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The effects of probiotics supplementation on glycaemic control among adults with type 2 diabetes mellitus: a systematic review and meta-analysis of randomised clinical trials.
Li, G, Feng, H, Mao, XL, Deng, YJ, Wang, XB, Zhang, Q, Guo, Y, Xiao, SM
Journal of translational medicine. 2023;21(1):442
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Type 2 diabetes mellitus (T2DM), an endocrine and metabolic disease, is influenced by host physiology and environmental factors. Recent studies have shown that the gut microbiota plays a key role in the maintenance of host homeostasis and pathogenesis of T2DM. The aim of this study was to evaluate the effects of a probiotic intervention on glycaemic control in T2DM patients and to evaluate the variations in these effects due to participant characteristics and intervention characteristics. This study was a systematic review and meta-analysis of thirty randomised-controlled studies including a total of 1,827 individuals. Results showed that probiotic supplementation had favourable effects on glycaemic control in T2DM patients. Bifdobacterium and food-type probiotics had greater glucose-lowering effects than other probiotic genera and types of vehicles used to deliver the probiotics. Authors concluded that the administration of probiotics may be a promising adjuvant therapy for glycaemic control in T2DM patients.
Abstract
OBJECTIVE This systematic review and meta-analysis study aimed to evaluate the effectiveness of probiotics supplementation on glycaemic control in patients with type 2 diabetes mellitus (T2DM) based on the data from the randomised clinical trials (RCTs). METHODS PubMed, Web of Sciences, Embase, and Cochrane Library were searched from the inception to October 2022, and RCTs about probiotics and T2DM were collected. The standardised mean difference (SMD) with 95% confidence interval (CI) was used to estimate the effects of probiotics supplementation on glycaemic control related parameters, e.g. fasting blood glucose (FBG), insulin, haemoglobin A1c (HbA1c), and homeostasis model of assessment of insulin resistance (HOMA-IR). RESULTS Thirty RCTs including 1,827 T2MD patients were identified. Compared with the placebo group, the probiotics supplementation group had a significant decrease in the parameters of glycaemic control, including FBG (SMD = - 0.331, 95% CI - 0.424 to - 0.238, Peffect < 0.001), insulin (SMD = - 0.185, 95% CI - 0.313 to - 0.056, Peffect = 0.005), HbA1c (SMD = - 0.421, 95% CI - 0.584 to - 0.258, Peffect < 0.001), and HOMA-IR (SMD = - 0.224, 95% CI - 0.342 to - 0.105, Peffect < 0.001). Further subgroup analyses showed that the effect was larger in the subgroups of Caucasians, high baseline body mass index (BMI ≥ 30.0 kg/m2), Bifidobacterium and food-type probiotics (Psubgroup < 0.050). CONCLUSION This study supported that probiotics supplementation had favourable effects on glycaemic control in T2DM patients. It may be a promising adjuvant therapy for patients with T2DM.
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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
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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.
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Effects of probiotic administration on overweight or obese children: a meta-analysis and systematic review.
Li, Y, Liu, T, Qin, L, Wu, L
Journal of translational medicine. 2023;21(1):525
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The prevalence of overweight or obesity in children is increasing due to changes in dietary structure and exercise habits, as determined by the body mass index (BMI) calculated from height and weight. Childhood obesity can cause some clinical complications such as hypertension, nonalcoholic fatty liver disease (NAFLD), and cardiovascular disease. The aim of this study was to examine the effects of probiotics on eight factors in children with overweight or obesity. This study was a systematic review and meta-analysis of four studies with a total of 206 overweight or obesity children. Among them, 105 were in the probiotic group, and 101 were in the placebo group. Results showed that probiotics can improve high- and low-density lipoprotein cholesterol, adiponectin, leptin, and TNF-α in overweight or obese children. The systematic review showed that probiotics work mainly by reshaping disturbed intestinal microbiota, regulating lipid metabolism, reducing inflammation and immune response, playing a positive effect of short-chain fatty acids produced, alleviating oxidative stress and endoplasmic reticulum stress, and inhibiting the growth and reproduction of pathogens in the gut. Authors concluded that probiotics could regulate lipid metabolism and immune response to some degree in children with overweight or obesity.
