The report, referred to by the WCRF as “the most authoritative ever report on bowel cancer risk”, examined the links between bowel cancer risk and diet, physical activity and weight, concluding that intake of red meats should be limited to 500 grams per week, whilst processed meats should be avoided altogether.
“Our review has found strong evidence that many cases of bowel cancer are not inevitable and that people can significantly reduce their risk by making changes to their diet and lifestyle,” said Professor Alan Jackson, chair of the WCRF Expert Panel.
“On meat, the clear message that comes out of our report is that red and processed meat increase risk of bowel cancer and that people who want to reduce their risk should consider cutting down the amount they eat,” he added.
Red meat and cancer
Lots of attention – and headlines – have been dedicated to the health risks said to be associated with consumption of red meat.
High consumption has been associated with many poor health outcomes, including diabetes, cardiovascular disease and several types of cancer (including lung and colorectal, prostate, and bladder)
In 2007 the World Cancer Research Fund published a report that directly linked diet to cancer, reporting that red and processed meats posing particular risks. However, analysis of data from over a half million people in Europe, as part of the EPIC study, recently found no association between dietary intakes of red meat and the risk of bladder cancer (EPIC study previously reported here).
The new WCRF report is part of its Continuous Update Project (CUP), which aims to update previous advice in reports based on new evidence. The findings are based on a systematic review of the evidence carried out by WCRF/AICR-funded scientists at Imperial College London. They added 263 new papers on bowel cancer to the 749 that were analysed as part of the 2007 Report.
The report follows recently published research from the British Nutrition Foundation which considered the nutritional value of meat, and its contribution to intakes of essential nutrients. The review looked at data on current red meat consumption in the UK and the contribution this makes to nutrient intakes,highlighting the nutritional benefits of eating red meats in moderation. (Nutrition Bulletin, Vol 36, Issue 1, Pages 34–77, March 2011).
Dr Laura Wyness, senior nutrition scientist with the BNF, told FoodNavigator that their review “concluded that moderate intakes of lean red meat can play an important part in a healthy balanced diet.
“Meat contributes protein, unsaturated fatty acids including omega 3s and micronutrients such as iron, zinc, selenium, vitamin D and vitamins B3 and B12. Some of these are already in short supply in the diets of some sections of the population,” she said.
However, the report also went on to state that, in line with current dietary advice, the average intakes of red and processed meat should not rise.
The WCRF/AICR said recommended that people “limit consumption to 500g (cooked weight) of red meat a week … and avoid processed meat.”
The advice was given after the reporting panel “confirmed that there is convincing evidence that both red and processed meat increase bowel cancer risk.” They added that consumption of an extra 100 grams of red meat per day could increase the bowel cancer risk by 17 per cent.
The review panel has also reassessed its view on the protective role of fibre, adding that the protection against bowel cancer afforded by eating foods containing fibre, such as wholegrains, pulses, fruit and vegetables is now “convincing”.
The panel also concluded that milk, garlic, and dietary supplements containing calcium, “probably” reduce the risk of developing bowel cancer.
They said that the conclusions on fibre were made after adding seven more studies to the existing eight from the 2007 Report. The result was that the evidence “became much more consistent.”
“There has been a lot of debate over the last few years about the strength of evidence that red and processed meat increase risk of cancer. We hope our review can help give clarity to those people who are still confused about the strength of the evidence,” said Prof. Jackson.