-
1.
Effect of prebiotics, probiotics, synbiotics on depression: results from a meta-analysis.
Zhang, Q, Chen, B, Zhang, J, Dong, J, Ma, J, Zhang, Y, Jin, K, Lu, J
BMC psychiatry. 2023;23(1):477
-
-
-
Free full text
Plain language summary
Major depressive disorder (MDD) is a mood disorder that impairs psychosocial function and quality of life. Recent studies show that prebiotics, probiotics, and synbiotics reveal a novel way to treat psychiatric disorders such as depression through the microbiota-gut-brain axis. The aim of this study was to evaluate the effectiveness of prebiotics, probiotics and synbiotics in alleviating depressive symptoms. This study was a meta-analysis of thirteen studies with a total of 786 participants who were allocated to the intervention group (n=427) and the placebo group (n=359). Results showed that the overall effects of probiotics, prebiotics and synbiotics on depressive symptoms were significantly superior to those of placebo. Additionally, biological sex was a vital factor that influenced patients’ responses to the treatment. Authors concluded that agents that manipulate gut microbiota might become a novel approach to treat patients with mild-to-moderate depression.
Abstract
Accumulating studies have shown the effects of gut microbiota management tools in improving depression. We conducted a meta-analysis to evaluate the effects of prebiotics, probiotics, and synbiotics on patients with depression. We searched six databases up to July 2022. In total, 13 randomized controlled trials (RCTs) with 786 participants were included. The overall results demonstrated that patients who received prebiotics, probiotics or synbiotics had significantly improved symptoms of depression compared with those in the placebo group. However, subgroup analysis only confirmed the significant antidepressant effects of agents that contained probiotics. In addition, patients with mild or moderate depression could both benefit from the treatment. Studies with a lower proportion of females reported stronger effects for alleviating depressive symptoms. In conclusion, agents that manipulate gut microbiota might improve mild-to-moderate depression. It is necessary to further investigate the benefits of prebiotic, probiotic and synbiotic treatments relative to antidepressants and follow up with individuals over a longer time before these therapies are implemented in clinical practice.
-
2.
Effects of dietary fibers or probiotics on functional constipation symptoms and roles of gut microbiota: a double-blinded randomized placebo trial.
Lai, H, Li, Y, He, Y, Chen, F, Mi, B, Li, J, Xie, J, Ma, G, Yang, J, Xu, K, et al
Gut microbes. 2023;15(1):2197837
-
-
-
Free full text
-
Plain language summary
Functional constipation is characterised by continuously difficult, incomplete, or infrequent defecation, without an organic origin. Effective intervention strategies are required to relieve the functional constipation difficulties, particularly in rapidly aging populations, such as Chinese populations. The aim of this study was to evaluate the effectiveness of three dietary fibre formulas (polydextrose, psyllium husk, and wheat bran + psyllium husk) and one probiotic supplement on the improvement of constipation symptoms among Chinese adults with functional constipation. This study was a double-blinded randomised placebo-controlled trial which enrolled 250 participants who were randomly assigned to one of the five groups. Results showed: - that daily supplement of three prebiotic formulas with dietary fibres, or a probiotic formula effectively relieved hard stool in functional constipation patients after 4 weeks intervention. - the capacity of gut microbial genera in shaping the intervention responsiveness in the improvement of bowel movement frequency, Bristol stool scale score, and degree of defecation straining. Authors conclude that the pre or probiotic interventions may modulate gut microbiota, associated with intestinal health.