Abstract
BACKGROUND This paper aimed to examine the effects of probiotics on eight factors in overweight or obese children by meta-analysis, namely, body mass index (BMI), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), adiponectin, leptin and tumor necrosis factor-α (TNF-α) and summarize the mechanisms of action of probiotics based on the existing researches. METHODS Six databases (PubMed, Web of Science, Embase, Cochrane Library, SinoMed and CNKI) were searched until March 2023. Review Manager 5.4 was used for meta-analysis. The data were analysed using weighted mean differences (WMDs) or standardized mean differences (SMDs) under a fixed effect model or random effect model to observe the effects of probiotic administration on the included indicators. RESULTS Four publications with a total of 206 overweight or obesity children were included. According to the meta-analysis, probiotics were able to significantly decrease the levels of HDL-C (MD, 0.06; 95% CI 0.03, 0.09; P = 0.0001), LDL-C (MD, - 0.06; 95% CI - 0.12, - 0.00; P = 0.04), adiponectin (MD, 1.39; 95% CI 1.19, 1.59; P < 0.00001), leptin (MD, - 2.72; 95% CI - 2.9, - 2.54; P < 0.00001) and TNF-α (MD, - 4.91; 95% CI - 7.15, - 2.67; P < 0.0001) compared to those in the placebo group. Still, for BMI, the palcebo group seemed to be better than the probiotic group (MD, 0.85; 95% CI 0.04, 1.66; P = 0.04). TC (MD, - 0.05; 95% CI - 0.12, 0.02; P = 0.14) and TG (MD, - 0.16; 95% CI - 0.36, 0.05; P = 0.14) were not different between two groups. CONCLUSIONS This review drew that probiotics might act as a role in regulating HDL-C, LDL-C, adiponectin, leptin and TNF-α in overweight or obesity children. Additionally, our systematic review yielded that probiotics might regulate lipid metabolism and improve obese associated symptoms by some paths. This meta-analysis has been registered at PROSPERO with ID: CRD42023408359.
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Orally administrated Lactobacillus gasseri TM13 and Lactobacillus crispatus LG55 can restore the vaginal health of patients recovering from bacterial vaginosis.
Qi, F, Fan, S, Fang, C, Ge, L, Lyu, J, Huang, Z, Zhao, S, Zou, Y, Huang, L, Liu, X, et al
Frontiers in immunology. 2023;14:1125239
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Bacterial vaginosis (BV) is a microecological disorder caused by decreased abundance of lactobacilli and an increased abundance of anaerobic bacteria, commonly affecting the female lower genital tract. The aim of this study was to evaluate the effectiveness of oral Chinese-origin probiotic strains (L. gasseri TM13 and L. crispatus LG55), with adjuvant primary treatment in treating Chinese BV patients, and investigate the dynamic of the intestine and vaginal microbiome using metagenomic sequencing. This study was a single-centre, prospective, parallel-group, randomized controlled clinical trial. Participants were randomly assigned to the control or probiotic group using a 1:1 ratio. Results showed that there was no significant difference in BV cure rates between the probiotic and control groups at day 14, day 30, and day 90. In addition, in the BV conversion population, the percentage of people in a transition state was lower in the probiotic group at all three time-points. Hence, oral administration of L. gasseri TM13 and L. crispatus LG55 is effective in restoring the vaginal health of patients recovered from BV. Authors conclude that an individualised intervention approach should be developed to restore the vaginal health of patients recovering from BV.
