IgA Targeting in the Infant Gut Is Modulated by Diet and Increasingly Directed Towards Persistent Species

Summary

This study adapted metagenomic immunoglobulin sequencing to profile species-level IgA targeting in infant faeces longitudinally across four complementary feeding patterns. IgA targeting strengthened significantly from 6 to 12 months, with the most pronounced effect for Bifidobacterium across all dietary arms; nutrient-specific associations emerged, with animal-derived cholesterol positively correlated with Bifidobacterium longum targeting, whilst plant-derived carotenoids associated with Flavonifractor plautii and Ruminococcus gnavus targeting. The findings suggest IgA may reinforce beneficial persistent colonisers during infancy and highlight how early nutritional interventions shape immune–microbiome development.

Regional applicability

This US-based study of infant immune–microbiome interactions during complementary feeding is broadly applicable to United Kingdom clinical and public health contexts, particularly informing recommendations for infant feeding practices and early-life nutritional interventions. Direct transferability to UK populations would benefit from validation, given potential differences in dietary patterns and microbiome composition, but the mechanistic insights on IgA–nutrient relationships are likely to be relevant to UK infant nutrition policy.

Key measures

IgA targeting by bacterial species using Metagenomic Immunoglobulin Sequencing (MIg-Seq); microbiome composition; correlation between nutrient intake (cholesterol, carotenoids) and IgA binding to specific taxa (Bifidobacterium longum, Flavonifractor plautii, Ruminococcus gnavus)

Outcomes reported

The study characterized species-level IgA targeting in infant faeces across four complementary feeding arms (meat-based, dairy-based, plant-based, and reference) at 6 and 12 months of age, measuring IgA binding patterns to specific bacterial taxa and their correlation with nutrient intake.

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