Does processed meat consumption cause colorectal cancer?
Processed meats are a big part of the diet in Australia, but experts at UNSW Sydney say they make the risk of getting cancer higher.
They are as important to summer as a nose covered in zinc or a game of cricket in the backyard. After the month of December, processed meats are served at every gathering. It is the bacon sizzling on the grill, the cured ham served at Christmas, and the salami on the grazing platter.
But a lot of us know that processed meats are linked to colorectal cancer, which kills more than 5,000 Australians every year. By consuming processed meats, do we increase our risk of developing cancer, or is this just a myth?
Australians consume a great deal of meat, of which a significant portion is processed. According to the Organisation for Economic Co-operation and Development (OECD), in 2018 we consumed roughly 110 kilogrammes per person, second only to the United States. According to the most recent national diet survey, conducted in 2011-12, approximately one-fourth of the meat consumed was salted, cured, fermented, smoked, or otherwise processed.
As a cancer-causing agent, processed meat is a carcinogen.
In 2015, the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO) looked at more than 800 studies to try to figure out the link between processed meats and cancer. So that they could focus on the effect of processed meats, the studies left out other things that can cause cancer, like being overweight.
Professor Bernard Stewart of UNSW Medicine & Health, an internationally recognised expert in environmental carcinogenesis, chaired the IARC Working Group (cancer causation).
In the end, the IARC decided that processed meat is a carcinogen. This means that they found enough proof that eating processed meats can cause colorectal cancer.
How then does this function? There are several explanations, with nitrites in processed meat products being the most prominent.
Professor Stewart says that sodium nitrite has been used to treat processed meat at least in the past. This nitrite can react with molecules in the body, resulting in the formation of cancer-causing N-nitroso compounds.
Cooking processed meat over high heat or an open flame can also contribute to the issue.
"There are also carcinogens that are not naturally present in meat, but are produced during cooking. Prof. Stewart mentioned polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs) as examples.
Should processed meat be labelled with a warning?
If processed meat is a carcinogen, should sausage and bacon packages carry warning labels similar to those on cigarettes? Professor Stewart asserts that it is not that simple.
"On the one hand, the evidence that processed meat consumption causes cancer is as conclusive as the evidence that smoking and asbestos cause lung cancer. In contrast, the same level of preventive measures is in no way warranted."
Different carcinogens exert varying degrees of influence on cancer risk. A nonsmoker's lifetime risk of developing lung cancer is 1%, while a heavy smoker's lifetime risk is 25%. Colorectal cancer risk, on the other hand, goes up from 5% to 6% for people who eat processed meat often instead of moderately.
This means that although there is substantial evidence that eating processed meats increases the risk of colorectal cancer, the actual impact on cancer risk is minimal.
Reducing the risk of colorectal cancer
Although eating salami may not be as dangerous as smoking cigarettes or inhaling asbestos fibers, it does contribute to the development of cancer. But there may be ways to partially fix the gut problems caused by processed meats. This includes fruit, vegetable, and whole grain consumption.
Associate Professor Sara Grafenauer, an accredited practicing dietitian from UNSW Medicine & Health, is conducting research on how consuming whole grains may protect against colorectal cancer. Whole grains can help prevent obesity, which is an indirect effect. They can also stop cancer-causing activity in the intestines, which is a direct effect. Significantly, diets that include whole grains may prevent disease and save millions of dollars on health care costs.
A/Professor Grafenauer remarked, "Whole grains contain an abundance of anti-carcinogenic nutrients." "It has a lot of compounds that protect the digestive tract and increase the activity of anti-oxidants there.
Also, because whole grains have a lot of fiber, they can bind to carcinogens and get rid of them from the digestive tract.
So, now that you know the risks of eating processed meat, is it "safe" to eat salami or a BLT? The answer is "yes," as a nibble poses no problem. Regular and daily consumption of processed meat is linked to an increase in the risk of cancer that can be measured. With this information, it is up to you to determine the summer menu.
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