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Breast-feeding influences thymic size in late infancy
H Hasselbalch1, M D Engelmann, A K Ersboll
1Department of Radiology, Hvidovre Hospital, University of Copenhagen, Kettegårds Allé 30, DK-2650 Hvidovre, Denmark.
Insights
Breast milk significantly increases thymus size in late infancy. Continued breastfeeding at 10 months correlates with a larger thymus, suggesting immune benefits of breast milk.
Area of Science:
- Immunology
- Pediatrics
- Human Biology
Background:
- Previous research indicated larger thymus size in breast-fed infants at 4 months.
- The impact of breastfeeding on thymus size in later infancy remained to be investigated.
Purpose of the Study:
- To determine if breastfeeding influences thymic size in late infancy.
- To assess the relationship between breastfeeding duration and thymic size at 10 months.
Main Methods:
- A cohort of 50 partially breast-fed infants was studied.
- Ultrasound assessment of thymic index was performed at 8 and 10 months.
- Statistical analysis controlled for infectious disease influence.
Main Results:
- Infants still breast-fed at 10 months had a significantly larger thymic index (P=0.05).
- This difference remained significant after controlling for infections (P=0.03).
- A positive correlation was found between daily breastfeeding frequency and thymic index (P=0.01).
Conclusions:
- Breastfeeding positively influences thymic size in late infancy.
- Immune-modulating factors in breast milk are likely responsible for this effect.
- Breast milk supports thymus development and immune function in infants.
Abstract:
We have previously shown that breast-fed infants have a considerably larger thymus at 4 months than formula-fed infants. The aim of the present study was to investigate whether breast-feeding also influences the thymic size in late infancy. In a cohort of 50 infants, all being partially breast-fed when recruited at 8 months, ultrasound assessment of the thymic index (a volume estimate) was performed at both 8 and 10 months of age. At 10 months the thymic index was significantly higher in those still being breast-fed compared to infants who had stopped breast-feeding between 8 and 10 months of age (P=0.05). This difference became more significant when controlled for the influence of infectious diseases (P=0.03). In infants still breast-fed at 10 months there was a significant correlation between the number of breast-feeds per day and their thymic index (P=0.01). Conclusion The effect of breast-feeding on thymus size is likely to be caused by immune modulating factors in breast milk. Breast milk influences thymic size in late infancy.