Effects of intermittent fasting on periodontal inflammation and subgingival microbiota

Background: Studies on the impact of intermittent fasting on periodontal health are still scarce. Thus, this study evaluated the effects of long-term intermittent fasting on periodontal health and the subgingival microbiota. Methods: This pilot study was part of a nonrandomized controlled trial. Overweight/obese participants (n = 14) entered an intermittent fasting program, specifically the 5:2 diet, in which they restricted caloric intake to about a quarter of the normal total daily caloric expenditure for two nonconsecutive days/week. Subjects underwent a thorough clinical and laboratory examination, including an assessment of their periodontal condition, at baseline and 6 months after starting the diet. Additionally, subgingival microbiota was assessed by 16S rRNA gene sequencing. Results: After 6 months of intermittent fasting, weight, body mass index, C-reactive protein, hemoglobin A1c (HbA1c), and the cholesterol profile improved significantly (p < 0.05). Moreover, significant reductions were observed in bleeding on probing (p = 0.01) and the presence of shallow periodontal pockets after fasting (p < 0.001), while no significant change was seen in plaque index (p = 0.14). While we did not observe significant changes in alpha- or beta-diversity of the subgingival microbiota related to dietary intervention (p > 0.05), significant differences were seen in the abundances of several taxa among individuals exhibiting >= 60% reduction (good responders) in probing pocket depth of 4-5 mm compared to those with <60% reduction (bad responders). Conclusion: Intermittent fasting decreased systemic and periodontal inflammation. Although the subgingival microbiota was unaltered by this intervention, apparent taxonomic variability was observed between good and bad responders.