Role of Diet in Colorectal Cancer Incidence: Umbrella Review of Meta-analyses of Prospective Observational Studies | Colorectal Cancer | JAMA Network Open | JAMA Network
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    1 Comment for this article
    Contact and systemic etiology.
    David Peters, D.O. | Private practice/ consulting
    An excellent work.
    It’s interesting regarding processed meats and red meat. We were led to believe it was nitrates in processes meats that were a problem. And probably are to some degree.
    Then alcohol shows up again as a potential carcinogen. Fiber intake and transit time makes intuitive sense, alcohol doesn’t. Alcohol isn’t in direct contact at that point, to any significant concentration. Fascinating.
    CONFLICT OF INTEREST: None Reported
    Views 21,907
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    Original Investigation
    Oncology
    February 16, 2021

    Role of Diet in Colorectal Cancer Incidence: Umbrella Review of Meta-analyses of Prospective Observational Studies

    Author Affiliations
    • 1Department of Pharmacotherapy, College of Pharmacy, University of Utah, Salt Lake City
    • 2School of Pharmacy, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia
    • 3Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City
    • 4Huntsman Cancer Institute, Cancer Control and Population Sciences Program, University of Utah, Salt Lake City
    • 5School of Medicine, Faculty of Health and Medical Sciences, Taylor’s University, Subang Jaya, Selangor, Malaysia
    • 6School of Pharmacy, Monash University Malaysia, Bandar Sunway, Subang Jaya, Selangor, Malaysia
    • 7Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
    • 8Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
    JAMA Netw Open. 2021;4(2):e2037341. doi:10.1001/jamanetworkopen.2020.37341
    Key Points

    Question  How credible is the evidence behind the association of dietary factors with colorectal cancer (CRC) risk in published meta-analyses of prospective observational studies?

    Findings  This umbrella review of 45 meta-analyses describing 109 associations found convincing evidence for an association between lower CRC risk and higher intakes of dietary fiber, dietary calcium, and yogurt and lower intakes of alcohol and red meat.

    Meaning  This study suggests that dietary factors may have a role in the development and prevention of CRC, but more research is needed on specific foods for which the evidence remains suggestive.

    Abstract

    Importance  Several meta-analyses have summarized evidence for the association between dietary factors and the incidence of colorectal cancer (CRC). However, to date, there has been little synthesis of the strength, precision, and quality of this evidence in aggregate.

    Objective  To grade the evidence from published meta-analyses of prospective observational studies that assessed the association of dietary patterns, specific foods, food groups, beverages (including alcohol), macronutrients, and micronutrients with the incidence of CRC.

    Data Sources  MEDLINE, Embase, and the Cochrane Library were searched from database inception to September 2019.

    Evidence Review  Only meta-analyses of prospective observational studies with a cohort study design were eligible. Evidence of association was graded according to established criteria as follows: convincing, highly suggestive, suggestive, weak, or not significant.

    Results  From 9954 publications, 222 full-text articles (2.2%) were evaluated for eligibility, and 45 meta-analyses (20.3%) that described 109 associations between dietary factors and CRC incidence were selected. Overall, 35 of the 109 associations (32.1%) were nominally statistically significant using random-effects meta-analysis models; 17 associations (15.6%) demonstrated large heterogeneity between studies (I2 > 50%), whereas small-study effects were found for 11 associations (10.1%). Excess significance bias was not detected for any association between diet and CRC. The primary analysis identified 5 (4.6%) convincing, 2 (1.8%) highly suggestive, 10 (9.2%) suggestive, and 18 (16.5%) weak associations between diet and CRC, while there was no evidence for 74 (67.9%) associations. There was convincing evidence of an association of intake of red meat (high vs low) and alcohol (≥4 drinks/d vs 0 or occasional drinks) with the incidence of CRC and an inverse association of higher vs lower intakes of dietary fiber, calcium, and yogurt with CRC risk. The evidence for convincing associations remained robust following sensitivity analyses.

    Conclusions and Relevance  This umbrella review found convincing evidence of an association between lower CRC risk and higher intakes of dietary fiber, dietary calcium, and yogurt and lower intakes of alcohol and red meat. More research is needed on specific foods for which evidence remains suggestive, including other dairy products, whole grains, processed meat, and specific dietary patterns.

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