Fecal Short-chain Fatty Acids Research Articles

Acupuncture for treating adolescent depression: Study protocol for a randomized controlled trial

The prevalence of depression among adolescents has been significantly increasing in recent years. However, current antidepressants for adolescents have limited safety and efficacy. Acupuncture has been shown to be effective in treating depression in adults, but there is a lack of high-quality evidence for its effect on the treatment of adolescent depression, and the underlying mechanism is still unclear. Therefore, we designed a randomized controlled trial to explore the effectiveness and the therapeutic mechanisms of acupuncture on adolescent depression. This study will be designed as a multi-center, sham and randomized controlled clinical trial. For this purpose, a total of 96 adolescent depression patients diagnosed with moderate and severe depression will be randomly divided into the manual acupuncture group and the sham one, respectively. The two groups received acupuncture treatment 3 times a week for a total course lasting 4 weeks. All patients will be assessed according to the primary outcomes including Beck Depression Inventory-II (BDI-II), Hamilton Depression Rating Scale (HAMD-24) and Zung self-rating depression scale (SDS) at baseline, week 2, 4 and 8. Additionally, the secondary outcomes will be assessed at baseline and week 4, which includes intestinal flora structure, fecal short chain fatty acids (SCFAs) content and serum serotonin (5-HT) level. This study is the first randomized trial of acupuncture treatment of adolescent depression. Trial registrationChinese Clinical Trial Registry, ChiCTR2200064359. Registered on October 4, 2022.

Fecal short chain fatty acids modify therapeutic effects of sleeve gastrectomy.

We aimed to investigate changes of fecal short chain fatty acids (SCFAs) and their association with metabolic benefits after sleeve gastrectomy (SG). Specifically, whether pre-surgery SCFAs modify surgical therapeutic effects was determined. 62 participants with measurements of fecal SCFAs and metabolic indices before and 1, 3, 6 months after SG were included. Changes of fecal SCFAs and their association with post-surgery metabolic benefits were calculated. Then, participants were stratified by medians of pre-surgery fecal SCFAs and modification effects of pre-surgery fecal SCFAs on surgical therapeutic effects were investigated, through calculating interaction of group by surgery. Fecal SCFAs were markedly changed by SG. Changes of propionate and acetate were positively correlated with serum triglycerides and total cholesterol, respectively. Notably, high pre-surgery fecal hexanoate group showed a better effect of SG treatment on lowering body weight (P=0.01), BMI (P=0.041) and serum triglycerides (P=0.031), and low pre-surgery fecal butyrate had a better effect of SG on lowering ALT (P=0.003) and AST (P=0.019). Fecal SCFAs were changed and correlated with lipid profiles improvement after SG. Pre-surgery fecal hexanoate and butyrate were potential modifiers impacting metabolic benefits of SG.

PSIX-3 A Veterinary Gastrointestinal Low-Fat Diet Affects Fecal Characteristics, Metabolites, Bile Acids, and Microbiota Concentrations of Antibiotic-Treated Dogs

Abstract In a recent dog study, the antibiotic metronidazole proved to be an effective disruptor of the fecal microbiota and resulted in looser stools and altered fecal bile acid (BA) profiles. Recovery took several weeks and was aided by a dietary supplement. The objective of this study was to determine how a veterinary gastrointestinal low-fat diet affected the fecal characteristics and metabolite, BA, and microbiota concentrations of dogs recovering from metronidazole administration. Twenty-four healthy adult dogs were used in an 8-wk completely randomized design study. The study began with a 2-wk baseline phase where all dogs consumed a leading grocery brand dry kibble diet (GBD; wk 0 to wk 2). Over the next 2 wk, dogs continued to consume GBD and received metronidazole (20 mg/kg BW; wk 2 to wk 4). At wk 4, dogs were randomly allotted to one of two treatments [GBD; Blue Buffalo Gastrointestinal Support Low-Fat (BB)] for the remaining 4 wk (wk 5 to wk 8). Fecal scores were recorded daily, and fresh fecal samples were collected at wk 2, 4, 5, 6, 7, and 8 for measurement of pH, dry matter, and metabolite and bile acid concentrations. Fecal microbiota populations were also analyzed by 16S rRNA sequencing and qPCR, which was used to calculate dysbiosis index. All data were analyzed as repeated measures using the Mixed Models procedure of SAS 9.4, with treatment treated as a fixed effect, dog as a random effect, and significance set at P < 0.05. As anticipated, metronidazole administration increased (P < 0.0001) fecal scores (looser stools) and drastically altered (P < 0.05) fecal metabolite concentrations, reducing fecal short-chain fatty acid (SCFA), branched-chain fatty acid (BCFA), phenol, and indole concentrations, increasing primary BA concentrations, and decreasing secondary bile acid concentrations. Metronidazole dramatically impacted fecal microbiota populations by reducing alpha diversity, altering the abundance of multiple bacterial taxa, and increasing dysbiosis index. Fecal outcome variables recovered over the next 4 wk, with some being impacted by diet. The change in fecal SCFA and immunoglobulin A concentrations were greater (P < 0.01), while the change in fecal BCFA, phenol, and indole concentrations were decreased (P < 0.05) in dogs fed BB. Dysbiosis index and alpha diversity measures recovered quickly for all dogs and without dietary effects. Recovery of over 25 bacterial genera were impacted by diet (P < 0.05). While many bacterial taxa returned to baseline levels after 4 wk, others had still not fully recovered. Fecal BA concentrations recovered quickly for all dogs. The change in lithocholic acid concentration was less (P < 0.0001) in dogs fed BB, but other BA concentrations were not affected by diet. In conclusion, metronidazole drastically alters the fecal microbiota and metabolites of dogs. While most variables return to normal over time, a veterinary gastrointestinal diet may aid in the recovery.

