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Review
. 2015 Dec 1;7(12):9804-24.
doi: 10.3390/nu7125509.

Effect of Replacing Animal Protein With Plant Protein on Glycemic Control in Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

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Free PMC article
Review

Effect of Replacing Animal Protein With Plant Protein on Glycemic Control in Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Effie Viguiliouk et al. Nutrients. .
Free PMC article

Abstract

Previous research on the effect of replacing sources of animal protein with plant protein on glycemic control has been inconsistent. We therefore conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to assess the effect of this replacement on glycemic control in individuals with diabetes. We searched MEDLINE, EMBASE, and Cochrane databases through 26 August 2015. We included RCTs ≥ 3-weeks comparing the effect of replacing animal with plant protein on HbA1c, fasting glucose (FG), and fasting insulin (FI). Two independent reviewers extracted relevant data, assessed study quality and risk of bias. Data were pooled by the generic inverse variance method and expressed as mean differences (MD) with 95% confidence intervals (CIs). Heterogeneity was assessed (Cochran Q-statistic) and quantified (I²-statistic). Thirteen RCTs (n = 280) met the eligibility criteria. Diets emphasizing a replacement of animal with plant protein at a median level of ~35% of total protein per day significantly lowered HbA1c (MD = -0.15%; 95%-CI: -0.26, -0.05%), FG (MD = -0.53 mmol/L; 95%-CI: -0.92, -0.13 mmol/L) and FI (MD = -10.09 pmol/L; 95%-CI: -17.31, -2.86 pmol/L) compared with control arms. Overall, the results indicate that replacing sources of animal with plant protein leads to modest improvements in glycemic control in individuals with diabetes. Owing to uncertainties in our analyses there is a need for larger, longer, higher quality trials.

Trial registration: ClinicalTrials.gov registration number: NCT02037321.

Keywords: animal protein; diabetes; glycemic control; plant protein.

Figures

Figure 1
Figure 1
Flow diagram depicting the literature search and selection process.
Figure 2
Figure 2
Forest plot of randomized controlled trials investigating the effect of replacing sources of animal with plant protein in individuals with diabetes on hemoglobin A1c (HbA1c). Pooled effect estimates for each subgroup and overall effect are represented by the diamonds. Data are expressed as weighted mean differences with 95% confidence intervals (CIs), using the generic inverse-variance method with random effects models. Paired analyses were applied to all crossover trials. Inter-study heterogeneity was tested by the Cochran Q-statistic and quantified by I2 at a significance level of p < 0.10; df, degrees of freedom.
Figure 3
Figure 3
Forest plot of randomized controlled trials investigating the effect of replacing sources of animal with plant protein in individuals with diabetes on fasting glucose. Pooled effect estimates for each subgroup and overall effect are represented by the diamonds. Data are expressed as weighted mean differences with 95% confidence intervals (CIs), using the generic inverse-variance method with random effects models. Paired analyses were applied to all crossover trials. Inter-study heterogeneity was tested by the Cochran Q-statistic and quantified by I2 at a significance level of p < 0.10; df, degrees of freedom.
Figure 4
Figure 4
Forest plot of randomized controlled trials investigating the effect of replacing sources of animal with plant protein in individuals with diabetes on fasting insulin. Pooled effect estimates for each subgroup and overall effect are represented by the diamonds. Data are expressed as weighted mean differences with 95% confidence intervals (CIs), using the generic inverse-variance method with random effects models. Paired analyses were applied to all crossover trials. Inter-study heterogeneity was tested by the Cochran Q-statistic and quantified by I2 at a significance level of p < 0.10; df, degrees of freedom.
Figure 5
Figure 5
Publication bias funnel plots for HbA1c (A); fasting glucose (B); and fasting insulin (C). The solid line represents the pooled effect estimate expressed as the weighted mean difference (MD) for each analysis; the dashed lines represent pseudo-95% confidence limits; and the circles represent effect estimates for each included study. p-values displayed in the top right corner of each funnel plot are derived from quantitative assessment of publication bias by Egger and Begg tests set at a significance level of p < 0.05; SE, standard error.

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