Timing of food introduction to the infant diet and risk of food allergy: a systematic review and Meta-analysis

Abstract

Objective: To evaluate the relationship between the timing of complementary feeding for infants and the occurrence of food allergy. Methods: The PubMed, Cochrane Library, China National Knowledge Infrastructure (CNKI), and WanFang Data database were searched for randomized controlled trials (RCTs) about the effects of early introduction of complementary foods in infants on the occurrence of food allergy. Papers published from the establishment of the databases to December 31, 2019 were extracted. The quality of the selected literature was evaluated using the risk-of-bias (ROB) tools in the Cochrane Handbook, and the RevMan 5.3 software was used for meta-analysis. For the complementary food analyzed in a few reports in literature, a systematic review was conducted. Results: A total of 8 RCTs were extracted, and the systematic review and Meta-analysis were carried out according to food types. The results of Meta-analysis showed that compared with late introduction (after 6 months of age), early introduction (before 6 months of age) of eggs (RR=0.60, 95%CI 0.46-0.79) could reduce the risk of egg allergy in infants. The subgroup analysis of the six studies about eggs demonstrated that in infants with a prior or family history of allergic diseases, the introduction of eggs before 6 months of age was associated with reduced risk of egg allergy (RR=0.55, 95%CI 0.40-0.75), and the introduction of raw eggs (RR=0.67, 95%CI 0.49-0.93) and small amount of eggs (equivalent to weekly protein 0-4 g) (RR=0.55, 95%CI 0.36-0.85) before 6 months of age were also associated with reduced risk of egg allergy. In addition, egg supplementation during 4-6 months of age reduced the occurrence of egg allergy compared with supplementation before 4 months of age (RR=0.58, 95%CI 0.43-0.78). The systematic review found no conclusive relationship between early peanut introduction and peanut allergy, nor the correlation between early cow's milk protein introduction and cow's milk protein allergy (P>0.05). Conclusion: Early introduction (before 6 months of age) of eggs in infants' complementary foods can prevent infant egg allergy, but the limitations of the study need to be considered.