We have previously demonstrated that subgingival levels of nitrate-reducing bacteria, as well as the in vitro salivary nitrate reduction capacity (NRC), were diminished in periodontitis patients, increasing after periodontal treatment. However, it remains unclear if an impaired NRC in periodontitis can affect systemic health. To determine this, the effect of nitrate-rich beetroot juice (BRJ) on blood pressure was determined in 15 periodontitis patients before and 70 days after periodontal treatment (i.e., professional mechanical plaque removal, oral hygiene instruction, and subgingival instrumentation), as well as in a healthy control group of 15 individuals. Additionally, subgingival and tongue samples were taken to analyse the bacterial composition with Illumina sequencing of the 16S rRNA gene. In healthy individuals, the systolic and diastolic blood pressure (SBP and DPB) decreased significantly (both P < 0.01) 90 min after BRJ intake, but not in periodontitis patients. However, after periodontal treatment, this blood pressure-lowering effect was recovered (P < 0.05 for SBP; P < 0.01 for DBP). Lower levels of salivary nitrate after identical doses of BRJ intake indicated a potentially higher NRC in healthy individuals (P < 0.05). Periodontitis-associated bacteria decreased in tongue and subgingival samples after periodontal treatment (P < 0.01). In contrast, nitrate-reducing bacteria were associated with health in both habitats, but increased only in subgingival plaque after periodontal treatment (P < 0.001). This is the first study showing that periodontitis could limit the blood-pressure lowering effects of nitrate reduction by the oral microbiota. We propose that an impaired NRC represents a potential link between periodontitis and systemic conditions, which should be confirmed in future randomized controlled trials. Future work should also aim to determine if nitrate prebiotic supplementation and/or tongue cleaning could improve the treatment of periodontitis and its associated comorbidities.

Background: Periodontitis continues to be a global public health burden that is associated with an increased risk of metabolic diseases such as type 2 diabetes mellitus, metabolic syndrome, and cardiovascular diseases. Several studies, unsystematized, have evaluated the relationship between consumption of specific foods, nutrients, or eating patterns and the disease, aiming to support personalized and holistic periodontal therapy. Objective: This scoping review aimed to evaluate which dietary intakes are linked to the pathology. Methods: The scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. A systematic search was conducted in PubMed. The inclusion criteria were original studies with adult populations that evaluated diet and nutrient intake in populations with periodontitis. Results: Thirty-six articles were included (26 cross-sectional, 6 cohort studies, 3 randomized clinical trials, and 1 case–control). Specifically, adequate protein intake significantly reduced bleeding on probing, while high fiber intake was inversely associated with alveolar bone loss and tooth loss. Furthermore, higher consumption of vitamins C and D correlated with a reduced periodontitis risk. Negative associations were observed between nutrient groups (vitamin A, C, E, K, flavonoid, fiber) and plant-based food groups (green–yellow vegetables, general vegetables, fruit) and community periodontal index, tooth loss, probing depth, and clinical attachment loss. Broader diet quality also mattered: adherence to healthy anti-inflammatory dietary patterns were consistently associated with lower periodontitis risk, whereas pro-inflammatory patterns were in the opposite direction. Conclusions: This review strengthens the importance of the links between single nutrients, food groups, and eating patterns in periodontitis. Integrating personalized nutritional advice into dental settings represents a valuable host-modulating strategy to optimize periodontal therapy outcomes.