193 Apparent Total Tract Nutrient Digestibility of Frozen Raw, Freeze-Dried Raw, Fresh, and Extruded Dog Foods and Their Effects on Fecal Characteristics and Metabolites of Adult Dogs

Abstract Various pet food diet formats are now available. Processing methods are known to impact nutrient digestibility and are thought to affect pet health but are poorly studied. Therefore, the objective of this study was to determine the apparent total tract macronutrient digestibility (ATTD) of frozen raw, freeze-dried raw, fresh, and extruded dog foods and assess their effects on fecal characteristics, and fecal metabolites of healthy adult dogs. Ten healthy adult spayed female dogs were used in a replicated 5x5 Latin square study to test the following diets: Chicken and Barley Recipe [extruded diet; Hill’s Science Diet (EXT)], Chicken and White Rice Recipe [fresh diet; Just Food for Dogs (FRSH)], Chicken Formula [raw frozen diet; Primal (FRZN)], Chicken and Sorghum Hybrid Freeze-dried Formula [hybrid freeze-dried raw diet; Primal (HFD)], and Chicken Dinner Patties [raw freeze-dried diet; Stella & Chewy (FD)]. The experiment was composed of five 35-day periods. Total feces excreted during a 5-day total collection phase was frozen until analyses and ATTD calculations. On the first day of fecal collections, one fresh fecal sample was collected for measurement of pH, dry matter (DM) content, and bile acid (BA) and fermentative metabolite concentrations. Data were analyzed statistically by Mixed Models using SAS 9.4, with P < 0.05 being significant. Widespread differences were noted among diets. Wet and DM fecal output was greater for EXT than other diets, and wet fecal output was greater for FRSH than FRZN, HFD, and FD. Protein ATTD was greater for FRZN and FD than other diets, and greater for HFD than FRSH and EXT. Fat ATTD was greater for HFD than FRZN and EXT, and less for EXT than other diets. Fecal pH was less in EXT and FRSH than other diets. Fecal scores were greater (looser) in EXT and FRSH than FRZN and FRZDR. Fecal DM% was greater in FD than other diets, and greater in FRZN and HFD than EXT and FRSH. In general, fecal short-chain fatty acids were highest in EXT, intermediate in FRSH and HFD, and least in FRZN and FD. Fecal branched-chain fatty acids were greatest in FDF, intermediate in EXT, FRZN, and FD, and least for FRSH. Fecal phenols and indoles were greatest in HYB and least in FRSH, with others being intermediate. Fecal primary BA were greater in FRSH than other diets, while fecal secondary BA were greater in FRZN than HFD, FRSH, and EXT, greater in FD than FRSH and EXT, and greater in HFD than FRSH. In summary, the diets tested were very different in regard to nutrient digestibility, fecal characteristics, and fecal metabolites. More research is necessary to distinguish how ingredient source, diet processing, macronutrient composition, and other factors may contribute to these differences.

199 Effects of Dietary Fiber and Biotic Supplementation on Apparent Total Tract Macronutrient Digestibility, Fecal Characteristics, and Fecal Metabolites of Healthy Adult Dogs