Abstract
UNLABELLED Bacterial vaginosis (BV) is a common infection of the lower genital tract with a vaginal microbiome dysbiosis caused by decreasing of lactobacilli. Previous studies suggested that supplementation with live Lactobacillus may benefit the recovery of BV, however, the outcomes vary in people from different regions. Herein, we aim to evaluate the effectiveness of oral Chinese-origin Lactobacillus with adjuvant metronidazole (MET) on treating Chinese BV patients. In total, 67 Chinese women with BV were enrolled in this parallel controlled trial and randomly assigned to two study groups: a control group treated with MET vaginal suppositories for 7 days and a probiotic group treated with oral Lactobacillus gasseri TM13 and Lactobacillus crispatus LG55 as an adjuvant to MET for 30 days. By comparing the participants with Nugent Scores ≥ 7 and < 7 on days 14, 30, and 90, we found that oral administration of probiotics did not improve BV cure rates (72.73% and 84.00% at day 14, 57.14% and 60.00% at day 30, 32.14% and 48.39% at day 90 for probiotic and control group respectively). However, the probiotics were effective in restoring vaginal health after cure by showing higher proportion of participants with Nugent Scores < 4 in the probiotic group compared to the control group (87.50% and 71.43% on day 14, 93.75% and 88.89% on day 30, and 77.78% and 66.67% on day 90). The relative abundance of the probiotic strains was significantly increased in the intestinal microbiome of the probiotic group compared to the control group at day 14, but no significance was detected after 30 and 90 days. Also, the probiotics were not detected in vaginal microbiome, suggesting that L. gasseri TM13 and L. crispatus LG55 mainly acted through the intestine. A higher abundance of Prevotella timonensis at baseline was significantly associated with long-term cure failure of BV and greatly contributed to the enrichment of the lipid IVA synthesis pathway, which could aggravate inflammation response. To sum up, L. gasseri TM13 and L. crispatus LG55 can restore the vaginal health of patients recovering from BV, and individualized intervention mode should be developed to restore the vaginal health of patients recovering from BV. CLINICAL TRIAL REGISTRATION https://classic.clinicaltrials.gov/ct2/show/, identifier NCT04771728.
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The role of probiotics in the treatment of adult atopic dermatitis: a meta-analysis of randomized controlled trials.
Umborowati, MA, Damayanti, D, Anggraeni, S, Endaryanto, A, Surono, IS, Effendy, I, Prakoeswa, CRS
Journal of health, population, and nutrition. 2022;41(1):37
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Allergic diseases, including atopic dermatitis (AD), are serious conditions that disrupt the quality of life of affected individuals. AD is a chronic inflammatory skin disease that is relapsing and whose onset is generally related to a patient’s or family’s atopic history such as asthma and allergic rhinitis. The aim of this study was to assess randomized control trials based on the PICO strategy—population = adult with AD; intervention = probiotic intervention; control = standard therapy; and outcome = clinical manifestations (Scoring Atopic Dermatitis index (SCORAD) evaluation, skin severity, itch severity), quality of life, and/or immune response. This study is a systematic review of six randomised controlled trials involving a total of 241 subjects, including 128 subjects in the probiotics group and 113 subjects in the placebo group. Results show that probiotic supplementation may have the potential to decrease disease severity (SCORAD) in adult AD. Therefore, decrease in disease severity may also improve the quality of life. Authors conclude that based on their findings, probiotics can be used as adjuvant treatment of adult AD.
Abstract
BACKGROUND Atopic dermatitis (AD) is chronic inflammatory skin disease that is relapsing and a serious condition that disrupts the quality of life of affected individuals. Probiotics are an immunomodulator that can enhance the immune control of atopic dermatitis. METHODS All randomized controlled trials of probiotics for the treatment of adult AD published before December 2020 were included in this study from the PubMed databases and manual searching. RESULTS Six randomized controlled trials (n = 241) were selected for this meta-analysis study. Probiotics were effective in treating adult patients with AD, indicated by the decrease in Scoring Atopic Dermatitis/SCORAD (Mean Difference (MD) - 7.90, 95% CI - 7.25 to - 6.92; p < 0.00001; I2 = 96%) and improved quality of life (MD - 7.68, 95% CI - 14.08 to - 1.29; p = 0.02; I2 = 47%) which were statistically significant. However, skin severity, itch severity, Dermatology Life Quality Index (DLQI), IL-4, TFN-γ, and IgE showed no significant difference in this meta-analysis study (p > 0.05). LIMITATIONS The study found no available data for side effects of probiotics. STRENGTH This meta-analysis analyzed a total of 241 AD patients of Asian and European origin. CONCLUSION The use of probiotics decreased SCORAD significantly in adult patients with AD. Probiotics can improve the quality of life of patients with AD. The use of probiotics in atopic dermatitis has been widely studied, with controversial results. This meta-analysis suggests that the use of probiotics can improve SCORAD and the quality of life of patients with atopic dermatitis.
