Timing of introduction of complementary foods and beverages and growth, size, and body composition: a systematic review

Background: The systematic review described in this article was conducted as part of the USDA and Department of Health and Human Services Pregnancy and Birth to 24 Months Project.

Objectives: The aim was to describe the relationship between timing of introduction of complementary foods and beverages (CFBs) and growth, size, and body-composition outcomes across the life span.

Methods: The literature was searched and selected using predetermined criteria. Data were extracted and risk of bias assessed for each included study. Evidence was qualitatively synthesized, conclusion statements were developed, and the strength of the evidence was graded.

Results: Eighty-one articles were included in this systematic review that addressed timing of CFB introduction relative to growth, size, and body-composition outcomes from infancy through adulthood. Moderate evidence suggests that introduction of CFBs between the ages of 4 and 5 mo compared with ∼6 mo is not associated with weight status, body composition, body circumferences, weight, or length among generally healthy, full-term infants. Limited evidence suggests that introduction of CFBs before age 4 mo may be associated with higher odds of overweight/obesity. Insufficient evidence exists regarding introduction at age ≥7 mo.

Conclusions: Although several conclusions were drawn in this systematic review, additional research is needed to address gaps and limitations in the evidence on timing of introduction of CFBs and growth, size, and body composition, such as randomized controlled trials that examine multiple outcomes and/or CFB introduction between the ages of 4 and 6 mo, and research that accounts for potential confounders such as feeding practices and baseline growth status and considers issues of reverse causality.