As a cancer doctor, it feels almost criminal that most hospitals in the UK continue to serve processed meat. This is despite the fact that in 2015 the World Health Organisation designated processed meat a Group 1 carcinogen i.e. a direct cause of cancer. The decision was reached by a panel of 22 scientists from 10 countries who reviewed more than 800 studies and concluded there was sufficient evidence that processed meat is a cause of colorectal cancer. Globally, more than 10,000 people die from cancer due to the consumption of processed meat and a further 227,150 years of life are lost from premature mortality or disability from a cancer diagnosis.
There is also sufficient suggestive data to support an association between consumption of processed meat and a higher incidence of lymphoma, bladder, breast, oesophageal, gastric, nasopharyngeal, oral cavity and oropharynx and prostate cancer. Like with most exposures there is a dose effect, such that the more processed meat consumed the higher the risk. However, there is no safe lower limit of consumption with as little as 50g eaten per day (one sausage or 2 slices of ham) increasing the relative risk of developing bowel cancer by 18%. To put this into absolute numbers, Cancer Research UK states that 13% of bowel cancer cases are caused by the consumption of processed meat, which in the UK is equivalent to around 5,400 cases per year.
We have some understanding of how processed meat consumption causes cancer. The addition of nitrates or nitrites or smoking of meat can lead to the formation of chemicals such as N-nitroso-compounds (NOC) and polycyclic aromatic hydrocarbons (PAH), which are implicated in cellular damage and cancer development. High temperature cooking also generates cancer causing chemicals such as heterocyclic aromatic amines and PAH. The high salt content is a risk factor for cancer, especially stomach cancer. Processed meat can be high in haem iron, which also leads to the generation of damaging NOCs.
Processed meat consumption also causes a number of additional health harms, including an increased risk of premature death. In a large analysis of nearly half a million men and women from the UK biobank study, processed meat consumption was associated with an increased risk of ischaemic heart disease, type 2 diabetes, diverticular disease and pneumonia. These chronic health conditions can themselves increase the risk of cancer. It is interesting to consider that when swapping processed meat for plant sources of protein, there are numerous health benefits up for grabs.
Given that dietary risk factors are thought to contribute to up to a third of all cases of cancer cases, it is worth considering what the ideal dietary pattern should be for cancer prevention and for living well after a cancer diagnosis. Here, there is scientific consensus. In general, vegetarian diets have been associated with significantly lower rates of certain types of cancer, especially when the diet is centred around healthy plant-based foods, such as fruits, vegetables, whole grains, beans, nuts and seeds. Diets that “limit or not include red or processed meat” are recommended by international cancer agencies because it limits exposure to known carcinogens, promotes a healthier gut microbiome, reduces inflammation and insulin resistance and supports a healthier body weight. These factors are all important for cancer prevention.
Healthcare institutions should be showcasing lifestyle habits that promote health and reduce the risk of chronic conditions. Any encounter with healthcare should raise awareness of healthy and sustainable diets for patients and their families. Serving cancer-causing foods contravenes the basic tenets of healthcare; ‘first do no harm’. When healthcare systems are caving under the pressure of chronic ill health, it’s time to start putting the evidence into practice. Luckily, some are doing just that. In New York City, the Mayor Eric Adams has spearheaded the implementation of plant-based meals as the default option for patients in 11 city hospitals. This has resulted in 60% of patients sticking with the plant-based choice, excellent feedback from patients and has also led to a 36% fall in food-related greenhouse emissions. At my hospital, King’s College Hospital, our five-year strategy has committed to move towards a plant-based food environment and progressively remove processed red meat from menus, but we are yet to achieve this objective. We asked our patients whether they would mind if processed red meat was removed from menus due to health concerns. Most responded that it would not bother them.
I hope to see the day that the serving and eating of processed meat is considered taboo in institutions that are dedicated to promoting health. I pray that this happens before I retire from hospital work.
Dr Kassam runs an online course for medical practitioners with the University of Winchester. The course provides the knowledge and skills required to implement evidence-based lifestyle medicine strategies for cancer prevention and living well after a cancer diagnosis.