Mediation Analysis as a Means of Identifying Dietary Components That Differentially Affect the Fecal Microbiota of Infants Weaned by Modified Baby-Led and Traditional Approaches

Abstract

The introduction of 'solids' (i.e. complementary foods) to the milk-only diet of early infancy affects the development of the gut microbiota. The aim of this study was to determine whether a 'baby-led' approach to complementary feeding, that encourages early introduction of an adult type diet, results in alterations to gut microbiota composition compared to traditional spoon-feeding. The Baby-Led Introduction to SolidS (BLISS) study randomized 206 infants to BLISS (a modified version of Baby-Led Weaning (BLW): introduction of solids at 6 months of age, followed by self-feeding of family foods) or Control (traditional spoon-feeding of purées) groups. Fecal microbiotas and 3-day weighed diet records were analysed from a subset of 74 infants at 7 and 12 months of age. The composition of the microbiota was determined by sequencing 16S rRNA genes amplified by PCR from bulk DNA extracted from feces. Diet records were used to estimate food and dietary fiber intake. Alpha diversity (number of Operational Taxonomic Units; OTUs) was significantly lower in BLISS infants at 12 months (difference, 95% CI: 31, 3.4 to 58.5; p = 0.028) and, while there were no significant differences between Control and BLISS infants in relative abundances of or at 7 or 12 months of age, OTUs representing the genus were less prevalent in BLISS microbiotas at 12 months. Mediation models demonstrated that 'fruit and vegetables' and 'dietary fiber' intake explained 29% and 25% respectively of the relationship between group (BLISS versus Control) and alpha diversity. The introduction of solid foods (complementary feeding, weaning) to infants leads to more complex compositions of microbial communities (microbiota, microbiome) in the gut. In Baby Led Weaning (BLW), infants are given only finger foods they can pick up and feed themselves - there is no parental spoon-feeding of puréed baby foods - and infants are encouraged to eat family meals. BLW is a new approach to infant feeding that is increasing in popularity in the United States, New Zealand, the United Kingdom and Canada. We used mediation modeling, commonly used in health research but not until now in microbiota studies, to identify particular dietary components that affected the development of the infant gut microbiota.

Fecal Microbiotas of Indonesian and New Zealand Children Differ in Complexity and Bifidobacterial Taxa during the First Year of Life

“…The NZ cohort has been described previously (8) and comprised a subset of infants enrolled in the Baby-Led Introduction to SolidS (BLISS) randomized controlled trial. The design of this trial and metadata for the infants and mothers have been published previously (23).…”

“…The design of this trial and metadata for the infants and mothers have been published previously (23). Fecal microbiota data from BLISS and non-BLISS infants were amalgamated because there were no differences in the relative abundances of the most abundant families (Ͼ1% relative abundance [8]). Fecal samples were obtained from these infants at 7 months of age (73 infants) and at 12 months of age (68 infants).…”

“…T he transition of an infant from a mainly milk diet to the introduction of solid foods (complementary feeding period) is accompanied by transformation of the composition of the gut microbiota (1)(2)(3)(4)(5)(6)(7)(8). In Western countries, it is recommended that complementary feeding start at around 6 months of age and that infants eat mainly "family" foods by 1 year (9)(10)(11).…”

“…In general, in studies of Western infants, members of the genus Bifidobacterium that utilize lactose (and human milk oligosaccharides [HMOs] for some species) for growth are abundant in the fecal microbiota of exclusively milk-fed infants. Bacterial species capable of degrading and fermenting plant polysaccharides and their components (Bacteroidaceae, Lachnospiraceae, and Ruminococcaceae) are dominant by the end of the complementary feeding period (1)(2)(3)(4)(5)(6)(7)(8).…”

Relative Validity and Reproducibility of a Food Frequency Questionnaire to Assess Nutrients and Food Groups of Relevance to the Gut Microbiota in Young Children

“…A dietary component of particular interest is dietary fiber, as it is the main food source for the gut microbiota [ 5 , 6 ]. Because different classes (soluble, insoluble) or fractions (e.g., arabinoxylan from whole grains, pectin from fruits, and cellulose from vegetables) of fiber appear to impact gut microbiota in different ways [ 7 , 8 , 9 , 10 ], appropriate dietary assessment techniques must be used to improve understanding of how diet influences the microbiota and subsequent health outcomes. While weighed diet records (WDR) or 24-h recalls are generally considered gold standard methods of dietary assessment [ 11 ], they entail considerable respondent and researcher burden, and do not directly assess ‘usual’ intake.…”