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The Efficacy and Safety of Probiotics for Allergic Rhinitis: A Systematic Review and Meta-Analysis.
Luo, C, Peng, S, Li, M, Ao, X, Liu, Z
Frontiers in immunology. 2022;13:848279
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Allergic rhinitis (AR) is characterized by a nasal sensitive inflammation. Common symptoms of AR are nasal itching, sneezing, rhinorrhoea, and nasal congestion. In addition, some patients experience symptoms of allergic rhinoconjunctivitis, such as watery or itchy or red eyes. The aim of this study was to address the effect and safety of probiotics on AR and to explore the possible causes of between-study heterogeneity via subgroup. This study is a systematic review and meta-analysis of twenty-eight randomised controlled trials. Results showed that probiotics supplementation for patients with AR can ameliorate AR symptoms and improve the quality of life. Probiotics supplementation can correct the T helper cell 1/ T helper cell 2 balance. Furthermore, there was no significant change in overall or antigen-specific immunoglobulin E levels between probiotic-treated and placebo-treated subjects. Authors conclude that in spite of the positive results of some outcomes, there is weak evidence that probiotics have a potential benefit in the treatment of AR.
Abstract
Background: Probiotics have proven beneficial in a number of immune-mediated and allergic diseases. Several human studies have evaluated the efficacy and safety of probiotics in allergic rhinitis; however, evidence for their use has yet to be firmly established. Objective: We undertook a systematic review and meta-analysis aiming to address the effect and safety of probiotics on allergic rhinitis. Methods: We systematically searched databases [MEDLINE (PubMed), Embase, and the Cochrane Central Register of Controlled Trials] from inception until June 1, 2021. Qualified literature was selected according to inclusion and exclusion criteria, the data were extracted, and a systematic review and meta-analysis was conducted. Results: Twenty-eight studies were included. The results showed that probiotics significantly relieved allergic rhinitis symptoms (standardized mean difference [SMD], -0.29, 95% confidence interval (CI) [-0.44, -0.13]; p = 0.0003, I 2 = 89%), decreased Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) scores compared with the control group (SMD, -0.64, 95% CI [-0.79, -0.49], p < 0.00001, I 2 = 97%), and increased T helper cell 1(Th1)/Th2 ratio (mean difference [MD], -2.47, 95% CI [-3.27, -1.68], p < 0.00001, I 2 = 72%). There was no significant change in overall or specific IgE levels between probiotic-treated and placebo-treated subjects (SMD, 0.09, 95% CI [-0.16, 0.34], I 2 = 0%, and SMD, -0.03, 95% CI [-0.18, 0.13], p = 0.72, I 2 = 0%, respectively). Conclusions: To sum up, probiotic supplement seems to be effective in ameliorating allergic rhinitis symptoms and improving the quality of life, but there is high heterogeneity in some results after subgroup analysis and clinicians should be cautious when recommending probiotics in treating allergic rhinitis. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/, PROSPERO (CRD42021242645).
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The vaginal microbiome and the risk of preterm birth: a systematic review and network meta-analysis.
Gudnadottir, U, Debelius, JW, Du, J, Hugerth, LW, Danielsson, H, Schuppe-Koistinen, I, Fransson, E, Brusselaers, N
Scientific reports. 2022;12(1):7926
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Preterm birth is a major cause of neonatal mortality and morbidity. Many factors can trigger premature labour onset, including preterm premature rupture of membranes, infections and microbial invasion of the amniotic cavity. The vaginal microbiome is thought to protect from such infections. The aim of this study was to assess the association between the vaginal microbiome and the risk of preterm birth. This study is a systematic review and meta-analysis of 17 cohort studies. The number of pregnancies per study ranged between 38 and 539, with 8 and 107 preterm births. Results show that women with a “low-lactobacilli” vaginal microbiome composition were at higher risk of preterm birth (spontaneous and overall) compared to women with L. crispatus (microbiome) dominant microbiome compositions. Authors conclude that the diversity of the vaginal microbiome seems to play a part in the risk of preterm birth.
Expert Review
Conflicts of interest:
None
Take Home Message:
- The diversity of the vaginal microbiome is reported to play a part in the risk of preterm births.
