Exploring the effects of formula feeding on infant immune development in China: A prospective cohort study.

Abstract

The worldwide exclusive breastfeeding rate is suboptimal and this study aims to evaluate effects on infant immune development of formula feeding. A prospective study including 221 infants fed with breast milk or formula was conducted. At 3-month and 9-month, the concentrations of total immunoglobulin (Ig)G, IgM, IgA, IgG1, IgG2, interleukin (IL)-4, interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) were measured by using enzyme-linked immunosorbent assay (ELISA). Natural killer (NK) cell activity and lymphocyte transformation testing were conducted. Furthermore, the occurrence of infantile diarrhea, respiratory infections and allergic diseases were questioned. The levels of total IgG (Z=-3.21, p=0.001), IgG1 (Z=-2.12, p=0.034), IFN-γ (t=-2.09, p=0.039) and NK cell activity (t=-2.14, p=0.034) were significant higher in formula-fed infants compared to breast-fed after 3 months. At 9-month, the levels of total IgG (Z=-4.34, p<0.001), IgA (Z=-2.05, p=0.041) and TNF-α (t=-2.10, p=0.037) of formula-fed infants were higher, but the lymphocyte stimulation index (t=2.76, p=0.007) was lower than breast-fed infants. While, no significant differences were found in the incidences of diarrhea and respiratory tract infection (p>0.05). This investigation suggested that formula- and breast-feeding have different contributions to infant immune development, but the formula feeding would not cause significantly increase of diarrhea and respiratory infections.