Abstract
Dietary fibers/probiotics may relieve constipation via optimizing gut microbiome, yet with limited trial-based evidences. We aimed to evaluate the effects of formulas with dietary fibers or probiotics on functional constipation symptoms, and to identify modulations of gut microbiota of relevance. We conducted a 4-week double-blinded randomized placebo-controlled trial in 250 adults with functional constipation. Intervention: A: polydextrose; B: psyllium husk; C: wheat bran + psyllium husk; D: Bifidobacterium animalis subsp. lactis HN019 + Lacticaseibacillus rhamnosus HN001; Placebo: maltodextrin. Oligosaccharides were also included in group A to D. 16S rRNA sequencing was used to assess the gut microbiota at weeks 0, 2, and 4. A total of 242 participants completed the study. No time-by-group effect was observed for bowel movement frequency (BMF), Bristol stool scale score (BSS), and degree of defecation straining (DDS), while BSS showed mean increases of 0.95-1.05 in group A to D (all P < 0.05), but not significantly changed in placebo (P = 0.170), and 4-week change of BSS showed similarly superior effects of the interventions as compared placebo. Group D showed a marginal reduction in plasma 5-hydroxytryptamine. Group A resulted in a higher Bifidobacterium abundance than placebo at week 2 and 4. Fourteen genera showed intervention-specific increasing or decreasing trends continuously, among which Anaerostipes showed increasing trends in groups B and C, associated with BMF increase. Random forest models identified specific baseline microbial genera panels predicting intervention responders. In conclusion, we found that the dietary fibers or probiotics may relieve hard stool, with intervention-specific changes in gut microbiota relevant to constipation relief. Baseline gut microbiota may predispose the intervention responsiveness. ClincialTrials.gov number, NCT04667884. What is the context?Supplementation of dietary fibers, such as psyllium husk or wheat bran (10 ~ 15 g/day) may relieve constipation symptoms, but bloating and flatulence are major concerns on a high fiber intake.Functional constipation patients had alternated gut microbiota profiles, while meta-analysis suggested that multispecies probiotics may increase bowel movement frequency and relieve hard stool in functional constipation.Dietary fibers or probiotics may lead to before-after changes of gut microbiota in patients with functional constipation, but time-series continued changes of gut microbiota during the intervention are unknown.Elevation of 5-hydroxytryptamine synthesis in enterochromaffin cells may affect bowel movement. And the elevated plasma 5-hydroxytryptamine was observed in functional constipation patients.What is new? Daily supplement of three prebiotic formulas with dietary fibers (polydextrose, psyllium husk, wheat bran, together with oligosaccharides), or a probiotic formula with Bifidobacterium animalis subsp. lactis HN019 + Lacticaseibacillus rhamnosus HN001 effectively relieved hard stool in functional constipation patients after 4 weeks intervention.We identified continued increasing or decreasing gut microbial genera over the intervention. Dietary fiber – gut microbiota (Anaerostipes)—constipation relieve (bowel movement frequency) evidence axis was identified in this human trial.Probiotic supplementation marginally reduced plasma 5-hydroxytryptamine, possibly associated with changes in BMF-related gut microbial genera.Intervention-specific baseline gut microbiota well predicted the responsiveness of constipation symptom relief.What is the impact? We provided references for the dosage and duration of dietary fiber/probiotics recommendations for adults with functional constipation, and advanced the microbial genera evidences of the fibers/probiotics-microbiota-laxation theory in humans.
-
3.
Effect of synbiotic supplementation on immune parameters and gut microbiota in healthy adults: a double-blind randomized controlled trial.
Li, X, Hu, S, Yin, J, Peng, X, King, L, Li, L, Xu, Z, Zhou, L, Peng, Z, Ze, X, et al
Gut microbes. 2023;15(2):2247025
-
-
-
Free full text
-
Plain language summary
The gut microbiota is involved in regulating immunity and synbiotics, that is combinations of pro- and prebiotics, may therefore modulate immunity via the gut microbiota. The aim of this randomised, double-blind, placebo-controlled trial was to evaluate the immune-modulatory effects of a synbiotic supplement (containing Bifidobacterium lactis HN019, Lactobacillus rhamnosus HN001 and fructo-oligosaccharide) in healthy adults. Outcome measures included C-reactive protein (CRP, an inflammatory marker), various pro- and anti-inflammatory cytokines, stool and salivary secretory IgA (sIgA), leukocytes, microbial stool analysis and occurrence, duration, and severity of upper respiratory tract infections (URTI). Compared to the control group, a significant reduction in the inflammatory markers CRP and interferon-gamma and an increase in the anti-inflammatory interleukin-10 and stool sIgA were observed in the supplementation group. There were no differences in types of leukocytes or URTIs between groups. Significant favourable changes in microbiome analysis were observed in the supplemented group which correlated with the observed improvements in inflammatory markers. These changes were dependent on the baseline composition of the microbiome. No adverse events were reported. The authors conclude that the data show that synbiotics are of benefit to healthy adults and support the concept of personalised supplementation.
