In mice, the maternal microbiome influences fetal immune development and postnatal allergic outcomes. Westernized populations have high rates of allergic disease and low rates of gastrointestinal ...carriage of Prevotella, a commensal bacterial genus that produces short chain fatty acids and endotoxins, each of which may promote the development of fetal immune tolerance. In this study, we use a prebirth cohort (n = 1064 mothers) to conduct a nested case-cohort study comparing 58 mothers of babies with clinically proven food IgE mediated food allergy with 258 randomly selected mothers. Analysis of the V4 region of the 16S rRNA gene in fecal samples shows maternal carriage of Prevotella copri during pregnancy strongly predicts the absence of food allergy in the offspring. This association was confirmed using targeted qPCR and was independent of infant carriage of P. copri. Larger household size, which is a well-established protective factor for allergic disease, strongly predicts maternal carriage of P. copri.
When researchers selectively report significant positive results, and omit non-significant or negative results, the published literature skews in a particular direction. This is called 'reporting ...bias', and it can cause both casual readers and meta-analysts to develop an inaccurate understanding of the efficacy of an intervention. This paper identifies potential reporting bias in a recent high-profile higher education meta-analysis. It then examines a range of potential factors that may make higher education learning and teaching research particularly susceptible to reporting bias. These include the fuzzy boundaries between learning and teaching research, scholarship and teaching; the positive agendas of 'learning and teaching' funding bodies; methodological issues; and para-academic researchers in roles without tenure or academic freedom. Recommendations are provided for how researchers, journals, funders, ethics committees and universities can reduce reporting bias.
The effects of dairy and dairy-derived products on the human gut microbiota remains understudied. A systematic literature search was conducted using Medline, CINAHL, Embase, Scopus, and PubMed ...databases with the aim of collating evidence on the intakes of all types of dairy and their effects on the gut microbiota in adults. Risk of bias was assessed using the Cochrane risk-of-bias tool.The search resulted in 6,592 studies, of which eight randomized controlled trials (RCTs) met pre-determined eligibility criteria for inclusion, consisting of a total of 468 participants. Seven studies assessed the effect of type of dairy (milk, yogurt, and kefir) and dairy derivatives (whey and casein) on the gut microbiota, and one study assessed the effect of the quantity of dairy (high dairy vs low dairy). Three studies showed that dairy types consumed (milk, yogurt, and kefir) increased the abundance of beneficial genera Lactobacillus and Bifidobacterium. One study showed that yogurt reduced the abundance of Bacteroides fragilis, a pathogenic strain. Whey and casein isolates and the quantity of dairy consumed did not prompt changes to the gut microbiota composition. All but one study reported no changes to bacterial diversity in response to dairy interventions and one study reported reduction in bacterial diversity in response to milk intake.In conclusion, the results of this review suggest that dairy products such as milk, yogurt, and kefir may modulate the gut microbiota composition in favor to the host. However, the broader health implications of these findings remain unclear and warrant further studies.
Mental disorders including depression and anxiety are often comorbid with gut problems, suggesting a bidirectional relationship between mental health and gut function. Several mechanisms might ...explain this comorbidity, such as inflammation and immune activation; intestinal permeability; perturbations in the hypothalamic-pituitary-adrenal axis; neurotransmitter/neuropeptide dysregulation; dietary deficiencies; and disturbed gut microbiome composition. The potential of modulating the microbiome-gut-brain axis, and subsequently mental health, through the use of functional foods, is an emerging and novel topic of interest. Fermented foods are considered functional foods due to their putative health benefits. The process of microbial fermentation converts food substrates into more nutritionally and functionally rich products, resulting in functional microorganisms (probiotics), substrates that enhance proliferation of beneficial bacteria in the gut (prebiotics), and bioactive components (biogenics). These functional ingredients act biologically in the gastrointestinal tract and have the ability to modify the gut microbiota, influence translocation of endotoxins and subsequent immune activation, and promote host nutrition. This narrative review explores the theoretical potential of the functional components present in fermented foods to alter gut physiology and to impact the biological mechanisms thought to underpin depression and anxiety. Pre-clinical studies indicate the benefits of fermented foods in relieving perturbed gut function and for animal models of depression and anxiety. However, in humans, the literature relating to the relevance of fermented food for treating or preventing depression and anxiety is sparse, heterogeneous and has significant limitations. This review identifies a critical research gap for further evaluation of fermented foods in the management of depression anxiety in humans.
Despite compositional alterations in gastrointestinal microbiota being purported to underpin some of the therapeutic effects of ginger, the effect of a standardized ginger supplement on gut ...microbiota has not been tested in humans.
