Stratified dietary inflammatory potential identifies oral and gut microbiota differences associated with cognitive function in older adults

Diet is a crucial factor that shapes the composition of the microbiota throughout the life cycle. Systemic chronic inflammation and microbial imbalance may play a key role in the pathogenesis of cognitive disorders. Inflammatory diets can influence the host microbiome and inflammatory state. This study investigated the impact of the inflammatory potential of the diet on the diversity and composition of the oral-gut microbiome, as well as on cognitive performance, in older adults over 60 years of age. The Energy-adjusted Dietary Inflammatory Index (E-DII) and 16S rRNA sequencing were used to analyze dietary inflammatory properties and oral-gut microorganisms in 54 patients. The results showed that significant differences in the diversity of oral microbiota among different E-DII groups was detected (p < 0.05), whereas gut microbiota diversity didn't exhibit variations. In the anti-inflammatory diet group, the class Saccharimonadia, the order Corynebacteriaceae, the genera TM7x, Eubacterium_yurii_group, and Centipeda were more abundant in oral microbiomes, and lower abundance of Holdemanella and Haemophilus was observed in the gut microbiomes. Specific oral and gut genera were associated with MMSE, MoCA, AVLT-LR, BNT, and VFT scores (p < 0.05). These results provide insights into anti-inflammatory diets were associated with an increased abundance of beneficial microbes, and a specific oral and gut microbial composition was associated with cognition.