- Practitioners could consider testing the virginal microbiome for low Lactobacilli or the dominance of Gardnerella and Prevotella and then recommending a probiotic supplement to pregnant patients who have low Lactobacilli vaginal microbiome.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
A systematic review and network meta-analysis was conducted to investigate the association between vaginal microbiome and risk of preterm births.
Methodology
- Seventeen longitudinal cohort studies were included. Seven originated from North America, three from Europe, two from South America, three from Asia, and two from Africa. The number of pregnancies per study ranged between 38 and 539, with 8 and 107 preterm births. 16S Sequencing techniques were used to identify the microbial species. Preterm birth was defined as birth before 37 weeks of gestation.
- Microbiome community state types (CSTs) were grouped into five categories based on dominating species: L. crispatus, L. gasseri, L. iners,“low-lactobacilli” and L. jensenii. “Low-lactobacilli” was defined as an increased diversity of anaerobic or mixture of aerobe and facultative anaerobe bacteria (such as Gardnerella and Prevotella) based on the cut-offs and categorization used in the individual studies.
Results
Primary clinical outcomes were:
- Among women who delivered preterm, the pooled proportion with “low-lactobacilli” was 0.41 (95% CI 0.30-0.53) compared to 0.29 (95% CI 0.20-0.38) of women with full-term deliveries.
- The risk of preterm births was higher among women with “low-lactobacilli” compared to L. crispatus (OR 1.69, 95%CI 1.15 -2.49).”Low-lactobacilli” included Garnerella and Provotella, both of which are known to promote inflammatory cytokines and are commonly found in vaginal microbiome just before preterm premature rupture of membranes (PPROM).
Clinical practice applications:
- The diversity of the vaginal microbiome is reported to play an important role in the risk of preterm births.
- Women with low Lactobacilli seem to be at a greater risk of delivering preterm compared to women with L. crispatus dominant microbiome.
- Based on this study, practitioners could therefore consider testing the vaginal microbiome of their patients for low Lactobacilli and/or the dominance of Gardnerella and Prevotella.
- Practitioners may also consider recommending specific probiotic supplementation during pregnancy to increase the dominance of Lactobacilli and L. crispatus vaginal microbiome.
Considerations for future research:
- In the past, researchers have grouped the microbiome into categories based on dominating species, which is not ideal. Therefore, further studies are needed where individual microbiome sequencing data is used to make comparisons.
- Additionally, longitudinal studies are needed with higher sample sizes to investigate the natural changes of the vaginal microbiome during pregnancy and the physiological mechanisms underlying these apparent different risk profiles.
- Furthermore, randomized-controlled trials are needed to establish if pregnant women could benefit from specific probiotic supplementation during pregnancy.
Abstract
Preterm birth is a major cause of neonatal morbidity and mortality worldwide. Increasing evidence links the vaginal microbiome to the risk of spontaneous preterm labour that leads to preterm birth. The aim of this systematic review and network meta-analysis was to investigate the association between the vaginal microbiome, defined as community state types (CSTs, i.e. dominance of specific lactobacilli spp, or not (low-lactobacilli)), and the risk of preterm birth. Systematic review using PubMed, Web of Science, Embase and Cochrane library was performed. Longitudinal studies using culture-independent methods categorizing the vaginal microbiome in at least three different CSTs to assess the risk of preterm birth were included. A (network) meta-analysis was conducted, presenting pooled odds ratios (OR) and 95% confidence intervals (CI); and weighted proportions and 95% CI. All 17 studies were published between 2014 and 2021 and included 38-539 pregnancies and 8-107 preterm births. Women presenting with "low-lactobacilli" vaginal microbiome were at increased risk (OR 1.69, 95% CI 1.15-2.49) for delivering preterm compared to Lactobacillus crispatus dominant women. Our network meta-analysis supports the microbiome being predictive of preterm birth, where low abundance of lactobacilli is associated with the highest risk, and L. crispatus dominance the lowest.
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The effect of gluten in adolescents and young adults with gastrointestinal symptoms: a blinded randomised cross-over trial.
