A Mediterranean-like diet is associated with reduced intestinal inflammation and altered microbial composition in first-degree relatives of patients with Crohn disease (CD), according to study results published in Gastroenterology.
As studies have suggested that diet contributes to risk for Crohn disease, researchers sought to investigate the effects of a Mediterranean-like diet on the gut microbiome and gut inflammatory markers in first-degree relatives of patients with Crohn disease.
The study included 2289 asymptomatic first-degree relatives of people with CD. All relatives participated in the Crohn’s and Colitis Canada (CCC) Genetic, Environmental, Microbial (GEM) project, which included collecting a stool sample and answering a validated food frequency questionnaire on dietary habits during the year leading up to stool sample collection. Analysis was conducted to identify 3 microbial compositions and 3 dietary clusters. The association between dietary clusters and the Mediterranean diet was examined via the correlation between the food frequency questionnaire clusters and adherence to the Mediterranean diet.
A strong association was observed between dietary cluster 3 (Mediterranean diet) and defined microbial composition, with a higher presence of taxa like Faecalibacterium and fiber-degrading bacteria like Ruminococcus. Compared with other clusters, dietary cluster 3 also correlated with reduced subclinical gut inflammation as defined by fecal calprotectin. Individual food items did not significantly correlate with fecal calprotectin, lending support to long-term dietary patterns, instead of individual food items as a means to reduce gut inflammation. Mediation analysis revealed that microbiota partially mediated the direct effect of dietary cluster 3 on subclinical inflammation.
Limitations to the study included potential recall bias, an inability to capture dietary changes after enrollment, and potential residual confounding.
The study authors concluded that “consumption of a Mediterranean-like diet was strongly associated with decreased subclinical intestinal inflammation. This effect was partially mediated by the gut microbiome, suggesting that future interventions aiming to reduce or prevent gut inflammation in asymptomatic [first-degree relatives] of patients with CD should consider a modification of the diet using a Mediterranean-like diet in concert with a shift of gut microbial composition.”
Turpin W, Dong M, Sasson G, et al. Mediterranean-like dietary pattern associations with gut microbiome composition and sub-clinical gastrointestinal inflammation. Gastroenterology. Published online May 25, 2022. doi:10.1053/j.gastro.2022.05.037