Abstract Synbiotics, or mixtures of live microorganisms and substrates selectively utilized by host microorganisms, may confer complementary or synergistic health benefits to the host. Although synbiotics have demonstrated the potential to modulate the gut microbiome and improve gastrointestinal health in many host species, research trials in companion animal diets are limited. Therefore, this study was conducted to determine the apparent total tract macronutrient digestibility (ATTD) of diets supplemented with fibers or biotics and to evaluate their effects on the fecal characteristics, metabolites, microbiota, and immunoglobulin (Ig) A concentrations of dogs consuming them. Healthy adult female beagles (n = 12; age= 6.2 ± 1.6 yr; BW = 9.5 ± 1.1 kg) were used in a replicated 3 x 3 Latin square design to test three dietary treatments: 1) basal diet based on rice, chicken meal, tapioca starch, and cellulose and without probiotics or prebiotics + a placebo treat (control, CT); 2) diet based on rice, chicken meal, garbanzo beans, and cellulose + placebo treat (GB); 3) diet based on rice, chicken meal, and garbanzo beans, and functional fiber/prebiotic blend (mannanoligosaccharides; fructooligosaccharides, inulin, pea fiber, alfalfa meal, Saccharomyces cerevisiae fermentation product) + probiotic-containing treat (synbiotic treatment, SYN). The probiotic treat contained Bacillus subtilus and Bacillus amyloliquefaciens (2 x 109 CFU/d). In each 28-day period, a 22-day diet adaptation was followed by a 5-day fecal collection phase for measurement of ATTD and fecal characteristics, metabolites, microbiota, and IgA concentrations. Fasted blood samples were collected on day 28 for serum chemistry and complete blood count. All data were analyzed using the Mixed Models procedure of SAS 9.4, with P < 0.05 being significant. ATTD of dry matter (DM), organic matter, and energy were less and DM fecal output was greater in dogs fed SYN than those fed CT or GB, whereas ATTD of crude protein was greater in dogs fed CT and SYN than those fed GB. ATTD of fat was higher and wet fecal output was less in dogs fed CT than those fed GB or SYN. Fecal DM% was greater in dogs fed CT than those fed SYN or GB, and greater in dogs fed SYN than those fed GB. Fecal short-chain fatty acids (SCFA; acetate, propionate, total SCFA) were higher in dogs fed GB than those fed CT or SYN, and higher in dogs fed GB than those fed SYN. Fecal IgA concentrations were greater in dogs fed GB than those fed CT. Serum triglycerides were less in dogs fed GB than those fed SYN or CT. Our results demonstrate that legume-based dietary fibers, with or without prebiotics and probiotics, slightly reduce nutrient digestibility, increase stool output, beneficially shift fecal metabolites, and reduce blood lipids of adult dogs.

PSIX-4 A Veterinary Gastrointestinal Diet Affects Fecal Characteristics, Metabolites, Bile Acids, and Microbiota Concentrations of Antibiotic-Treated Cats

Abstract Antibiotics are often used to treat animals with gastrointestinal diseases or infections, but their use is known to have negative effects on the intestinal microbiota community. Identifying dietary strategies that may aid in the recovery from antibiotic use is of interest. The objective of this study was to determine how a veterinary gastrointestinal diet affected the fecal characteristics and metabolite, bile acid (BA), and microbiota concentrations of cats recovering from metronidazole administration. Twenty-four healthy adult cats were used in an 8-wk completely randomized design study. The study began with a 2-wk baseline phase where all cats consumed a leading grocery brand dry diet (GBD; wk 0 to wk 2). Over the next 2 wk, cats continued to consume GBD and received metronidazole (20 mg/kg BW; wk 2 to wk 4). At wk 4, cats were randomly allotted to one of two treatments [GBD; Blue Buffalo Gastrointestinal Support (BB)] for the remaining 4 wk (wk 5 to wk 8). Fecal scores were recorded daily, and fresh fecal samples were collected at wk 2, 4, 5, 6, 7, and 8 for measurement of pH, dry matter, and metabolite and BA concentrations. Fecal microbiota were analyzed by 16S rRNA sequencing and qPCR, which was used to calculate dysbiosis index. All data were analyzed as repeated measures using the Mixed Models procedure of SAS 9.4, with treatment treated as a fixed effect, cat as a random effect, and significance set at P< 0.05 and trends at P < 0.10. Metronidazole administration had dramatic effects on the outcomes measured, including increased fecal scores (looser stools), reduced fecal pH and dry matter %, reduced fecal short-chain fatty acid (SCFA), branched-chain fatty acid, ammonia, phenol, and indole concentrations, and altered fecal BA concentrations (increased primary BA; reduced secondary BA). Furthermore, fecal bacterial alpha diversity was reduced, dysbiosis index was increased, and the abundance of several individual bacterial taxa were altered. Fecal outcome variables partially recovered over the next 4 wk, with some being impacted by diet. The change in fecal acetate concentrations were greater and the change in total SCFA concentrations tended to be greater in cats fed BB. Dysbiosis index and alpha diversity measures slowly recovered over 4 wk, without differences due to diet. Recovery of about 20 bacterial genera were impacted by diet. Primary and secondary BA concentrations and ratios demonstrated a prolonged impairment of primary to secondary BA conversion. Most of these changes were an effect of time, but the change of fecal cholic acid concentrations were less in cats fed BB. In conclusion, our data demonstrate that metronidazole is a powerful antibiotic that has long-lasting effects on the fecal microbiota and metabolites of cats. The veterinary gastrointestinal diet tested aided in the recovery of some variables measured.

