Effects of Heat-Treated Lactobacillus helveticus CP790-Fermented Milk on Gastrointestinal Health in Healthy Adults: A Randomized Double-Blind Placebo-Controlled Trial.

Probiotic-fermented milk is commonly used to maintain intestinal health. However, the effects of heat-treated fermented milk, which does not contain live microorganisms, on intestinal function are not yet fully understood. This study aimed to investigate whether heat-treated Lactobacillus helveticus CP790-fermented milk affects fecal microbiota and gut health as a "postbiotic". A randomized, double-blind, placebo-controlled trial was conducted in healthy Japanese individuals aged 20-59 years with a tendency toward constipation. Participants consumed 100 mL of either the test beverage (n = 60) or placebo beverage (n = 60) for four weeks. The test beverages were prepared with heat-treated CP790-fermented milk, while the placebo beverages were prepared with nonfermented milk flavored with lactic acid. Fecal samples were analyzed using 16S rRNA gene sequencing. Constipation symptoms were assessed using defecation logs and the Patient Assessment of Constipation Symptoms (PAC-SYM) questionnaire. Mood state was also assessed using the Profile of Mood States 2 (POMS2) questionnaire to explore its potential as a "psychobiotic". Desulfobacterota were significantly decreased by CP790-fermented milk intake. PICRUSt2 analysis predicted a decrease in the proportion of genes involved in the sulfate reduction pathway following the consumption of CP790-fermented milk. The CP790-fermented milk intervention significantly improved stool consistency and straining during defecation. These improvements were correlated with a decrease in Desulfobacterota. After the intervention, overall mood, expressed as total mood disturbance, and depression-dejection were significantly better in the CP790 group than in the placebo group. These results suggest that the intake of CP790-fermented milk could be effective in modulating gut microbiota and improving constipation symptoms and mood states.

Effects of Prebiotic Yeast Mannan on Gut Health and Sleep Quality in Healthy Adults: A Randomized, Double-Blind, Placebo-Controlled Study.

Human gut health is closely related to sleep. We aimed to evaluate the efficacy of yeast mannan (YM) in improving bowel habits and sleep quality, along with metabolomics in fecal samples. A total of 40 healthy adults (age range, 22-64 years) with discomfort in defecation were enrolled and randomly allocated to receive either YM (n = 20; 1.1 g/day) or placebo (n = 20) for four weeks. Participants recorded their defecation habits throughout the test periods. Sleep electroencephalogram (EEG) recording using an EEG device and fecal sampling were performed pre- and post-treatment. The YM group significantly increased defecation frequency and stool volumes compared to the placebo group. After 4 weeks of treatment, the non-REM sleep stage 3 (N3) duration in the YM group was significantly higher than that in the placebo group. YM ingestion significantly lengthened total time in bed (TIB) and significantly shortened N3 latency compared to placebo intake during the trial. The metabolomics analysis found a total of 20 metabolite differences between the YM and placebo groups. As a result of stepwise linear regression, changes in fecal propionate and gamma-aminobutyric acid (GABA) levels were identified as the primary factors explaining changes in TIB and N3 latency, respectively. Our findings suggest that the prebiotic YM could be beneficial to gut health and sleep quality.

Effects of Yeast Mannan Which Promotes Beneficial Bacteroides on the Intestinal Environment and Skin Condition: A Randomized, Double-Blind, Placebo-Controlled Study.

Yeast mannan (YM) is an indigestible water-soluble polysaccharide of the yeast cell wall. In vitro fecal fermentation studies showed that YM could exhibit a notable prebiotic effect. The aim of this randomized, double-blind, placebo-controlled study was to assess the efficacy of YM intake on the intestinal environment and skin condition. One hundred and ten healthy female subjects aged 30-49 years were supplemented with YM or placebo for eight weeks. Skin dryness was set as the primary endpoint. No side effects were observed during the study. Microbiota analyses revealed that YM intake selectively increased the relative abundance of Bacteroides thetaiotaomicron and Bacteroides ovatus compared to that by placebo. Feces and urine analyses showed that YM intake lowered the concentration of fecal p-cresol, indole, and skatole, and elevated urinal equol levels compared to those in placebo. Furthermore, YM supplementation ameliorated subjective skin dryness. This study suggests that YM intake could promote beneficial Bacteroides and improve the intestinal environment and skin condition.

Prebiotic effects of yeast mannan, which selectively promotes Bacteroides thetaiotaomicron and Bacteroides ovatus in a human colonic microbiota model.

Yeast mannan (YM) is an indigestible water-soluble polysaccharide of the yeast cell wall, with a notable prebiotic effect on the intestinal microbiota. We previously reported that YM increased Bacteroides thetaiotaomicron abundance in in vitro rat faeces fermentation, concluding that its effects on human colonic microbiota should be investigated. In this study, we show the effects of YM on human colonic microbiota and its metabolites using an in vitro human faeces fermentation system. Bacterial 16S rRNA gene sequence analysis showed that YM administration did not change the microbial diversity or composition. Quantitative real-time PCR analysis revealed that YM administration significantly increased the relative abundance of Bacteroides ovatus and B. thetaiotaomicron. Moreover, a positive correlation was observed between the relative ratio (with or without YM administration) of B. thetaiotaomicron and B. ovatus (r = 0.92), suggesting that these bacteria utilise YM in a coordinated manner. In addition, YM administration increased the production of acetate, propionate, and total short-chain fatty acids. These results demonstrate the potential of YM as a novel prebiotic that selectively increases B. thetaiotaomicron and B. ovatus and improves the intestinal environment. The findings also provide insights that might be useful for the development of novel functional foods.

Yeast mannan increases Bacteroides thetaiotaomicron abundance and suppresses putrefactive compound production in in vitro fecal microbiota fermentation.

Yeast mannan is a part of yeast cell wall and can potentially affect gut microflora as a soluble dietary fiber. We demonstrated that yeast mannan suppressed putrefactive production and increased the relative abundance of Bacteroides thetaiotaomicron in in vitro fecal fermentation. These results suggest that yeast mannan can be used as a novel prebiotic food ingredient.