Search Results (60)

Background/Objectives: An increasing number of apparently healthy individuals are adhering to a gluten-free lifestyle without any underlying medical indications, although the evidence for the health benefits in these individuals remains unclear. Although it has already been shown that a low- or gluten-free diet alters the gut microbiota, few studies have examined the effects of this diet on healthy subjects. Therefore, our aim was to evaluate whether and how a prolonged low-gluten diet impacts gut microbiota composition and function in healthy adults, bearing in mind its intimate link to the host’s health. Methods: Forty healthy volunteers habitually consuming a gluten-containing diet (HGD, high-gluten diet) were included in a randomised control trial consisting of two successive 8-week dietary intervention periods on a low-gluten diet (LGD). After each 8-week period, gut microbiota composition was assessed by 16S rRNA gene sequencing, molecular quantification by qPCR, and a cultural approach, while its metabolic capacity was evaluated through measuring faecal fermentative metabolites by ¹H NMR. Results: A prolonged period of LGD for 16 weeks reduced gut microbiota richness and decreased the relative abundance of bacterial species with previously reported potential health benefits such as Akkermansia muciniphila and Bifidobacterium sp. A decrease in certain plant cell wall polysaccharide-degrading species was also observed. While there was no major modification affecting the main short-chain fatty acid profiles, the concentration of the intermediate metabolite, ethanol, was increased in faecal samples. Conclusions: A 16-week LGD significantly altered both composition and metabolic production of the gut microbiota in healthy individuals, towards a more dysbiotic profile previously linked to adverse effects on the host’s health. Therefore, the evaluation of longer-term LDG would consolidate these results and enable a more in-depth examination of its impact on the host’s physiology, immunity, and metabolism. Full article

Pig large intestines (PLIs) are usually processed into various dishes for consumption through cooking methods such as stir frying, stewing, and braising, which are difficult for many consumers to accept because of their unique and pungent off-odours. To reduce the number of off-odour substances present in PLIs, we compared the effects of an untreated control group (blank), added flour (WF), and added S. cerevisiae mixed 4% flour in PLIs for fermentation (SC) on the treatment of PLIs. We analysed colour, thiobarbituric acid reactive substance (TBARS) values, and total volatile basic nitrogen (TVB-N) values; additionally, sensory evaluations were performed. The results showed that after 5 h of fermentation, the S. cerevisiae mixed flour exhibited the most significant effect on reducing the off-odour of PLIs, exhibited the least effect on the TBARS value and TVB-N was controlled within a reasonable range, while simultaneously maintaining good quality. A total of 415 volatile compounds were identified via flavouromics. Combined with principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA), the key off-odour substances, including indole (faecal odour), 2-pentylthiophene (fat odour), (E)-2-octenal (fishy odour), and 2-methoxy-phenol (smoky odour), were reduced by 28.1%, 23.90%, 21%, and 22.89%, respectively, after fermentation. Moreover, the content of ethyl octanoate increased 31.04-fold, which enriched the flavour components of the PLIs. The results showed that fermentation of S. cerevisiae mixed flour could be used as a method to reduce the off-odours of PLIs. Full article

Fucoidans have demonstrated a wide range of bioactivities including immune modulation and benefits in gut health. To gain a deeper understanding on the effects of fucoidan from Undaria pinnatifida (UPF) on the colonic microbiome, the short-term Simulator of the Human Intestinal Microbial Ecosystem^®, a validated in vitro gut model, was applied. Following a three-week intervention period on adult faecal samples from three healthy donors, microbial community activity of the colonic microbiota was assessed by quantifying short-chain fatty acids while composition was analysed utilising 16S-targeted Illumina sequencing. Metagenomic data were used to describe changes in community structure. To assess the secretion of cytokines, co-culture experiments using Caco-2 and THP1-Blue™ cells were performed. UPF supplementation over a three-week period had a profound butyrogenic effect while also enriching colonic microbial diversity, consistently stimulating saccharolytic genera, and reducing genera linked with potentially negative health effects in both regions of the colon. Mild immune modulatory effects of UPF were also observed. Colonic fermentation of UPF showed anti-inflammatory properties by inducing the secretion of the anti-inflammatory cytokines IL-6 and IL-10 in two out of three donors in the proximal and distal colon. In conclusion, UPF supplementation may provide significant gut health benefits. Full article

