title: Dietary n-3 polyunsaturated fatty acids and the aetiology of ulcerative colitis: a UK prospective cohort study.
abstract: OBJECTIVE
  The aetiology of ulcerative colitis (UC) is largely unknown, although it is plausible that dietary n-3 polyunsaturated fatty acids (PUFAs) may be protective. Metabolites derived from n-3 PUFAs are less proinflammatory than those from n-6 PUFAs. Earlier, no prospective cohort studies have investigated this hypothesis, using dietary information collected from food diaries. The aim of this study was to investigate the total dietary intake of n-3 PUFAs and the specific n-3 PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the risk of developing incident UC.
  
  
  METHODS
  Twenty-five thousand six hundred and thirty-nine participants, living in Norfolk UK, aged 45-74 years (median age at recruitment of 59.2 years), completed 7-day food diaries. These were interpreted using a computer programme, which converted food items into nutrients, including n-3 PUFAs. The cohort was monitored for participants who developed UC. Each case was matched with four controls and an analysis performed using conditional logistic regression.
  
  
  RESULTS
  In the cohort, 22 incident cases of UC were identified after a median follow-up time of 4.2 years (range 1.8-8.3 years). A statistically significant protective odds ratio (OR) for the trend across tertiles was found for DHA [OR = 0.43, 95% confidence interval (CI)=0.22-0.86, P = 0.02] and borderline statistically significant differences for trends for total total n-3 PUFAs (OR = 0.56, 95% CI=0.28-1.13, P = 0.10) and EPA (OR = 0.53, 95% CI=0.27-1.03, P = 0.06) after adjusting for age, sex, total energy intake, smoking, and other fatty acids.
  
  
  CONCLUSIONS
  Total dietary n-3 PUFAs, EPA, and DHA, particularly DHA were associated with protection from UC in a cohort aged over 45 years. If the association is causal, then increasing the population's intake of n-3 PUFAs from oily fish may help prevent UC.
authors.affiliation: Norfolk and Norwich University Hospital NHS Trust, Norwich, UK.
authors.forename: Sneha
authors.initials: S
authors.lastname: John
authors.forename: Robert
authors.initials: R
authors.lastname: Luben
authors.forename: Subodha Shakya
authors.initials: SS
authors.lastname: Shrestha
authors.forename: Ailsa
authors.initials: A
authors.lastname: Welch
authors.forename: Kay-Tee
authors.initials: KT
authors.lastname: Khaw
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Hart
mesh_terms: D000368:Aged; D015331:Cohort Studies; D003093:Colitis, Ulcerative / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D016208:Databases, Factual; D015930:Diet Records; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage*; D019587:Dietary Supplements; D004281:Docosahexaenoic Acids / Q000008:administration & dosage; D015118:Eicosapentaenoic Acid; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage*; D005231:Fatty Acids, Unsaturated / Q000008:administration & dosage; D005260:Female; D005395:Fish Oils / Q000008:administration & dosage*; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D004042:Dietary Fats, Unsaturated; D015525:Fatty Acids, Omega-3; D005231:Fatty Acids, Unsaturated; D005395:Fish Oils; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid