Fasting and Oral Microbiome
Aim To evaluate the effect of prolonged fasting on the oral microbiome in patients with metabolic syndrome (MetS). Material and Methods This follow-up study evaluated changes in the oral microbiome in a sub-cohort of 42 patients with MetS during a prolonged fast. Periodontal parameters such as bleeding on probing (BOP), plaque index (PI) and gingival crevicular fluid (GCF) measured in Periotron units (PU) and supra- and subgingival plaque samples were taken at baseline (T1), after a 5-10 day prolonged fast (T2) and at a 4-5-month follow-up (T3). Sequencing of the V4 hypervariable region of the 16S rRNA gene was performed to analyze 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 PU ± 27.8 to 67.9PU ± 30.3 (p<0.01) post-fasting. Microbiome alpha- and beta-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 supragingival samples.  Conclusion Within the constraints of this analysis, prolonged fasting was associated with reduced periodontal inflammation and selected shifts in oral microbial composition. Larger, controlled trials are needed to confirm these exploratory findings and determine their clinical relevance.