A study led by scientists from the International Agency for Research on Cancer (IARC) found that regular consumption of fish, at recommended levels, was associated with a lower risk of colorectal cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort.
The researchers examined the association between risk of colorectal cancer and fish consumption, dietary and circulating levels of omega-3 long-chain polyunsaturated fatty acids, and the ratio of omega-6 to omega-3 long-chain polyunsaturated fatty acids.
They postulate that the reduction in risk is due to exposure to omega-3 long-chain polyunsaturated fatty acids.
Background & Aims: There is an unclear association between intake of fish and long-chain n-3 polyunsaturated fatty acids (n-3 LC-PUFAs) and colorectal cancer (CRC). We examined the association between fish consumption, dietary and circulating levels of n-3 LC-PUFAs, and ratio of n-6:n-3 LC-PUFA with CRC using data from the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort.
Methods: Dietary intake of fish (total, fatty/oily, lean/white) and n-3 LC-PUFA were estimated by food frequency questionnaires given to 521,324 participants in the EPIC study; among these, 6291 individuals developed CRC (median follow up, 14.9 years). Levels of phospholipid LC-PUFA were measured by gas chromatography in plasma samples from a sub-group of 461 CRC cases and 461 matched individuals without CRC (controls). Multivariable Cox proportional hazards and conditional logistic regression models were used to calculate hazard ratios (HRs) and odds ratios (ORs), respectively, with 95% CIs.
Results: Total intake of fish (HR for quintile 5 vs 1, 0.88; 95% CI, 0.80–0.96; Ptrend = .005), fatty fish (HR for quintile 5 vs 1, 0.90; 95% CI, 0.82–0.98; Ptrend = .009), and lean fish (HR for quintile 5 vs 1, 0.91; 95% CI, 0.83–1.00; Ptrend = .016) were inversely associated with CRC incidence. Intake of total n-3 LC-PUFA (HR for quintile 5 vs 1, 0.86; 95% CI, 0.78–0.95; Ptrend = .010) was also associated with reduced risk of CRC, whereas dietary ratio of n-6:n-3 LC-PUFA was associated with increased risk of CRC (HR for quintile 5 vs 1, 1.31; 95% CI, 1.18–1.45; Ptrend < .001). Plasma levels of phospholipid n-3 LC-PUFA was not associated with overall CRC risk, but an inverse trend was observed for proximal compared with distal colon cancer (Pheterogeneity = .026).
Conclusions: In an analysis of dietary patterns of participants in the EPIC study, we found regular consumption of fish, at recommended levels, to be associated with a lower risk of CRC, possibly through exposure to n-3 LC-PUFA. Levels of n-3 LC-PUFA in plasma were not associated with CRC risk, but there may be differences in risk at different regions of the colon.
Elom K Aglago, Inge Huybrechts, Neil Murphy, Corinne Casagrande, Genevieve Nicolas, Tobias Pischon, Veronika Fedirko, Gianluca Severi, Marie-Christine Boutron-Ruault, Agnès Fournier, Verena Katzke, Tilman Kühn, Anja Olsen, Anne Tjønneland, Christina C Dahm, Kim Overvad, Cristina Lasheras, Antonio Agudo, Maria-Jose Sánchez, Pilar Amiano, José Maria Huerta, Eva Ardanaz, Aurora Perez-Cornago, Antonia Trichopoulou, Anna Karakatsani, Georgia Martimianaki, Domenico Palli, Valeria Pala, Rosario Tumino, Alessio Naccarati, Salvatore Panico, Bas Bueno-de-Mesquita, Anne May, Jeroen WG Derksen, Sophie Hellstrand, Bodil Ohlsson, Maria Wennberg, Bethany Van Guelpen, Guri Skeie, Magritt Brustad, Elisabete Weiderpass, Amanda J Cross, Heather Ward, Elio Riboli, Teresa Norat, Veronique Chajes, Marc J Gunter
Dr Anna Diaz Font, head of research funding at the World Cancer Research Fund, which funded the research, said in a report in The Daily Telegraph: “This large study adds to the scientific evidence suggesting that consuming fish could reduce the risk of bowel cancer.
“The biological reasons by which fish consumption potentially lowers risk are not fully understood but one of the theories include specific fatty acids such as omega-3, found almost exclusively in fish, being responsible for this protective effect via their anti-inflammatory properties.”
The research follows a study last year which suggested that oily fish could also reduce delay the onset of the menopause by three years.