Prenatal and postnatal probiotics reduces maternal but not childhood allergic diseases: a randomized, double-blind, placebo-controlled trial

Dietary Interventions in Atopic Dermatitis: A Comprehensive Scoping Review and Analysis

BACKGROUND

This scoping review aims to critically assess gaps in the current literature on atopic dermatitis (AD) by evaluating the overall effectiveness of dietary interventions. Through a comprehensive analysis that follows the Preferred Reporting Item for Systematic Review and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines, we conducted a thorough search on the Web of Science database in May 2023 using specific search strategies to identify all relevant studies on the research topic.

SUMMARY

A total of 104 full-text articles were included for review. Our synthesis identified seven notable categories of dietary interventions for AD, showcasing the diversity of interventions utilized. This includes vitamin supplementation, probiotic and prebiotic supplementation, dietary fat, biological compounds, foods from natural sources, major nutrients, and diet-related approaches. Further analyses stratified by targeted populations revealed a predominant focus on pediatrics, particularly in probiotic supplementation, and on adults, with an emphasis on vitamin D and E supplementation.

KEY MESSAGES

Despite most dietary interventions demonstrating overall effectiveness in improving AD severity and its subjective symptoms, several significant gaps were identified. There was a scarcity of studies on adults and whole-diet interventions, a prevalence of short-term interventions, heterogeneity in study outcomes, designs, and population, occasional disparity between statistical significance and clinical relevance, and a lack of a comprehensive multidisciplinary approach. Nonetheless, these findings offer valuable insights for future AD research, guiding additional evidence-driven dietary interventions and informing healthcare professionals, researchers, and individuals, advancing both understanding and management of AD.

Maternal supplementation with Limosilactobacillus reuteri FN041 for preventing infants with atopic dermatitis: study protocol for a randomized controlled trial

Background

Atopic dermatitis (AD) has increased rapidly with rapid urbanization; however, the treatment options for AD are lacking because the commonly used therapies can only alleviate symptoms. Limosilactobacillus reuteri (L. reuteri), FN041 is a specific strain isolated from human breast milk, and its protective potential against AD has been confirmed. This study aims to assess the efficacy of maternal consumption of L. reuteri FN041 during late pregnancy and lactation in preventing infantile AD.

Methods

First, a randomized, double-blind, placebo-controlled intervention study will be conducted on 340 pregnant females with babies at high risk for AD. These subjects will be randomly divided into four groups of different doses of L. reuteri FN041 (1 × 109, 5 × 109, and 1 × 1010 CFU/d) along with a placebo. The safety and efficacy of maternal use of L. reuteri FN041 for preventing infantile AD will be analyzed, and the most efficient dosage of L. reuteri FN041 will be determined. Subsequently, a multicenter cohort study of 500 pregnant females with babies at high risk for AD will be conducted to promote the maternal application of L. reuteri FN041. These subjects will be administered L. reuteri FN041 at the optimal dose determined during the first stage of late pregnancy and lactation, and their babies will be analyzed for AD development. Recruitment was initiated in October 2022.

Discussion

The primary outcome is the cumulative incidence of AD at 24 months after maternal consumption of L. reuteri FN041 during late pregnancy and lactation, whereas the secondary outcome is the efficiency of L. reuteri FN041 transfer from the mother's gut to breast milk and then the infant's gut after oral supplementation. This study will demonstrate the efficacy of edible probiotics isolated from breast milk in preventing or treating AD in infants. Accordingly, we provide population-based advice for administering specific probiotics for the primary prevention of AD in pregnant females. Understanding the underlying mechanisms of probiotic strains derived from breast milk can promote their application in preventing infant diseases associated with intestinal microbiota imbalance and immune disorders.

Clinical trial registration

https://www.chictr.org.cn/, identifier [ChiCTR2300075611].

