Dietary interventions and host-microbiome interaction

The term microbiome refers to the whole community of living microorganisms in a sample along with their potential activities that might influence the metabolic capabilities and functioning of such micro-environment. In particular, the human gut microbiome includes symbiotic bacteria, viruses, fungi and archaea located in the last part of our gastrointestinal tract. Each individual has a unique gut microbial composition as a peculiar fingerprint and it has been agreed that the development of several types of diseases in humans might be linked to gut microbiome perturbation in its microbial equilibrium, such condition known as dysbiosis. To this regard, in the last decades a worrisome increase in food allergy prevalence linked to a defect in immune tolerance mechanisms has been observed. The onset of such multifactorial disease is in turn associated to a gut microbiota alteration and mediated by both genetic and environmental risk factors, especially in pediatric age. Moreover, it's known that the immune system may control microbial composition and diversity. It should be considered that most of the knowledge on the associations between gut microbiota and immunity system derives from animal model studies. For this reason, the understanding of the relationship between food allergies and intestinal dysbiosis could be translated into advances regarding i) knowledge in prevention of onset of such diseases and ii) clinical practice with diet-directed therapeutic interventions using pro- or prebiotics, aimed at modulating the compromised immune system indirectly through gut microbiota activities. Indeed, the role of diet in influencing the gut microbiota composition and functions is widely recognized and the existence of the axis diet-microbiota-health is nowadays well established. The food-human interplay is of interest because the most recent trends are oriented towards a profitable use of diet to provide benefits to human health. In this respect, the Mediterranean diet received great attention as an appropriate strategy for the prevention and improvement of human health status. In fact, it has been demonstrated such dietary pattern being beneficial for the treatment of obesity, type II diabetes, inflammatory diseases, colorectal cancer and cardiovascular diseases. The significant and tangible evidence of the link between the Mediterranean diet and gut microbiota opens encouraging paths towards the establishments of diet-based health care and disease prevention. Despite such evidences, many challenges still exist since most of the studies assessed the impact of diet over human microbiome through correlation as well as association researches. Further efforts are necessary to understand the complicate host-microbiome interaction and to contribute to shed light on novel and different dietary strategies in order to beneficially impact human microbiome as well as human health. The overall aim of this thesis is to contribute to the evidences regarding the effects of dietary interventions in modulating the human microbiome which might in turn significantly impact human health, as to support the improvement of knowledge in such context