Impact of Prolonged Fasting on the Oral Microbiome in Patients With Metabolic Syndrome: An Exploratory Secondary Analysis.

AIM To evaluate the effect of prolonged fasting on the oral microbiome in patients with metabolic syndrome (MetS). MATERIALS AND METHODS This follow-up study evaluated changes in the oral microbiome in a sub-cohort of 42 patients with MetS during prolonged fasting. Periodontal parameters such as bleeding on probing (BOP), plaque index (PI) and gingival crevicular fluid (GCF) measured in Periotron units (PU) as well as supra- and subgingival plaque samples were taken at baseline (T1), after 5-10 days of prolonged fasting (T2) and at 4-5-month follow-up (T3). Sequencing of the V4 hypervariable region of the 16S rRNA gene was performed to analyse the microbiome composition. RESULTS Significant reductions were observed in BOP: 36.4% ± 18.2% to 30.4% ± 15.6% (p = 0.01), PI: 66.9% ± 19.5% to 58.8% ± 23.4% (p < 0.01) and GCF: 83.6 ± 27.8 PU to 67.9 ± 30.3 PU (p < 0.01) post fasting. Microbiome α- and β-diversity did not change significantly. However, significant changes in specific bacterial genera were noted: Lachnospiraceae [G-3] increased only in subgingival samples; Eikenella and Peptostreptococcaceae [XI][G-7] increased; while Mitsuokella and Atopobium decreased in both sub- and supra-gingival samples. CONCLUSION Within the constraints of this analysis, prolonged fasting was found to be associated with reduced periodontal inflammation and selected shifts in the oral microbial composition. Larger controlled trials are needed to confirm these exploratory findings and determine their clinical relevance.