Periodontal diseases affect up to 90% of the population worldwide. Deficiencies in vitamins, minerals and polyphenolic compounds, whose main sources are fruit and vegetables (F&V), may predispose to these diseases. The PICO (Patient, Intervention of interest, Comparison or Control Intervention, and Outcome) question was: What is the effect of F&V intake on the outcomes of periodontal diseases, observed in either experimental or observational studies of human populations suffering from periodontitis or gingivitis, compared to controls without intervention or healthy people. The review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol for search strategy, selection criteria and data extraction. The searched databases included MEDLINE (PubMed), Scopus and Google Scholar. A total of 181 potentially relevant articles were identified, which were then evaluated according to pre-specified criteria relating to relevance and quality. Finally, 15 articles were selected for review. Four articles described intervention studies, 3 reported on prospective and retrospective cohort studies, and 8 concerned cross-sectional studies. A total of 10,604 people aged 15-90 years took part in the studies. On the basis of the research it can be concluded that the consumption of at least 5 servings of F&V per day may prevent the progression of periodontal diseases, especially periodontitis, and even tooth loss. Moreover, incorporation of specific F&V into the diet or, alternatively, their lyophilized forms, and nutritional education activities seem to support the standard of care therapy of gingivitis and periodontitis. However, further observational and well-designed experimental studies, with homogeneous periodontal status outcomes, are needed to confirm these findings. Furthermore, professional dietetics care for periodontal patients should become an integral component of the healthcare program.