In 2014 more than 14,000 Australians were diagnosed with bowel cancer and around 4000 of us die from the disease each year. Today, a scientific report from the World Health Organisation's International Agency for Research on Cancer (IARC) drew definite links between processed meats and bowel cancer, with red meats also cited as a possible cause. Here's what you need to know.
Eating sausages, bacon and other processed meats causes colon cancer, and there is strong epidemiological evidence that suggests unprocessed red meats also have a cancer-causing effect. These are the startling claims made in a new IARC report that analysed 800 studies from around the world.
After sifting through decades' worth of scientific literature, an IARC working group of 22 experts from 10 countries classified the consumption of processed meat as a Group 1 carcinogen to humans. This means there is "sufficient evidence" that the consumption of processed meat causes bowel, or colorectal, cancer.
Worryingly, this is the same category of cancer-causing agents as tobacco smoke and asbestos. "Each 50-gram portion of processed meat eaten daily increases the risk of colorectal cancer by 18 per cent," the agency claimed in a statement.
Red meat, meanwhile, was categorised as a "Group 2A probable carcinogen" based on limited evidence. This basically means that a positive association has been observed as it relates to the onset of colorectal cancer in humans, but more research is needed. In addition to colorectal cancer, associations were also seen for pancreatic cancer and prostate cancer.
Based on the available evidence, the increased risk of cancer was estimated to be 17% for people who consume 100g of red meat daily.
Here's what the IARC had to say on the link between meats and cancer:
Meat consists of multiple components, such as haem iron. Meat can also contain chemicals that form during meat processing or cooking. For instance, carcinogenic chemicals that form during meat processing include N-nitroso compounds and polycyclic aromatic hydrocarbons. Cooking of red meat or processed meat also produces heterocyclic aromatic amines as well as other chemicals including polycyclic aromatic hydrocarbons, which are also found in other foods and in air pollution. Some of these chemicals are known or suspected carcinogens, but despite this knowledge it is not yet fully understood how cancer risk is increased by red meat or processed meat.
Processed meats have long been associated with an increased risk of cancer. However, the latest report is one of the most aggressive stances ever taken by a medical body.
So what does this mean for your diet? According to Cancer Council Australia's chief scientific advisor Professor Bernard Stewart, the important thing to do is exercise moderation.
“No-one’s proposing that we ban bacon, put warnings on hot dogs or take beef off the barbie. But this WHO review provides compelling evidence that the long-term consumption of red meat and/or processed meat increases your risk of cancer," Stewart said in a statement.
"This report...is one of the most complex assessments of the medical and scientific literature ever undertaken concerning a particular cancer risk. The findings provide a new degree of certainty for health authorities who produce evidence-based dietary guidelines.”
It's worth noting that you can reduce the risk of bowel cancer by regularly eating foods that are high in dietary fibre, such as wholegrains, legumes, high-fibre cereals, vegetables and fruit. It is estimated that for every ten grams of fibre you consume per day, your risk reduces by 10%.
Naturally, you should try to be as physically active as possible. As little as 30 minutes of exercise per day can help to reduce the risk of bowel cancer. You can also check how processed meats are chemically preserved. (Hamburger patties from the butcher usually contain no additives, for example.)
In conclusion, processed meats should definitely be avoided as a daily indulgence: if you're eating 50g per day, are overweight and aren't getting much exercise, you might want to make some changes.
Red meats should be capped at no more than seven 65g serves per week. As long as you stick to those guidelines, the health benefits of red meat probably outweigh the risks.
Additional reporting by George Dvorsky