The press are credulously reporting a World Health Organisation report: “Bacon, ham and sausages rank alongside cigarettes as a major cause of cancer, the World Health Organisation has said.”
They add: “Its report says each 50g of processed meat a day - the equivalent of one sausage, or less than two slices of bacon - increases the chance of developing bowel cancer by 18 per cent.”
An increase of 18% sounds very bad, almost as if your lifespan will be reduced by 18%
I know that sensible people would not touch a WHO report with a very long stick for fear of catching something, but this is very silly, even by their standards. They have ranked bacon sandwiches in that category not on their risk, but on the strength of the evidence that there is a very high probability of there being some risk, even if if it is very slight. That is, if WHO are certain that the risk is trivial, it goes into the top category of evidence based statements!
“Global health experts listed processed meat as a cancer-causing substance - the highest of five possible rankings, shared with alcohol, asbestos, arsenic and cigarettes.”
This is stupid, stupid, stupid.
It is part of a mendacious habit in which charities and health groups propagandise relative risks without mentioning absolute risks.
Here is the WHO press release, which gives the relative risk as 18% and without quantifying it further adds that the risk “remains small”. In which case, why the press release?
Gerd Giggerenzer took all this nonsense apart in “Reckoning with Risk” 2002. Please read it again and again.
In fact, since the absolute risk of bowel cancer is low, that low absolute risk has simply become a little bit higher. (I have not looked at all the research: I am taking it on trust at the moment). To put it in context, Dr Ian Johnson, nutrition researcher and Emeritus Fellow, Institute of Food Research, said: " the (meat effect) mechanism is poorly understood, and the effect is much smaller than cigarette smoking on the risk of lung cancer. It is also worth noting that there is little or no evidence that vegetarians in the UK have a lower risk of bowel cancer than meat-eaters.” “Professor Robert Pickard, Emeritus Professor of Neurobiology at the University of Cardiff, highlighted a study of 60,000 Britons last year which found similar levels of bowel cancer in vegetarians and meat-eaters”.
The crude incidence rate in the UK is 65.8 per 100,000. The age-adjusted rate is 47 per 100,000 because cancer is largely an age-related condition. A very nasty thing to have, but as we age the probability of something having to be written on our death certificate increases.
Assume that everyone in the UK is vegetarian (the actual figures reflect the fact that the majority are omnivores already consuming red meat and processed meat) and the worst case scenario is that bacon will raise the age-related incidence rate from 47 to 55.5 per 100,000. Or, take things as they are, ban processed meat, and the age-related incidence rate falls from 47 to 40 per 100,000.
Science journalists: I think I was writing about them only a day ago.