What is the link between the dietary inflammatory index and the gut microbiome? A systematic review.

Purpose: One highlighted pathogenesis mechanism of diseases is the negative impact of pro-inflammatory diets (PD) on the gut microbiome. This systematic review aimed to study the link between dietary inflammatory index (DII), as an indicator of PD, and gut microbiome.

Methods: A systematic search was done in PubMed and Scopus, adhering to the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analysis. The assessment of the included studies' quality was performed using the critical appraisal checklist from the Joanna Briggs Institute.

Results: Ten articles were included eight cross-sectional, one case-control, and, one cohort study. Seven and three included articles reported a weak and moderate relationship between gut microbiome and DII scores, respectively. DII scores were linked to variety in microbiome composition and diversity/richness. More importantly, anti-inflammatory diets as measured by lower DII scores were linked to a more desirable gut microbiome profile. Prevotella stercorea, Veillonella rogosae, Morganella morganii, Ruminococcus torques, Eubacterium nodatum, Alistipes intestine, Clostridium leptum, Morganellaceae family, Enterobacteriaceae family, and, Bacteroides thetaiotaomicron were related to higher DII scores. While, Butyrate-producing bacteria such as Ruminococcaceae and Lachnospiraceae families, Faecalibacterium prausnitzii, and Akkermansia muciniphila were related to lower DII scores.

Conclusion: An anti-inflammatory diet, as measured by a lower DII score, might be linked to variations in the composition and variety of the microbiome. Therefore, the DII score could be useful in microbiota research, however, this possibility needs to be investigated more precisely in future studies.