Effect of bovine milk fat-based infant formulae on microbiota, metabolites and stool parameters in healthy term infants in a randomized, crossover, placebo-controlled trial

Abstract

Background Natural enrichment of sn-2 palmitate content of infant formulae by using bovine milk fat is known to reduce formation of faecal fatty acid soaps and to improve stool consistency, but effects on gut microbiota composition are unknown. The purpose of this study was to test the influence of milk fat-based formula high in sn-2 palmitate on the infants’ gut microbiota composition and to confirm the beneficial effects of the formula on formation of faecal fatty acid soaps and stool consistency. Methods Twenty-two healthy term, formula-fed infants were enrolled in a single-blinded randomized, crossover, placebo-controlled trial. After a 2-week run-in period, infants received either a 50% milk fat-based formula containing 39% sn-2 palmitate (MF) or a vegetable fat-based formula (VF) containing 10% sn-2 palmitate in a 2 × 2-week crossover design. Faecal microbiota composition was the primary outcome of the study. Other outcomes included faecal fatty acid soap excretion, calcium excretion, gut comfort parameters and faecal metabolites. Results Microbiota analysis showed that bifidobacteria dominated the gut microbiota of most infants. Neither alpha- nor beta-diversity was significantly influenced by the intervention. Also, abundance of metabolic pathways was independent of the intervention. The MF formula resulted in significantly lower faecal levels of palmitic acid soap (p = 0.0002) and total fatty acid soaps (p = 0.0001) than the VF formula. Additionally, calcium excretion and palmitic acid concentration were significantly (p = 0.0335) lower in stool samples after MF intervention. Furthermore, a significant physiological effect on softer stools was observed in the MF intervention compared to the VF intervention (p = 0.02). Of the 870 measured faecal metabolites, 190 were significantly different after MF and VF intervention (FDR corrected p < 0.05). Most of these were found at higher levels after MF intervention, potentially indicative of the complex structure of milk fat. Metabolites with more than twofold change between interventions were mostly lipid-derived and included several milk fat-specific fatty acids. Conclusions Replacing part of the vegetable fat in infant formula with bovine milk fat with high sn-2 palmitate levels did not change the microbiota composition, although a reduction in faecal palmitate soaps, total fatty acid soaps and calcium excretion while improving stool consistency in the MF intervention was confirmed. In addition, 190 faecal metabolites were significantly different, many related to the fat source. Trial registration Netherlands Trial Registry Identifier: NL7815 19/06/2019.

Using FT-IR as a fast method to measure fatty acid soaps in in vivo and in vitro digests

“…We used 31 samples from a previous study 13 to set-up a model to calculate the calcium soap content in in vivo samples based on FT-IR measurements. Samples were measured with FT-IR and resulting absorption peak heights were used to calculate A Ca-soap with eqn (4).…”

“…A C-H Fig. 2 Fit between absorbance of calcium soaps (A Ca-soap ) as measured with FT-IR and calcium soap concentration (C Ca-soap ) as measured with GC-FID, on dry faeces samples from the study described in Looijesteijn et al 13 With the model (-), 95% confidence interval on mean of prediction (/) and 95% confidence interval on single prediction (-). Fig.…”

“…The objective of the current study was to develop a simple method to measure fatty acid soaps, representative for the soap formation observed in clinical trials. Therefore, we set-up a new method based on FT-IR and correlated these to the soap levels measured with the GC-FID method for faecal soap analysis in the faecal samples obtained from Looijesteijn et al 13 Next to this, FT-IR measurement of fatty acid soaps formed after in vitro digestion was explored. This method would enable the screening of different fat blend compositions for soap formation capacity via in vitro digestion and select the most optimal fat blend for clinical testing.…”

Early-Life Gut Health Indicators and Reported Prevalence of Infant Functional Constipation by Healthcare Professionals

“…In contrast, the palmitic acid in the Sn-2 position is not associated with this problem. Recent studies have shown that infants have softer stools and reduced fecal palmitate soaps upon consumption of bovine milk containing natural milk fat rich in PA in the sn-2 position compared to a vegetable fat-based formula [ 31 ]. In addition, the application of structured triglycerides with a high sn2-palmitic acid content (OPO) in infant formula has been shown to reduce calcium soaps in feces and enhance stool frequency [ 32 ].…”

Comparing early life nutritional sources and human milk feeding practices: personalized and dynamic nutrition supports infant gut microbiome development and immune system maturation

“… 60 , 153 However, most vegetable FAs are attached to triglycerides at different structural positions (sn-1 and sn-3) compared to human milk FAs (sn-2). 154 One study has shown that infants receiving synthetic sn-2 positioned palmitic acid for six weeks had an increased abundance of fecal Lactobacillus and Bifidobacterium when compared to infants receiving a control formula. 155 Optimizing the FA profile of human milk substitutes is an active area of research.…”