The study subjects were derived from the Fukuoka
colorectal cancer study, a community-based case-control study. The study subjects were 816 cases of
colorectal cancer and 815 community-based controls. The consumption of 148 food items was assessed by a computer-assisted interview. We used the consumption of 97 food items to estimate dietary intakes of total,
tea and
coffee polyphenols. The
Phenol-Explorer database was used for 92 food items. Of the 5 foods which were not listed in the
Phenol-Explorer Database,
polyphenol contents of 3 foods (sweet potatoes, satoimo and daikon) were based on a Japanese study and 2 foods (soybeans and fried potatoes) were estimated by ORAC-based
polyphenol contents in the United States Department of Agriculture Database. Odds ratios (OR) and 95%CI of
colorectal cancer risk according to quintile categories of intake were obtained by using logistic regression models with adjustment for age, sex, residential area, parental history of
colorectal cancer, smoking, alcohol consumption, body mass index 10 years before, type of job, leisure-time physical activity and dietary intakes of
calcium and n-3
polyunsaturated fatty acids.
RESULTS: There was no measurable difference in total or
tea polyphenol intake between cases and controls, but intake of
coffee polyphenols was lower in cases than in controls. The multivariate-adjusted OR of
colorectal cancer according to quintile categories of
coffee polyphenols (from the first to top quintile) were 1.00 (referent), 0.81 (95%CI: 0.60-1.10), 0.65 (95%CI: 0.47-0.89), 0.65 (95%CI: 0.46-0.89) and 0.82 (95%CI: 0.60-1.10), respectively (P trend = 0.07). Similar, but less pronounced, decreases in the OR were also noted for the third and fourth quintiles of total
polyphenol intake.
Tea polyphenols and non-
coffee polyphenols showed no association with
colorectal cancer risk. The site-specific analysis, based on 463
colon cancer cases and 340
rectal cancer cases, showed an inverse association between
coffee polyphenols and
colon cancer. The multivariate-adjusted OR of
colon cancer for the first to top quintiles of
coffee polyphenols were 1.00 (referent), 0.92 (95%CI: 0.64-1.31), 0.75 (95%CI: 0.52-1.08), 0.69 (95%CI: 0.47-1.01), and 0.68 (95%CI: 0.46-1.00), respectively (P trend = 0.02). Distal
colon cancer showed a more evident inverse association with
coffee polyphenols than proximal
colon cancer. The association between
coffee polyphenols and
rectal cancer risk was U-shaped, with significant decreases in the OR at the second to fourth quintile categories. There was also a tendency that the OR of colon and
rectal cancer decreased in the intermediate categories of total
polyphenols. The decrease in the OR in the intermediate categories of total
polyphenols was most pronounced for distal
colon cancer. Intake of
tea polyphenols was not associated with either colon or
rectal cancer. The associations of
coffee consumption with colorectal, colon and
rectal cancers were almost the same as observed for
coffee polyphenols. The trend of the association between
coffee consumption and
colorectal cancer was statistically significant.
CONCLUSION: