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Review
. 2016 Mar 4;8(3):136.
doi: 10.3390/nu8030136.

Effect of Flaxseed Intervention on Inflammatory Marker C-Reactive Protein: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

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Free PMC article
Review

Effect of Flaxseed Intervention on Inflammatory Marker C-Reactive Protein: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Guan-Yu Ren et al. Nutrients. .
Free PMC article

Abstract

Functional food-flaxseed and its derivatives (flaxseed oil or lignans) are beneficial for human health, possibly because of their anti-inflammatory effects. C-reactive protein (CRP), a sensitive marker of inflammation was chosen to evaluate the anti-inflammatory effects of flaxseed. We searched randomized controlled trials from PubMed and the Cochrane Library in October 2015 and conducted a meta-analysis to evaluate the effectiveness of flaxseed and its derivatives on CRP. The mean differences (net change) in CRP (mg/L) concentrations were pooled with a random- or a fixed-effects model depending on the results of heterogeneity tests. Overall, flaxseed interventions had no effects on reduction of CRP (p = 0.428). The null effects were consistent in the subgroup analysis with multiple studies and population characteristics. Significant heterogeneity was observed in most of the analyses. Meta-regression identified baseline body mass index (BMI) as a significant source of heterogeneity (P-interaction = 0.032), with a significant reduction in CRP of 0.83 mg/L (95% confidence interval -1.34 to -0.31; p = 0.002) among subjects with a BMI of ≥30 kg/m². In conclusion, our meta-analysis did not find sufficient evidence that flaxseed and its derivatives have a beneficial effect on reducing circulating CRP. However, they may significantly reduce CRP in obese populations.

Keywords: C-reactive protein; flaxseed; meta-analysis; randomized controlled trials.

Figures

Figure 1
Figure 1
Flow chart of study selection.
Figure 2
Figure 2
Meta-analysis of flaxseed intervention on net changes (95% CI) of CRP. CI: confidence interval. WMD: weighted mean difference; The horizontal lines denote the 95% CIs: some of which extend beyond the limits of the scales. The square represents the point estimate of each study. The diamond represents the overall pooled estimate of the treatment effect.
Figure 3
Figure 3
Funnel plots for testing publication bias.

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