To determine the effect of a standardized ginger (Zingiber officinale) root powder, compared to placebo, on gastrointestinal bacteria and associated outcomes in healthy adults.
A randomized double-blind placebo-controlled trial allocated participants aged 18 to 30 y to ginger or microcrystalline cellulose (MCC) placebo. The intervention comprised 1.2 g/d of ginger (4 capsules per day totaling 84 mg/d of active gingerols/shogaols) for 14 d following a 1-wk run-in period. Primary outcomes were gastrointestinal community composition, alpha and beta diversity, and differential abundance, measured using 16S rRNA gene sequencing of fecal samples. Secondary outcomes were gastrointestinal symptoms, bowel function, depression, anxiety, stress, fatigue, quality of life, and adverse events.
Fifty-one participants were enrolled and analyzed (71% female; mean age 25 ± 3 y; ginger: n = 29, placebo: n = 22). There was a greater increase in relative abundance of phylum, Actinobacteria, observed following ginger supplementation compared to placebo (U: 145.0; z: -2.1; P = 0.033). Ginger was associated with a greater abundance of the genera Parabacteroides, Bacillus, Ruminococcaceae incertae sedis, unclassified Bacilli, families Defluviitaleaceae, Morganellaceae, and Bacillaceae as well as lower abundance of the genus Blautia and family Sphingomonadaceae (P < 0.05). An improvement in indigestion symptoms was observed with ginger supplementation (U: 196.0; z: -2.4; P = 0.015). No differences between ginger and placebo groups were found for alpha and beta diversity or other secondary outcomes. No moderate or severe adverse events were reported.
Supplementation with ginger root powder was safe and altered aspects of gastrointestinal bacteria composition; however, it did not change alpha- or beta diversity, bowel function, gastrointestinal symptoms, mood, or quality of life in healthy adults. These results provide further understanding regarding the mechanisms of action of ginger supplementation. This trial was registered in the Australia New Zealand Clinical Trials Registry as ACTRN12620000302954p and the Therapeutic Goods Administration as CT-2020-CTN-00380-1.
Objective
In the present study, we describe a novel class of small‐molecule synthetic compounds that ameliorate seizure‐like behavior, using an electroshock assay to examine seizure duration in ...Caenorhabditis elegans. We also examine the hypothesis that these compounds, which we have called resveramorphs (RVMs), act by an irreversible binding mechanism.
Methods
Our electroshock assay examines seizure duration in C. elegans and can be used as a drug‐screening platform for the identification of novel anti‐seizure agents. The use of C. elegans allows for a rapid and efficient method of drug screening that may take years in other higher‐order model organisms. A novel wash method, paired with our electroshock assay, allows us to discern differences in biological activity when the C. elegans are incubated in different drug solutions, to establish whether these compounds can be “washed” off.
Results
One of the RVMs (RVM‐3), reported here for the first time, was found to be potent at picomolar concentrations. Insights also provided information on the potential mechanisms of action of this compound. Covalent binding is thought to provide a strong irreversible bond because of a change in structure between two of the novel RVMs described in this work. This was also discerned through the novel wash method paired with our electroshock assay.
Significance
RVM‐3 was evaluated using our assay and found to possess anti‐seizure activity at picomolar concentrations. These insights also provide information on the potential mechanisms of action of these compounds, which may include covalent binding. This was also discerned through a novel wash method paired with our electroshock assay.
•Thirteen studies investigating 12 kynurenine metabolites were included in the review.•Across the prebiotic (n = 2) and probiotic (n = 12) interventions, 11 reported an effect on ≥ 1 ...metabolite.•Probiotics were found to affect kynurenine and the kynurenine:tryptophan ratio in meta-analysis.•Preliminary evidence indicates probiotics can modulate metabolic activity along the kynurenine pathway.•Evidence is limited regarding the effect of prebiotics on kynurenine pathway metabolism.
This systematic review aimed to synthesise the results from studies investigating the effects of prebiotics and probiotics on kynurenine pathway metabolism. Thirteen studies were identified for inclusion, comprising 12 probiotic and two prebiotic arms. Participants included healthy individuals and individuals with various clinical conditions. Twelve metabolites were examined across the studies, using a range of biological samples. Across all interventions, 11 reported an effect on ≤ metabolite. Although limited by clinical and methodological heterogeneity, pooled analysis (n = 253) found probiotics to significantly affect serum kynurenine (g = 0.315, CI = 0.070 to 0.560, p = 0.012, 4 studies, I2 = 0%) and the kynurenine:tryptophan ratio (g = 0.442, CI = 0.074 to 0.810, p = 0.018, 4 studies, I2 = 42 %). Risk of bias across the studies was generally low. The results provide preliminary evidence that probiotics can modulate kynurenine pathway metabolism, with less evidence available regarding prebiotics. Future studies which further consider methodological confounds and sample characteristics are required, to establish intervention efficacy. PROSPERO registration #CRD42019154677.
