Polyphenol Intake, Determined By Dietary Questionnaire And Plasma Biomarkers, And Risk Of Colorectal Cancer In The European Prospective Investigation Into Cancer And Nutrition (EPIC) Cohort Study

Raul ZAMORA-ROS, International Agency for Research on Cancer (IARC), France

1 Nutrition and Metabolism Section, International Agency for Research on Cancer (IARC), Lyon, France.
2 Biomarkers and Nutrimetabolomics Laboratory, Nutrition and Food Science Department, Catalonian Reference Network on Food Technology (XaRTA), Institute for Research on Nutrition and Food Safety (INSA-UB), Campus Torribera, Pharmacy and Food Sciences Faculty, University of Barcelona, Barcelona, Spain.

Purpose. Epidemiological evidence on the association between polyphenol intake and colorectal cancer (CRC) risk is still inconsistent. Case-control studies suggest inverse associations, but these have not been confirmed in cohort studies so far. We aimed to investigate the association between polyphenol intake and CRC risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.
Methods. The study included 477,386 subjects aged 35-70 years from 10 European countries. Dietary questionnaires and plasma samples were collected at enrollment. Dietary polyphenol intakes were estimated using dietary questionnaires and the Phenol-Explorer database, including data on 502 individual polyphenols. Thirty-four polyphenols, representative of the main polyphenol classes, are being measured in plasma by tandem mass spectrometry currently.
Results. After a mean follow-up of 11 years, 4,701 validated incident CRC cases (2,979 colon and 1,722 rectal cancers) were identified and included in the analysis. A wide range of total polyphenol intake and a South-to-North geographical gradient (ranging from 584mg/d in Greek women to 1,786mg/d in Danish men) were observed. Phenolic acids (52.6%) and flavonoids (42.4%) were the main contributors to polyphenol intake. Coffee, tea and fruits were the major food sources of polyphenols. Using Cox regression, multivariable adjusted models showed a significantly inverse association between both stilbene (HRlog2 0.98, 95%CI:0.97-0.99) and tyrosol intakes (HRlog2 0.98, 95%CI:0.97-0.99) and CRC risk. Phenolic acid intake was associated with increased rectum tumor risk in women (HRlog2 1.11, 95%CI:1.02-1.21), but inversely associated with colon tumor risk in men (HRlog2 0.90, 95%CI:0.83-0.97). Multivariable logistic regressions will be conducted to investigate the relationships between plasma polyphenol concentrations and CRC risk in a nested case-control subset (700 cases and 700 controls).
Conclusions. This is the first study evaluating the association between the intake of all polyphenols, using questionnaires and biomarkers, and CRC risk.
Funding source. INCa grant 2011-105 and WCRF NL 2012/604