Bacon and biltong have been linked to cancer – but how big is the risk, really?

The World Health Organisation’s International Agency for Research on Cancer (IARC) has declared processed meats, including bacon and biltong, a class 1 carcinogen – meaning there is a causal link between eating these products and getting cancer.

This puts bacon on the same level of cancer-causing agents such as tobacco, alcohol and sunlight – a move which has sparked outcry among rasher lovers (and medical experts) all over the world.

The global health group also classified red meat as a class 2A carcinogen – putting it on the same level as steroids and exposure to some chemicals.

This association was observed mainly for colorectal cancer, but associations were also seen for pancreatic cancer and prostate cancer.

The real question now hovering over the findings is, will eating meat really give you cancer?

Meat and cancer

According to studies by the WHO, for every 50 grams of processed meat you eat per day, your risk of bowel cancer increases by 18%.

The findings were presented and assessed by a working group of 22 experts from 10 countries, which considered more than 800 studies that investigated associations of more than a dozen types of cancer with the consumption of red meat or processed meat in many countries and populations with diverse diets.

The most influential evidence came from large prospective cohort studies conducted over the past 20 years, the WHO said.

While the data shows an increased risk of developing cancer from eating processed meat, it doesn’t necessarily mean that eating these products automatically stacks up your risk of getting cancer.

Due to the nature of the studies conducted – mostly self-reporting and surveys over time – compared to people in the study who ate less of these products, the people who ate 50 grams or more were more likely to develop cancer. This leaves the data open to wider interpretation.

Some nutritionists, including Low-Carb-High-Fat (LCHF) proponent Tim Noakes, have called the WHO classification of processed and red meat “scaremongering”, pointing out that the data is flawed – even going as far as calling it “bad science“.

Critics point out the unreliability of dietary questionnaires; the exclusion of lifestyle factors in these studies; no data on the quality of meats eaten by the study subjects; drawing lines of association, rather than causation; and the focus on relative, rather than absolute risk of cancer.

Is bacon as bad as smoking?

Another hot topic is bacon’s categorization with products like tobacco and alcohol.

According to medical researchers, just because the IARC has put bacon in the same category as tobacco, doesn’t mean that the risk of cancer is the same.

This infographic from Cancer Research UK, shows exactly how processed meats compare to tobacco in terms of cancer risk:

The confusion comes from the IARC’s classification scale, which is what has pushed the alarming headlines across the world.

The IARC’s scale goes from group 1 to group 4, with group 2 split into two parts.

The scale only represents the level of evidence there is linking a substance to cancer – and does not detail the severity or level of risk.

The group has assessed over 900 substances since 1971, and only one substance has ever been classified as not carcinogenic – caprolactam, a substance used in the manufacturing of synthetic fibres.

Smoking, exposure to sunlight, alcohol and now processed meats are group 1 – where there is sufficient evidence to causally link these things to cancer.

Steroids, red meat and working in hairdressing are in group 2A, which has limited evidence linked to cancer in humans, and sufficient evidence in animals.

Coffee, petrol and pickled vegetables are in group 2B, which has limited evidence linked to cancer in humans, and insufficient evidence in animals.

The infographic below, from chemistry website, Compound Interest details the IACR’s classification.