Infant formula interface and fat source impact on neonatal digestion and gut microbiota

Abstract

Human milk is generally recognized as the gold standard in neonatal nutrition. The structure andcomposition of human milk are better mimicked in infant formulas that include cow s milk lipids andmilk fat membrane extracts, which could also improve physiological properties. Nevertheless, very fewinfant formulas use cow' s milk lipids that are more expensive than vegetable lipids. The potential impactof milk lipid structure and composition on neonatal digestive hydrolysis, intestinal physiology, and gutmicrobiota was recently underlined by several scientific teams. In this context, the purpose of the presentreview was to summarize the specificity of composition and structure of human milk and to highlight therecent results on the modulation of infant formula interfacial composition and fat source on neonataldigestive hydrolysis, intestinal physiology, and gut microbiota. More specifically, the interfacialcomposition of model emulsions stabilized with milk polar lipids will be unraveled as well as the additionof apolar milk fat extracts in replacement to vegetable lipids in infant formulas. The impact of partiallyreplacing vegetable lipids by milk lipids stabilized by milk fat membranes was investigated in the piglets.This replacement in fluenced the neonatal intestinal physiology through the release of immune-modulatory lipids, the modulation of proteolysis, and the modification of gut microbiota.PracticalApplications:The potential development of infant formulas including cow’s milk lipid fractions with a structure closer to human milk is discussed. These more biomimetic formulas should result in enhanced nutritional benefits concerning neonatal digestive hydrolysis, physiology, and gut microbiota developmen

Towards infant formula biomimetic of human milk structure and digestive behaviour

“…At this stage, however, the fact that kinetics of lipid digestion could further modulate plasma TG appearance (Michalski et al, 2006) and b-oxidation rate (Michalski et al, 2005a) was already established in animal models and later on confirmed in human (Vors et al, 2013). In a further study (Oosting et al, 2014), still using a very close design study in mice, it was shown (2015) and Bourlieu et al (2015a).…”

“…These compounds can be added in the IF premix. An important aspect of such addition is not only their protein/phospholipids ratios but also the order of introduction of these two amphiphiles in the emulsion which can impact on the emulsion interfacial composition and structure (Bourlieu et al, 2015a;Gallier et al, 2015). The precise interfacial composition of such biomimetic IF remains to be characterized as well as its susceptibility to digestion.…”

“…This regiodistribution differs between bovine and HM (Fig. 1), but also more importantly between IF and HM, since the source of fat in IF is in most cases a combination of blended vegetable oils which mimics the FA composition of HM (Bourlieu et al, 2015a;Zou et al, 2016). Vegetable fats also show non-random regiodistribution but in the opposite way to dairy fat: their saturated FA are typically positioned on the external sn-1,3 positions, whereas unsaturated FA are mainly located in sn-2 position (Straarup et al, 2006;Innis, 2011).…”

“…For instance, MCFA (C8:0 to C12:0) are mainly esterified in sn-3 position in HM, and thus selectively released by the sn-3 stereospecific human gastric lipase (HGL). These medium chain FA are then absorbed via the portal vein, transported to the liver to be b-oxidized, and thus constitute a rapid source of energy for the newborn (Bourlieu et al, 2015a). Oleic acid (C18:1 n-9) is usually found at the sn-1 and sn-3 positions, which corresponds to the stereo-specificity of the human pancreatic lipase.…”

“…In addition, IF lipids structure has remained up to now very different from HM, which can lead to a difference in the kinetics of digestion and assimilation of nutrients (Armand et al, 1996;Bourlieu and Michalski, 2015;Bourlieu et al, 2015a). Indeed lipids in HM are found under the form of dispersed droplets called Milk Fat Globules (MFG, Ø 0.1-20 mm, average = 4 mm).…”