Background: Dietary fibre plays a crucial role in metabolic regulation, inflammation, and microbiome composition. However, its impact on systemic and oral health, particularly in periodontitis, remains unclear. This study investigated the effects of high- and low-fibre diets on body composition, glycaemic control, inflammation, microbiome, and metabolome in a murine model of experimental periodontitis. Methods: Thirty-six male C57BL/6 mice were randomised to a high-fibre (40% fibre) or low-fibre (5% fibre) diet for eight weeks. Body weight, fat mass, lean mass, fasting blood glucose, serum inflammatory markers, alveolar bone loss, and root length were assessed. Oral and faecal microbiome composition was analysed using 16S rRNA sequencing. Metabolomic and short-chain fatty acid (SCFA) profiling was conducted using liquid chromatography–mass spectrometry (LC-MS). Results: Mice on the high-fibre diet exhibited significantly lower body weight (p < 0.0001), fat mass (p = 0.0007), and lean mass (p < 0.0001) compared to the low-fibre group. Fasting blood glucose levels were significantly lower in the high-fibre group (p = 0.0013). TNF-α and IFN-γ levels were significantly elevated in the low-fibre group (p < 0.0001), suggesting a heightened pro-inflammatory state. While alveolar bone loss and root length did not differ significantly, microbiome analysis revealed distinct bacterial compositions (PERMANOVA, p < 0.05), with fibre-fermenting taxa enriched in high-fibre-fed mice. Metabolomic analysis identified 19 significantly altered metabolites, indicating dietary adaptations. Conclusions: A high-fibre diet improves glycaemic control, reduces systemic inflammation, and alters microbial and metabolic profiles in experimental periodontitis. These findings highlight dietary fibre’s role in modulating metabolic and inflammatory pathways relevant to periodontal and systemic diseases. Full article

Controlled fermentation carried out by selected starters might enhance the safety, nutritional, and biological profiles of non-dairy fermented products. This research aims to study the biological potential and impact on the human gut microbiota of a novel fermented finger millet-based product. Finger millet (Eleusine coracana), suspended in an aqueous sucrose-based solution, was fermented by Weissella confusa 2LABPT05 and Lactiplantibacillus plantarum 299v (1%, 1:1 ratio (v/v)), at 30 °C/200 rpm in an orbital incubator until pH ≈ 4.5–5.0. Microbial growth, phenolic compounds, antioxidant, and antidiabetic activities were evaluated. In vitro digestion followed by in vitro faecal fermentation were used to study the impact of the fermented plant-based functional beverage (PBFB) on the human gut microbiota. Antidiabetic activity (21% vs. 14%) and total phenolics (244 vs. 181 mg of gallic acid equivalents/kg PBFB) increased with fermentation. The digested fermented PBFB contributed to the increase, over the first 6 h, of the Bifidobacterium’s 16S rRNA gene copy numbers, concomitant with significant release of the acetic, propionic, and butyric short chain fatty acids, and also lactic acid. The novel PBFB has been shown to have antidiabetic potential and bifidogenic effects, and consequently its consumption might positively impact blood glucose levels and the human gut microbiota. Full article

Background: The human gut microbiota develops in concordance with its host over a lifetime, resulting in age-related shifts in community structure and metabolic function. Little is known about whether these changes impact the community’s response to microbiome-targeted therapeutics. Providing critical information on this subject, faecal microbiomes of subjects from six age groups, spanning from infancy to 70-year-old adults (n = six per age group) were harvested. The responses of these divergent communities to treatment with the human milk oligosaccharide 2’-fucosyllactose (2’FL), fructo-oligosaccharides (FOS), and lactose was investigated using the Ex vivo SIFR^® technology that employs bioreactor fermentation and is validated to be predictive of clinical findings. Additionally, it was evaluated whether combining faecal microbiomes of a given age group into a single pooled microbiome produced similar results as the individual microbiomes. Results: First, marked age-dependent changes in community structure were identified. Bifidobacterium levels strongly declined as age increased, and Bifidobacterium species composition was age-dependent: B. longum, B. catenulatum/pseudocatenulatum, and B. adolescentis were most prevalent for breastfed infants, toddlers/children, and adults, respectively. Metabolomic analyses (LA-REIMS) demonstrated that these age-dependent differences particularly impacted treatment effects of 2’FL (more than FOS/lactose). Further analysis revealed that while 2’FL enhanced production of short-chain fatty acids (SCFAs) and exerted potent bifidogenic effects, regardless of age, the specific Bifidobacterium species enhanced by 2’FL, as well as subsequent cross-feeding interactions, were highly age-dependent. Furthermore, single-pooled microbiomes produced results that were indicative of the average treatment response for each age group. Nevertheless, pooled microbiomes had an artificially high diversity, thus overestimating treatment responses (especially for infants), did not recapitulate interindividual variation, and disallowed for the correlative analysis required to unravel mechanistic actions. Conclusions: Age is an important factor in shaping the gut microbiome, with the dominant taxa and their metabolites changing over a lifetime. This divergence affects the response of the microbiota to therapeutics, demonstrated in this study using 2’FL. These results evidence the importance of screening across multiple age groups separately to provide granularity of how therapeutics impact the microbiome and, consequently, human health. Full article

