Objectives Habitual diet plays a major role in shaping the composition of the gut microbiota, and also determines the repertoire of microbial metabolites that can influence the host. The typical Western diet corresponds to that of an omnivore; however, the Mediterranean diet (MD), common in the Western Mediterranean culture, is to date a nutritionally recommended dietary pattern that includes high-level consumption of cereals, fruit, vegetables and legumes. To investigate the potential benefits of the MD in this cross-sectional survey, we assessed the gut microbiota and metabolome in a cohort of Italian individuals in relation to their habitual diets.
Design and results We retrieved daily dietary information and assessed gut microbiota and metabolome in 153 individuals habitually following omnivore, vegetarian or vegan diets. The majority of vegan and vegetarian subjects and 30% of omnivore subjects had a high adherence to the MD. We were able to stratify individuals according to both diet type and adherence to the MD on the basis of their dietary patterns and associated microbiota. We detected significant associations between consumption of vegetable-based diets and increased levels of faecal short-chain fatty acids, Prevotella and some fibre-degrading Firmicutes, whose role in human gut warrants further research. Conversely, we detected higher urinary trimethylamine oxide levels in individuals with lower adherence to the MD.
Conclusions High-level consumption of plant foodstuffs consistent with an MD is associated with beneficial microbiome-related metabolomic profiles in subjects ostensibly consuming a Western diet.
Trial registration number This study was registered at clinical trials.gov as NCT02118857.
- SHORT CHAIN FATTY ACIDS
- INTESTINAL BACTERIA
- DIETARY FIBRE
- ENTERIC BACTERIAL MICROFLORA
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Contributors DE was responsible for the development of the study and preparation of the manuscript. DE, EN, LC, PB and MG contributed to the study design and coordinated the recruitment sites. RDC, IF, CL and ST recruited subjects and collected biospecimens. FDF and ALS performed the 16S rRNA gene sequencing. NP collected and analysed the dietary information. LV, LL and DIS performed the metabolome analysis. FDF and IBJ carried out the bioinformatics and statistical analyses and generated the manuscript figures. PWOT supervised the data analysis and contributed to manuscript preparation. MG is the project coordinator. All authors revised and approved the final version of the manuscript.
Funding This study was supported by the Italian Ministry of University and Research (MIUR) programme PRIN 2010–2011 (grant number 2010WZ2NJN). Work in PWOT's laboratory was supported by Science Foundation Ireland through a Centre award to the Alimentary Pharmabiotic Centre, and by an FP7 award to the NuAge project.
Competing interests None declared.
Patient consent Obtained.
Ethics approval The study was approved by the Ethics Committee of (a) Azienda Sanitaria Locale (Bari) (protocol N.1050), (b) Azienda Ospedaliera Universitaria of Bologna (protocol N.0018396), (c) Province of Parma (protocol N.22884) and (d) University of Torino (protocol N.1/2013/C).
Provenance and peer review Not commissioned; externally peer reviewed.