title: Dietary intake of PUFAs and colorectal polyp risk.
abstract: BACKGROUND
  Marine-derived n-3 (omega-3) PUFAs may reduce risk of developing colorectal cancer; however, few studies have investigated the association of n-3 PUFA intakes on colorectal polyp risk.
  
  
  OBJECTIVE
  The objective of this study was to examine the associations of dietary PUFA intake on risk of colorectal adenomatous and hyperplastic polyps.
  
  
  METHODS
  This was a colonoscopy-based case-control study that included 3166 polyp-free control subjects, 1597 adenomatous polyp cases, and 544 hyperplastic polyp cases. Dietary PUFA intake was calculated from food-frequency questionnaires and tested for association by using unconditional logistic regression. The urinary prostaglandin E(2) metabolite, which is a biomarker of prostaglandin E(2) production, was measured in 896 participants by using liquid chromatography and tandem mass spectrometry.
  
  
  RESULTS
  n-6 PUFAs were not associated with adenomatous or hyperplastic polyps in either men or women. Marine-derived n-3 PUFAs were associated with reduced risk of colorectal adenomas in women only, with an adjusted OR of 0.67 (95% CI: 0.47, 0.97) for the highest quintile of intake compared with the lowest quintile of intake (P-trend = 0.01). Dietary intake of α-linolenic acid was associated with an increased risk of hyperplastic polyps in men (P-trend = 0.03), which was not seen in women. In women, but not in men, dietary intake of marine-derived n-3 PUFAs was negatively correlated with urinary prostaglandin E(2) production (r = -0.18; P = 0.002).
  
  
  CONCLUSIONS
  Higher intakes of marine-derived n-3 PUFAs are associated with lower risk of adenomatous polyps in women, and the association may be mediated in part through a reduction in the production of prostaglandin E(2). This trial was registered at clinicaltrials.gov as NCT00625066.
authors.affiliation: Division of General Internal Medicine, Vanderbilt University School of Medicine, Nashville, TN 37203, USA. harvey.j.murff@vanderbilt.edu
authors.forename: Harvey J
authors.initials: HJ
authors.lastname: Murff
authors.forename: Martha J
authors.initials: MJ
authors.lastname: Shrubsole
authors.forename: Qiuyin
authors.initials: Q
authors.lastname: Cai
authors.forename: Walter E
authors.initials: WE
authors.lastname: Smalley
authors.forename: Qi
authors.initials: Q
authors.lastname: Dai
authors.forename: Ginger L
authors.initials: GL
authors.lastname: Milne
authors.forename: Reid M
authors.initials: RM
authors.lastname: Ness
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
mesh_terms: D018256:Adenomatous Polyps / Q000517:prevention & control; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000652:urine; D016022:Case-Control Studies; D003111:Colonic Polyps / Q000453:epidemiology*; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000517:prevention & control; D019587:Dietary Supplements; D015232:Dinoprostone / Q000652:urine; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D011795:Surveys and Questionnaires
chemical_list: D015415:Biomarkers; D015525:Fatty Acids, Omega-3; D015232:Dinoprostone