Anorexia nervosa (AN) is a psychiatric illness with harmful physical consequences. Studies have observed differences in the faecal microbiota of patients with AN compared to healthy controls. Diet has an impact on the gut microbiota, facilitating an altered community, such changes could impact the gut–brain axis. In this study, a three-stage gut model system that mimics the luminal microbiology of the large intestine was conducted to identify relationships between diet and gut microbiota. A microbial medium was developed to provide nutrients more appropriate to restricting subtype AN (R-AN). The model was inoculated with faeces and samples were taken to compare differences in the microbiota and end products following the fermentation of healthy control medium (HC) compared to R-AN medium. Then, 16S amplicon sequencing along with flow cytometry–fluorescence in situ hybridisation were used to ascertain changes in the microbiota. Gas chromatography (GC) was used to assess changes in microbial metabolites. There were reduced levels of SCFA following the fermentation of R-AN medium. The fermentation of R-AN media led to fewer total bacteria numbers, along with less bifidobacteria and Rumincoccus proximally, but more Clostridium and Enterobacteriaceae. Nutrient-deficient medium resulted in reduced neurotransmitter-producing bacteria, reduced butyrate-producing bacteria, and increased protein-utilising bacteria, all of which could be maintaining factors in AN. The model system provides a novel tool for exploring how extreme dietary changes impact the microbiota and could therefore could be useful for assessing appropriate gut–brain targeted treatments. Full article

The rumen microbiota of dairy cows plays a crucial role in fermenting fibrous material, essential for nutrient extraction and overall productivity, detoxification of anti-nutritional toxic compounds, synthesis of vital nutrients, and is essential for optimal animal health. This study investigated the impact of Lentilactobacillus-, Lactocaseibacillus-, and Lacticaseibacillus-based direct-fed microbial (DFM) supplementation on dairy cows’ faecal microbial composition and diversity. The study was carried out on a commercial dairy farm using 50 Holstein-Friesian cows randomly assigned into control (CON) and treatment (TRT) groups. Faecal samples were collected directly from the rectum every two months from September 2021 to January 2023. The bacterial 16S rRNA gene and fungal ITS-1 regions were amplified, sequenced, and analysed. Microbial diversity was assessed through alpha- and beta-diversity metrics. Linear discriminant analysis effect size (LEfSe) was performed to identify which taxa were driving the changes seen in the microbiota over time and treatment. Bacteroidaceae were the most prevalent bacterial family, followed by Lachnospiraceae and Muribaculaceae in both CON and TRT cows. Ascomycota, Basidiomycota, and Mucoromycota were the dominant three fungal phyla in the faeces of both CON and TRT cows. Bacterial genera Fructilactobacillus was abundant in the CON and Absicoccus in the TRT groups. Fungal taxa Chaetothryriales_incertae_sedis and Pseudomentella were absent in the faeces of TRT cows. Significant temporal and specific taxonomic differences were observed between the CON and TRT groups. The study’s findings underscore the dynamic nature of microbial communities and the importance of targeted dietary interventions. Further research is necessary to elucidate these microbial shifts, long-term impacts, and functional implications, aiming to optimise ruminant nutrition and enhance dairy cow performance. Full article

Short-chain fatty acids (SCFAs) are produced by the fermentation of undigested polysaccharides; they are a group of metabolites resulting from the activity of intestinal bacteria. The main SCFAs are acetic, butyric, propionic, valeric, and caproic acid, and their levels and proportions depend on various factors. The aim of this study was to investigate the relationship between the concentration of SCFAs and the occurrence of specific gastrointestinal symptoms in infants. This study was conducted using faecal samples obtained at 1, 3, 6, and 12 months of age. The SCFA content was measured using gas chromatography. At 1 month, an association was found between butyric acid and flatulence. At 3 months, an association was found between butyric acid and flatulence/gas and between 3,4-methylovaleric acid and mucus in the stool. At 6 months, an association was found between butyric and valeric acids and flatulence. By 12 months, the gastrointestinal symptoms had decreased significantly. This study confirms that there is an association between SCFA levels and the presence of bloating, gas, mucus in the stool, and constipation in the gastrointestinal tract. Higher levels of butyric and valeric acids may lead to an increase in troublesome symptoms, such as flatulence and gas, in the first few months of life but are not associated with the occurrence of intestinal colic. The level of 3,4-methylovaleric acid is associated with the presence of allergies, whereas a decrease in acetic acid and an increase in isovaleric acid may exacerbate defecation problems in infants. Full article

