THE SUNDAY TELEGRAPH – 09 July 2000
Scientists who should carry a health warning
Once a year, the weekly survey of news and views called, appropriately enough, The Week, publishes a round-up of the health scares of the previous 12 months.
The most recent crop includes the warning to anyone eating pheasant that the levels of lead (from the shot) in the flesh can be more than "10 times the recommended safety limit"; to bikini-wearers that their swimsuits damage their intelligence (psychological tests have apparently revealed that self-consciousness from wearing a bikini can affect mental alertness); to parents that leaving the nursery light on in the bedroom can damage their baby’s eyesight; to users of mobile-phone users that they heat the brain, killing off nerve cells and inducing malignant change.
There were also no fewer than three hazards of television watching – both the chemicals found in the casing of the set and the "harmful radiation" impair concentration, while the physical non-activity of spending long hours in front of the box leads to obesity.
The source of these health scares, it must be emphasised, is not, as is frequently alleged, the febrile imagination of journalists looking for a good story. They are all "findings" of contemporary medical research which have been published in academic journals. They also cannot possibly be true. So what is going on?
Consider a particularly instructive example also from last year – that coffee and tea have a "conflicting relationship" with heart problems: those drinking four or more cups of coffee a day reduce their risk of a coronary by half, whereas four or more cups of tea have the reverse effect of increasing the risk of a coronary.
The source of this discovery, published in a reputable medical journal, could not be more respectable. Professor Hugh Tunstall-Pedoe of Dundee University compared the coffee and tea drinking habits of more than 11,000 men and women, as recorded a decade ago, with their subsequent health records. Sure enough, the more coffee consumed, the better for the heart; the more tea, the worse.
The results are methodically documented with tables, diagrams and statistics – none of which, regrettably, can detract from the fact that it must be nonsense. Both tea and coffee contain the same active ingredient, caffeine, and there is no way that its presence could be beneficial in one beverage and harmful in another.
So if the conclusion is nonsense, then the methods by which it was arrived at must be flawed, and herein lies the problem. The origin of most health scares stems from the same method, in which the everyday lives of thousands of men and women are analysed in a search for some distinguishing factor in those with one type of illness. This is then presented as being "the cause".
In this way coffee, besides (as here) allegedly protecting against heart attacks, has also been shown to cause them, as well as, for good measure, being implicated in cancers of the bladder and pancreas, congenital defects, miscarriages and much else. But coffee is not the cause of these misfortunes; rather, they are spurious statistical associations whose contribution to useful knowledge is zero.
There are two reasons for this anxiety-mongering. First, this type of study is easy to do; it takes no special expertise to switch on a computer, trawl through the social habits of a large group of people and come up with a "new" finding. Second, they have the veneer of scientific objectivity, with lots of figures and statistics whose publication in a journal is visible evidence of the researcher’s productivity.
It is certainly hard to imagine that Professor Tunstall-Pedoe really believes that coffee is good for the heart, and tea bad. Indeed, the insouciance with which those responsible for this type of research report their findings suggests they do not expect anyone else to believe them either. It would, after all, be very serious if coffee really did, or did not, protect against heart attacks and cause cancers and the tragedy of miscarriage. This is not science but quackery.
Copyright: Telegraph Group Ltd