Using probiotics in paediatric populations

This statement defines probiotics and reviews the most recent literature on their use in paediatrics. Many studies have examined the potential benefit of probiotics, but significant variation in the strains and doses of probiotics used, the patient populations studied, and in study design, have led to heterogeneous results. Present evidence suggests that probiotics can decrease mortality and lower incidence of necrotizing enterocolitis in preterm and low birth weight neonates. Probiotics may also be beneficial in reducing feeding intolerance. In infants, probiotics may be considered to reduce symptoms of colic. In older children, probiotics can be considered to prevent antibiotic-associated diarrhea and Clostridium difficile -associated diarrhea. Probiotic supplements used in conjunction with standard therapy can help with Helicobacter pylori eradication and decrease the side effects of treatment. Lactobacillus species can be considered to treat irritable bowel syndrome. Probiotics can also be considered to help prevent atopic dermatitis and eczema. To optimize paediatric policy and practice, large, quality studies are needed to determine what types and combinations of probiotics are most efficacious.

L’utilisation des probiotiques dans la population pédiatrique

Le présent document de principes définit les probiotiques et fournit une analyse des publications scientifiques les plus récentes sur leur utilisation en pédiatrie. De nombreuses études ont évalué les avantages potentiels des probiotiques, mais en raison des variations importantes dans les souches et les doses utilisées, des populations de patients étudiées et des méthodologies privilégiées, les résultats sont hétérogènes. Selon les données probantes à jour, les probiotiques peuvent réduire le taux de mortalité et l’incidence d’entérocolite nécrosante chez les nouveau-nés prématurés et de petit poids à la naissance. Ils peuvent également être bénéfiques pour réduire l’intolérance alimentaire. Chez les nourrissons, on peut envisager de les utiliser pour limiter les symptômes de coliques, et chez les enfants plus âgés, pour prévenir la diarrhée associée aux antibiotiques ou au Clostridium difficile . Les suppléments de probiotiques utilisés conjointement avec un traitement standard peuvent contribuer à éradiquer l’Helicobacter pylori et à atténuer les effets secondaires du traitement. On peut envisager d’utiliser des espèces de Lactobacillus pour traiter le syndrome du côlon irritable ou de recourir à des probiotiques pour contribuer à prévenir la dermatite atopique et l’eczéma. Afin d’optimiser les politiques et les pratiques en pédiatrie, de vastes études de qualité devront être réalisées pour déterminer les types et les combinaisons de probiotiques les plus efficaces.

Lactobacillus rhamnosus Used in the Perinatal Period for the Prevention of Atopic Dermatitis in Infants: A Systematic Review and Meta-Analysis of Randomized Trials

Background

Numerous systematic reviews and meta-analyses have examined the effects of probiotics used perinatally on prevention or treatment of atopic disease in infants and children. However, to date, no review has examined randomized controlled trials of Lactobacillus rhamnosus, specifically, administered both prenatally and postnatally and its effect over a long period of time.

Objective

The objective was to determine if L. rhamnosus either used solely or in conjunction with other probiotics demonstrates a long-term preventive effect on atopic disease in pediatric patients when used perinatally.

Methods

A systematic review was undertaken to identify those studies where L. rhamnosus was used (either solely or in conjunction with other probiotics). The following databases were searched from the year 2000 through December 8, 2021: PubMed, Cochrane Reviews and Cochrane Central Database of Controlled Trials; systematic reviews were hand searched to identify randomized controlled trials (RCTs). Meta-analytic statistical techniques were then employed. Evaluation of the incidence of atopic eczema was also examined longitudinally based on timeframe. Grading of Recommendations, Assessment, Development and Evaluations (GRADE) assessments were employed to determine the quality of the evidence.

Results

Eleven randomized controlled trials were identified which examined L. rhamnosus in its effect on atopy. Risk of bias was low on the majority of the domains assessed. Meta-analysis of the timeframes ≤ 2 years (RR 0.60, 95% CI 0.47–0.75; p < 0.00001) and 6–7 years (RR 0.62, 95% CI 0.50–0.75; p < 0.00001) demonstrated statistically significant reductions in atopic eczema with use of L. rhamnosus. For the 4 to 5-year (RR 0.74, 95% CI 0.55–1.00; p = 0.05) and 10–11-year (RR 0.68, 95% CI 0.37–1.27; p = 0.23) timeframes there was no statistically significant reduction. GRADE assessment for each timeframe was considered moderate in two, owing to high attrition rates in all of the studies, and low in two due to imprecision.