Keeving is the removal of nutrients from apple musts due to their binding to pectin, resulting in a slower fermentation and spontaneous arrest. The aim of this study was to determine the effect of keeving on the chemical composition of fermented apple must and on the volatile profile and sensory analysis of apple brandies. We compared the application of keeving during spontaneous fermentation with fermentation carried out by Saccharomyces cerevisiae (SafSpirit HG-1). We evaluated the impact of adding different doses of calcium chloride on various parameters of fermented musts and distillates. Calcium chloride had a greater effect on the ethanol concentration, total extract, and fermentation efficiency than on the type of fermentation used. However, a different phenomenon was observed with respect to the volatiles. The concentration of most of the higher alcohols, acetaldehyde, dodecanal, and geranylaceton, decreased after spontaneous fermentation and increased during the fermentation carried out with Saccharomyces cerevisiae SafSpirit HG-1. In general, the application of keeving contributed to a decrease in the concentration of ethyl and methyl esters, but caused an increase in the concentration of all acetate esters and terpenoids. When the amount of nutrients in the environment is limited and starvation occurs, microorganisms use the available nutrients for basic metabolic processes that allow them to survive and limit the formation of side metabolites such as volatiles. However, most of the samples fermented after the faecal depletion achieved high scores for the floral, fruity, and “overall note” parameters in the sensory analysis. This means that this method, carried out with a properly selected yeast strain, could be feasible for the distilling industry. Full article

The effect of including micronised fibre sources (FS) differing in fermentability and hydration capacity (HC) on growth performance, faecal digestibility, and caecal fermentation was investigated in piglets. There were four dietary treatments: a control diet (CON) and three treatments differing in the HC and fermentability of FS added at 1.5% to prestarter (28–42 d) and starter (42–61 d) diets. These were: LHC (low-HC by-product-based insoluble fibre (IF) with a prebiotic fraction (PF) from chicory root); MHC (medium-HC by-product-based IF with a PF); and HHC (high-HC non-fermentable wood-based IF with no PF). There were eight replicates per treatment. Over the entire period, LHC and MHC piglets showed a 10% increase in daily growth and feed intake (p ≤ 0.019) and tended to have a reduced feed conversion ratio (p = 0.087) compared to HHC piglets. At 42 d, faecal protein digestibility increased by 5% in the LHC and MHC groups compared with the HHC group (p = 0.035) and did not differ from the CON group. Both LHC and MHC fibres were more fermented in vitro with caecal inocula from 61 d old piglets than HHC fibre (p ≤ 0.003). These results suggest that balanced soluble and insoluble fibre concentrates can improve piglet performance. Full article

The relationship between the gut microbiota and cognitive health is complex and bidirectional, being significantly impacted by our diet. Evidence indicates that polyphenols and inulin can impact cognitive function via various mechanisms, one of which is the gut microbiota. In this study, effects of a wild blueberry treatment (WBB) and enriched chicory inulin powder were investigated both in vitro and in vivo. Gut microbiota composition and metabolites, including neurotransmitters, were assessed upon faecal microbial fermentation of WBB and inulin in a gut model system. Secondly, microbiota changes and cognitive function were assessed in children within a small pilot (n = 13) trial comparing WBB, inulin, and a maltodextrin placebo, via a series of tests measuring executive function and memory function, with faecal sampling at baseline, 4 weeks post-intervention and after a 4 week washout period. Both WBB and inulin led to microbial changes and increases in levels of short chain fatty acids in vitro. In vivo significant improvements in executive function and memory were observed following inulin and WBB consumption as compared to placebo. Cognitive benefits were accompanied by significant increases in Faecalibacterium prausnitzii in the inulin group, while in the WBB group, Bacteroidetes significantly increased and Firmicutes significantly decreased (p < 0.05). As such, WBB and inulin both impact the microbiota and may impact cognitive function via different gut-related or other mechanisms. This study highlights the important influence of diet on cognitive function that could, in part, be mediated by the gut microbiota. Full article