Abstract
Synbiotics are increasingly used by the general population to boost immunity. However, there is limited evidence concerning the immunomodulatory effects of synbiotics in healthy individuals. Therefore, we conducted a double-blind, randomized, placebo-controlled study in 106 healthy adults. Participants were randomly assigned to receive either synbiotics (containing Bifidobacterium lactis HN019 1.5 × 108 CFU/d, Lactobacillus rhamnosus HN001 7.5 × 107 CFU/d, and fructooligosaccharide 500 mg/d) or placebo for 8 weeks. Immune parameters and gut microbiota composition were measured at baseline, mid, and end of the study. Compared to the placebo group, participants receiving synbiotic supplementation exhibited greater reductions in plasma C-reactive protein (P = 0.088) and interferon-gamma (P = 0.008), along with larger increases in plasma interleukin (IL)-10 (P = 0.008) and stool secretory IgA (sIgA) (P = 0.014). Additionally, synbiotic supplementation led to an enrichment of beneficial bacteria (Clostridium_sensu_stricto_1, Lactobacillus, Bifidobacterium, and Collinsella) and several functional pathways related to amino acids and short-chain fatty acids biosynthesis, whereas reduced potential pro-inflammatory Parabacteroides compared to baseline. Importantly, alternations in anti-inflammatory markers (IL-10 and sIgA) were significantly correlated with microbial variations triggered by synbiotic supplementation. Stratification of participants into two enterotypes based on pre-treatment Prevotella-to-Bacteroides (P/B) ratio revealed a more favorable effect of synbiotic supplements in individuals with a higher P/B ratio. In conclusion, this study suggested the beneficial effects of synbiotic supplementation on immune parameters, which were correlated with synbiotics-induced microbial changes and modified by microbial enterotypes. These findings provided direct evidence supporting the personalized supplementation of synbiotics for immunomodulation.
-
4.
Effects of galactooligosaccharides on maternal gut microbiota, glucose metabolism, lipid metabolism and inflammation in pregnancy: A randomized controlled pilot study.
Wan, J, An, L, Ren, Z, Wang, S, Yang, H, Ma, J
Frontiers in endocrinology. 2023;14:1034266
-
-
-
Free full text
Plain language summary
During pregnancy, a disordered gut microbiome and abnormal glucose metabolism may be possible mechanisms for pregnancy complications such as gestational diabetes mellitus (GDM). Different from probiotics, galactooligosaccharides (GOS) is a prebiotic that is not digested and absorbed by the host, but can selectively promote the metabolism and proliferation of beneficial bacteria in the body, particularly Lactobacillus and Bifidobacterium. The aim of this study was to evaluate the feasibility, acceptability, and safety of prebiotic intervention in healthy pregnant women, and conduct a preliminary exploration of the possible benefits for pregnant women. This study was a prospective double-blinded randomised clinical trial involving pregnant women. Participants were randomly assigned to the control group and the intervention group at a 1:1 ratio. Results showed that GOS intervention had no significant effect on reducing the incidence of GDM and improving glucose and lipid metabolism. Furthermore, there was no significant difference in glucose and lipid metabolism levels between GOS group and placebo group. Authors conclude that GOS can be considered as a dietary supplement during pregnancy. However, further clinical studies are needed to strengthen the findings of this study.
Abstract
BACKGROUND Gut microbiota of pregnant women change with the gestational week. On the one hand, they participate in the metabolic adaptation of pregnant women. On the other hand, the abnormal composition of gut microbiota of pregnant women is more likely to suffer from gestational diabetes mellitus (GDM). Therefore, gut microbiota targeted treatment through dietary supplements is particularly important for prevention or treatment. Prebiotic supplements containing galactooligosaccharides (GOS) may be an intervention method, but the effect is still unclear. OBJECTIVE This study aims to evaluate the feasibility and acceptability of prebiotic intervention in healthy pregnant women during pregnancy, and to explore the possible effects of intervention on pregnant women and the influence on gut microbiota as preliminaries. METHODS After recruitment in first trimester, 52 pregnant women were randomly assigned to receive GOS intervention or placebo containing fructooligosaccharides. 16S rRNA sequencing technology was used to detect the composition, diversity and differential flora of gut microbiota. Lipid metabolism, glucose metabolism and inflammatory factors during pregnancy were also analyzed. RESULTS The adverse symptoms of GOS intervention are mild and relatively safe. For pregnant women, there was no significant difference in the GDM incidence rates and gestational weight gain (GWG) in the GOS group compared with placebo (P > 0.05). Compared with the placebo group, the levels of FPG, TG, TC, HDL-C LDL-C, and IL-6 had no significant difference in GOS group (P > 0.05). For newborns, there was no significant difference between GOS group and placebo group in the following variables including gestational week, birth weight, birth length, head circumference, chest circumference, sex, and delivery mode (P > 0.05). And compared with the placebo group, the GOS group had a higher abundance of Paraprevotella and Dorea, but lower abundance of LachnospiraceaeUCG_001. CONCLUSIONS GOS prebiotics appear to be safe and acceptable for the enrolled pregnancies. Although GOS intervention did not show the robust benefits on glucose and lipid metabolism. However, the intervention had a certain impact on the compostion of gut microbiota. GOS can be considered as a dietary supplement during pregnancy, and further clinical studies are needed to explore this in the future.
