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Ruminant Trans-Fatty Acids and Risk of Breast Cancer: A Systematic Review and Meta-Analysis of Observational Studies Publisher Pubmed



Kolahdouz Mohammadi R1, 2 ; Bagheri M3 ; Kolahdouz Mohammadi M1, 4 ; Shidfar F1, 2
Authors
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Authors Affiliations
  1. 1. Studes Research Committee, Faculty of Public Health Branch, Iran University of Medical Sciences, Hemaat Highway, Tehran, 1449614535, Iran
  2. 2. Department of Nutrition, School of Public Health, Iran University of Medical Sciences, Tehran, Iran
  3. 3. Department of Community Nutrition, School of Nutritional Sciences and Dietetic, Tehran University of Medical Sciences, Tehran, Iran
  4. 4. Cellular and Molecular Biology Department, International Kish Campus, University of Tehran, Tehran, Iran

Source: Minerva Endocrinologica Published:2017


Abstract

INTRODUCTION: Ruminant trans-fatty acids, especially cis9, trans11-conjugated linoleic acid (c9, t11-CLA) and trans11-18:1 vaccenic acid (t11-18:1 VA) appear to have anticarcinogenic activity against breast cancer in animal and in vitro experiments. However, the results remain inconsistent. We therefore conducted a systematic review and metaanalysis to assess the association of c9, t11-CLA, and t11-18:1 VA (intake or serum levels) with breast cancer risk. EVIDENCE ACQUISITION: Relevant studies were identified by a search of PubMed, OVID, SCOPUS and Google scholar databases through 25 May 2015. We included case-control and cohort studies that reported relative risk (RR) estimates with 95% confidence intervals (CIs) for the association between c9, t11-CLA and t11-18:1 VA intake or their serum levels and the risk of breast cancer. This meta-analysis was conducted according to the guidelines for the meta-analysis of observational studies in epidemiology. EVIDENCE SYNTHESIS: Three studies on c9, t11-CLA and t11-18:1 VA serum levels and t11-18:1 VA intake were evaluated in the systematic review only (narrative synthesis) and four studies (2 case-control and 2 cohort studies on c9, t11-CLA intake) were included in the meta-analysis (quantitative synthesis). The pooled RR for the highest vs lowest category of c9, t11-CLA intake was 0.94 (95% CI: 0.64-1.25) with evidence of heterogeneity (with 67, 533 participants, I2=78.3%, P=0.003). Studies that could not be included in the quantitative syntheses were inconclusive. CONCLUSIONS: No association was found between c9, t11-CLA intake and breast cancer risk, but the number of studies identified was small. © 2016 Edizioni Minerva Medica.