Household food insecurity (HFI) and poorer prenatal diet quality are both associated with adverse perinatal outcomes. However, research assessing the relationship between HFI and diet quality in ...pregnancy is limited. A cross-sectional online survey was conducted to examine the relationship between HFI and diet quality among 1540 pregnant women in Australia. Multiple linear regression models were used to examine the associations between HFI severity (marginal, low, and very low food security compared to high food security) and diet quality and variety, adjusting for age, education, equivalised household income, and relationship status. Logistic regression models were used to assess the associations between HFI and the odds of meeting fruit and vegetable recommendations, adjusting for education. Marginal, low, and very low food security were associated with poorer prenatal diet quality (adj β = -1.9, -3.6, and -5.3, respectively;
< 0.05), and very low food security was associated with a lower dietary variety (adj β = -0.5,
< 0.001). An association was also observed between HFI and lower odds of meeting fruit (adjusted odds ratio AOR: 0.61, 95% CI: 0.49-0.76,
< 0.001) and vegetable (AOR: 0.40, 95% CI: 0.19-0.84,
= 0.016) recommendations. Future research should seek to understand what policy and service system changes are required to reduce diet-related disparities in pregnancy.
The microbiota-gut-brain axis' role in Parkinson's disease (PD) pathophysiology, and how this differs from typical ageing, is poorly understood. Presently, gut-bacterial diversity, taxonomic ...abundance and metabolic bacterial pathways were compared across healthy young (n = 22, 18–35 years), healthy older (n = 33, 50–80 years), and PD groups (n = 18, 50–80 years) using shotgun sequencing and compositional data analysis. Associations between the gut-microbiome and PD symptoms, and between lifestyle factors (fibre intake, physical activity, and sleep) and the gut-microbiome were conducted. Alpha-diversity did not differ between PD participants and older adults, whilst beta-diversity differed between these groups. Lower abundance of Butyricimonas synergistica, a butyrate-producer, was associated with worse PD non-motor symptoms in the PD group. Regarding typical ageing, Bifidobacterium bifidum, was greater in the younger compared to older group, with no difference between the older and PD group. Abundance of metabolic pathways related to butyrate production did not differ among the groups, while other metabolic pathways differed among the three groups. Sleep efficiency was positively associated with Roseburia inulinivorans in the older group. These results highlight the relevance of gut-microbiota to PD and that reduced butyrate-production may be involved with PD pathophysiology. Future studies should account for lifestyle factors when investigating gut-microbiomes across ageing and in PD.
This article is part of the Special Issue on “Microbiome & the Brain: Mechanisms & Maladies”.
•Shotgun sequencing and compositional data analysis of gut bacteria data.•Butyrate producer, B. synergistica, associated with worse PD non-motor symptoms.•Lifestyle factors were differently related to gut bacteria across groups.•Bacterial metabolic functions differed across healthy ageing and in PD groups.
To evaluate the hypothesis that a perinatal educational dietary intervention focused on 'eating for the gut microbiota' improves diet quality of pregnant women pre- and postnatally.
The Healthy ...Parents, Healthy Kids study is a prospectively registered randomised controlled trial designed to evaluate the efficacy of a dietary intervention in altering the maternal and infant gut microbiota and improving perinatal diet quality. Eligible pregnant women were randomised to receive dietary advice from their healthcare provider or to additionally receive a three session dietary intervention. Dietary data were collected at gestation weeks 26, 31, 36 and postnatal week 4. Outcome measures were diet quality, dietary variety, prebiotic and probiotic food intakes, energy, fibre, saturated fat and discretionary food intakes. Between-group differential changes from baseline before and after birth in these dietary measures were assessed using generalised estimating equations.
Melbourne, Australia.
Healthy pregnant women from gestation week 26.
Forty-five women were randomised (twenty-two control, twenty-three intervention). Compared with the control group, the intervention group improved diet quality prior to birth (5·66 (95 % CI 1·65, 9·67), Cohen's d: 0·82 (se 0·33)). The intervention improved dietary variety (1·05 (95 % CI 0·17, 1·94), d: 0·66 (se 0·32)) and increased intakes of prebiotic (0·8 (95 % CI 0·27, 1·33), d: 0·91 (se 0·33)) and probiotic foods (1·05 (95 % CI 0·57, 1·53), d: 1·3(se 0·35)) over the whole study period compared with the control group.
A dietary intervention focused on 'eating for the gut microbiota' can improve aspects of perinatal diet quality during and after pregnancy.
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