Crawley, C, Savino, N, Halby, C, Sander, SD, Andersen, AN, Arumugam, M, Murray, J, Christensen, R, Husby, S
Alimentary pharmacology & therapeutics. 2022;55(9):1116-1127
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The gluten-free diet (GFD) has gained increasing popularity among healthy people without coeliac disease or wheat allergy. The main reasons for following a GFD are weight control, the perception that a GFD is healthier, and the presence of symptoms after gluten ingestion. The aim of this study was to address the hypothesis that adding gluten to the diet results in a self-reported worsening of gastrointestinal symptoms (primary outcome) and mental health (key secondary outcomes) in a well-characterised group of adolescents. This study was arranged in two phases; the first phase began with 2 weeks of a GFD, and if the participants responded to the GFD, they proceeded to phase 2. Phase 2 was a double-blinded randomised trial with cross-over and consisted of three periods, each lasting 7 days: (1) a challenge with gluten/placebo, (2) wash-out phase, and (3) the second challenge with placebo/gluten. Results show that it was not possible to detect a difference in symptoms between gluten and placebo at a group level. Furthermore, on an individual level, there was a comparable number of gluten responders and placebo responders, underscoring the insignificant difference between gluten and placebo. Authors conclude that adding gluten to the diet does not induce gastrointestinal symptoms or worsened mental health in adolescents.
Abstract
BACKGROUND The popularity of the gluten-free diet and sales of gluten-free products have increased immensely. AIMS To investigate whether gluten induces gastrointestinal symptoms, measured by self-reported questionnaires, as well as mental health symptoms in adolescents from a population-based cohort. METHODS The eligible participants (n = 273) were recruited from a population-based cohort of 1266 adolescents and had at least four different gastrointestinal symptoms. Phase one (n = 54) was a run-in phase where the participants lived gluten-free for 2 weeks. If they improved they continued to phase 2 (n = 33), a blinded randomised cross-over trial. Participants were blindly randomised either to start with 7 days of gluten, eating two granola bars containing 10 g of gluten or to 7 days on placebo, eating two granola bars without gluten, followed by the reverse and separated by a 7-day washout period. The effects of the intervention on gastrointestinal symptoms and mental health symptoms were assessed. RESULTS In total, 54/273 participants entered the run-in phase and 35 were eligible for randomization. A total of 33 were randomised and 32 completed the trial. The median age was 20.3 (IQR 19.2-20.9) and 32/33 participants were females. Compared with a placebo, gluten did not induce gastrointestinal symptoms. The difference in the average VAS was -0.01 (95% confidence interval -2.07 to 2.05). Nor did we find a difference in the outcomes measuring mental health. CONCLUSION Compared with placebo, adding gluten to the diet did not induce gastrointestinal symptoms or worsened mental health in adolescents recruited from a population-based cohort. The trial registration number is NCT04639921.
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Dietary macronutrients and the gut microbiome: a precision nutrition approach to improve cardiometabolic health.
Jardon, KM, Canfora, EE, Goossens, GH, Blaak, EE
Gut. 2022;71(6):1214-1226
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The global rise in the prevalence of obesity is strongly associated with an increase in the incidence and prevalence of cardiometabolic diseases, including insulin resistance (IR) and type 2 diabetes mellitus. In recent years, advancements have been made in understanding the involvement of the gut microbiome in obesity and related cardiometabolic complications as regulator of host energy and substrate metabolism. This study is a review that discusses the latest research describing interactions between dietary composition, the gut microbiome and host metabolism. Results show that current evidence for developing optimal dietary interventions targeting bodyweight control and IR via the gut microbiota is still in its infancy and does not capture the complexity of the integration of a whole-diet approach, the microbial and the host’s metabolic phenotype. Furthermore, implementation of targeted, precision nutrition intervention strategies or dietary guidelines for individuals or subgroups in public health requires further insight in the mechanisms involved in (non-)response to dietary intervention. Authors conclude that future studies are needed and these should focus on assessing detailed individual phenotyping and gaining insight into the balance between carbohydrate and protein fermentation by the gut microbiota as well as the site of fermentation in the colon.