-
5.
Targeting the gut-lung axis by synbiotic feeding to infants in a randomized controlled trial.
Sjödin, KS, Sjödin, A, Ruszczyński, M, Kristensen, MB, Hernell, O, Szajewska, H, West, CE
BMC biology. 2023;21(1):38
-
-
-
Free full text
Plain language summary
Infants are at increased risk of infections, and respiratory tract infections are a leading cause of morbidity and mortality globally. Although the respiratory and gastrointestinal tracts are separate, they share a mucosal immune system called the “gut-lung axis.” The aim of this study was to compare the impacts of feeding prebiotic infant formula with the same prebiotic infant formula supplemented with probiotic Lactobacillus F19 (synbiotics) until 6 months of age on infant gut microbiota development in the first year of life. This study was a multicentre, double-blind randomised controlled study. Infants were randomised to control group - prebiotic formula or experimental group - synbiotic formula. Results showed additional benefit of feeding specific synbiotics to formula-fed infants over prebiotics only. In fact, synbiotic feeding led to the underrepresentation of Klebsiella [bacteria], enrichment of bifidobacteria, and slight increases in microbial degradation metabolites. Authors concluded that their findings support future clinical evaluation of synbiotic formula in the prevention of infections and associated antibiotic treatment as a primary outcome when breastfeeding is not feasible.
Abstract
BACKGROUND Formula-fed infants are at increased risk of infections. Due to the cross-talk between the mucosal systems of the gastrointestinal and respiratory tracts, adding synbiotics (prebiotics and probiotics) to infant formula may prevent infections even at distant sites. Infants that were born full term and weaned from breast milk were randomized to prebiotic formula (fructo- and galactooligosaccharides) or the same prebiotic formula with Lactobacillus paracasei ssp. paracasei F19 (synbiotics) from 1 to 6 months of age. The objective was to examine the synbiotic effects on gut microbiota development. RESULTS Fecal samples collected at ages 1, 4, 6, and 12 months were analyzed using 16S rRNA gene sequencing and a combination of untargeted gas chromatography-mass spectrometry/liquid chromatography-mass spectrometry. These analyses revealed that the synbiotic group had a lower abundance of Klebsiella, a higher abundance of Bifidobacterium breve compared to the prebiotic group, and increases in the anti-microbial metabolite d-3-phenyllactic acid. We also analyzed the fecal metagenome and antibiotic resistome in the 11 infants that had been diagnosed with lower respiratory tract infection (cases) and 11 matched controls using deep metagenomic sequencing. Cases with lower respiratory tract infection had a higher abundance of Klebsiella species and antimicrobial resistance genes related to Klebsiella pneumoniae, compared to controls. The results obtained using 16S rRNA gene amplicon and metagenomic sequencing were confirmed in silico by successful recovery of the metagenome-assembled genomes of the bacteria of interest. CONCLUSIONS This study demonstrates the additional benefit of feeding specific synbiotics to formula-fed infants over prebiotics only. Synbiotic feeding led to the underrepresentation of Klebsiella, enrichment of bifidobacteria, and increases in microbial degradation metabolites implicated in immune signaling and in the gut-lung and gut-skin axes. Our findings support future clinical evaluation of synbiotic formula in the prevention of infections and associated antibiotic treatment as a primary outcome when breastfeeding is not feasible. TRIAL REGISTRATION ClinicalTrials.gov NCT01625273 . Retrospectively registered on 21 June 2012.
-
6.
An open label, non-randomized study assessing a prebiotic fiber intervention in a small cohort of Parkinson's disease participants.
