According to Jill Norris, PhD, MPH, of the Colorado School of Public Health in Aurora, and colleagues, compared with exposing children to solid food for the first time at ages 4 or 5 months, introducing solid food both earlier and later was associated with greater risks of developing type 1 diabetes (hazard ratio 1.91 for early and HR 3.02 for later).
The specific food category associated with the greatest risk was rice or oats when first exposure occurred at age 6 months or later (HR 2.88, 95% CI 1.36-6.11).
"These results suggest the safest age to introduce solid foods in children at increased genetic risk for type 1 diabetes is between 4 and 5 months of age," they wrote, noting that the findings are consistent with the American Academy of Pediatrics’ recommendation to start giving solid foods at 4 to 6 months of age, but should be confirmed in a larger study.
Previous studies looking at the association between the timing of the introduction of solid foods and risk of type 1 diabetes have yielded conflicting results, and Norris and colleagues further explored the issue using data from the Diabetes Autoimmunity Study in the Young (DAISY), a longitudinal investigation of risk factors for the disease.
The current analysis included 1,835 children who either underwent screening for diabetes-susceptibility alleles or had a first-degree relative with type 1 diabetes. Only those followed from birth with complete information about solid food exposure were included.
During the study, 53 of the children were diagnosed with type 1 diabetes.
Introducing solid foods in general too soon or too late was associated with a greater risk of developing type 1 diabetes after adjustment for human leukocyte antigen genotype, having a first-degree relative with the disease, maternal education, and type of delivery.
Early exposure to fruit — excluding fruit juice — was associated with a greater risk (HR 2.23, 95% CI 1.14-4.39), although the relationship became nonsignificant after accounting for other food exposures.
"The risk predicted by early exposure to solid foods might suggest a mechanism involving an abnormal immune response to solid food antigens in an immature gut immune system in susceptible individuals," the authors wrote. "As the increased risk is not limited to a specific food, it is possible many solids, including cereals and fruits, contain a common component that triggers an immature response."
On the other hand, the relationship between late exposure to solid foods and risk of type 1 diabetes "may be related to the larger amounts given at initial exposure to older children. Also, if solid foods are introduced too late, when breast milk alone no longer meets the infant’s energy and nutrient needs, nutrient deficiencies may occur, which may play a role in increasing … risk," according to the researchers.
"Additionally, the increased risk predicted by late exposure to solid foods may be related to the cessation of breastfeeding before solid foods are introduced, resulting in a loss of the protective effects of breast milk at the introduction of foreign food antigens," they wrote.
Although breastfeeding duration was not related to diabetes risk in the current study, breastfeeding at the time of the first exposure to wheat or barley was associated with a lower risk of developing the disease (HR 0.47, 95% CI 0.26-0.86), "suggesting that breast milk may protect against an abnormal immune response to new antigens in an immature gut," according to Norris and colleagues.
The timing of exposure to meats, vegetables, and cow’s milk was not associated with the risk of type 1 diabetes.
- The study results suggest the safest age to introduce solid foods in children at increased genetic risk for type 1 diabetes is between 4 and 5 months of age.
- In children with an increased genetic risk of type 1 diabetes, both early and late first exposure to any solid food predicted development of the disease.