No abstract

AM. Highprotein diet modifies colonic microbiota and luminal environment but not colonocyte metabolism in the rat model: the increased luminal bulk connection. Am J Physiol Gastrointest Liver Physiol 307: G459-G470, 2014. First published June 26, 2014; doi:10.1152/ajpgi.00400.2013.-High-protein diets are used for body weight reduction, but consequences on the large intestine ecosystem are poorly known. Here, rats were fed for 15 days with either a normoproteic diet (NP, 14% protein) or a hyperproteichypoglucidic isocaloric diet (HP, 53% protein). Cecum and colon were recovered for analysis. Short-and branched-chain fatty acids, as well as lactate, succinate, formate, and ethanol contents, were markedly increased in the colonic luminal contents of HP rats (P Ͻ 0.05 or less) but to a lower extent in the cecal luminal content. This was associated with reduced concentrations of the Clostridium coccoides and C. leptum groups and Faecalibacterium prausnitzii in both the cecum and colon (P Ͻ 0.05 or less). In addition, the microbiota diversity was found to be higher in the cecum of HP rats but was lower in the colon compared with NP rats. In HP rats, the colonic and cecal luminal content weights were markedly higher than in NP rats (P Ͻ 0.001), resulting in similar butyrate, acetate, and propionate concentrations. Accordingly, the expression of monocarboxylate transporter 1 and sodium monocarboxylate transporter 1 (which is increased by higher butyrate concentration) as well as the colonocyte capacity for butyrate oxidation were not modified by the HP diet, whereas the amount of butyrate in feces was increased (P Ͻ 0.01). It is concluded that an increased bulk in the large intestine content following HP diet consumption allows maintenance in the luminal butyrate concentration and thus its metabolism in colonocytes despite modified microbiota composition and increased substrate availability.protein; microbiota; SCFA; transport; metabolism HIGH-PROTEIN (HP) diets are commonly used for body weight loss (36,38). In fact, such diets have been shown to increase satiety, to modify lipid metabolism, and to facilitate short-and middle-term weight reduction (24,61,72). However, the consequences on gut microbiota composition, on microbial-derived metabolites in the large intestine luminal content, and on colonocyte epithelial cell metabolic capacities have been little studied.Increasing protein intake induces an increase in the proportion of nitrogenous compounds, mainly protein, peptides, and to a lesser extent amino acids, entering the large intestine (13,23,25,51,64). They are subjected to luminal proteolysis and subsequent metabolism by the large number of microorganisms of the large intestine microbiota (about 10 11 to 10 12 viable bacteria/g content) (29) leading to the production of numerous amino acid-derived metabolites (53), including phenols, indoles, amines, sulfide, ammonia, and monocarboxylic acids. Monocarboxylic acids include short-chain fatty acids (SCFA), branched-chain fatty acids (BCFA) and several other organ...

This work originally reports on the use of electrohydrodynamic processing (EHDP) to encapsulate Aloe vera (AV, Aloe barbadensis Miller) using both synthetic polymers, i.e., polyvinylpyrrolidone (PVP) and poly(vinyl alcohol) (PVOH), and naturally occurring polymers, i.e., barley starch (BS), whey protein concentrate (WPC), and maltodextrin. The AV leaf juice was used as the water-based solvent for EHDP, and the resultant biopolymer solution properties were evaluated to determine their effect on the process. Morphological analysis revealed that, at the optimal processing conditions, synthetic polymers mainly produced fiber-like structures, while naturally occurring polymers generated capsules. Average sizes ranged from 100 nm to above 3 μm. As a result of their different and optimal morphology and, hence, higher AV content, PVP, in the form of nanofibers, and WPC, of nanocapsules, were further selected to study the AV stability against ultraviolet (UV) light exposure. Fourier transform infrared (FTIR) spectroscopy confirmed the successful encapsulation of AV in the biopolymer matrices, presenting both encapsulants a high chemical interaction with the bioactive components. Ultraviolet-visible (UV-vis) spectroscopy showed that, while PVP nanofibers offered a poor effect on the AV degradation during UV light exposure (∼10% of stability after 5 h), WPC nanobeads delivered excellent protection (stability of >95% after 6 h). This was ascribed to positive interactions between WPC and the hydrophilic components of AV and the inherent UV-blocking and oxygen barrier properties provided by the protein. Therefore, electrospraying of food hydrocolloids interestingly appears as a novel potential nanotechnology tool toward the formulation of more stable functional foods and nutraceuticals.

Poly(arylic acid) brushes are thoroughly investigated using QCM-D to elucidate their swelling behavior in the presence of salt.