Dietary diversity score (DDS) and odds of colorectal cancer and adenoma: a case-control study

Despite mounting evidence that dietary factors might have a protective role against risk of cancer, few studies have assessed the relationship between diet diversity with colorectal cancer (CRC) and colorectal adenoma (CRA). Thus, we examined the relationship between dietary diversity score (DDS) and the odds of CRC and CRA. Overall, 129 CRC diagnosed patients, 130 CRA diagnosed cases and 240 healthy hospitalised controls were studied. DDS was calculated based on information on the usual diet that was assessed by a valid and reliable food frequency questionnaire (FFQ). Multivariate logistic regression was used to estimate the relationship between DDS and odds of colorectal cancer and adenoma. After adjusting for potential confounders, the diversity of grains is associated with the increased odds of CRC (OR_grains: 2·96 (1·05-8·32); P = 0·032), while the diversity of vegetables and fruits are associated with decreased odds of CRC (OR_vegetables: 0·31 (0·16-0·62); P = 0·001, OR_fruits: 0·37 (0·23-0·61); P < 0·001). The diversity of vegetables, fruits and dairy are inversely associated with odds of CRA (OR_vegetables: 0·41 (0·21-0·78); P = 0·007, OR_fruits: 0·58 (0·36-0·93); P = 0·021, OR_dairies: 0·56 (0·37-0·83); P = 0·004). Also, higher DDS was related to decreased odds of both CRC (OR: 0·41 (0·23-0·72); P for trend = 0·002) and CRA (OR: 0·36 (0·21-0·65); P for trend = 0·001). Our results indicated that higher dietary diversity and particularly a diet varied in fruits and vegetables may reduce the odds of CRC and CRA. Also, the consumption of dairy products may decrease the odds of CRC, whereas the consumption of grains may increase the odds of CRC.