Does a high-sugar diet alter the bacterial diversity of the oral cavity?

www.nature.com/ebd COMMENT Oral health Does a high-sugar diet alter the bacterial diversity of the oral cavity? Kunaal Dhingra 1✉ and Jiiang-Huei Jeng2 © The Author(s), under exclusive licence to British Dental Association 2023 A COMMENTARY ON Angarita-Díaz MDP, Fong C, Bedoya-Correa CM, Cabrera-Arango CL. Does high sugar intake really alter the oral microbiota?: A systematic review. Clin Exp Dent Res. 2022; 8: 1376-1390. PRACTICE POINTS ● 1234567890();,: ● This systematic review concluded that high sugar intake led to a significant decrease in microbial diversity of the oral microbiome and predominance of several bacteria, including Streptococcus, Scardovia, Veillonella, Rothia, Actinomyces, and Lactobacillus. Our critical appraisal found the systematic review to be of ‘critically low’ quality, which raises questions on the trustworthiness of the findings of the systematic review. DATA SOURCES: The electronic databases PubMed, Scopus, and Science Direct from 2010 onwards were searched to identify the eligible studies to determine the effect of sugar intake on oral microbiota diversity. STUDY SELECTION: Clinical trials, cohort studies, and case-control studies in English and Spanish language were selected by four reviewers independently. DATA EXTRACTION AND SYNTHESIS: Data extraction (which comprised authors and year of publication, type of study, patients, origin, selection criteria, method of determining sugar consumption, amplified region, relevant results, and bacteria identified in patients with high sugar intake) was performed by three reviewers. Quality assessment of included studies was done by two reviewers using the Newcastle-Ottawa scale. RESULTS: 374 papers were identified through three databases searched, out of which eight studies were finally selected. These included two interventional studies, two case-control studies, and four cohort studies. All except one study reported that the richness and diversity of oral microbes in the saliva, dental biofilm, and oral swab sample were significantly lower in participants with higher sugar consumption. There was a decrease in the population of certain bacteria but an enhancement of specific bacterial genera, such as Streptococcus, Scardovia, Veillonella, Rothia, Actinomyces, and Lactobacillus. Additionally, communities associated with high sugar intake showed enrichment of sucrose and starch metabolism pathways. All eight included studies had a low risk of bias. CONCLUSIONS: Within the limitations of the included studies, the authors concluded that consuming a sugar-rich diet leads to dysbiosis of the oral ecosystem, thereby increasing carbohydrate metabolism and the overall metabolic activity of oral microorganisms. Evidence-Based Dentistry (2023) 24:9–11; https://doi.org/10.1038/s41432-023-00862-y GRADE Rating: 1 COMMENTARY Objectives and key findings of the systematic review The association between the sugar-rich diet and change in the oral bacterial population is a subject of ongoing interest among dental researchers. The objective of the systematic review by Angarita-Díaz et al.1 was to evaluate the impact of sugar intake on Division of Periodontics, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi, India. 2College of Dental Medicine, Kaohsiung Medical University, & Department of Dentistry, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan. ✉email: Received: 27 December 2022 Accepted: 5 January 2023 Published online: 8 March 2023 10 microbial diversity and the type of oral microorganisms that predominate under these conditions. Eight studies (two interventional studies, two case-control studies, and four cohort studies) were included in this systematic review. Most selected studies found that the richness and diversity of oral microorganisms in saliva, dental biofilm, and oral swab samples were significantly lowered in participants on a high-sugar diet. Additionally, bacterial species such as Streptococcus, Veilonella, Rothia, Actinomyces, and Lactobacillus increased in individuals consuming a sugar-rich diet. The systematic review also found that microbiomes in individuals with low and high sugar consumption adapt to environmental changes with the enrichment of acidogenic and acid-tolerant Table 1. species, counteracting pH reduction resulting from sugar consumption or a shift to anaerobic metabolism. There is also high metabolic activity in microbes associated with the activation of pathways related to sugar metabolism. All the included studies had a low risk of bias, as evaluated by the Newcastle-Ottawa scale. Methods of critical appraisal of this systematic review The quality of the systematic review by Angarita-Díaz et al.1 was assessed using the Critical Appraisal Skills Programme (CASP) systematic review checklist2 and AMSTAR 2 (A MeaSurement Tool to Assess systematic Reviews) checklist3. The quality assessment CASP scores for the systematic review by Angarita-Díaz et al.1. Question Response Section A: Are the results of the review valid? 1. Did the review address a clearly focused question? No 2. Did the authors look for the right type of papers? Yes 3. Do you think all the important, relevant studies were included? Yes 4. Did the review’s authors do enough to assess quality of the included studies? Yes 5. If the results of the review have been combined, was it reasonable to do so? Results of the review were not combined Section B: What are the results? 6. What are the overall results of the review? Apart from one study, all other studies reported that high sugar intake significantly decreased microbial diversity of the oral microbiome and led to predominance of several bacterial genera or species, including Streptococcus, Scardovia, Veillonella, Rothia, Actinomyces, and Lactobacillus. 7. How precise are the results? No statistical analysis was performed in the review Section C: Will the results help locally? 8. Can the results be applied to the local population? Yes 9. Were all important outcomes considered? Yes 10. Are the benefits worth the harms and costs? Yes Table 2. AMSTAR 2 scores for the systematic review by Angarita-Díaz et al.1. Item Response 1. Did the research questions and inclusion criteria for the review include the components of PICO? No 2. Did the report of the review contain an explicit statement that the review methods were established prior to the conduct of the review and did the report justify any significant deviations from the protocol? No 3. Did the review authors explain their selection of the study designs for inclusion in the review? No 4. Did the review authors use a comprehensive literature search strategy? No 5. Did the review authors perform study selection in duplicate? Yes 6. Did the review authors perform data extraction in duplicate? Yes 7. Did the review authors provide a list of excluded studies and justify the exclusions? Yes 8. Did the review authors describe the (...truncated)