Hall, DA, Voigt, RM, Cantu-Jungles, TM, Hamaker, B, Engen, PA, Shaikh, M, Raeisi, S, Green, SJ, Naqib, A, Forsyth, CB, et al
Nature communications. 2023;14(1):926
-
-
-
Free full text
Plain language summary
Risk determinants for Parkinson’s disease (PD) include both genetic and environmental factors. Whether sporadic or monogenetic in origin, environmental factors may be critical in triggering PD onset in a susceptible host or influencing disease progression. The aims of this study were to determine whether prebiotic fibres can increase short-chain fatty acids (SCFA) production in PD patient microbiota and (2) determine which prebiotics modify the microbiota and increase SCFA using a stool fermentation system. Results showed that 10 days of prebiotic intervention was both well-tolerated and safe in PD patients and decreased total gastrointestinal symptom severity score in treated PD participants. The prebiotic intervention was also associated with anti-inflammatory shifts in the intestinal microbiota, increased SCFA, reduced calprotectin (intestinal inflammation), reduced zonulin (a putative marker of intestinal barrier dysfunction/ inflammation), and a subtle, but statistically significant, reduction in neurofilament light (a marker of neurodegeneration). Authors concluded that a SCFA-promoting prebiotic fibre mixture can be used to modulate the intestinal microbiota in PD patients (i.e., the approach is feasible) and that the prebiotic mixture is well-accepted, tolerated, and safe for use in PD patients.
Abstract
A pro-inflammatory intestinal microbiome is characteristic of Parkinson's disease (PD). Prebiotic fibers change the microbiome and this study sought to understand the utility of prebiotic fibers for use in PD patients. The first experiments demonstrate that fermentation of PD patient stool with prebiotic fibers increased the production of beneficial metabolites (short chain fatty acids, SCFA) and changed the microbiota demonstrating the capacity of PD microbiota to respond favorably to prebiotics. Subsequently, an open-label, non-randomized study was conducted in newly diagnosed, non-medicated (n = 10) and treated PD participants (n = 10) wherein the impact of 10 days of prebiotic intervention was evaluated. Outcomes demonstrate that the prebiotic intervention was well tolerated (primary outcome) and safe (secondary outcome) in PD participants and was associated with beneficial biological changes in the microbiota, SCFA, inflammation, and neurofilament light chain. Exploratory analyses indicate effects on clinically relevant outcomes. This proof-of-concept study offers the scientific rationale for placebo-controlled trials using prebiotic fibers in PD patients. ClinicalTrials.gov Identifier: NCT04512599.
-
7.
Effects of inulin supplementation on body composition and metabolic outcomes in children with obesity.
Visuthranukul, C, Chamni, S, Kwanbunbumpen, T, Saengpanit, P, Chongpison, Y, Tepaamorndech, S, Panichsillaphakit, E, Uaariyapanichkul, J, Nonpat, N, Chomtho, S
Scientific reports. 2022;12(1):13014
-
-
-
Free full text
Plain language summary
The prevalence of overweight and obesity among children and adolescents has risen dramatically. Overweight and obese children are at risk of developing co-morbidities such as type 2 diabetes mellitus, hypertension, dyslipidaemia, metabolic syndrome, non-alcohol fatty liver disease and premature cardiovascular diseases. Furthermore, obese children are highly prone to become obese adults. The aim of this study was to determine the effects of prebiotic (as inulin) supplementation on body weight, adiposity, and metabolic profiles in obese Thai children. This study is a randomised double-blinded placebo-controlled trial. Participants (n=165) were randomly allocated to 3 groups: inulin, placebo, and dietary fibre advice group. Results show that the intensive behavioural modification and frequent follow-up are effective strategies to reduce body mass index and adiposity in obese children. Furthermore, even though inulin supplementation did not demonstrate considerable effect on adiposity and metabolic outcomes, it can increase fat-free mass in these children. Authors conclude that further research regarding the change of gut microbiota composition and their metabolites are needed to determine inulin’s impact on host microbe interaction in obese paediatric population.
Abstract
Inulin might improve body composition in obese children. We aimed to determine the effects of inulin supplementation on body composition and metabolic outcomes in obese children. A randomized, double-blinded placebo-controlled study was conducted in obese Thai children aged 7-15 years. Participants were assigned to 3 treatment groups for 6 months: 13 g of extracted inulin powder from Thai Jerusalem artichoke, isocaloric maltodextrin, and dietary fiber advice groups. Body composition was assessed by bioelectrical impedance analysis. One-hundred and fifty-five children completed the study (mean age 10.4 ± 2.2 years, BMI z-score 3.2 ± 1.0, 59% male). The drop-out rate was 6%. The inulin extract yielded more than 90% compliance without significant gastrointestinal side effects. All three groups demonstrated a significant decrease in BMI z-score, fat mass index (FMI), and trunk FMI, but the differences between groups were not observed. Fat-free mass index significantly increased only in the inulin group (16.18 ± 1.90 vs. 16.38 ± 1.98 kg/m2, P = 0.009). There were no significant differences in the metabolic profiles between groups. Despite showing no substantial effect on adiposity, inulin may increase fat-free mass in obese children. Further research in the change of gut microbiota composition is needed to determine inulin's impact on host-microbe interaction in pediatric obesity.