Fecal short-chain fatty acids in non-constipated irritable bowel syndrome: a potential clinically relevant stratification factor based on catabotyping analysis

ABSTRACT The gut microbiota is believed to be a critical factor in the pathogenesis of IBS, and its metabolic byproducts, such as short-chain fatty acids (SCFAs), are known to influence gut function and host health. Despite this, the precise role of SCFAs in IBS remains a topic of debate. In this study, we examined the bacterial community structure by 16S rRNA gene profiling and SCFA levels by UPLC-MS/MS in fecal samples from healthy controls (HC; n = 100) and non-constipated patients (IBS-D and IBS-M; NC-IBS; n = 240) enrolled in 19 hospitals in Italy. Our findings suggest a significant difference between the fecal microbiomes of NC-IBS patients and HC subjects, with HC exhibiting higher intra-sample biodiversity. Furthermore, we were able to classify non-constipated patients into two distinct subgroups based on their fecal SCFA levels (fecal catabotype “high” and “low”), each characterized by unique taxonomic bacterial signatures. Our results suggest that the fecal catabotype with higher SCFA levels may represent a distinct clinical phenotype of IBS that could have implications for its diagnosis and treatment. This study provides a new perspective on the intricate relationship between the gut microbiome and bowel symptoms in IBS, underscoring the importance of personalized strategies for its management.

Impaired gut microbiota-mediated short-chain fatty acid production precedes morbidity and mortality in people with HIV

Antiretroviral therapy (ART) has dramatically lengthened lifespan among people with HIV (PWH), but this population experiences heightened rates of inflammation-related comorbidities. HIV-associated inflammation is linked with an altered microbiome; whether such alterations precede inflammation-related comorbidities or occur as their consequence remains unknown. We find that ART-treated PWH exhibit depletion of gut-resident bacteria that produce short-chain fatty acids (SCFAs)-crucial microbial metabolites with anti-inflammatory properties. Prior reports establish that fecal SCFA concentrations are not depleted in PWH. We find that gut-microbiota-mediated SCFA production capacity is better reflected in serum than in feces and that PWH exhibit reduced serum SCFA, which associates with inflammatory markers. Leveraging stool and serum samples collected prior to comorbidity onset, we find that HIV-specific microbiome alterations precede morbidity and mortality in ART-treated PWH. Among these microbiome alterations, reduced microbiome-mediated conversion of lactate to propionate precedes mortality in PWH. Thus, gut microbial fiber/lactate conversion to SCFAs may modulate HIV-associated comorbidity risk.

Low Short-Chain-Fatty-Acid-Producing Activity of the Gut Microbiota Is Associated with Hypercholesterolemia and Liver Fibrosis in Patients with Metabolic-Associated (Non-Alcoholic) Fatty Liver Disease

The aim of this study was to investigate the short-chain fatty acid (SCFA) activity of the gut microbiota of patients with metabolic-associated fatty liver disease (MAFLD). The level and spectrum of short-chain fatty acids (SCFAs) were determined via gas–liquid chromatography. Liver fibrosis was assessed using the FIB-4 index and elastography. Among 42 non-cirrhotic MAFLD patients, 24 had high fecal SCFA levels (group H) and 18 had low fecal SCFA levels (group L). Patients in group H had lower serum uric acid, total cholesterol, and LDL cholesterol levels but a higher BMI than those in group L. All patients in group L and only 37.9% of those in group H were found to have hypercholesterolemia. In patients with hypercholesterolemia, the level of SCFAs was lower than that in patients without hypercholesterolemia. Patients in group H had less liver fibrosis than patients in group L. A total of 50.0% of the patients in group H and 92.3% of those in group L had significant liver fibrosis (≥F2). Patients with significant liver fibrosis had lower levels of fecal SCFAs—particularly acetate and butyrate. The fecal SCFA levels were positively correlated with gamma-glutamyl transferase, total bilirubin levels, BMI, and platelet count and were negatively correlated with FIB-4, liver stiffness, serum total, and LDL cholesterol levels.

32 Effect of Probiotics Supplementation Level on Growth Performance, Blood Parameters and Fecal Metabolites in Nursery Pigs

Abstract This experiment was conducted to evaluate the effects of dietary supplementation level of probiotics on growth performance, blood variables, and fecal metabolites in nursery pigs. Certain strains of Bacillus subtilis have been shown to reduce the incidence and severity of diarrhea and therefore improve growth performance of nursery pigs. A total of 54 newly weaned piglets were allotted to 3 treatments in 3 replicates with 6 pigs per pen based on body weight, gender, and breed for a 28-d feeding trial. Treatments were: 1) Control: no probiotics supplementation, 2) CERTILLUS 1x: probiotics supplementation at the recommended level, and 3) CERTILLUS 10x: probiotics supplementation at 10 times the recommended level. The CERTILLUS products consisted of two strains of Bacillus subtilis at a low and a high dose of 3.75 × 108 CFU/g and 3.75 × 109 CFU/g supplemented at 0.05% resulting in 1.875 × 105 CFU/g diet and 1.875 × 106 CFU/g diet for the 1x and 10x treatments, respectively. Corn-soybean meal-based diets were used for d 0-14 (Phase 1) and d 14-28 (Phase 2) postweaning. Body weight, blood glucose and creatinine, fecal short chain fatty acid (SCFA) and bile acid concentrations were measured at d 14 and 28 postweaning. Body weight at d 14 postweaning (P = 0.06; 11.98, 12.73, and 12.21 kg for the control, 1x, and 10x treatments, respectively) and average daily gain for d 0 to 14 postweaning (P < 0.05; 0.206, 0.259, and 0.222 kg/d, respectively) were greater in the 1x treatment than the control and 10x treatments although there was no significant difference in growth performance at d 28 postweaning. Blood glucose concentrations were greater in both probiotic treatments than the control treatment at d 14 postweaning (P < 0.05; 95.2, 111.7 and 114.3 mg/dL for the control, 1x, and 10x treatments, respectively). In the fecal SCFA concentrations, the butyrate concentrations were greater in the 1x treatment than the control and 10x treatments (P < 0.05; 36.17, 47.57, and 33.23 µmol/g feces for the control, 1x, and 10x treatments, respectively) and the acetate (120.02, 141.87, and 101.17 µmol/g feces, respectively), propionate (62.95, 71.42 and 55.27 µmol/g feces, respectively), and total SCFA (236.72, 282.23, and 205.80 µmol/g feces, respectively) concentrations were greater in the 1x treatment than the 10x treatment with the intermediate value in the control treatment (P < 0.05). There were no significant differences in fecal bile acid concentrations and blood creatinine concentrations at both d 14 and 28 postweaning. In conclusion, dietary probiotics supplementation to nursery diets at the recommended level could improve growth rate in the early postweaning period and increase fecal SCFA concentrations but not at a high level of supplementation.

