The equivalent of one bacon rasher or lamb chop a day, on average, raises an individual’s risk of bowel cancer by around 20 per cent, the University of Oxford researchers said.
Processed meats, like ham, bacon and sausages, have been classed as cancer-causing carcinogens by the World Health Organisation, which suggested the same is very probably true for red meat.
While cancer risks have previously been shown to increase above 50g of processed meat a day, the latest Cancer Research UK-funded study found sizeable increased risk at lower levels.
The findings, published in the International Journal of Epidemiology, show those averaging 76g of red and processed meat a day saw their risk of bowel cancer rise by a fifth compared to people eating 21g a day.
Guidelines from the Department of Health recommend anyone eating more than 90g of red or processed meat a day on average should aim to reduce it below 70g – roughly the UK average.
“The government guidelines on red and processed meat are general health advice and this study is a reminder that the more you can cut down beyond this, the more you can lower your chances of developing bowel cancer,” said Dr Julie Sharp, Cancer Research UK’s head of health information.
Dr Sharp and NHS advice also recommends taking red meat-free days, cooking with pulses or other vegetarian proteins, fish and chicken.
The Cancer Research UK study used health records of 475,581 people aged 40 to 69 and followed their diet and health over almost six years.
Around one in every 15 men and one in every 18 women born after 1960 will develop bowel cancer in their lifetime.
During the studied period, 2,609 people were diagnosed with the disease.
Broken down by the type of meat they were eating, the study showed people who ate around 29g of processed meat per day (roughly one slice of ham or rasher of bacon) had a 20 per cent higher risk, compared to someone who ate the equivalent of 5g per day.
For red meat only, the risk was 19 per cent higher for people who ate 54g per day (about one thick slice of roast beef or one lamb chop) on average compared with those who had 8g per day.
There was some evidence that people who ate more fibre from whole grain bread and breakfast cereals each day could lower their risk by around 14 per cent.
“Our results strongly suggest that people who eat red and processed meat four or more times a week have a higher risk of developing bowel cancer than those who eat red and processed meat less than twice a week,” said Professor Time Key, one of the study’s authors at Oxford University’s cancer epidemiology unit.
Dr Gunter Kuhnle, a nutrition and health expert with the University of Reading who was not involved with the study, said this was a “very thorough” piece of research which provides the best information yet for UK adults.
“The results of this study also question the recent focus on [processed meat preservative] nitrite as the main culprit for colorectal cancer,” he added.
“The authors found very small differences between red and processed meat in this study, even though only processed meat contains nitrite. A reduction or removal of nitrite from meat products would therefore have only little impact on cancer risk. An increased consumption of fibre, as shown by this study, would be of considerably more benefit.”
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