Eating hotdogs, bacon and other processed meat regularly or drinking more than two alcoholic drinks daily may increase the risk of colorectal cancer, a study has warned.
Other factors found to increase colorectal cancer include eating high amounts of red meat (above 500 grammes a week), such as beef or pork; and being overweight or obese, researchers said.
The report by the American Institute for Cancer Research (AICR) and the World Cancer Research Fund (WCRF) also found that whole grains, such as brown rice or whole-wheat bread, reduces colorectal cancer risk.
There was strong evidence that physical activity protects against colon cancer, researchers said.
"Colorectal cancer is one of the most common cancers, yet this report demonstrates there is a lot people can do to dramatically lower their risk," said Edward L Giovannucci, professor at Harvard TH Chan School of Public Health
"The findings from this comprehensive report are robust and clear: Diet and lifestyle have a major role in colorectal cancer," said Giovannucci.
The report evaluated the scientific research worldwide on how diet, weight and physical activity affect colorectal cancer risk.
It analysed 99 studies, including data on 29 million people, of whom over a quarter of a million were diagnosed with colorectal cancer.
The report concluded that eating approximately three servings (90 grams) of whole grains daily reduces the risk of colorectal cancer by 17 per cent.
It adds to previous evidence showing that foods containing fibre decreases the risk of this cancer.
People who are more physically active have a lower risk of colon cancer compared to those who do very little physical activity. Here, the decreased risk was apparent for colon and not rectal cancer.
"Many of the ways to help prevent colorectal cancer are important for overall health. Factors such as maintaining a lean body weight, proper exercise, limiting red and processed meat and eating more whole grains and fibre would lower risk substantially," said Giovannucci.
"Moreover, limiting alcohol to at most two drinks per day and avoidance or cessation of smoking also lower risk," he said.
"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," said Alice Bender, Director of Nutrition Programmes at AICR.
"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," said Bender.