Fecal microbiota transplantation and short-chain fatty acids improve learning and memory in fluorosis mice by BDNF-PI3K/AKT pathway

Fluoride, an environmental toxicant, not only arouses intestinal microbiota dysbiosis, but also causes neuronal apoptosis and a decline in learning and memory ability. The purpose of this study was to explore whether fecal microbiota transplantation (FMT) from healthy mice and bacteria-derived metabolites short-chain fatty acids (SCFAs) supplement protect against fluoride-induced learning and memory impairment. Results showed that FMT reversed the elevated percentage of working memory errors (WME) and reference memory errors (RME) in fluorosis mice during the eight-arm maze test. Nissl and TUNEL staining presented that fluoride led to a decreased proportion of Nissl bodies area in the hippocampal CA3 region and an increased apoptotic ratio of nerve cells in CA1, CA3 and DG areas, whereas FMT alleviated those pathological damages. Moreover, the expressions of mRNA in hippocampal BDNF, PDK1, AKT, Bcl-2, and Bcl-xL were downregulated in mice exposed to fluoride, but the levels of PI3K, Bax, Bak, and Caspase-7 mRNA were upregulated. NaF treatment had an increase in PI3K and Caspase-3 protein levels and reduced the expressions of these four proteins, including BDNF, p-PI3K, AKT and p-AKT. By contrast, FMT enhanced the expression of BDNF and thus activated the PI3K/AKT pathway. Besides, the 16S rRNA sequencing revealed that fluoride caused a reduction in certain SCFA producers in the colon as evidenced by a decline in Erysipelatoclostridiaceae, and a downward trend in Akkermansia, Blautia and Alistipes. However, the disordered gut microbiome was restored via frequent FMT. Of note, SCFAs administration also increased BDNF levels and regulated its downstream pathways, which contributed to cell survival and learning and memory function recovery. In conclusion, FMT and SCFAs may activate the BDNF-PI3K/AKT pathway to play an anti-apoptotic role and ultimately improve learning and memory deficits in fluorosis mice.

Influence of Brown or Germinated Brown Rice Supplementation on Fecal Short-Chain Fatty Acids and Microbiome in Diet-Induced Insulin-Resistant Mice.

Intake of whole grain foods is associated with improving metabolic profile compared to refined grain products, but the underlying mechanism remains unclear. The present study examined the effects of brown rice (BRR) or germinated brown rice (GBR) supplementation on fecal short-chain fatty acids (SCFAs), and relationship with gut microbiota, metabolism and inflammation in high fat (HF)-diet-fed mice. The results demonstrated that an HF diet supplemented with BRR or GBR comparably increased the abundance of fecal isobutyric acid compared to that in mice receiving HF+white rice (WHR) diet (p < 0.01). The abundance of valeric acid in HF+GBR-diet-fed mice was higher than those receiving HF+WHR diet (p < 0.05). The abundances of fecal isobutyric acid negatively correlated with fasting plasma glucose, insulin, cholesterol, triglycerides, tumor necrosis factor-α, plasminogen activator inhibit-1, monocyte chemotactic protein-1 and homeostatic model assessment of insulin resistance (p < 0.01). The abundance of valeric acids negatively correlated with insulin resistance (p < 0.05). The abundances of isobutyric acid positively correlated with Lactobacillus, but negatively correlated with Dubosiella genus bacteria (p < 0.05). The findings demonstrated that the increases in SCFAs in the feces of BRR and GBR-treated mice were associated with improvements in gut microbiome, metabolic and inflammatory profile, which may contribute to the antidiabetic and anti-inflammatory effects of the whole grains in HF-diet-fed mice.