Conclusion

Based on the meta-analysis and GRADE assessments, the use of L. rhamnosus with or without other probiotics appears to have a positive effect in reducing the incidence of atopic eczema in pediatric patients at least out to 7 years. Attrition rates temper these findings.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40257-022-00723-x.

Current Use of Probiotics and Prebiotics in Allergy

The microbiome plays an important role in the pathogenesis of allergic diseases. This review updates the reader on studies aimed at influencing allergic diseases through modulation of the gut microflora. A nonsystematic review of the literature was performed, focusing on relevant trials evaluating the effect of probiotics/prebiotics/symbiotics in the prevention and treatment of allergic disease. For each allergic disease, we were able to find not only a substantial number of clinical trials but also systematic reviews. Specific guidelines, based on systematic reviews and meta-analyses, are available for the prevention of allergic disease and for the treatment of food allergy. In each of the areas examined-allergic rhinitis, allergic asthma, atopic dermatitis, food allergy, and gastrointestinal allergies-there are substantial uncertainties in the efficacy of gut microflora modulation in prevention and treatment. At present, practicing clinicians can avail themselves of intestinal flora modulators as an adjunct in the prevention of atopic dermatitis but not of other forms of allergic diseases. Their effects on the treatment of allergic diseases remain controversial.

Efficacy of Direct or Indirect Use of Probiotics for the Improvement of Maternal Depression during Pregnancy and in the Postnatal Period: A Systematic Review and Meta-Analysis

The mother and infant form a unique bond, with maternal mental health affecting the interactions with the infant and infant behaviours impacting maternal mental health. One of the possible mechanisms influencing maternal mental health is the manipulation of the gut-brain axis by consuming probiotic supplements. Probiotics can also have an indirect influence on maternal mental health via the modulation of the infant microbiome and consequently improving the infant’s health and thus, indirectly leading to an improvement in maternal mood. This systematic review evaluated the efficacy of probiotics on maternal mental health by searching for randomised controlled trials via international databases: Cochrane Library, PubMed, Scopus, ScienceDirect, and Web of Science until January 2022. A meta-analysis was performed using the Cochrane Collaboration methodology where possible. We found seven clinical trials that included the word probiotics and addressed maternal depression and/or anxiety. Of these, five trials investigated the influence of maternal probiotic supplementation on the gut-brain axis. Two trials investigated the indirect influence of probiotics on maternal depression via supplementation of probiotics by infants and subsequent influence on the crying of colicky infants. Meta-analysis of two studies of pregnant and postnatal women and two studies of infants consuming probiotics on the outcome of the Edinburgh Postnatal Depression Scale for mothers showed no statistical difference. The findings indicate that maternal depression is very complex and is influenced by various bidirectional factors. One of the factors that can improve maternal mental health is probiotics, however, careful consideration must be given to correct strain selection as strain-specific effectiveness was observed. Further well-designed, robust clinical studies are warranted.

The Maternal–Fetal Gut Microbiota Axis: Physiological Changes, Dietary Influence, and Modulation Possibilities

The prenatal period and the first years of life have a significant impact on the health issues and life quality of an individual. The appropriate development of the immune system and the central nervous system are thought to be major critical determining events. In parallel to these, establishing an early intestinal microbiota community is another important factor for future well-being interfering with prenatal and postnatal developmental processes. This review aims at summarizing the main characteristics of maternal gut microbiota and its possible transmission to the offspring, thereby affecting fetal and/or neonatal development and health. Since maternal dietary factors are potential modulators of the maternal–fetal microbiota axis, we will outline current knowledge on the impact of certain diets, nutritional factors, and nutritional modulators during pregnancy on offspring’s microbiota and health.

