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Dietary Surveys and Nutritional Epidemiology
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These authors contributed equally to this work.
The association between the intake of vegetables and fruit and the risk of colorectal cancer is only suggestive(1). Most case-control studies have shown strong evidence of an inverse association between vegetable and fruit intake and colorectal cancer risk(2-5), whereas most(6-11)but not all(12,13)prospective cohort studies have found no statistically significant associations with total fruit and/or vegetable intake. All the previous studies have categorised vegetables and fruit by botanical family or the parts of the plant. Recently, Pennington & Fisher(14,15)devised a novel definition of fruit and vegetable colour groups based on a combination of their unique nutritional value and characteristics. The colour of the edible portion of vegetables and fruit reflects the presence of pigmented phytochemicals, such as carotenoids and flavonoids, and could, therefore, be an indicator of their nutrient profile and be used in their classification(14,15).
Studies that have examined the association between the intake of individual vegetable and fruit groups and the risk of colorectal cancer have yielded inconsistent results. One study carried out in Switzerland has shown a statistically significantly decreased risk of colorectal cancer with a high consumption of citrus fruit(16), whereas the NIH-AARP Diet and Health Study has shown no statistically significant association(17). Consistent evidence of a relationship between subgroups of fruit and vegetables and colorectal cancer risk has not been found, because previous studies have focused on only a limited number of fruit and vegetables selected on the basis of their botanical family or their content of one specific micronutrient or bioactive compound. However, the beneficial effect of vegetables and fruit may also depend on the combined effects of these different components in the natural food matrix(18). Thus, a further analysis of vegetable and fruit colour groups classified by the colour of their edible portion is needed.
To the best of our knowledge, no study has clearly investigated the consumption of various vegetable and...