Age and severity-dependent gut microbiota alterations in Tunisian children with autism spectrum disorder

Alterations in gut microbiota and short chain fatty acids (SCFA) have been reported in autism spectrum disorder (ASD). We analysed the gut microbiota and fecal SCFA in Tunisian autistic children from 4 to 10 years, and results were compared to those obtained from a group of siblings (SIB) and children from the general population (GP). ASD patients presented different gut microbiota profiles compared to SIB and GP, with differences in the levels of Bifidobacterium and Collinsella occurring in younger children (4–7 years) and that tend to be attenuated at older ages (8–10 years). The lower abundance of Bifidobacterium is the key feature of the microbiota composition associated with severe autism. ASD patients presented significantly higher levels of propionic and valeric acids than GP at 4–7 years, but these differences disappeared at 8–10 years. To the best of our knowledge, this is the first study on the gut microbiota profile of Tunisian autistic children using a metataxonomic approach. This exploratory study reveals more pronounced gut microbiota alterations at early than at advanced ages in ASD. Although we did not account for multiple testing, our findings suggest that early interventions might mitigate gut disorders and cognitive and neurodevelopment impairment associated to ASD.

A low-carb diet increases fecal short-chain fatty acids in feces of obese women following a weight-loss program: randomized feeding trial

To compare fecal level of short-chain fatty acid (SCFA) and some serum inflammatory markers between the low-carbohydrate (LCD) and the habitual (HD) diet, subjects were enrolled from our previous study on the effect of LCD vs. HD on gut microbiota in obese women following an energy-restricted diet. Serum interleukin-6 (IL-6) significantly increased in the HD group (p < 0.001). Adjusted for the baseline parameters, fecal level of butyric, propionic, and acetic acid were significantly different between the LCD and HD groups (p < 0.001, p = 0.02, and p < 0.001, respectively). Increase in serum insulin level correlated with decrease in fecal propionic acid by 5.3-folds (95% CI = − 2.7, − 0.15, p = 0.04). Increase in serum high sensitive C-reactive protein (hs-CRP) correlated with decrease in the percentage of fecal butyric acid by 25% (p = 0.04). Serum fasting blood sugar (FBS) and insulin showed a significant effect on fecal acetic acid (p = 0.009 and p = 0.01, respectively). Elevated serum FBS and insulin correlated with increase in fecal acetic acid by 2.8 and 8.9-folds (95%CI = 0.34, 1.9 and 1.2, 9.2), respectively. The LCD increased fecal SCFAs and a significant correlation was seen between serum IL-6 and fecal propionic acid level. More studies are needed to reach a concise correlation.Trial registration number: The trial was registered in Iranian ClinicalTrials.gov IRCT20200929048876N3.

An Improved Validated Method for the Determination of Short-Chain Fatty Acids in Human Fecal Samples by Gas Chromatography with Flame Ionization Detection (GC-FID).

Short-chain fatty acids (SCFAs) are metabolites produced by the gut microbiota through the fermentation of non-digestible carbohydrates. Recent studies suggest that the gut microbiota composition, diet and metabolic status play an important role in the production of SCFAs. The primary objective of this study was to develop a simplified method for SCFA analysis in human fecal samples by gas chromatography with flame ionization detection (GC-FID). The secondary objective was to apply the method to fecal samples collected from a clinical trial. The developed GC-FID method showed excellent linearity (R2 > 0.99994), with a limit of detection (LOD) ranging from 0.02 to 0.23 µg/mL and a limit of quantification (LOQ) ranging from 0.08 to 0.78 µg/mL. Recovery for the method ranged between 54.24 ± 1.17% and 140.94 ± 2.10%. Intra- and inter-day repeatability ranged from 0.56 to 1.03 and from 0.10 to 4.76% RSD, respectively. Nine SCFAs were identified and quantified (acetic, propionic, iso-butyric, butyric, iso-valeric, valeric, 4-methyl valeric, hexanoic and heptanoic acids) in freeze-dried fecal samples. The clinical trial compared participants with prediabetes mellitus and insulin resistance (IR-group, n = 20) to metabolically healthy participants (reference group, R-group, n = 9) following a 4-week intervention of a daily red raspberry smoothie (RRB, 1 cup fresh-weight equivalent) with or without fructo-oligosaccharide (RRB + FOS, 1 cup RRB + 8 g FOS). The statistical analysis (Student's t-test, ANCOVA) was performed on PC-SAS 9.4 (SAS Institute). Acetic acid was higher in the R-group compared to the IR-group at baseline/week 0 (p = 0.14). No significant changes in fecal SCFA content were observed after 4 weeks of either RRB or RRB + FOS.

Cholecystectomy Significantly Alters Gut Microbiota Homeostasis and Metabolic Profiles: A Cross-Sectional Study.

