Effect of specifically designed prebiotic foods on human gut microbiota composition

Background: The gut microbiota is the set of microorganisms that inhabit the intestine, in symbiosis with the human body, playing a relevant role in several of its functions including energy homeostasis and inflammation regulation. However, there are many microbiota profiles due to individual variances, that define various enterotypes; and the effects of specific dietary patterns and foods are still mostly unknown. Objectives: In the context of the BIOTAGUT project, we have designed eight specific foods with potential prebiotic activity whose capacity to modulate the intestinal microbiota was evaluated in vitro and in vivo. Methods: The capacity of the eight foods (three functional drinks based on fruits and vegetables, two breads, one herbal infusion, a Bifidobacterium yogurt, and bimi) to modify gut microbiota and metabolome composition was tested in an in vitro simulator of the human gastrointestinal tract (Ainia, Valencia, Spain). After that, a total of 120 Spanish volunteers were recruited and divided into 8 groups of 15 volunteers each. Each group was assigned to a different prebiotic food that was included in their habitual diet for 3 weeks. The effects of the experimental foods on gut microbiota were studied by analyzing the hypervariable regions V3–V4 of the prokaryotic 16S rRNA gene in fecal samples collected before and after the 3-week period. Results: The intake of the all the experimental foods had an impact on the composition of the gut microbioma, and in some cases also in the diversity and richness. However, most of the individuals kept the same microbial enterotype before and after the treatment. Conclusions: The experimental foods had a mild influence on bacterial species and genus composition, diversity and richness, without the risk of causing a microbial imbalance or even a dysbiosis. The results strongly support the technical procedure (first in vitro, secondly in vivo) to design new functional foods with potential prebiotic activity. Also, this study demonstrates that the intake of specifically designed prebiotic foods constitutes a novel strategy to modulate gut microbiota composition and to revert dysbiotic states with the ultimate goal of providing a benefit for the host.