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Indexed/Abstracted in: EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
Impact Factor 1,118
Roya KOLAHDOUZ MOHAMMADI 1, Minoo BAGHERI 2, Mina KOLAHDOUZ MOHAMMADI 3, Farzad SHIDFAR 1
1 Department of Nutrition, School of Public Health, Iran University of Medical Sciences, Tehran, Iran; 2 Department of Community Nutrition, School of Nutritional Sciences and Dietetic, Tehran University of Medical Sciences, Tehran, Iran; 3 Cellular & Molecular Biology Department, International Kish Campus, University of Tehran, Tehran, Iran
INTRODUCTION: R-TFA (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 meta- analysis 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 metaanalysis 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.