Meat and cancer

Media headlines were filled last week with warnings of the dire consequences of eating red meat, especially processed meats. Many people will have been left confused, particularly after all the banting hype. So does eating red meat or processed meat really cause cancer? According to Dr Peter Hill, a director of Met-S Care and specialist in metabolic syndrome, the answer is no. He says the most important problem with the hypothesis that red meat and processed meat causes cancer, lies in the word ‘causes’. “In medical science one can only ever speak of cause in the context of the gold standard of medical research called the randomised controlled trial,” explains Hill. “Simply put, if we wanted to see if red or processed meat causes cancer then we would have to divide a large group of equally matched people who had never eaten red or processed meat into two very similar groups. We would then need to feed the two groups exactly the same food except that the one group would also eat meat,” he says. The reality is that cancer often takes many years to develop and so one would need to extend this same experiment over a number of years. Nothing could be added or taken away from the two diets over the ensuing years and you would need to ensure that both groups were equally exposed to any known or suspected carcinogens. Hill says no researcher has ever done such an experiment and no one ever will because it is not only impractical but it would also be unethical to conduct an experiment in the hope of inducing cancer in the meat eating group. The studies that informed the headlines last week were not based on the medical research gold standard of the randomised controlled trial but rather observational studies, i.e. the researchers simply observed the dietary and other habits of people and looked at any diseases they developed. “I would challenge any good medical scientist to use observational studies to prove cause. It is virtually impossible,” says Hill. He says at best they can point to association, but not cause. The question remains, is eating meat associated with cancer then? Hill says a very large study called the EPIC study that looked at meat consumption and cancer as well as other disease-related causes of death was published in 2013 (BMC Medicine 2013,11:63). The researchers enrolled 448568 adults without cancer, stroke or heart disease and followed this very large group of people for many years. At the end of the study the researchers found an association between early death from heart disease and cancer in people who consumed processed meat, but no association with red meat consumption. “Of interest, and probably worth a headline, the association between death and processed meat ONLY held true for smokers and ex-smokers. There was no association for those who never smoked.” Hill says it is so easy to misinterpret or even manipulate scientific findings. While readers should definitely take heed of warnings, they do need to interrogate the background a little more discerningly and try and look at contentious health-related issues in a balanced manner.