title: Accumulation and interactions of beta-carotene and alpha-tocopherol in patients with adenomatous polyps.
abstract: OBJECTIVE
  The aims of the present study were: (1) to determine whether short-term supplementation of beta-carotene (BC) or vitamin E (VE; alpha-tocopherol) would result in their respective accumulation in normal colonic mucosa and in adenomatous polyps; (2) to determine whether the intake of BC would interfere with the concentration of VE in these target tissues.
  
  
  METHODS
  Blood and colonic biopsy samples were taken before and after supplementation.
  
  
  METHODS
  Eighteen volunteers with colonic adenomatous polyps were enrolled into this study.
  
  
  METHODS
  The supplementation lasted for 43 days and patients were examined over the whole period. Subjects were randomised into four groups according to the four different supplementations: placebo, natural BC (25 000 IU/day), natural VE (400 IU/day), combination BC/VE.
  
  
  RESULTS
  Initially we were aiming for recruitment of 20 patients in each group, however after 2 y of study (1997-1999), we terminated the study because of slow recruitment and analysed the data. In placebo subjects after supplementation, the plasma concentrations of BC and VE remained unchanged, however only two patients were recruited in this group and therefore we did not include this group in our final analysis. In BC group, the plasma BC concentrations increased significantly (P<0.001), while VE concentrations were unchanged. In VE group, VE concentrations increased (P<0.01) and BC did not change, and in BC/VE group both BC (P<0.001) and VE levels (P<0.01) increased significantly. After supplementation, the tissue concentration of BC in normal colonic mucosa in BC group increased significantly (P<0.01) while the VE concentration did not change. In VE group, the concentration of VE in normal colonic mucosa increased slightly but did not reach statistical significance. However, VE concentration increased significantly (P<0.05) in the polyps of this group. In BC/VE group, in which patients received the combination treatment, the BC concentration of normal colonic mucosa increased (P<0.05) but, surprisingly, the VE concentration decreased significantly (P<0.01). Interestingly in the polyps, although the BC concentration increased (P<0.01), the concentration of VE was reduced moderately but did not reach statistical significance.
  
  
  CONCLUSIONS
  Supplementation of BC in doses used in this study may have significantly interfered with the VE concentration in the examined tissue and probably with its metabolic pathway.
authors.affiliation: Human Nutrition Unit, National Research Institute for Food and Nutrition, Rome, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Simone
authors.forename: G
authors.initials: G
authors.lastname: Pappalardo
authors.forename: G
authors.initials: G
authors.lastname: Maiani
authors.forename: A
authors.initials: A
authors.lastname: Guadalaxara
authors.forename: R
authors.initials: R
authors.lastname: Bugianesi
authors.forename: A M
authors.initials: AM
authors.lastname: Conte
authors.forename: E
authors.initials: E
authors.lastname: Azzini
authors.forename: S
authors.initials: S
authors.lastname: Mobarhan
mesh_terms: D018256:Adenomatous Polyps / Q000737:chemistry / Q000378:metabolism*; D000328:Adult; D000368:Aged; D000975:Antioxidants / Q000008:administration & dosage* / Q000378:metabolism / Q000493:pharmacokinetics; D001706:Biopsy; D003106:Colon / Q000737:chemistry / Q000378:metabolism*; D003110:Colonic Neoplasms / Q000737:chemistry / Q000378:metabolism*; D019587:Dietary Supplements; D004347:Drug Interactions; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000737:chemistry / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D014018:Tissue Distribution; D024502:alpha-Tocopherol / Q000008:administration & dosage* / Q000378:metabolism / Q000493:pharmacokinetics; D019207:beta Carotene / Q000008:administration & dosage* / Q000378:metabolism / Q000493:pharmacokinetics
chemical_list: D000975:Antioxidants; D019207:beta Carotene; D024502:alpha-Tocopherol