New research has found that eating whole grains each day, such as brown rice and whole-wheat bread, can reduce the risk of colorectal cancer, adding to the body of evidence that suggests a fiber-rich diet can protect against the disease.
Carried out by the American Institute for Cancer Research (AICR) and the World Cancer Research Fund (WCRF), the research is the first from the two organizations to independently link whole grains to a lower risk of colorectal cancer, the third most common cancer among both men and women in the USA.
For the report the team analyzed 99 studies carried out across the world which included data on 29 million people.
They found that around three servings of whole grains daily, equal to around 90g, reduces the risk of colorectal cancer by 17 percent.
The results also suggested that other aspects of a healthy diet could potentially lower the risk of colorectal cancer, however the associations were not as clear.
The team found that a lower risk of colorectal cancer was linked to both fish and foods containing vitamin C, such as oranges, strawberries and spinach, although the evidence that a low intake of non-starchy vegetables and fruit increases the risk was limited. Consuming less than 100 grams per day (about a cup) of each did appear to increase the risk however.
There was also strong evidence that physical activity can also have a protective effect against when compared to those who do very little physical activity.
Other factors that were found to be associated with an increased risk of colorectal cancer included consuming processed meats regularly, such as hot dogs and bacon, eating large amounts of red meat such as beef or pork (more than 500 grams cooked weight a week), drinking two or more daily alcoholic drinks (30 grams of alcohol), and being overweight or obese.
Although the research is still emerging, Alice Bender, MS, RDN, AICR Director of Nutrition Programs, did comment that the evidence points to the benefits of a plant-based diet.
"Replacing some of your refined grains with whole grains and eating mostly plant foods, such as fruits, vegetables and beans, will give you a diet packed with cancer-protective compounds and help you manage your weight, which is so important to lower risk."
"When it comes to cancer there are no guarantees, but it's clear now there are choices you can make and steps you can take to lower your risk of colorectal and other cancers."
AICR estimates that 47 percent of US colorectal cancer cases could be prevented each year through healthy lifestyle changes.
The report can be found online and is part of the Continuous Update Project (CUP), which monitors and analyzes research on cancer prevention from around the world and draws conclusions on how weight, diet and physical activity can reduce the risk of developing cancer.