Every year, more than 3000 Kiwis are diagnosed with bowel cancer.

Many of the risks of getting bowel cancer could be avoided simply by eating more healthily and exercising more, a new study suggests.

An article in the New Zealand Medical Journal highlights six lifestyle risk factors: obesity, alcohol consumption, insufficient physical activity, smoking, eating red meat, and eating processed meat.

More than 3000 people are diagnosed with colorectal cancer each year in New Zealand, giving it one of the highest rates in the world.

123RF Choosing a healthier lifestyle could cut your chances of developing bowel cancer.

The study, published on Friday, estimates as many as 9 per cent of those cases are caused by obesity, and 7 per cent by alcohol.

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However, changes in diet and exercise regimes can reduce the risk of exposure to bowel cancer, as well as to other cancers, heart disease and diabetes, according to researcher Ann Richardson, of the University of Canterbury.

The study findings were backed by Wellington dietitian Sarah Elliot, who advised people to have at least two alcohol-free days a week, as well as eating more fibre and vitamin C.

Fruits, vegetables and whole grains were all good to protect bowels, she said. "Don't neglect fish and lentils."

Red meat twice a week was OK, but no more. And those who liked processed meats, such as bacon and salami, should balance it with foods high in vitamin C, such as tomatoes and kiwifruit.

The study says: "These findings have considerable public health relevance, since they suggest that it is possible to prevent an appreciable proportion of colorectal cancer by changing a few selected lifestyle factors.

"In addition to reducing the incidence of colorectal cancer, a reduction in obesity, alcohol consumption and smoking, and an increase in physical activity, would also reduce the incidence of other cancers, cardiovascular disease and diabetes in New Zealand."

It found the risk factors were 9 per cent for obesity, 7 per cent for alcohol, 4 per cent for insufficient physical activity, 3 per cent for smoking, 5 per cent for eating red meat, and 3 per cent for processed meat.

A national bowel screening programme, starting in the Hutt Valley and Wairarapa, will be rolled out progressively in 2017.

The programme will offer bowel screening every two years to eligible people aged 60 to 74 years.