Lipid Quality in Infant Nutrition: Current Knowledge and Future Opportunities

Abstract

Dietary lipids are key for infants to not only meet their high energy needs but also fulfill numerous metabolic and physiological functions critical to their growth, development, and health. The lipid composition of breast milk varies during lactation and according to the mother's diet, whereas the lipid composition of infant formulae varies according to the blend of different fat sources. This report compares the compositions of lipids in breast milk and infant formulae, and highlights the roles of dietary lipids in term and preterm infants and their potential biological and health effects. The major differences between breast milk and formulae lie in a variety of saturated fatty acids (such as palmitic acid, including its structural position) and unsaturated fatty acids (including arachidonic acid and docosahexaenoic acid), cholesterol, and complex lipids. The functional outcomes of these differences during infancy and for later child and adult life are still largely unknown, and some of them are discussed, but there is consensus that opportunities exist for improvements in the qualitative lipid supply to infants through the mother's diet or infant formulae. Furthermore, research is required in several areas, including the needs of term and preterm infants for long-chain polyunsaturated fatty acids, the sites of action and clinical effects of lipid mediators on immunity and inflammation, the role of lipids on metabolic, neurological, and immunological outcomes, and the mechanisms by which lipids act on short- and long-term health.

FIGURE 1

Structure of a milk fat globule. Adapted from (5).

FIGURE 2

Ranges (minimum–maximum) of short- and medium-chain fatty acids (C4:0-C10:0, A), lauric (C12:0, B), myristic (C14:0, C), palmitic (C16:0, D), oleic (C18:1n-9) acid contents, expressed in percentage of total fatty acids in breast milk and infant formulae according to the fat sources used (see for numerical values; breast milk data sources are detailed in; infant formulae data come from unpublished analyses performed in a certified laboratory). FA = fatty acid; TFA = total fatty acid.

FIGURE 3

LA (C18:2 n-6, black circles) and ALA (C18:3 n-3, open circles) content in mature breast milk of US women. ALA = α-linolenic acid; LA = linoleic acid. Reproduced from (12).

FIGURE 4

Biochemical pathways leading from the LA and ALA to LC-PUFAs. AdA = adrenic acid; ALA = α-linolenic acid; ARA = arachidonic acid; (D)GLA = (di-homo) γ-linolenic acid; DHA = docosahexaenoic acid; DPA = docosapentaenoic acid; EPA = eicosapentaenoic acid; ETA = eicosatetraenoic acid; LA = linoleic acid; LC-PUFA = long-chain polyunsaturated fatty acid; SA = stearidonic acid; TFA = total fatty acid; THA = tetrahexaenoic acid; TPA = tetraeicosapentaenoic acid; TTA = tetracosatetraenoic acid.