Infants Develop Allergies Based on When Solid Food is Introduced

Development of food allergies can be curbed in infants by introducing solid food to a breast milk diet starting at week 17, according to research from the University of Southampton.

Writing in the journal Pediatrics, Kate Grimshaw, a dietitian and senior research fellow at the University of Southampton, reports that giving a baby solid food along with breast milk helps it develop a stronger immune system that's better equipped to fight allergies.

"Introducing solid foods alongside breastfeeding can benefit the immune system," Grimshaw said 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."

While 17 weeks appear to be the sweet-spot for introducing solid food, infants generally are intolerant of solid food before four to six months age.

The study, which was funded by the UK Food Standards Agency, examined 1,140 infants. Forty-one of the infants grew up to develop a food allergy by the time they were two years old. The diet of these children was compared to the diet of 82 infants who did not develop a food allergy by the time they were two years old.

The researchers found that children who developed allergies began eating solid food earlier -- at roughly 16 weeks old -- compared to the children with no allergies. The children who developed allergies were also more likely to not be fed breast milk upon the introduction of cow's milk.

Grimshaw said women who are not breastfeeding should introduce solid food to their infants starting at 17 weeks.

The research supports recommendations from other institutions such as the American Academy of Pediatrics and the European Society of Pediatric Gastroenterology, Hepatology and Nutrition, which urge mothers not to introduce solid foods before four to six months of age.

The findings also support the American Academy of Pediatrics' breastfeeding recommendations that breastfeeding should continue while solid foods are introduced into the diet.