-
8.
Pregnancy outcomes in women taking probiotics or prebiotics: a systematic review and meta-analysis.
Jarde, A, Lewis-Mikhael, AM, Moayyedi, P, Stearns, JC, Collins, SM, Beyene, J, McDonald, SD
BMC pregnancy and childbirth. 2018;18(1):14
-
-
-
Free full text
Plain language summary
It has been suggested that probiotics might help prevent premature birth, but two previous systematic reviews found possible increases in risk. The objective of this meta-analysis was to perform an up-to-date review of the risk of premature birth and other pregnancy outcomes in pregnant women taking probiotics or prebiotics. The authors pooled data from 27 studies, one using prebiotics and the rest probiotics. Taking probiotics or prebiotics during pregnancy did not change the risk of premature birth, or other pregnancy outcomes. The authors concluded that more studies are required to assess the safety and effects of taking probiotics and prebiotics during pregnancy.
Abstract
BACKGROUND Probiotics are living microorganisms that, when administered in adequate amounts, confer a health benefit. It has been speculated that probiotics might help prevent preterm birth, but in two previous systematic reviews possible major increases in this risk have been suggested. Our objective was to perform a systematic review and meta-analysis of the risk of preterm birth and other adverse pregnancy outcomes in pregnant women taking probiotics, prebiotics or synbiotics. METHODS We searched six electronic databases (MEDLINE, EMBASE, CINAHL, Cochrane Central Register of Controlled Trials, Web of Science's Core collection and BIOSIS Preview) up to September 2016 and contacted authors for additional data. We included randomized controlled trials in which women with a singleton pregnancy received a probiotic, prebiotic or synbiotic intervention. Two independent reviewers extracted data using a piloted form and assessed the risk of bias using the Cochrane risk of bias tool. We used random-effects meta-analyses to pool the results. RESULTS We identified 2574 publications, screened 1449 non-duplicate titles and abstracts and read 160 full text articles. The 49 publications that met our inclusion criteria represented 27 studies. No study used synbiotics, one used prebiotics and the rest used probiotics. Being randomized to take probiotics during pregnancy neither increased nor decreased the risk of preterm birth < 34 weeks (RR 1.03, 95% CI 0.29-3.64, I2 0%, 1017 women in 5 studies), preterm birth < 37 weeks (RR 1.08, 95% CI 0.71-1.63, I2 0%, 2484 women in 11 studies), or most of our secondary outcomes, including gestational diabetes mellitus. CONCLUSIONS We found no evidence that taking probiotics or prebiotics during pregnancy either increases or decreases the risk of preterm birth or other infant and maternal adverse pregnancy outcomes. TRIAL REGISTRATION We prospectively published the protocol for this study in the PROSPERO database ( CRD42016048129 ).
-
9.
Functional interactions between the gut microbiota and host metabolism.
Tremaroli, V, Bäckhed, F
Nature. 2012;489(7415):242-9
-
-
-
Plain language summary
This literature review aims to discuss evidence for the role of the gut microbiota in metabolism and possible links to obesity. Obesity and caloric intake can influence the microbiota, but whether the reverse is true in humans remains unclear. Much of the mechanisms have been determined in rodents, determining similar pathways in humans is difficult. The interplay of diet, host and gut microbiota may cause increased gut permeability (leaky gut) that could lead to an increase in inflammation that may cause obesity, fatty liver disease and insulin resistance. It is increasingly accepted that gut microbiota can contribute to diseases such as obesity, diabetes and cardiovascular disease, but exactly how and by how much remains unclear. Evidence for treating the microbiota to help with these metabolic diseases, either by pre- or probiotic supplementation, is building. However, double-blind, placebo-controlled studies are required to determine effects. The influence of the gut microbiota is a promising area, but one that needs further research.
Abstract
The link between the microbes in the human gut and the development of obesity, cardiovascular disease and metabolic syndromes, such as type 2 diabetes, is becoming clearer. However, because of the complexity of the microbial community, the functional connections are less well understood. Studies in both mice and humans are helping to show what effect the gut microbiota has on host metabolism by improving energy yield from food and modulating dietary or the host-derived compounds that alter host metabolic pathways. Through increased knowledge of the mechanisms involved in the interactions between the microbiota and its host, we will be in a better position to develop treatments for metabolic disease.