title: Systemic folate status, rectal mucosal folate concentration and dietary intake in patients at differential risk of bowel cancer (The FAB2 Study).
abstract: OBJECTIVE
  Folate has been strongly implicated in the aetiology of colorectal cancer. However, the relationship between dietary folate intake, rectal mucosal folate status and colorectal cancer risk is uncertain. The study aimed to estimate nutrient intakes and measure systemic folate status and rectal mucosal folate concentration in people at differential risk of developing colorectal cancer.
  
  
  METHODS
  Two hundred and twenty-eight individuals were recruited from gastroenterology clinics and subdivided into three patient groups: untreated colorectal cancer (n = 43), adenomatous polyps (n = 90) or normal bowel (n = 95). Biopsies from macroscopically normal rectal mucosa and blood were collected and used for the measurement of rectal mucosal 5-methyltetrahydrofolate (5-MeTHF) and systemic markers of folate status, respectively. Nutrient intake was estimated using a validated food frequency questionnaire.
  
  
  RESULTS
  Dietary intake variables, plasma 5-MeTHF and red cell folate and plasma homocysteine concentrations were similar in all three subject groups and 95% CI fell within normal range for each variable. Rectal mucosal 5-MeTHF concentration was higher in the normal mucosa of adenomatous polyp patients than in normal subjects (P = 0.055). Rectal mucosal 5-MeTHF was associated significantly with plasma folate (P < 0.001, r = 0.294), red cell folate (P = 0.014, r = 0.305), plasma homocysteine (P = 0.017, r = -0.163) and dietary folate intake (P = 0.036, r = 0.152).
  
  
  CONCLUSIONS
  This study demonstrates adequate folate status of patients attending gastroenterology clinics for the investigation of bowel symptoms, with no significant difference in dietary intakes or systemic folate status indices according to diagnosis. Rectal mucosal 5-MeTHF concentrations were elevated in adenomatous polyp patients, but failed to reach significance. Further studies are required to determine the biological significance of this observation.
authors.affiliation: Human Nutrition Unit, Department of Oncology, Faculty of Medicine, Dentistry and Health Sciences, University of Sheffield, Sheffield, S10 2RX, UK, e.a.williams@sheffield.ac.uk.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Williams
authors.forename: Mark
authors.initials: M
authors.lastname: Welfare
authors.forename: Alison
authors.initials: A
authors.lastname: Spiers
authors.forename: Marilyn H
authors.initials: MH
authors.lastname: Hill
authors.forename: Wendy
authors.initials: W
authors.lastname: Bal
authors.forename: Eileen R
authors.initials: ER
authors.lastname: Gibney
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Duckworth
authors.forename: Hilary J
authors.initials: HJ
authors.lastname: Powers
authors.forename: John C
authors.initials: JC
authors.lastname: Mathers
mesh_terms: D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology; D004032:Diet; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage* / Q000097:blood*; D005980:Glutathione Reductase / Q000097:blood; D006710:Homocysteine / Q000097:blood; D006801:Humans; D007413:Intestinal Mucosa; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics / Q000378:metabolism; D008875:Middle Aged; D015596:Nutrition Assessment; D009752:Nutritional Status; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013763:Tetrahydrofolates / Q000097:blood*; D014805:Vitamin B 12 / Q000097:blood
chemical_list: D013763:Tetrahydrofolates; D006710:Homocysteine; D005492:Folic Acid; C573423:MTHFR protein, human; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D005980:Glutathione Reductase; D014805:Vitamin B 12; C005984:5-methyltetrahydrofolate