Cholecystectomy (CCE) is a standard clinical treatment for conditions like gallstones and cholecystitis. However, its link to post-CCE syndrome, colorectal cancer, and nonalcoholic fatty liver disease has raised concerns. Additionally, studies have demonstrated the disruptive effects of CCE on gut microbiota homeostasis and bile acid (BA) metabolism. Considering the role of gut microbiota in regulating host metabolic and immune pathways, the use of dietary and probiotic intervention strategies to maintain a stable gut ecosystem after CCE could potentially reduce associated disease risks. Inter-study variations have made it challenging to identify consistent gut microbiota patterns after CCE, a prerequisite for targeted interventions. In this study, we first meta-analyzed 218 raw 16S rRNA gene sequencing datasets to determine consistent patterns of structural and functional changes in the gut microbiota after CCE. Our results revealed significant alterations in the gut microbiota's structure and function due to CCE. Furthermore, we identified characteristic gut microbiota changes associated with CCE by constructing a random model classifier. In the validation cohort, this classifier achieved an area under the receiver operating characteristic curve (AUC) of 0.713 and 0.683 when distinguishing between the microbiota of the CCE and healthy groups at the family and genus levels, respectively. Further, fecal metabolomics analysis demonstrated that CCE also substantially modified the metabolic profile, including decreased fecal short-chain fatty acid levels and disrupted BA metabolism. Importantly, dietary patterns, particularly excessive fat and total energy intake, influenced gut microbiota and metabolic profile changes post-CCE. These dietary habits were associated with further enrichment of the microbiota related to BA metabolism and increased levels of intestinal inflammation after CCE. In conclusion, our study identified specific alterations in gut microbiota homeostasis and metabolic profiles associated with CCE. It also revealed a potential link between dietary patterns and gut microbiota changes following CCE. Our study provides a theoretical basis for modulating gut microbiota homeostasis after CCE using long-term dietary strategies and probiotic interventions.

Gastrointestinal Fermentable Polysaccharide Is Beneficial in Alleviating Loperamide-Induced Constipation in Mice.

To investigate the role of gastrointestinal (GI) polysaccharide fermentation in alleviating constipation, two polysaccharide fractions were isolated from a soluble fiber extract with determined anti-constipation activity: a 2.04 kDa neutral fraction (SSP-1) contained 99.29% glucose, and a 41.66 kDa acidic fraction (SSP-2) contained 63.85% uronic acid. After mice were given loperamide for 14 d to induce constipation, the GI transit rate increased significantly in the SSP-1 group (p < 0.05) but not in the SSP-2 group. The stool weight in the SSP-2 group was significantly higher than that in SSP-1 (383.60 mg vs. 226.23 mg) (p < 0.05). Both SSP-1 and SSP-2 groups had significantly increased serum gastrin and motilin levels (p < 0.05) and changes in their fecal short-chain fatty acid (SCFA) profiles, while SSP-1 showed better fermentation properties than SSP-2 in terms of statistically higher fecal contents of acetic acid and total SCFAs (p < 0.05). Bioinformatic analysis indicated that SSP-1 upregulated bacteria such as Oscillibacter to improve SCFA metabolism and stimulate GI hormone secretion, while SSP-2 had less influence on the gut microbiota. These results suggest that the neutral polysaccharide with superior GI fermentation properties exerted beneficial effects on constipation, while the less fermentable pectic fraction might act as a stool-bulking agent.

FRI010 Human Gut Microbiota And Metabolic Profiles Are Associated With Obesity In Five African-Origin Populations

Abstract Disclosure: J. Jorgensen: None. C. Choo-Kang: None. G. Ecklu-Mensah: None. J. Gilbert: None. A. Luke: None. K. Bedu-Addo: None. T.E. Forrester: None. P. Bovet: None. E.V. Lambert: None. D. Rae: None. L. Dugas: None. Y. Dai: None. B.T. Layden: None. Obesity is a global public health crisis, which since 1975 has tripled world-wide. Concomitantly, obesity-related conditions such as cardiovascular disease, stroke, and type 2 diabetes have also increased. An accepted common obesogenic factor has been a shift away from fiber-rich diets to ultra-processed foods. Fiber is digested by the gut microbiota, resulting in the production of short-chain fatty acids (SCFAs), and diets that are rich in fiber are associated with greater microbial diversity and increased serum and fecal SCFA levels. Yet, the mechanistic link between dietary fiber and improved metabolic outcomes, via SCFAs, is not clearly defined. We analyzed data from a large ongoing prospective study of African-origin adults from 5 countries (Ghana, South Africa, Jamaica, Seychelles &amp; US), each with distinct dietary fiber intakes. Standard methods were used to assess taxonomy, Shannon alpha diversity and beta diversity, as well as taxonomic differences by fecal SCFA levels as a proxy for fiber intake. Thereafter, microbiota taxa were used to predict functional metabolite profiles, as well as the metabolic pathway abundances to identify differential metabolites correlated with SCFA levels. These profiles and pathways were correlated with SCFA levels within and between sites. As microbes interact and impact each other, we constructed differential microbial co-occurrence networks to identify hub species and differences in community configuration across sites comparing SCFA levels via Network Construction and comparison for Microbiome data (NetCoMi). The final sample included 1904 participants (age=42.57±8.04 yr). The mean BMI was lowest in Ghana (BMI=26.72±5.88 kg/m2), and highest in the US (BMI=34.42±9.06 kg/m2) with a p-value &amp;lt; 2.2e-16. Conversely, diets in Ghana had the highest fiber intake resulting in the highest fecal SCFA levels (8026.97±2605.38 µg/g) which was significantly greater than US SCFA levels (p-value &amp;lt; 2e-16). Not surprisingly, differences in microbial diversity were unique to each site as well as adiposity levels. Overall, non-obese individuals had a higher proportion of Prevotella, Allaprevotella compared to obese individuals who had higher proportions of Firmicutes. Prevotella and Allaprevotella are known SCFAs producers and previously shown to be anti-inflammatory in the gut, while Firmicutes are positively correlated with gut inflammation. We provide evidence that fiber-rich diets may act through the anti-inflammatory pathways associated with the gut microbiota in humans. Future research should elucidate the gut microbial mediated anti-inflammatory effects and the metabolic pathways to develop novel anti-inflammatory therapeutics. Presentation: Friday, June 16, 2023

