As many as 23 per cent of colorectal cancer cases could be prevented if people consistently followed five healthy lifestyle recommendations, say researchers from Denmark.

The researchers, led by Helene Kirkegaard at the Institute for Cancer Epidemiology in Copenhagen, Denmark, studied data on 55,487 men and women aged between 50 and 64 who had not previously been diagnosed with cancer.

Participants filled in lifestyle questionnaires and the researchers then ranked the participants on a "healthy lifestyle index," using recommendations from the World Health Organization and other groups.

The recommendations included:

  • not smoking
  • doing at least 30 minutes a day of physical activity
  • having no more than seven servings of alcohol a week for women, and 14 drinks a week for men
  • having a waist circumference below 88 cm (35 inches) for women and 102 cm (40 inches) for men
  • eating a healthy diet that includes dietary fibre, at least 600 grams (3 cups) of fruit and vegetables a day, and no more than 500 grams (just over one pound) of red and processed meat a week, and less than 30 per cent of total calories derived from fat

The patients were followed for nearly a decade, up to 2006. During that time, 678 people were diagnosed with colorectal cancer.

After analyzing how well the participants had kept to the five lifestyle recommendations, the researchers calculated that if all of them had followed even one extra guideline, around 13 per cent of colon cancer cases could have been prevented.

If all of them had followed all five, 23 per cent of cases could have been avoided, the researchers report in the British Medical Journal.

Only one per cent of the group scored the highest on the healthy lifestyle index, meaning that they consistently followed all of the healthy lifestyle recommendations.

The link between lifestyle and colorectal cancer was more pronounced in men than in women, the researchers found. They suggested the difference might be due to biological differences, or it may be because the women tended to overestimate the consumption of "desirable" food items more than men.

"Our study reveals the useful public health message that even modest differences in lifestyle might have a substantial impact on colorectal cancer risk and emphasises the importance of continuing vigorous efforts to convince people to follow the lifestyle recommendations," the authors conclude.

It is estimated that 22,500 new cases of colorectal cancer will be diagnosed in Canada in 2010. It's the second leading cause of death from cancer in Canadian men and women combined, after lung cancer.