A Comparison of Risk and Protective Factors for Colorectal Cancer in the Diet of New Zealand Maori and non-Maori

By international standards New Zealand (population 3.8 x 106) has a high rate of colorectal cancer, with ‍approximately 2000 new cases occurring and approximately 1000 deaths each year. But within the New Zealand ‍population, a lower incidence of colorectal cancer is reported for Maori than for non-Maori New Zealanders (22.2 ‍and 43.7 per 100,000 respectively). Information from the New Zealand National Nutrition Survey 1997 shows that ‍in comparison to non-Maori, Maori eat more in total, eat more red meat, drink more alcohol, consume more saturated ‍fat, have a higher prevalence of obesity and have a lower proportion of individuals consuming a given level of fruit ‍and vegetables per day. All these factors would be expected to increase colorectal cancer risk. Puha (sow thistle; ‍Sonchus sp.) and watercress (Nasturtium officinale, N.aquaticum) are foods with plausible cancer protective properties ‍which are components of the Maori, but not the non-Maori diet.