Dietary fiber, vegetables, and colon cancer: Critical review and meta-analyses of the epidemiologic evidence

Bruce Trock, Elaine Lanza, Peter Greenwald

Research output: Contribution to journalArticlepeer-review


Whether colon cancer risk can be modified by a diet rich in vegetables, grains, and fruit, and, if so, whether the protective factor is dietary fiber or other biologically active components correlated with a high-fiber diet are questions of active research interest. Because studies on diet are susceptible to bias from a number of sources, in this review we evaluated the adequacy of study methodology as well as study results to clarify how much protection, if any, is conferred by a high-fiber diet. The review consisted of an aggregate assessment of the strength of evidence from 37 observational epidemiologic studies as well as meta-analyses of data from 16 of the 23 case-control studies. Both types of analyses revealed that the majority of studies gave support for a protective effect associated with fiber-rich diets; an estimated combined odds ratio (OR) of 0.57 (95% confidence interval = 0.50,0.64) was obtained when the highest and lowest quantiles of intake were compared. Risk estimates based on vegetable consumption (OR = 0.48) were only slightly more convincing than those based on an estimate of fiber intake (OR = 0.58), but the data do not permit discrimination between effects due to fiber and nonfiber effects due to vegetables. [J Natl Cancer Inst 82:650-661,1990].

Original languageEnglish (US)
Pages (from-to)650-661
Number of pages12
JournalJournal of the National Cancer Institute
Issue number8
StatePublished - Apr 18 1990
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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