Nutritional and Physiological Properties of Thymbra spicata: In Vitro Study Using Fecal Fermentation and Intestinal Integrity Models.

(Poly)phenolic-rich Mediterranean plants such as Thymbra spicata have been associated with several health-promoting effects. The nutritional value, as well as physiological interaction of T. spicata with the gastrointestinal tract, has not been investigated before. The nutritional composition of T. spicata leaves was here characterized by standard analytical methods. T. spicata leaves were subjected to ethanolic extraction, simulated gastrointestinal digestion, and anaerobic microbial gut fermentation. Phenols/flavonoid contents and radical scavenging activity were assessed by colorimetric methods. The volatile organic compounds (VOCs) were detected by gas chromatography coupled with mass spectrometry. The effect on intestinal integrity was evaluated using a Caco-2 monolayers mounted in a Ussing chamber. T. spicata contains a high amount of fiber (12.3%) and unsaturated fatty acids (76% of total fat). A positive change in VOCs including short-chain fatty acids was observed without significant change in viable microbe. T. spicata and carvacrol (main phenolic compound) enhanced ionic currents in a concentration-dependent manner without compromising the Caco-2 monolayer's integrity. These effects were partially lost upon simulated digestion and completely abolished after colonic fermentation in line with polyphenols and carvacrol content. Conclusion: T. spicata represents a promising nutrient for the modulation of gut microbiota and the gut barrier. Further studies must better define its mechanisms of action.

Metataxonomics and Metabolomics Profiles in Metabolic Dysfunction-Associated Fatty Liver Disease Patients on a "Navelina" Orange-Enriched Diet.

BACKGROUND/OBJECTIVES: Metabolic dysfunction-associated fatty liver disease (MAFLD) is currently the most common cause of chronic liver disease. Systemic inflammatory status and peripheral metabolic symptoms in the clinical picture have an impact on gut commensal bacteria. METHODS: Our designed clinical trial was based on a cohort of patients with MAFLD whose diet included the daily consumption of 400 g of "Navelina" oranges for 28 days, compared with a control group of patients with the same pathologic conditions whose diet did not include the consumption of oranges and other foods containing similar nutrients/micronutrients. We used 16S metataxonomics and GC/MS analyses to identify taxa and urine/fecal VOCs, respectively. RESULTS: A set of micronutrients from the diet were inspected, and some specific fatty acids were identified as the main contributors in terms of cluster sample separation. Metataxonomics and metabolomics profiles were obtained, and a stringent statistical approach allowed for the identification of significant taxa/VOCs, which emerged from pairwise group comparisons in both fecal and urine samples. CONCLUSIONS: In conclusion, a set of taxa/VOCs can be directly referred to as a marker of dysbiosis status and other comorbidities that, together, make up the pathologic burden associated with MAFLD. The investigated variables can be a target of therapeutic strategies.

In vivo evaluation of an innovative synbiotics on stage IIIb-IV chronic kidney disease patients.

Background: Microbiota unbalance has been proven to affect chronic kidney disease (CKD) patients and, noteworthy, microbiota composition and activity are implicated in CKD worsening. The progression of kidney failure implies an exceeding accumulation of waste compounds deriving from the nitrogenous metabolism in the intestinal milieu. Therefore, in the presence of an altered intestinal permeability, gut-derived uremic toxins, i.e., indoxyl sulfate (IS) and p-cresyl sulfate (PCS), can accumulate in the blood. Methods: In a scenario facing the nutritional management as adjuvant therapy, the present study assessed the effectiveness of an innovative synbiotics for its ability to modulate the patient gut microbiota and metabolome by setting a randomized, single-blind, placebo-controlled, pilot trial accounting for IIIb-IV stage CKD patients and healthy controls. Metataxonomic fecal microbiota and fecal volatilome were analyzed at the run-in, after 2 months of treatment, and after 1 month of wash out. Results: Significant changes in microbiota profile, as well as an increase of the saccharolytic metabolism, in feces were found for those CKD patients that were allocated in the synbiotics arm. Conclusions: Noteworthy, the here analyzed data emphasized a selective efficacy of the present synbiotics on a stage IIIb-IV CKD patients. Nonetheless, a further validation of this trial accounting for an increased patient number should be considered. Clinical trial registration: https://clinicaltrials.gov/, identifier NCT03815786.

How Metabolomics Provides Novel Insights on Celiac Disease and Gluten-Free Diet: A Narrative Review.

Celiac disease (CD) is an inflammatory autoimmune disorder triggered by the ingestion of gluten from wheat and other cereals. Nowadays, its positive diagnosis is based on invasive approaches such as the histological examination of intestinal biopsies and positive serology screening of antibodies. After proven diagnosis, the only admissible treatment for CD individuals is strict life-long adherence to gluten-free diet (GFD), although it is not a conclusive therapy. Acting by different mechanisms and with different etiologies, both CD and GFD have a great impact on gut microbiota that result in a different taxa composition. Altered production of specific metabolites reflects these microbiota changes. In this light, the currently available literature reports some suggestions about the possible use of specific metabolites, detected by meta-omics analyses, as potential biomarkers for a CD non-invasive diagnosis. To highlight insights about metabolomics application in CD study, we conducted a narrative dissertation of selected original articles published in the last decade. By applying a systematic search, it clearly emerged how the metabolomic signature appears to be contradictory, as well as poorly investigated.