The effect of plant-based dietary patterns on C-reactive protein: A systematic review and meta-analysis of randomised controlled trials

AIMS: Chronic low-grade inflammation, termed "inflammageing", accelerates many age-related diseases. C-reactive protein (CRP) is a well-validated biomarker of inflammation and is an independent predictor of cardiovascular events. Plant-based dietary patterns (PBDPs) supply greater intakes of antioxidants and unsaturated fats than omnivorous diets and have been linked to lower circulating CRP concentrations in observational studies, but a causal relationship remains unclear. The main objective of this meta-analysis was to determine the effects of PBDPs on CRP concentration when compared to omnivorous dietary patterns in controlled clinical trials. DATA SYNTHESIS: MEDLINE, Embase and Web of Science were searched to identify trials investigating the effect of PBDPs on CRP concentration. Standardised mean differences in CRP and 95% confidence intervals were pooled using a random-effects model. Risk of bias, heterogeneity and sensitivity were assessed. Of the 2962 studies identified, only 7 clinical trials met the inclusion criteria, generating eight data sets (541 participants of median age 55 years). In the analysis of all 7 trials, the consumption of PBDPs was associated with significantly lower CRP (-1.13 mg/L (95% CI, -1.52 to -0.75). Subgroup analysis excluding studies with exercise prescriptions showed PBDPs were associated with significantly lower CRP (-0.94 mg/L (95% CI -1.43 to -0.46). Heterogeneity was high and the certainty of the results was low. CONCLUSIONS: Consumption of PBDPs may lower CRP concentration but further evidence gathering is required to validate this finding.