The analysis of 800 studies from around the world by the International Agency for Research on Cancer (IARC) found “sufficient evidence in humans that the consumption of processed meat causes colorectal cancer”.
The category includes meat that has been salted, cured, fermented or smoked – hot dogs, sausages, corned beef, dried meat like beef jerky or South African biltong, canned meat or meat-based sauces.
The finding supports “recommendations to limit intake of meat” – particularly in processed forms, said the IARC.
“In view of the large number of people who consume processed meat, the global impact on cancer incidence is of public health importance,” IARC official Kurt Straif said in a statement.
For an individual, the risk of getting cancer from eating processed meat was statistically “small”, the agency said, but “increases with the amount of meat consumed.”
“Each 50-gram portion of processed meat eaten daily increases the risk of colorectal cancer by 18 per cent.”
For unprocessed red meat – beef, veal, pork, lamb, mutton, horse or goat – the review found “strong” evidence of a cancer-causing effect, but not sufficient to place it in the same group of cancer-causing agents as tobacco smoke, asbestos, and now also processed meat.
As for processed meat, the red meat risk was mainly for cancer of the colon and rectum, but also the pancreas and prostate, said the report.
The agency cited research attributing about 34,000 cancer deaths per year worldwide to diets high in processed meat.
As for red meat – if the suspected link were to be confirmed – it would account for some 50,000 cancer deaths per year worldwide.
The numbers were dwarfed by the estimated one million cancer deaths per year due to tobacco smoking, 600,000 from alcohol use, and more than 200,000 due to air pollution, said the agency.
Meat producers slammed the report, as independent experts urged caution in interpreting the numbers.
The North American Meat Institute (NAMI) said the IARC “tortured the data to ensure a specific outcome”.
“Followers of the Mediterranean diet eat double the recommended amount of processed meats. People in countries where the Mediterranean diet is followed, like Spain, Italy and France, have some of the longest lifespans in the world and excellent health,” said Betsy Booren, NAMI vice-president of scientific affairs.
Health experts said the findings were no reason to drop steak from the menu, although it was probably wise for big eaters of it to cut back.
British nutrition expert Elisabeth Lund said via the Science Media Centre: “Very few people in Europe eat sufficient meat to fall into the high meat consumption category.
“Meat is such a good source of iron and zinc and many women are short of these key micronutrients … Iron is much more … available from meat than from vegetables or supplements.”
She said obesity and lack of exercise were a far bigger cancer risks.
“Overall, I feel that eating meat once a day combined with plenty of fruit, vegetable and cereal fibre plus exercise and weight control, will allow for a low risk of CRC,” she said, referring to colo-rectal cancer.
“It should also be noted that some studies have shown that if meat is consumed with vegetables or a high-fibre diet, the risk of CRC is reduced.”
Ian Johnson of the UK-based Institute of Food Research, said meat consumption was “probably one of many” factors contributing to relatively high rates of bowel cancer in the United States, Western Europe and Australia – parts of the developed world where more meat has traditionally been eaten.
However, “there is little or no evidence that vegetarians in the UK have lower risk of bowel cancer than meat-eaters,” he said.
According to the World Health Organization, bowel cancer is the third most common type, with some 900,000 new cases every year, and 500,000 deaths.
Generally, dietary advice is to limit red-meat intake to once or twice a week, said nutrition professor Tom Sanders of King’s College London – the equivalent of about two steaks or three hamburgers.
“The problem with this issue is that food is not like tobacco – we have to eat something.”
The report of the IARC, based in Lyon, France, was compiled by 22 experts from 10 countries.
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