Dietary Diversity, Rather Than Quality, Parallels a Reduction in Metabolic Syndrome and a Favorable Gut Microbiome: The Dietary Diversity Score.

Objective: Diet plays a crucial role in the development of metabolic syndrome (MetS). While dietary recommendations primarily focus on quality of food intake, the relevance and mechanisms of dietary diversity for the prevention of obesity and metabolic diseases are unclear. Here, we investigate the respective associations of dietary diversity and quality with MetS and gut microbiota composition.

Methods: Pooled data from 2 independent population-based cohorts of the Study of Health in Pomerania (n = 6753) were used. Based on a validated food frequency questionnaire a novel dietary diversity score (DDS) and an established dietary quality score (DQS) were calculated. Both were correlated with anthropometric data and clinical components of MetS as well as with intestinal microbial composition (16S rRNA gene sequencing).

Results: DDS was associated with a healthier metabolic phenotype and lower MetS risk in both cross-sectional (odds ratio [OR], 0.90; 95% CI, 0.82-0.93; p < 0.001) and longitudinal analyses of 5-year follow-up data (OR, 0.89; 95% CI, 0.79-0.99; p = 0.029). In contrast, there were hardly any favorable associations between DQS and MetS, neither cross-sectionally nor longitudinally. DDS explained 42.6% more beta diversity variation in gut microbiota than DQS and was linked to a more favorable microbial composition (e.g., less Escherichia/Shigella [q = 0.00576] and greater Ruminococcaceae [q = 0.01263] abundance).

Conclusions: Dietary diversity, as determined by the novel DDS, reduces MetS risk, whereas dietary quality was less important in that regard. Greater dietary diversity was paralleled by greater microbiota diversity and a healthier gut microbiome. Future dietary recommendations should emphasize dietary diversity rather than absolute consumption of nutritional components.