Diet Influences the Oral Microbiota of Infants during the First Six Months of Life

Abstract

Oral bacteria and fungi contribute to oral health and establishment of the distal gastrointestinal tract microbiota; however, the impact of diet on the oral microbiota of infants is under‐investigated. We aimed to characterize the influence of feeding method (exclusive human milk [HM], formula [FF], HM + FF [mixed], and solid foods) on oral bacterial and fungal communities in vaginally delivered infants during the first 6 mo of life. Infant (N=12) feeding records and tongue and cheek swabs were collected within 24 hr of birth, and at 2, 4, and 6 mo of age. DNA was extracted, sequenced on an Illumina MiSeq, and analyzed with QIIME 1.8 and SAS. Bacterial diversity was lowest in HM and highest in FF and solid food fed infants (p<0.01). Principal coordinates analysis (PCoA) of UniFrac distances between samples based on their 97% OTU composition and abundances indicated that bacterial communities were impacted by feeding method (p<0.005). Infants fed HM or mixed diets had reduced relative abundances of Bacteroidetes while solid foods increased Fusobacteria (p<0.05). Infants had greater proportions of Proteobacteria at birth compared to other time points (p<0.05). Among genera, Streptococcus predominated in all infants, with the highest proportions in HM or mixed diets. Compared to HM, the relative abundances of Prevotella were increased with FF (p=0.01) and solid foods (p=0.02). Fungal communities were not impacted by diet. Five infants had detectable levels of fungi within 24 hr of birth, 4 at 2 mo, 9 at 4 mo, and 10 at 6 mo. These novel findings demonstrate that the oral microbiota of infants differs depending on dietary composition during the first 6 mo of life. Funded by Hatch Project #ILLU‐971‐350.