Abstract
Accumulating evidence indicates that the gut microbiome is an important regulator of body weight, glucose and lipid metabolism, and inflammatory processes, and may thereby play a key role in the aetiology of obesity, insulin resistance and type 2 diabetes. Interindividual responsiveness to specific dietary interventions may be partially determined by differences in baseline gut microbiota composition and functionality between individuals with distinct metabolic phenotypes. However, the relationship between an individual's diet, gut microbiome and host metabolic phenotype is multidirectional and complex, yielding a challenge for practical implementation of targeted dietary guidelines. In this review, we discuss the latest research describing interactions between dietary composition, the gut microbiome and host metabolism. Furthermore, we describe how this knowledge can be integrated to develop precision-based nutritional strategies to improve bodyweight control and metabolic health in humans. Specifically, we will address that (1) insight in the role of the baseline gut microbial and metabolic phenotype in dietary intervention response may provide leads for precision-based nutritional strategies; that (2) the balance between carbohydrate and protein fermentation by the gut microbiota, as well as the site of fermentation in the colon, seems important determinants of host metabolism; and that (3) 'big data', including multiple omics and advanced modelling, are of undeniable importance in predicting (non-)response to dietary interventions. Clearly, detailed metabolic and microbial phenotyping in humans is necessary to better understand the link between diet, the gut microbiome and host metabolism, which is required to develop targeted dietary strategies and guidelines for different subgroups of the population.
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Low FODMAP diet reduces gastrointestinal symptoms in irritable bowel syndrome and clinical response could be predicted by symptom severity: A randomized crossover trial.
Algera, JP, Demir, D, Törnblom, H, Nybacka, S, Simrén, M, Störsrud, S
Clinical nutrition (Edinburgh, Scotland). 2022;41(12):2792-2800
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Irritable bowel syndrome (IBS) is a common disorder of gut-brain interaction, characterised by chronic abdominal pain and altered bowel habits. Currently, many patients follow an exclusion diet where specific food components are eliminated. One of these exclusion diets is a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs). The primary aim of this study was to compare the effects of diets with low vs. moderate FODMAP content on gastrointestinal (GI) symptoms in IBS. This study was a double-blind, randomised, controlled, crossover study which enrolled 31 participants who were randomly assigned to the diet periods. Results showed that the severity of GI symptoms was reduced, and bowel habits were affected in the direction of less frequent and firmer stool by the low FODMAP diet, but not by a diet with moderate amounts of FODMAPs. Authors conclude that assessment of overall IBS severity and predominant bowel habits before the intervention may be helpful for clinicians in their IBS management before considering a trial period with the low FODMAP diet as a treatment option.
Expert Review
Conflicts of interest:
None
Take Home Message:
A low (4 g/day) FODMAP diet could provide clinical benefits in the context of an acute strategy for IBS clients with frequent loose stools (IBS-Diarrhoea and/or IBS-Mixed) compared to those with hard and less frequent stools (IBS-Constipation) to improve the severity of GI symptoms, including lower abdominal pain intensity and frequency, bowel habits, daily life interference, and psychological distress.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
The aim of this paper was to investigate the effects of diets with low vs. moderate FODMAP content on gastrointestinal (GI) symptoms and bowel habits, and to identify possible predictors of clinical response to a low FODMAP diet and FODMAP sensitivity in Irritable Bowel Syndrome (IBS).
Methods
- This study involved a double-blind, randomised, controlled, crossover trial of 29 participants (18-75 years), mostly female, diagnosed with IBS (Rome IV)
- The primary outcome was to assess the effects of a low (4 g/day) vs. moderate (23 g/day) FODMAP diet on GI symptoms over a 7-day period
- Secondary outcomes involved assessing the effects of low vs. moderate FODMAP diets on i) somatic symptoms, ii) psychological distress, iii) predictors of clinical and IBS-Severity Scoring System (IBS-SSS) sensitivity to FODMAP
- Breakfast was standardised, with prescribed low FODMAP list deviations recorded
- Main dishes and snacks were also provided
- Participants were requested to limit alcohol, caffeine, fatty- and spicy foods, ate regularly, chewed thoroughly and drank enough water
- GI symptoms and bowel habits were recorded during the 7-day screening period, then participants undertook a Lactulose Nutrient Challenge Test (LNCT)
- The first 7-day diet started one day after the LNCT
- A 14-day wash-out period allowed participants to eat and drink as usual, thereafter following the second 7-day diet period as part of the cross over design.
