March 7, 2013

expert reaction to EPIC study into health effects of eating processed meat

A study of half a million men and women in  BMC Medicine suggested an association between processed meat and cardiovascular disease and cancer, after having controlled for various factors associated with ill health.

Catherine Collins, Principal Dietitian at St George’s Hospital NHS Trust, said:

“This population study showed that processed meats were associated with an increased risk of heart disease. It also showed they were more weakly associated with an increased risk of cancer, although this was not statistically significant across all the models they used. (Previous studies have suggested a link between processed meat intake and bowel cancer). The risks of heart disease appeared greater the more processed meats were consumed, with intakes above 40g a day suggesting an increased population risk of premature death from heart disease. The reason for this can’t be established from this study, but saturated fat content, salt and nitrates, and ‘burnt proteins’ (heterocyclic amines) from the cooking process may all play some part. However, it’s impossible to estimate personal risk from this data as other factors – such as the overall diet and lifestyle choices (such as obesity, smoking, exercise) could potentiate the effect of diet even though accounted for in the data.

“Should we be concerned in the UK? Our most recent government National Diet and Nutrition Survey (NDNS) suggests the average adult intake of processed meats (burgers, kebabs, meat pies, sausages and other meat products) averages a measly 37g a day, so not really something to worry about. However, it did show that for some adults up to 100g of processed meats daily was the norm. Whilst not as risky as this study’s top range of over 150g/d, it does suggest that those living on a daily diet of pies and sausages would be at potentially increased risk.

“There are problems in collecting the data as in any large study of this type, such as accuracy of recall, and how exactly would you code a pepperoni pizza? Processed meat or cheese dish? So the take home message for the public is to choose a variety of meats (red meat is fine), include more chicken and fish dishes, and why not add a vegetarian, egg or cheese dish as a meat substitute a couple of times a week?”

Prof David Spiegelhalter, Winton Professor of the Public Understanding of Risk, University of Cambridge, said:

“If we took these findings at face value, 50g of processed meat a day would be associated with losing around 2 years off your life expectancy – that’s as if a daily sausage or bacon sandwich were taking an hour off your life. But I would judge that this is too much – there are a lot of assumptions underlying their risk estimates, in particular the effects of smoking and the way of dealing with errors in assessing how much processed meat was eaten.”

Prof Tom Sanders, Head of the Nutritional Sciences Research Division, Kings College London, said:

“This a pan European study, it demonstrates a weak association but is confounded by the association of processed meat consumption with low social class and cigarette smoking. Tobacco use is such an enormously potent factor that it contaminates the findings of the study. Does this mean we should not eat processed meat like ham, bacon, sausages, burgers? There are reasons to advocate only eating them occasionally because they tend to be high in salt or saturated fat. But I find 20g figure hard to swallow based on predicted effects on known risk factors.”

‘Meat consumption and mortality – results from the European Prospective Investigation into Cancer and Nutrition’ by Rohrmann et al. is published  in BMC Medicine.