November 21, 2013
Overlapping Breast Milk With Solids ‘Trains’ Infants Against Allergies
Introducing solid food while continuing to breast feed could reduce food allergies in infants, according to research funded by the UK Food Standards Agency and appearing in the latest edition of the journal Pediatrics.
In the study, University of Southampton dietitian and senior research fellow Dr. Kate Grimshaw and her colleagues report that starting babies on solid food in addition to breast milk after the 17th week following birth helps the child develop stronger immune systems with which to fight food allergies.
“Introducing solid foods alongside breastfeeding can benefit the immune system,” Dr. Grimshaw explained Wednesday in a statement. "It appears the immune system becomes educated when there is an overlap of solids and breast milk because the milk promotes tolerogenic mechanisms against the solids.”
“Additionally, our findings suggest 17 weeks is a crucial time point, with solid food introduction before this time appearing to promote allergic disease whereas solid food introduction after that time point seems to promote tolerance,” she added. Infants typically do not become tolerant of solid food until they are four to six months of age, most likely due to the relative immaturity of the infant gut, the researchers said.
The research team recruited 1,140 newborn infants from the Hampshire region in England, and of those youngsters, 41 went on to develop food allergies by the age of two. The diets of those youngsters were compared to the food consumption habits of 82 babies who did not develop food allergies by the time they were 24 months old.
The researchers found that children who had developed allergies had started eating solid food earlier than children without allergies – on average, 16 weeks or earlier, according to Grimshaw. Furthermore, children with allergies were also more likely to not be receiving mother’s milk when they were introduced to cow’s milk protein from any source, as women who are not breastfeeding are urged to introduce solids after 17 weeks of age.
“Mothers should continue to breast-feed beyond introducing solids into the diet so the immune system can benefit from the immunological factors in breast milk that educate the immune system,” the lead researcher told HealthDay. “My theory was that if food allergens – those things that infants actually become allergic to – aren't there at the same time as the breast milk, the breast milk can't educate the immune system.”
Dr. Vivian Hernandez-Trujillo, director of allergy and immunology at Miami Children's Hospital, says that while the study supports the importance of breast-feeding, it falls short of fully explaining why infants develop food allergies.
“Unfortunately, we still don't have all the answers when it comes to food allergies,” she added. “It appears that breast-feeding may be protective, but we still don't know why... It may have to do with [antibodies], but that would be totally speculative.”