title: The effect of a low-fat, high fiber, fruit and vegetable intervention on rectal mucosal proliferation.
abstract: BACKGROUND
  Because studies of diet and colorectal carcinoma tend to be large and complex, researchers have long been interested in the investigation of dietary exposures in relation to putative intermediate markers of large bowel malignancy, such as colorectal epithelial cell proliferation. The basic hypothesis underlying these investigations is that specific dietary components may reduce or increase the rate of cell proliferation, which, in turn, may reduce or increase neoplastic changes in the large bowel.
  
  
  METHODS
  The authors assessed the effects of a 4-year, low-fat, high-fiber, fruit and vegetable-enriched dietary intervention on colorectal epithelial cell proliferation among 399 participants from the Polyp Prevention Trial, a randomized multicenter trial with adenoma recurrence as the primary endpoint. Rectal biopsies were taken from flat, normal appearing mucosa on patients at baseline, after 1 year, and after 4 years. Two assays, bromodeoxyuridine (Brd U) and proliferating cell nuclear antigen (PCNA), were used to evaluate two summary measures of proliferation: the labeling index (LI) and the proliferative height (PH).
  
  
  RESULTS
  There were no significant differences between changes in LI and PH over the 4-year period for the intervention and control groups. This finding parallels the finding in the larger primary study, in which the dietary intervention did not alter adenoma recurrence rates.
  
  
  CONCLUSIONS
  A low-fat, high-fiber, fruit and vegetable-enriched dietary intervention did not alter rectal mucosal cell proliferation rates.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, The National Institutes of Health, Bethesda, Maryland 20892-7244, USA. pfeiffer@mail.nih.gov
authors.forename: Ruth
authors.initials: R
authors.lastname: Pfeiffer
authors.forename: Lisa
authors.initials: L
authors.lastname: McShane
authors.forename: Michael
authors.initials: M
authors.lastname: Wargovich
authors.forename: Randall
authors.initials: R
authors.lastname: Burt
authors.forename: Walter
authors.initials: W
authors.lastname: Kikendall
authors.forename: Michael
authors.initials: M
authors.lastname: Lawson
authors.forename: Elaine
authors.initials: E
authors.lastname: Lanza
authors.forename: Arthur
authors.initials: A
authors.lastname: Schatzkin
mesh_terms: D002455:Cell Division; D004041:Dietary Fats / Q000008:administration & dosage*; D004043:Dietary Fiber / Q000008:administration & dosage*; D005260:Female; D005638:Fruit; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000166:cytology*; D008297:Male; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D012007:Rectum / Q000166:cytology*; D014675:Vegetables
chemical_list: D004041:Dietary Fats; D004043:Dietary Fiber