a reduced risk for death…’, and the headline(!) ‘Eating spicy food makes you 10 % less likely to die…’, from Andrew Gregory in the UK newspaper The Mirror.

Now hitherto I naïvely thought that there was a 100 % likelihood that we will all die, i.e. probability of death was 1·0, the ultimate ‘dead cert’. But reflecting upon the latter journalist’s statement and taking it at face value, the prospect of avoiding that terminal condition altogether, or even getting into the 14 % (or just the 10 %…) of the population that apparently will be immortal – that’s what The Mirror says!** – has to be good, right? Now that is a fantastic story.

And even if spices don’t delay a visit from the Grim Reaper, they do make food taste great***. So ‘spice up your life, every boy and every girl’!

* I’m sure readers will be as interested as I was to discover that in the reported study statistical significance was defined as P < 0·05. Whilst acknowledging that researchers are at liberty to choose the P-value they want for their work, I had been under the impression that the burden of proof was higher in biomedical research – such as this study – and that something like P < 0·01 was more usual. And recognising that ‘extraordinary claims require extraordinary evidence’, one wonders what difference using that higher value might make to any of the study’s conclusions, however tentative.

** I’d be interested to know if that phrasing is in any way covered by the Society of Professional Journalists’ Code of Ethics.

*** Or, if you don’t like spices, walking – briskly! – for 25 minutes a day could add an extra 7 years to your lifespan according to a report presented at the European Society of Cardiology Congress.