Introduction: The introduction of solids is an important dietary event during infancy that causes dramatic shifts in gut microbial composition contributing to the shift toward a more adult-like state. The objective herein is to investigate dietary intake during this period and its relationship with gut bacterial dynamics in healthy, breast-fed infants.
Methods: Food diaries were collected over a 17-day period surrounding the introduction of solid foods from 15 infants in the Baby, Food & Mi study. Stool samples were collected before, during and after this period, up to 1 year. Gut microbiota was characterized using 16S rRNA gene sequencing. Nutritional patterns were analyzed using ESHA’s Food Processor software. Infants (n = 14) were divided into groups based on four dietary characteristics: dominant macronutrient, protein intake, dominant food group and vegetarianism. The relationship between early nutrition and gut microbiota metrics, including alpha and beta diversity, and taxonomic relative abundance, were investigated using linear regression and principal coordinate analysis.
Results: he mean age at introduction was 5.5 (SD = 0.7) months. The proportion of energy from solids was low; averaged 7.5% (SD = 6.74%) of total energy intake. Alpha diversity for each infant increased steadily over time and was highest at 1 year. Although the microbiome structure was not stable prior to the introduction of solid food, by the end of the study period all communities had changed substantially from their original composition. No differences in beta diversity between dietary groups were detected after introducing solids. Infants with diets high in protein had higher alpha diversity (p<0.05). Of macronutrients, only calories from carbohydrates were related to observed alpha diversity (p = 0.077).
Conclusion: The alpha diversity of the gut microbiome was increased with higher protein intake. Further research is needed to investigate key bacterial taxa and how they change with dietary composition.
Sara Dizzell– Research Assistant, Department of Medicine, McMaster University
Jenifer Li– Research Coordinator, Department of Obstetrics & Gynecology, McMaster University
Elizabeth Gunn– Clinical Research Coordinator, Department of Pediatrics, McMaster University, Centre for Metabolism, Obesity and Diabetes Research
Russell De Souza– Assistant Professor, Department of Health Research Methods, Evidence and Impact, McMaster University
Eileen Hutton– Professor Emeritus, Department of Obstetrics & Gynecology, McMaster University, Co-Principal Investigators of the Baby & Mi Study
Jennifer Stearns– Assistant Professor, Department of Medicine, McMaster University
Katherine Morrison– Associate Professor, Department of Pediatrics, McMaster University, Centre for Metabolism, Obesity and Diabetes Research, Co-Principal Investigators of the Baby & Mi Study