Dairy and plant based protein beverages: In vitro digestion behaviour and effect on intestinal barrier biomarkers.

The consumer demand for protein-enriched food products continues to grow, in parallel with consumers' interest in plant based alternatives. The replacement of milk protein by plant protein is likely to be occur predominantly in prepared consumer foods such as nutritional beverages. This study aimed to compare and contrast powder beverages formulated with commercially available dairy versus plant ingredients in terms of protein digestion and gut barrier health. After simulated static in vitro gastrointestinal digestion, the release of free amino acids increased for all model beverages. In addition, the majority of peptides present in digested beverages were < 0.8 kDa in size. Gastrointestinal digestion did not increase the degree of protein hydrolysis in beverages formulated with prehydrolysed milk protein, whey or pea ingredients. A 2 h permeability assessment of digested beverages across the intestinal barrier, using Caco-2/HT-29/MTX co-cultures, revealed reduced transcription of tight junction protein 1, claudin-1 and mucus protein 2 albeit gut barrier impedance was unchanged. IL-8 mRNA levels in cell monolayers was significantly increased with digested fluids treatment but even more so with digesta from hydrolysed milk protein beverage. Overall, the response observed on intestinal biomarkers with digested plant beverages was similar to dairy based beverages supporting the replacement of dairy with plant proteins in powder beverage formulations.

Dairy matrix effects: response to consumption of dairy fat differs when eaten within the cheese matrix-a randomized controlled trial.

Background: Dairy fat consumed as cheese has different effects on blood lipids than that consumed as butter. It is unknown whether the effect is specific to fat interaction with other cheese nutrients (calcium, casein proteins), or to the cheese matrix itself. Objective: We aimed to test the effect of 6 wk daily consumption of ∼40 g dairy fat, eaten within macronutrient-matched food matrices, on markers of metabolic health, in overweight adults aged ≥50 y. Design: The study was a 6-wk randomized parallel intervention; 164 volunteers (75 men) received ∼40 g of dairy fat/d, in 1 of 4 treatments: (A) 120 g full-fat Irish cheddar cheese (FFCC) (n = 46); (B) 120 g reduced-fat Irish cheddar cheese + butter (21 g) (RFC + B) (n = 45); (C) butter (49 g), calcium caseinate powder (30 g), and Ca supplement (CaCO3) (500 mg) (BCC) (n = 42); or (D) 120 g FFCC, for 6 wk (as per A) (n = 31). Group D first completed a 6-wk "run-in" period, where they excluded all dietary cheese before commencing the intervention. Results: There was no difference in anthropometry, fasting glucose, or insulin between the groups at pre- or postintervention. However, a stepwise-matrix effect was observed between the groups for total cholesterol (TC) (P = 0.033) and LDL cholesterol (P = 0.026), with significantly lower postintervention TC (mean ± SD) (5.23 ± 0.88 mmol/L) and LDL cholesterol (2.97 ± 0.67 mmol/L) when all of the fat was contained within the cheese matrix (Group A), compared with Group C when it was not (TC: 5.57 ± 0.86 mmol/L; LDL cholesterol: 3.43 ± 0.78 mmol/L). Conclusion: Dairy fat, eaten in the form of cheese, appears to differently affect blood lipids compared with the same constituents eaten in different matrices, with significantly lower total cholesterol observed when all nutrients are consumed within a cheese matrix This trial was registered at ISRCTN as ISRCTN86731958.

Preparation of a standardised faecal slurry for ex-vivo microbiota studies which reduces inter-individual donor bias.

BACKGROUND: In-vitro gut fermentation systems provide suitable models for studying gut microbiota composition and functionality. However, such methods depend on the availability of donors and the assumption of reproducibility between microbial communities before experimental treatments commence. The aim of this study was to develop a frozen standardised inoculum (FSI) which minimizes inter-individual variation and to determine its stability over time using culture-dependent and culture-independent techniques. RESULTS: A method for the preparation difference of a FSI is described which involves pooling the faecal samples, centrifugation and pelleting of the cell biomass and finally homogenising the cell pellets with phosphate buffer and glycerol. Using this approach, no significant difference in total anaerobe cell viability was observed between the fresh standardised inoculum (before freezing) and the 12days post freezing FSI. Moreover, Quantitative PCR revealed no significant alterations in the estimated bacterial numbers in the FSI preparations for any of the phyla. MiSeq sequencing revealed minute differences in the relative abundance at phylum, family and genus levels between the FSI preparations. Differences in the microbiota denoted as significant were limited between preparations in the majority of cases to changes in percentage relative abundance of ±0.5%. The independently prepared FSIs revealed a high degree of reproducibility in terms of microbial composition between the three preparations. CONCLUSIONS: This study provides a method to produce a standardised human faecal inoculum suitable for freezing. Based on culture-dependent and independent analysis, the method ensures a degree of reproducibility between preparations by lessening the effect of inter-individual variation among the donors, thereby making the system more suitable for the accurate interpretation of the effects of experimental treatments.

Gum arabic establishes prebiotic functionality in healthy human volunteers in a dose-dependent manner.

The present study was undertaken to determine the prebiotic efficacy of gum arabic upon consumption by man for up to 4 weeks and, if any, to establish the dose-effect relationship. Human healthy volunteers consumed various daily doses (5, 10, 20, 40 g) of gum arabic (EmulGold) in water for up to 4 weeks. Daily consumption of water was taken as the negative control and that of 10 g inulin as the positive control. At 0, 1, 2 and 4 weeks quantification of bacterial numbers in stool samples was performed via real time-PCR techniques and questionnaires were filled in to account for potential drawbacks. The genera of Bifidobacteria and Lactobacilli were taken as potentially beneficial bacteria and those of Bacteroides, Clostridium difficile and Enterococci as potentially non-beneficial, this distinction was dependent on the issue of these numbers being or becoming out of balance in the host. Compared with the negative control the numbers of Bifidobacteria and Lactobacilli 4 weeks after consumption were significantly higher for gum arabic: the optimal dose being around 10 g. Moreover, at this dose the numbers of Bifidobacteria, Lactobacilli and Bacteroides were significantly higher for gum arabic than for inulin. No significant drawback was encountered during the study. It is concluded that gum arabic establishes prebiotic efficacy, at least as good as inulin. The optimal daily dose was found to be 10 g.