Your risk of developing colorectal cancer is much higher if you consume red and processed meat regularly, while consumption of foods containing fiber helps protect you against the disease, researchers from Imperial College London revealed today. They say this is the most authoritative and comprehensive report on colorectal cancer risk to be published to date.

Elisa Bandera, MD, PhD, who served on the World Cancer Research Fund/American Institute for Cancer Research's Continuous Update Project (CUP) Expert Panel that authored the report, said:

"This report shows that colorectal cancer is one of the most preventable cancers. AICR has estimated that about 45 percent of colorectal cancer cases could be prevented if we all ate more fiber-rich plant foods and less meat, drank less alcohol, moved more and stayed lean. That's over 64,000 cases in the US every year."

(WCDR = World Cancer Research Fund. AICR = American Institute for Cancer Research)

As part of WCRF/AICRs Continuous Update Project, the report examined what impact diet, physical activity and bodyweight might have on colorectal cancer risk.

Scientists from Imperial College London added 263 new papers on colorectal cancer to the 749 that were evaluated and studied in the 2007 report.

Red and Processed Meat Link

10 new cohort studies were added to the existing 14 in the 2007 report. The authors concluded that there is compelling evidence linking red and processed meat consumption to a higher colorectal cancer risk.

According to AICR, we should limit our red meat consumption to 18 ounces per week, approximately the equivalent of five or six small portions of pork, lamb or beef. We should avoid all processed meats. Processed meat raises the risk of colorectal cancer twice as much as red meat does, the authors found.

Fiber Protects More Than Previously Realized

After reviewing new evidence since the 2007 report, the authors say that fiber protects much more against colorectal cancer than previously thought. While in 2007 they described fiber's protective qualities are probable, today they describe it as convincing.

There were 8 studies in the 2007 report, now there are seven more.

The AICR says we should eat plenty of plant-based foods, including those containing plenty of fiber, such as beans, vegetables, fruits and whole grains.

Physical Activity, Body Weight and Alcohol Consumption

Maintaining a healthy body weight helps protect you from developing rectal cancer, while being physically active and having a healthy body weight protects you from colon cancer.

Not only does alcohol consumption raise colorectal cancer risk in males, it also appears to increase the risk in women.

Dr. Alan Jackson, Chair of the WCRF/AICR CUP Expert Panel, said:

"Our review has found strong evidence that many cases of colorectal cancer are not inevitable and that people can significantly reduce their risk by making changes to their diet and lifestyle.

Because our judgments are based on more evidence than ever before, the public can be confident that this represents the best advice available on preventing colorectal cancer. 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 bout the strength of the evidence.

"On meat, the clear message that comes out of our report is that red and processed meat increase risk of colorectal cancer and that people who want to reduce their risk should consider cutting down the amount they eat."

CUP Expert Panel member Dr. Elisa Bandera said:

"Many people feel confused about cancer prevention because it can seem like a new study is published every week that suggests something either causes or prevents cancer.

But the CUP takes the latest scientific findings and adds them to the existing body of evidence in a systematic way that ensures our advice takes the latest research into account. This means people can be confident that AICR's recommendations represent the most up-to-date, evidence-based information on cancer prevention available."

In short - the report states that when an individual adopts some lifestyle changes, such as eating a healthy diet with no processed meat, exercises and maintains a healthy body weight, their risk of developing colorectal cancer may be 45% lower.

There are over 64,000 new colon cancer diagnoses in the USA each year.

An individual who eats 3.5 ounces of red meat each day has a 17% higher chance of developing colorectal cancer compared to somebody who never eats red meat, the authors wrote. Consuming 7 ounces of red meat a day raises the risk by 34%.

Scientists are not sure, but they believe that when red meat is cooked at high temperature heterocyclicamines are produced - heterocyclicamines may play a role in colorectal cancer risk. Processed meats are made by salting, smoking, curing or adding nitrates - our body converts nitrates into nitrosamines, which we know increases cancer risk.

Written by Christian Nordqvist