One for the birds
Zebra finches – cute little birds with orange/red beaks that too often sadly end up in the cages of their human 'fanciers' or, it seems, Glasgow laboratories – are featuring prominently in the diet and nutrition news. Last month they were the basis for a rather silly story suggesting that eating carrots can make men more attractive to women. (See Carrots are top for the food of love; Boffin claims root vegetable is aphrodisiac) In the study conducted by Dr Jonathan Blount, male finches fed on a diet that included carotenoid pigments became more attractive to females.
The reason for this, of course, was quite obvious. The orange/red beak of the male finch acts as a primary means of display in courtship rituals – and the deeper the colour the better, even if artificially boosted by carrots. But human males, fortunately or unfortunately, tend not have orange/red beaks. The suggestion, then, by Dr Blount that eating carrots might lead to similar improvements in an unfeathered bloke's pulling power sounds a bit feeble.
Undeterred, however, other researchers in Glasgow's finch laboratory are back with a new study reported in a number of newspapers and most prominently in BBC Online's Junk food link to ageing. In the study the finches fed on a poor diet in the first too weeks of their lives had, perhaps unsurprisingly, shorter lives than their better fed cousins. The diet, however, was not quite the avian equivalent of Pot Noodle and Hawaiian Pizza. It was simply regular birdseed in unlimited quantities, but of low quality and lacking in essential proteins and vitamins.
So what has this got to do with evil junk food? Very little, it seems. But we have to read half way though the BBC's article before we discover that. All that the first paragraph tells us is:
"An early diet of junk food makes it harder to fight off the effects of ageing, scientists have found"
And that is all most casual readers will remember. They may also have failed to read on to where one of the authors of the study, Professor Neil Metcalfe, was quoted later as saying "I think it's not yet clear whether the same things happen in humans", adding lamely "but it's possible." He also conceded, way down the article in paragraph 16, that 'human junk food' could be high in protein – something that was deliberately lacking in the finches' diet.
The fact that studies of this kind – completely lacking in evidence that has any potential for informing us about human diet – can receive such uncritical coverage in both the print media and online science and health news is depressing. I suppose the headline "Nutritionally depleted diet leads to lowered levels of anti-oxidants in Taeniopygia guttata" might not be particularly catchy. But we expect more of sub-editors at BBC Online than a simple 'sexing up' of an otherwise dull and quite irrelevant story.
Peter Marsh – 3 July 2003