Fecal short chain fatty acids and urinary 3-indoxyl sulfate do not discriminate between patients with Crohn´s disease and ulcerative colitis and are not of diagnostic utility for predicting disease severity

BackgroundUrinary 3-indoxyl sulfate levels as well as fecal short chain fatty acid (SCFA) concentrations are surrogate markers for gut microbiota diversity. Patients with inflammatory bowel diseases (IBDs) and patients with primary sclerosing cholangitis (PSC), a disease closely associated with IBD, have decreased microbiome diversity. In this paper, the fecal SCFAs propionate, acetate, butyrate and isobutyrate of patients with IBD and patients with PSC-IBD and urinary 3-indoxyl sulfate of IBD patients were determined to study associations with disease etiology and severity.MethodsSCFA levels in feces of 64 IBD patients and 20 PSC-IBD patients were quantified by liquid chromatography with tandem mass spectrometry (LC–MS/MS). Urinary 3-indoxyl sulfate levels of 45 of these IBD patients were analysed by means of reversed-phase liquid chromatography-electrospray ionization-tandem mass spectrometry. Feces of 17 healthy controls and urine of 13 of these controls were analyzed in parallel. These cohorts had comparable sex distribution and age.ResultsUrinary 3-indoxyl sulfate concentrations (normalized to urinary creatinine levels) was increased (P = 0.030) and fecal isobutyrate levels (normalized to dry weight of the stool sample) of IBD patients were decreased (P = 0.035) in comparison to healthy controls. None of the analyzed metabolites differed between patients with Crohn´s disease (CD) and patients with ulcerative colitis (UC). Fecal acetate and butyrate positively correlated with fecal calprotectin (P = 0.040 and P = 0.005, respectively) and serum C-reactive protein (P = 0.024 and P = 0.025, respectively) in UC but not CD patients. UC patients with fecal calprotectin levels above 150 µg/g, indicating intestinal inflammatory activity, had higher fecal acetate (P = 0.016), butyrate (P = 0.007) and propionate (P = 0.046) in comparison to patients with fecal calprotectin levels < 50 µg/g. Fecal SCFA levels of PSC-IBD and IBD patients were comparable.ConclusionsCurrent findings suggest that analysis of urinary 3-indoxyl-sulfate as well as fecal SCFAs has no diagnostic value for IBD and PSC-IBD diagnosis or monitoring of disease severity.

Effect of esomeprazole with and without a probiotic on fecal dysbiosis, intestinal inflammation, and fecal short-chain fatty acid concentrations in healthy dogs.

Proton pump inhibitors can cause diarrhea and a transient increase in fecal dysbiosis index in dogs. It is unknown if concurrent probiotic administration mitigates these effects. To assess the fecal Canine Microbial Dysbiosis Index (CMDI), fecal short chain fatty acid (SCFA), and fecal calprotectin concentrations in dogs administered esomeprazole with and without a probiotic. Eleven healthy dogs. Prospective, within-subjects before and after study. All dogs received 7-day courses of esomeprazole (1 mg/kg PO q 24h) alone followed by esomeprazole with a probiotic (15 billion CFU/kg), separated by a 4-week washout period. Data were compared between phases using mixed effects ANOVA or generalized estimating equations with post-hoc Holm adjustment for 2-way comparisons. Compared to baseline (mean CMDI -2.66, SD 3.04), fecal CMDI was not different with esomeprazole administration alone (mean CMDI -1.48, SD 3.32, P = .08), but there was a significant increase (Diff 3.05, 95% CI [1.37, 4.74], P < .001, Effect size 2.02) when esomeprazole and a probiotic were administered concurrently (mean CMDI 0.39, SD 2.83). CMDI was significantly higher when esomeprazole was administered with a probiotic than alone (Diff 1.87, 95% CI [0.19, 1.87], P = .02, Effect size 1.24). Fecal calprotectin and SCFA concentrations did not differ between phases. The occurrence of vomiting and diarrhea was not different from baseline when esomeprazole was administered alone (36%/27%) or with a probiotic (46%/9%). In healthy dogs, concurrent administration of a probiotic is unlikely to lessen adverse effects associated with esomeprazole administration.