Relationships between the Intakes of Human Milk Components and Body Composition of Breastfed Infants: A Systematic Review

Abstract

Human milk provides all of the elements necessary for infant growth and development. Previous studies have reported associations between breastfeeding and a reduced risk of developing obesity and late-onset metabolic disorders; however, the underlying mechanisms are poorly understood. Recently, intakes of human milk components have been associated with infant body composition, which is likely partially implicated in the reduced risk of developing childhood obesity among breastfed infants. In this systematic review, we searched electronic bibliographic databases for studies that explored relationships between the 24 h intakes of human milk macronutrients and bioactive components and infant body composition and/or growth parameters. Of 13 eligible studies, 10 assessed relationships of infant body composition and growth outcomes with human milk macronutrients, while 8 studies assessed relationships with human milk bioactive components. Significant time-dependent relationships with infant anthropometrics and body composition were found for intakes and no relationships for concentrations of several human milk components, such as lactose, total protein, and human milk oligosaccharides, suggesting that measuring concentrations of human milk components without quantifying the intake by the infant may provide a limited understanding. Future studies investigating the effect of human milk components on infant growth and body composition outcomes should consider measuring the actual intake of components and employ standardised methods for measuring milk intake.

Keywords: bioactive molecules; breastfeeding; dose; early life nutrition; growth; human milk intake; infant body composition; lactation; macronutrients; systematic review.

Figure 3

Summary of the results of quantitative synthesis for studies investigating relationships between human milk macronutrient intake and infant anthropometry, fat-free mass, and adiposity. Each cell represents one or multiple significant or non-significant results reported by the study. Significance level was determined by the study and, where multiple comparisons adjustment was performed (indicated by #), only results significant after the adjustment are presented; if no adjustment was performed, the results for p < 0.05 are presented. MFGM, milk fat globule membrane lipid species [29,34,35,37,38,39,41,42,44,45].

Figure 1

PRISMA diagram.

Figure 2

Risk of bias in studies [29,34,35,36,37,38,39,40,41,42,43,44,45] assessing the relationship between intakes of human milk components and infant body composition and anthropometry using the National Institute for Clinical Excellence methodological checklist.

Figure 4

Summary of the results of quantitative synthesis for studies investigating relationships between intake of human milk bioactive components and infant anthropometry, fat-free mass, and adiposity. Each cell represents one or multiple significant or non-significant results reported by the study. Significance level was determined by the study and, where multiple comparisons adjustment was performed (indicated by #), only results significant after the adjustment are presented; if no adjustment was performed, the results for p < 0.05 are presented [35,36,37,38,40,41,43,44].

Figure 5

Summary of multiple significant relationships between infant anthropometry and body composition and concentrations and daily intakes of human milk (HM) components. Relationships are indicated by arrows (green—positive; red—negative), while numbers represent the quantity of studies that have reported at least one positive or negative relationship.