Wednesday, 6 July 2011

Shambolic science in the Daily Express

In a week where certain sections of the media are getting a well deserved bashing, it's important to remember the kind of damage they can do through perfectly legal means. Indeed, there is a front page story in the Daily Express today that will garner very little criticism, but could very easily lead to major health problems for its readership because of its abuse of scientific research.

Their front page, as seen to the right, proudly declares that 'Now salt is safe to eat', claiming that reducing your intake 'does nothing to reduce your risk of heart disease.' (They also call Public Health specialists 'Health fascists' for good measure)

It is very easy to see how they came to this conclusion, but easier still to see how they got it completely and dangerously wrong. This headline is essentially extrapolated from one piece of research, published in the Cochrane Library. As such, it comes from one of the most reliable sources possible, and we can be sure that the research is thorough, but it seems the Daily Express only read what they wanted to believe.

The review of literature covered nearly 7,000 participants, and found that although lowering your salt intake was correlated with a lower BP, they couldn't find a link to a reduction in your chances of developing heart disease.

That would seem to vindicate the Daily Express would it not? There is no evidential proof that lowering salt intake leads to fewer health problems? Well no, it doesn't vindicate them, because that part of the research is clearly where the health reporter stopped reading, having sniffed a juicy front page story. What the researchers also say next is just as important.

First of all, cardiovascular risk is not the only health issue associated with high salt intake, and so to claim that research looking solely at heart disease can show that 'salt is safe' is ludicrous.

Secondly, this is what the researchers said in their conclusion:

"Despite collating more event data than previous systematic reviews of RCTs ... there is still insufficient power to exclude clinically important effects of reduced dietary salt on mortality or CVD morbidity."

And that is the important sentence. Just because they failed to find the link does not mean the link doesn't exist. They categorically state in the research that the sample size was too small to expect to find firm conclusions, and that they would need at least 18,000 participants before expecting to find the statistical link.

The research was consistent with what they would expect to find, but the benefits will not be visible in such a small sample. To use this single piece of research to declare that salt is safe is comparable to the single piece of research that the MMR vaccine was linked to autism, and we see now the damage that irresponsible research and subsequent bad journalism has done to children's health.

I am not going to be melodramatic, I do not believe that upon reading this headline all Daily Express readers will suddenly start quadrupling their salt intake. But it does undermine health strategies - and the public perception of those strategies - which are aimed at reducing the nation's salt intake. In doing so, it is having a very real, and very negative, impact on the health of its readership.

Bad journalism can do more damage than you might think.

No comments: