(P25-039-25) Sweet Saliva Trial: Impact of Thai Desserts With Varying Glycemic Indices on the Salivary Microbiome

Objectives: This study investigated the microbiome composition of Thai desserts with varying glycemic indices (GI) and their short-term effects on salivary microbiota, addressing the impact of dietary glycemic load on oral microbial ecosystems.

Methods: A randomized trial included 30 adults aged 18–45 years, divided into three groups based on dessert GI and serving size: low-GI (Phetchaburi’s Custard Cake, GI=53.4, 192 g), medium-GI (Saraburi’s Curry Puff, GI=61.8, 98 g), and high-GI (Lampang’s Crispy Rice Cracker, GI=149.3, 68 g). Desserts were consumed with breakfast. Microbiome profiling of desserts and saliva samples (baseline and 24 hours) was conducted using 16S rRNA sequencing to assess bacterial diversity and relative abundance at the phylum and genus levels.

Results: Desserts exhibited distinct bacterial profiles. Low-GI desserts were dominated by Bacillus (98.3±1.5%), while medium- and high-GI desserts showed greater diversity, including Streptococcus, Anoxybacillus, and Terrilactibacillus. Salivary microbiota analysis revealed increased Firmicutes abundance across all groups, with the largest shift in the high-GI group. Actinobacteriota declined significantly in the high-GI group (-2.28±4.28, p< 0.05), while Proteobacteria showed slight reductions. At the genus level, the high-GI group exhibited increased Porphyromonas (2.23±2.83) and reduced Veillonella (-1.97±2.95) and Actinomyces (-1.68±1.88). Rare genera from high-GI desserts, such as Geobacillus and Terrilactibacillus, influenced salivary microbiota, while the low-GI group showed minimal changes.

Conclusions: Desserts with varying GIs significantly altered salivary microbiota, with pronounced effects in the high-GI group. These findings underscore the influence of dietary glycemic load on oral microbial ecosystems and highlight the need for further research into long-term health implications.

Funding Sources: Chulalongkorn University and Ministry of Public Health