From an imbalance to a new imbalance: Italian-style gluten-free diet alters the salivary microbiota and metabolome of African celiac children

Fourteen Saharawi celiac children following an African-style gluten-free diet for at least two years were subjected to a change of diet to an Italian-style gluten-free diet for 60 days. Significant differences were identified in the salivary microbiota and metabolome when Saharawi celiac children switched from African- to Italian-style dietary habits. An Italian-style gluten-free diet caused increases in the abundance of Granulicatella, Porphyromonas and Neisseria and decreases in Clostridium, Prevotella and Veillonella, altering the 'salivary type'of the individuals. Furthermore, operational taxonomic unit co-occurrence/exclusion patterns indicated that the initial equilibrium of co-occurring microbial species was perturbed by a change in diet: the microbial diversity was reduced, with a few species out-competing the previously established microbiota and becoming dominant. Analysis of predicted metagenomes revealed a remarkable change in the metabolic potential of the microbiota following the diet change, with increased potential for amino acid, vitamin and co-factor metabolism. High concentrations of acetone and 2-butanone during treatment with the Italian-style gluten-free diet suggested metabolic dysfunction in the Saharawi celiac children. The findings of this study support the need for a translational medicine pipeline to examine interactions between food and microbiota when evaluating human development, nutritional needs and the impact and consequences of westernisation.