Results
A low FODMAP intervention (compared to a moderate FODMAP diet); resulted in:
- Reduced overall IBS rating (10 ± 72 vs. 57 ± 108, P=0.04)
- Improved abdominal pain frequency (10 ± 32 vs. 18 ± 29 (P=0.02)
- Improved stool consistency (0.2 ± 1.0 vs. 0.6 ± 1.2, P= 0.01) and frequency (0.1 ± 0.7 vs. 0.4 ± 0.7, P= 0.01)
- Overall, 34% of participants positively responded to the low FODMAP diet, which could be predicted based on higher baseline IBS-SSS scores (P=0.02)
- Participants sensitive to FODMAPs had increased pre- and postprandial ratings of gas, abdominal pain and bloating and higher exhaled methane concentrations compared to non-sensitive participants to FODMAPs
- Authors highlighted a non-significant association between FODMAP sensitivity and GI symptoms during the LNCT, with higher visceral hypersensitivity (45 ± 20, P=0.73) after ingestion of poorly absorbed and fermentable carbohydrates, with no independent predictors identified.
Conclusions
This study showed that a diet low in FODMAPs reduces GI symptoms and positively impacts bowel habits in IBS, compared with a moderate FODMAP diet.
Clinical practice applications:
- While this was a short term study, a low FODMAP diet reduced GI symptoms and affected bowel habits (more firm and less frequent stools) in IBS, compared with a diet containing moderate amounts of FODMAPs
- Knowing the above, an assessment of overall IBS severity and predominant bowel habits before the intervention may be helpful for clinicians working with younger females in their IBS management before considering a trial period with the low FOD-MAP diet as a treatment option.
Considerations for future research:
- Future trials could target a larger sample size with a more representative population, as well as assessing low FODMAP interventions over longer timeframes
- . Additionally, the assessment of biological measures such as microbiota diversity and stability, as well as metabolites (such as short chain fatty acids) could be important to understand mechanistic attributes of low FODMAP diets in IBS.
Abstract
BACKGROUND & AIMS Fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) can provoke symptoms in patients with irritable bowel syndrome (IBS). We aimed to compare the effects of diets with low vs. moderate FODMAP content on gastrointestinal (GI) symptoms and bowel habits, and to identify possible predictors of clinical response to a low FODMAP diet and FODMAP sensitivity in IBS. METHODS Adult participants with IBS (Rome IV criteria, n = 29) were included and adhered to two 7-day diet periods, with either low (4 g/day) or moderate (23 g/day) amounts of FODMAPs, in this randomized, double-blind, crossover study. The periods were separated by a wash-out period (≥14 days). IBS-Severity Scoring System (IBS-SSS) and a stool diary (Bristol Stool Form) were completed before and after the diet periods. At baseline, severity of GI symptoms and gut microbial fermentation were assessed (every 15 min, 4 h) during the Lactulose Nutrient Challenge Test (LNCT). Clinical response and FODMAP sensitivity were defined by reduction after low FODMAP period, and increase after moderate FODMAP period in IBS-SSS (≥50 points), respectively. RESULTS Severity of GI symptoms (P = 0.04), stool consistency (P = 0.01), and stool frequency (P = 0.01) differed between the interventions, with reduced overall GI symptom severity, abdominal pain intensity and frequency, bowel habits dissatisfaction, and daily life interference (P < 0.05 for all), as well as more firm (P = 0.03) and less frequent (P < 0.01) stools after low FODMAP intervention, but not after moderate FODMAP intervention. A third (34%) responded clinically to the low FODMAP diet, and the response could be predicted by higher IBS-SSS at baseline (P = 0.02). Although modest associations between FODMAP sensitivity (22%) and GI symptoms during LNCT were observed, no independent predictors could be identified. CONCLUSIONS A diet low in FODMAPs reduces GI symptoms and affects bowel habits in IBS, compared with a moderate FODMAP diet. Assessment of IBS severity before the intervention may be used to predict clinical response to a low FODMAP diet. Trial registry (http://www. CLINICALTRIALS gov): Registered under Clinical Trial number NCT05182593.