Carotenoids, prominent lipid-soluble phytochemicals in the human diet, are responsible for vibrant colours in nature and play crucial roles in human health. While they are extensively studied for their antioxidant properties and contributions to vitamin A synthesis, their interactions with the intestinal microbiota (IM) remain poorly understood. In this study, beta (β)-carotene, lutein, lycopene, a mixture of these three pigments, and the alga Osmundea pinnatifida were submitted to simulated gastrointestinal digestion (GID) and evaluated on human faecal samples. The results showed varying effects on IM metabolic dynamics, organic acid production, and microbial composition. Carotenoid exposure influenced glucose metabolism and induced the production of organic acids, notably succinic and acetic acids, compared with the control. Microbial composition analysis revealed shifts in phyla abundance, particularly increased Pseudomonadota. The α-diversity indices demonstrated higher diversity in β-carotene and the pigments’ mixture samples, while the β-diversity analysis indicated significant dissimilarity between the control and the carotenoid sample groups. UPLC-qTOF MS analysis suggested dynamic changes in carotenoid compounds during simulated fermentation, with lutein exhibiting distinct mass ion fragmentation patterns. This comprehensive research enhances our understanding of carotenoid-IM interactions, shedding light on potential health implications and the need for tailored interventions for optimal outcomes. Full article

Background: The rapid production of gas during the colonic fermentation of highly soluble fermentable fibres may cause unpleasant gastrointestinal symptoms. In vivo feeding studies are often used to assess symptomatic response to fibres; however, in vitro fermentation studies are quicker, cheaper, and more reproducible. The aim of this study was to validate an in vitro colonic fermentation model of gas production against in vivo experiences of symptoms following inulin consumption. Methods: Healthy volunteers (n = 21, 18–65 y/o, M/F) provided a stool sample used to inoculate an in vitro colonic fermentation model. Fermentation bottles containing faecal slurry, a fermentation medium, and a fibre substrate (inulin) were incubated at 37 °C for 24 h in a shaking water bath. The total gas production (mL) over 24 h (minus control) was measured. Each stool donor added 15 g inulin to a low-fibre diet and recorded experiences of gastrointestinal symptoms for 48h. In vitro gas production and in vivo symptom experience were compared for each donor following tertile classification. Low in vitro gas production was classed as <45mL (<1st quartile of dataset), medium as 45–78 mL (1st quartile–3rd quartile), and high as >78 mL (>3rd quartile). In vivo symptom response was classed as low if symptoms were mild and/or short-lived (<1 h duration); medium if moderate and/or prolonged (1 h); and high when abdominal pain or multiple prolonged (3 h) symptoms occurred. Results: In vitro gas production was high in six cases (29%); medium in ten (48%); and low in five (24%). Symptom experience was high in seven cases (33%); medium in five (24%); and low in nine (43%). The same classification occurred in 57% of cases and classification into adjacent categories occurred in 43%; no complete misclassification occurred. Agreement between the methods was fair: weighted kappa = 0.378 (p < 0.01). Discussion: The level of agreement between the in vitro model of gas production and in vivo symptom reports, and the absence of any cases of complete misclassification, is promising. This simple in vitro batch-fermentation model may be used in future to screen fibres for their potential impact on gastrointestinal symptoms. This will help develop strategies to increase fibre consumption generally and optimise their use in food reformulation. Full article

Cystic Fibrosis-related gut dysbiosis (CFRGD) has become a recognised complication in children with this condition, and current evidence remains insufficient to guide the selection of probiotic strains for supplementation treatments. The aim of this study was to characterise the effect of three probiotic strains on CFRGD by means of a dynamic in vitro simulation of the colonic fermentation (SHIME^®). The configuration of the system included three bioreactors colonised with the faecal inoculum of a child with cystic fibrosis. For 20 days, each bioreactor was supplied daily with either Lacticaseibacillus rhamnosus GG (ATCC 53103 TM), Limosilactobacillus reuteri (DSM 17938) or Lactiplantibacillus plantarum (DSM 22266). The baseline microbiota was characterised by a high abundance of Prevotella, Faecalibacterium and Acidaminococcus genera. After 20 days of supplementation, L. rhamnosus and L. plantarum reduced Prevotella significantly, and the three strains led to increased Faecalibacterium and Bifidobacterium and decreased Acidaminococcus, with some of these changes being maintained 10 days after ceasing supplementation. The metabolic activity remained unaltered in terms of short-chain fatty acids, but branched-chain fatty acids showed a significant decrease, especially with L. plantarum. Additionally, ammonia decreased at 20 days of supplementation, and lactate continuously increased with the three strains. The effects on colonic microbiota of L. rhamnosus, L. reuteri or L. plantarum were established, including increased beneficial bacteria, such as Faecalibacterium, and beneficial metabolites such as lactate; and on the other hand, a reduction in pathogenic genera, including Prevotella or Acidaminococcus and branched-chain fatty acids, overall supported their use as probiotics in the context of CFRGD. Full article