Associations Between Diet Diversity During Infancy and Atopic Disease in Later Life: Systematic Review

The purpose of this study is to explore whether introducing a larger variety of foods in infancy is associated with decreased risk of developing atopic disease such as atopic dermatitis (AD), allergic rhinitis (AR), asthma, and food allergy.Data were collected based on questionnaires, dietary diaries, and interviews with caregivers of children aged 3 months to 2 years in studies based in Europe, Asia, and New Zealand, with sample sizes ranging from 100 to 5225.This systematic review used research databases such as PubMed and the Cochrane Library to search for studies on diet diversity as related to atopic disease from inception to February 2023. Specifically, they included studies examining the association between diet diversity during infancy and asthma, eczema, food allergy, atopic dermatitis, and rhinitis. Two independent authors assessed the risk of bias for each study, and 15 high-quality publications were included in the final analysis. Researchers extracted data and organized them according to atopic disease to perform a narrative synthesis.In terms of asthma, 4 out of 6 studies showed an inverse association between early food diversity and asthma development. One study in particular showed a 26% decreased incidence of asthma for each new food introduced. Two out of 6 studies did not observe a clear association. In terms of AR, 4 total studies examined the relationship of complementary foods and AR. One study reported that an insufficient variety of foods increased the risk of AR; however, the other 3 did not find an association. One study found that decreased food diversity was associated with an increased risk of wheezing. A total of 5 studies examined eczema; 3 studies reported a relationship. Two reported higher odds of eczema with early diverse introduction; 1 lost significance after adjusting for confounders. With AD, 3 out of 5 studies showed a protective association with food diversity, whereas 2 showed no significant difference. All 5 studies examining food allergies showed that food diversity in infancy could reduce the risk of food allergy.Increasing the variety of complementary foods in infancy appears to help in the prevention of food allergy, reduce the risk of asthma, and reduce the risk of AD. However, the impact on eczema, AR, and other diseases is still unclear.This systematic review addresses how dietary diversity may influence atopic diseases and provides a synthesis of evidence across multiple conditions to support the conclusions. Importantly, this study aligns with landmark studies like LEAP (Learning Early About Peanut), which suggest the important role of early introduction. It is important to note the heterogeneity of the studies in their own definitions of food diversity and the effect cultural infant feeding practices may have on the results. Future studies may benefit from standardizing the definition of food diversity.