Addition of milk fat globule membrane as an ingredient of infant formulas for resembling the polar lipids of human milk

Abstract

Polar lipid (PL) contents in human milk (HM) from two different geographic zones in Spain (central and coastal) were determined. These PLs were also analysed in several infant formulas (IFs), three of which contained milk fat globule membrane (MFGM), an ingredient used to resemble the PL profile of HM. Total PL in HM decreased significantly (p < 0.05) from transitional milk (48.62 mg 100 mL⁻¹) to 6 months (28.66 mg 100 mL⁻¹). In HM, sphingomyelin was the most abundant PL, followed by phosphatidylethanolamine; in IFs the most abundant PL was phosphatidylethanolamine. Only IFs with MFGM (54.79–58.07 mg 100 mL⁻¹) could supply the total and individual PL content present in all lactation periods, with the exception of sphingomyelin, which did not match the content in transitional milk. PL intake by infants fed HM or IFs was determined to be 96–306 and 152–575 mg day⁻¹, respectively.

Introduction

Human milk (HM) is considered the optimal food for infants during the first 6 months of life (Kramer & Kakuma, 2001). The lipid fraction, in addition to representing almost 50% of the dietary calories, provides bioactive compounds localised in the fat globules as polar lipids (PLs), cholesterol, enzymes, proteins, glycoproteins and glycosphingolipids (cerebrosides and gangliosides) (German & Dillard, 2006).

The PLs phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS) and sphingomyelin (SM) are quantitatively minor constituents of HM fat globules, but they have interesting nutritional properties and are important structural components. Furthermore, they also afford long chain polyunsaturated fatty acids, which play an essential role in the growth and brain development of newborns infants (Wang et al., 2000). Of these PLs, the PC and SM contents are considered to be of great importance for the development of infants, acting as precursors of intracellular messengers such as ceramides and diacylglycerols (Zeisel & Blusztajn, 1994). Furthermore, approximately 17% of the total choline received by the newborn infant comes from these PLs (PC and SM), while the remaining choline is found in free form as phosphocholine and glycerophosphocholine (Holmes et al., 2000, Holmes-McNary et al., 1996, Ilcol et al., 2005). Choline is an essential nutrient involved in several biological processes, mainly metabolism, but also membrane construction in the brain and nervous tissue (Zeisel, 2000). The choline content is secreted into HM from the maternal circulation, and increases during lactation, because neonates require large amounts of this compound for rapid organ growth and membrane biosynthesis. In this regard, the recommended choline intake in the postnatal period is about 125 and 150 mg day⁻¹ at 0–6 months and 6–12 months, respectively (IOM, 2006).

Several authors have reported the PL content in HM in the different stages of lactation in Asian women (Giuffrida et al., 2013, Thakkar et al., 2013, Wang et al., 2000) and in women in northern Europe (Garcia et al., 2012, Harzer et al., 1983, Lopez and Ménard, 2011, Zou et al., 2012). Nevertheless, we found only one study in southern Europe focussing on the content and composition of PLs in the different stages of lactation (Sala-Vila, Castellote, Rodriguez-Palmero, Campoy, & López-Sabater, 2005).

When breastfeeding is not possible, use is made of infant formulas (IFs) with macronutrient and micronutrient compositions as similar as possible to those of HM. The composition of HM initially served as a basis for the development of IFs, particularly its lipid composition, which is of great importance for visual acuity (Birch, Birch, Hoffman, & Uauy, 1992), cognitive performance, proper growth and development of the immune system (Koletzko, Agostoni, Bergmann, Ritzenthaloer, & Shamir, 2011). Several studies have determined the PL contents in IFs (i.e., adapted, partially adapted, special formulas, bovine-derived formulas and soy-derived formulas) using different analytical methods such as high performance liquid chromatography–evaporative light scattering detection (HPLC–ELSD; Braun et al., 2010, Sala-Vila et al., 2003), thin layer chromatography- (TLC-) densitometry (Ilcol et al., 2005, Zeisel et al., 1986), HPLC–UV (Kynast & Schmitz, 1988) and HPLC–tandem mass spectrometry (Fong, Ma, & Norris, 2013), among others (Holmes et al., 2000, Holmes-McNary et al., 1996), and some have compared the contents with HM. Recently, a review of different aspects of PLs (contents, biological effects, methodology and method validation) in IFs and HM has been published (Cilla, Diego-Quintaes, Barberá, & Alegría, 2015).

Recently, studies on IF supplemented with MFGM have shown promising results on neurodevelopment (Timby, Domellöf, Hernell, Lönnerdal, & Domellöf, 2014) and defence against infections (Timby et al., 2015). The addition of MFGM to IF can vary the PL content (phospholipids and SM) in IFs. This study for the first time evaluates the PL content and intakes supplied by these IFs with MFGM, to determine whether they resemble those provided by HM. In addition, HM is a dynamic matrix whose fat composition is influenced by factors such as maternal diets, the stage of lactation, the duration of pregnancy and genetics, in addition to other potential associated factors such as the geographical setting, cultural traditions and socioeconomic status (Pita et al., 1985, Smit et al., 2002). Based on the above, we considered it of interest to investigate the PL content in the course of lactation (from colostrum to mature milk) and in two different zones in Spain (central and coastal), with a view to determining whether the use of MFGM is able to improve the resemblance between IFs and HM.