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

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.

Clinical trials, cohort studies, and case-control studies in English and Spanish language were selected by four reviewers independently.

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.

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.

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.