Fermented foods and inflammation: A systematic review and meta-analysis of randomized controlled trials

The effect of fermented foods consumption on inflammation has been investigated in several studies, but findings are inconsistent. Therefore we conducted a meta-analysis to examine the effect of fermented foods on inflammatory biomarkers including C-reactive protein (CRP), interleukin (IL)-6 and tumor necrosis factor (TNF)-α in the general adult population.

systematic review and meta-analysis.

In this systematic review and meta-analysis, randomized controlled trials in the general adult population comparing fermented foods with a control product were searched from two literature databases (PubMed and Scopus) up to June 4, 2019. Trials with mean difference (MD) of 95% confidence interval (CI) were pooled using random effect model. Heterogeneity was assessed using Cochran's Q and I² tests. Subgroup analysis was applied to define possible sources of heterogeneity.

The search strategy identified 3293 documents. Overall, 26 publications with 1461 people met the inclusion criteria. Our results indicated that intake of fermented foods could reduce serum TNF-α levels ((WMD = -8.26, 95% CI: -14.61, -1.91, p = 0.01; I² = 99.9%, p < 0.001)). However, no change was observed in serum levels of CRP ((WMD = -0.21, 95% CI: -0.47, 0.05, p = 0.11), I² = 93.8%, p < 0.001) and IL-6 ((WMD = 0.31, 95% CI:-3.79, 4.43, p = 0.88), I² = 99.3%, p < 0.001).

Our findings showed that intake of fermented foods did not improve serum CRP and IL-6. We observed a reduction in pooled effect of TNF-α following intake of fermented foods.