Adjunctive Probiotics Alleviates Asthmatic Symptoms via Modulating the Gut Microbiome and Serum Metabolome

Asthma is a multifactorial disorder, and microbial dysbiosis enhances lung inflammation and asthma-related symptoms. Probiotics have shown anti-inflammatory effects and could regulate the gut-lung axis. Thus, a 3-month randomized, double-blind, and placebo-controlled human trial was performed to investigate the adjunctive efficacy of probiotics in managing asthma. Fifty-five asthmatic patients were randomly assigned to a probiotic group (n = 29; received Bifidobacterium lactis Probio-M8 powder and Symbicort Turbuhaler) and a placebo group (n = 26; received placebo and Symbicort Turbuhaler), and all 55 subjects provided details of their clinical history and demographic data. However, only 31 patients donated a complete set of fecal and blood samples at all three time points for further analysis. Compared with those of the placebo group, co-administering Probio-M8 with Symbicort Turbuhaler significantly decreased the fractional exhaled nitric oxide level at day 30 (P = 0.049) and improved the asthma control test score at the end of the intervention (P = 0.023). More importantly, the level of alveolar nitric oxide concentration decreased significantly among the probiotic receivers at day 30 (P = 0.038), and the symptom relief effect was even more obvious at day 90 (P = 0.001). Probiotic co-administration increased the resilience of the gut microbiome, which was reflected by only minor fluctuations in the gut microbiome diversity (P > 0.05, probiotic receivers; P < 0.05, placebo receivers). Additionally, the probiotic receivers showed significantly changes in some species-level genome bins (SGBs), namely, increases in potentially beneficial species Bifidobacterium animalis, Bifidobacterium longum, and Prevotella sp. CAG and decreases in Parabacteroides distasonis and Clostridiales bacterium (P < 0.05). Compared with that of the placebo group, the gut metabolic potential of probiotic receivers exhibited increased levels of predicted microbial bioactive metabolites (linoleoyl ethanolamide, adrenergic acid, erythronic acid) and serum metabolites (5-dodecenoic acid, tryptophan, sphingomyelin) during/after intervention. Collectively, our results suggested that co-administering Probio-M8 synergized with conventional therapy to alleviate diseases associated with the gut-lung axis, like asthma, possibly via activating multiple anti-inflammatory pathways. IMPORTANCE The human gut microbiota has a potential effect on the pathogenesis of asthma and is closely related to the disease phenotype. Our trial has demonstrated that co-administering Probio-M8 synergized with conventional therapy to alleviate asthma symptoms. The findings of the present study provide new insights into the pathogenesis and treatment of asthma, mechanisms of novel therapeutic strategies, and application of probiotics-based therapy.

Microbiome Modulation as a Therapeutic Approach in Chronic Skin Diseases

There is a growing quantity of evidence on how skin and gut microbiome composition impacts the course of various dermatological diseases. The strategies involving the modulation of bacterial composition are increasingly in the focus of research attention. The aim of the present review was to analyze the literature available in PubMed (MEDLINE) and EMBASE databases on the topic of microbiome modulation in skin diseases. The effects and possible mechanisms of action of probiotics, prebiotics and synbiotics in dermatological conditions including atopic dermatitis (AD), psoriasis, chronic ulcers, seborrheic dermatitis, burns and acne were analyzed. Due to the very limited number of studies available regarding the topic of microbiome modulation in all skin diseases except for AD, the authors decided to also include case reports and original studies concerning oral administration and topical application of the pro-, pre- and synbiotics in the final analysis. The evaluated studies mostly reported significant health benefits to the patients or show promising results in animal or ex vivo studies. However, due to a limited amount of research and unambiguous results, the topic of microbiome modulation as a therapeutic approach in skin diseases still warrants further investigation.

