Phytoestrogens and Colonic Adenomatous Polyps


INTRODUCTION: The data obtained by experimental studies about the influence of phytoestrogens on colorectal cancer (CRC) have been very promising. On the other hand, clinical trials have produced conflicting results. The literature suggests that some subclasses of phytoestrogens may have protective effects against CRC and colon adenomas, but most of these results come from population studies based on the dietary intake of phytoestrogens. On these premises, it is possible to hypothesize that the variability of the data reported in the literature may be due to the fact that the real absorption of phytoestrogens (by assessing their concentration in the serum or urine) and/or the ability of the single individual of producing equol was not evaluated. PURPOSE: In the present study, the association between the phytoestrogens intake and the prevalence of colon adenomas was evaluated not only on the basis of the simply dietary intake but also on the measurement their intestinal absorption. Moreover, a specific evaluation of equol production by the intestinal flora was performed. Finally, intestinal bacteria involved in equol production were evaluated.

Full Title of Study: “Bioavailability of Phytoestrogens and Prevalence of Adenomatous Polyps in Human Colon”

Study Type

  • Study Type: Observational [Patient Registry]
  • Study Design
    • Time Perspective: Cross-Sectional
  • Study Primary Completion Date: June 15, 2017

Detailed Description

MATERIALS AND METHODS: Patients with sporadic colon adenomas were enrolled in group I (case) and patients without sporadic colorectal adenomas matched for sex, age and BMI were enrolled in group II (control). All participants underwent the following evaluations: BMI, dietary history (for quantitative and qualitative analysis of dietary habits), quantitative analysis of phytoestrogens (by dietary questionnaires), medications (chronic assumption of aspirin at low doses), characteristics of the polyps (for a calculation the cancer risk), analysis of urinary excretion of phytoestrogens [by high pressure liquid chromatography (HPLC)] and intestinal flora [by mass spectrometry with Matrix Assisted Laser Desorption Ionization Time-of-Flight (MALDI-TOF) technology]. At the enrolment, patients will be invited to assume a standard quantitative of phytoestrogens at 8:00 and collect both a fecal sample and the urine of the following 24 hrs.

Arms, Groups and Cohorts

  • Patients with polyps
    • urinary phytoestrogen excretion and intestinal microbiota evaluation
  • Patients without polyps
    • urinary phytoestrogen excretion and intestinal microbiota evaluation

Clinical Trial Outcome Measures

Primary Measures

  • Phytoestrogen absorption
    • Time Frame: one day
    • It will be evaluated on the basis of their 24h urine excretion

Secondary Measures

  • Intestinal microbiota
    • Time Frame: one day
    • It will be evaluated on fecal samples

Participating in This Clinical Trial

Inclusion Criteria

  • subjects of both sexes aged between 50 and 75 years – colonoscopy within 3 months from the study evaluation Exclusion Criteria:

  • age < 50 and > 75 years – previous diagnosis of colon cancer or inflammatory bowel diseases (IBD) – Hereditary intestinal tumors (FAP, HNPCC, …) – ongoing infections – intake, in the last 4 weeks, of drugs that alter the intestinal bacterial flora – creatinine clearance below 60 ml/min – liver failure

Gender Eligibility: All

Minimum Age: 50 Years

Maximum Age: 75 Years

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • University of Bari
  • Provider of Information About this Clinical Study
    • Principal Investigator: Michele Barone, Researcher – University of Bari
  • Overall Official(s)
    • Alfredo Di Leo, Study Chair, University of Bari


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Atkinson C, Frankenfeld CL, Lampe JW. Gut bacterial metabolism of the soy isoflavone daidzein: exploring the relevance to human health. Exp Biol Med (Maywood). 2005 Mar;230(3):155-70. Review.

Jin H, Leng Q, Li C. Dietary flavonoid for preventing colorectal neoplasms. Cochrane Database Syst Rev. 2012 Aug 15;(8):CD009350. doi: 10.1002/14651858.CD009350.pub2. Review.

Kocic B, Kitic D, Brankovic S. Dietary flavonoid intake and colorectal cancer risk: evidence from human population studies. J BUON. 2013 Jan-Mar;18(1):34-43. Review.

Setchell KD, Brown NM, Lydeking-Olsen E. The clinical importance of the metabolite equol-a clue to the effectiveness of soy and its isoflavones. J Nutr. 2002 Dec;132(12):3577-84. Review.

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