Prospective Associations of Breastfeeding Parents' Postpartum Dietary Intake With Infant Gut Microbiome at Age 6 Months in the Pregnancy Eating Attributes Study.

BACKGROUND: Oligosaccharides in breast milk facilitate colonization of the infant gut microbiota that reduce the risk of metabolic disorders. Although diet influences human milk composition, no study to date has examined the association of breastfeeding parents' dietary intake, exclusively during the postpartum period, with infant gastrointestinal microbiome. OBJECTIVE: To examine the relationship of postpartum diet quality of the breastfeeding parent, as measured by Healthy Eating Index 2015 (HEI-2015), with gut microbiota of infants at age 6 months. DESIGN: A secondary data analysis of a prospective pregnancy cohort participating in the Pregnancy Eating Attributes Study in North Carolina. PARTICIPANTS/SETTINGS: Of 458 participants enrolled from November 2014 through October 2016, this study included 103 breastfeeding parent-infant dyads. Dietary recalls collected at 4 to 6 weeks and 23 to 31 weeks postpartum estimated diet quality. Infants were classified into 1 of the following groups based on their feeding exposures at age 6 months: breast milk only, breast milk and solids, and breast milk and formula (with/without solids). MAIN OUTCOME MEASURES: Infant rectal swabs, collected 23 to 31 weeks following delivery, were used for deoxyribonucleic acid extraction and sequencing. The paired-end FASTQ files were input into the Just A Microbiology System pipeline. STATISTICAL ANALYSES: Multivariate linear models examined relationships between HEI-2015 components and abundances of infant microbial taxa in the full sample and by feeding groups. RESULTS: In the overall sample, higher breastfeeding parents' total HEI-2015 score (β ± SE) was associated with lower abundance of Campylobacter hominis (-.0012 ± .0003; P < .001; false discovery rate [FDR] q = 0.002) and Acidaminococcus (unclassified) (-.0012 ± .0003; P < .001; FDR q = 0.002). Among infants exclusively fed breast milk, a higher HEI-2015 total protein foods score (β ± SE) was associated with lower abundance of Streptococcus (unclassified) (-.078 ± .012; P < .001; FDR q ≤ 0.001) and Anaerococcus tetradius (-.014 ± .003; P < .001; FDR q = 0.043). Among infants fed breast milk and solid foods, a higher HEI-2015 refined grain score (β ± SE) was associated with lower abundance of Clostridiaceae (-.002 ± .0004; P < .001; FDR q = 0.013). Among infants fed breast milk and formula, a higher HEI-2015 total protein foods score (β ± SE) was associated with lower abundance of Atopobium (unclassified) (-.01 ± .004; P < .001; FDR q = 0.04). CONCLUSIONS: Higher breastfeeding parents' HEI-2015 scores were associated with lower abundance of gut microbial genera that have been previously implicated in inflammation. Findings suggest the potential of the parents dietary intake during breastfeeding to support the development of the infant gut microbiome is associated with favorable short- and long-term health outcomes.