Purpose: To investigate the effect of vitamin C supplementation with or without flavonoids on periodontal conditions, and microbial and systemic variables before and after non-surgical periodontal treatment (NSPT). Materials and Methods: A case series derived from a randomized controlled trial was conducted to explore the effects of daily vitamin C supplementation, with or without flavonoids, on periodontal conditions. The study population was recruited from patients with periodontitis who had been referred to the Department of Periodontology at the Academic Centre for Dentistry Amsterdam (ACTA). The study consisted of a 2-month observation of untreated periodontitis followed by a 3-month period after NSPT. Descriptive statistics, correlation and clustering analyses, and dimensionality reduction methods were used to evaluate the interventions’ impact. Results: Due to COVID-19, the study was prematurely terminated and reported findings from 13 patients. Results indicate a correlation between higher plasma vitamin C levels and reduced gingival inflammation, suggesting benefits for untreated periodontal conditions. Clustering analysis showed no differences based on supplementation type, indicating it did not affect outcomes, and microbiological data had limited effects. Principal Component Analysis visualized clusters and illustrated no distinct groups corresponding to supplementation types. Violin plots highlighted variability, with one cluster comprising individuals with more severe periodontal conditions. Conclusions: Higher plasma vitamin C levels were associated with lower gingival inflammation. However, daily vitamin C supplementation, with or without flavonoids, did not show additional benefits on periodontal conditions before or after treatment. Clustering suggests that periodontal severity, rather than supplementation, influenced patient profiles. The study’s small sample size limits the generalizability of the findings.

Background: The aim of this study is to investigate the relationship between reported vitamin C intake and gingival bleeding severity. Methods: In this cross‐sectional study, 336 participants were screened, and 262 (118 females, 144 males) were eligible. Vitamin C intake was derived from the Food Frequency Questionnaire (FFQ). The body mass index (BMI), plaque index (PI), bleeding on marginal probing (BOMP), and bleeding on pocket probing (BOPP) were scored. Means and standard deviations (SD) were calculated overall and by sex. Spearman's correlations assessed links between vitamin C intake and clinical variables. Sex differences were analyzed using Fisher's exact test and the Mann‐Whitney U test. Generalized regression models evaluated relationships between BOMP/BOPP and vitamin C intake, sex, age, and PI. Results: The participants had a mean age of 22.6 years, mean BMI of 22.9 kg/m ² , and mean PI of 0.98. Average daily vitamin C intake was 108 mg (SD = 53), ranging from 19 to 425 mg. Mean BOMP and BOPP scores were 0.38 and 0.52, respectively. Regression models revealed no significant associations between vitamin C intake and BOMP or BOPP. However, PI was positively associated with both bleeding indices, while age was negatively associated. Conclusion: In this non‑deficient young adult population, vitamin C intake was not significantly associated with gingival bleeding after adjusting for covariates. Gingival bleeding was positively associated with PI and negatively with age.