Mechanisms of microbe-immune system dialogue within the skin

The prevalence and severity of dermatological conditions such as atopic dermatitis have increased dramatically during recent decades. Many of the factors associated with an altered risk of developing inflammatory skin disorders have also been shown to alter the composition and diversity of non-pathogenic microbial communities that inhabit the human host. While the most densely microbial populated organ is the gut, culture and non-culture-based technologies have revealed a dynamic community of bacteria, fungi, viruses and mites that exist on healthy human skin, which change during disease. In this review, we highlight some of the recent findings on the mechanisms through which microbes interact with each other on the skin and the signalling systems that mediate communication between the immune system and skin-associated microbes. In addition, we summarize the ongoing clinical studies that are targeting the microbiome in patients with skin disorders. While significant efforts are still required to decipher the mechanisms underpinning host-microbe communication relevant to skin health, it is likely that disease-related microbial communities, or Dermatypes, will help identify personalized treatments and appropriate microbial reconstitution strategies.

Comparative effectiveness of probiotic strains on the prevention of pediatric atopic dermatitis: A systematic review and network meta-analysis

BACKGROUND

Atopic dermatitis is the most common chronic skin disease affecting the pediatric population. Probiotics have been proposed to be effective in preventing the development of pediatric atopic dermatitis. Although studies show promise for the use of probiotics, the evidence is still inconclusive due to significant heterogeneity and imprecision.

OBJECTIVE

To determine the comparative effectiveness of the different types of probiotic strains in preventing the development of atopic dermatitis among pediatric patients.

METHODOLOGY

A systematic search of Cochrane Library, MEDLINE, TRIP Database, and Centre for Research and Dissemination was conducted. Manual search of the reference lists and search for unpublished articles were also done. All randomized controlled trials available from inception until April 12, 2020, on the use of probiotics in the prevention of atopic dermatitis among children were included. The comparator groups considered are other probiotic strains and placebo. The primary outcome of interest was the development of atopic dermatitis. Two authors independently searched for articles, screened the articles for inclusion, appraised the articles using the Cochrane risk of bias tool version 2, and extracted the data. In case of disagreement, the two authors discussed the source of disagreement until consensus was reached. If consensus was not reached, an independent third party reviewer was consulted. Frequentist network meta-analysis was conducted using STATA 14 software. The ranking probabilities and surface under the cumulative ranking curve (SUCRA) values were obtained to determine ranking of the different probiotic strains based on efficacy and safety data.

RESULTS

We included 21 original studies represented by 35 records and a total of 5406 children with atopic dermatitis as diagnosed by clinicians or fulfillment of validated diagnostic criteria. All studies were randomized placebo-controlled trials. The top 3 probiotic preparations in terms of efficacy in reducing the risk of atopic dermatitis are Mix8 (Lactobacillus paracasei ST11, Bifidobacterium longum BL999), LP (Lactobacillus paracasei ssp paracasei F19) and Mix3 (Lactobacillus rhamnosus GG, Bifidobacterium animalis ssp lactis Bb-12). Mix8 compared with placebo probably reduces the risk of atopic dermatitis based on low-quality evidence (RR = 0.46, 95% CI 0.25-0.85). Mix3 compared with placebo also probably reduces the risk of atopic dermatitis based on low-quality evidence (RR = 0.50, 95% CI 0.27-0.94). It is uncertain whether LP compared with placebo reduces the risk of atopic dermatitis due to very-low-quality certainty of evidence (RR = 0.49, 95% CI 0.20-1.19). In terms of adverse events, LGG may slightly lead to less adverse events compared with placebo based on low-quality evidence (RR = 0.70, 95% CI 0.32-1.52). Mix4 may slightly lead to more adverse events compared with placebo based on low-quality evidence (RR = 1.06, 95% CI 0.02-51.88). Based on subgroup analysis of studies involving infants, Mix3 compared with placebo probably reduces the risk of atopic dermatitis based on low-quality evidence (RR = 0.46, 95% CI 0.22-0.97). In the subgroup analysis of studies where probiotics were administered to pregnant women and to infants, LRH compared with placebo probably reduces the risk of atopic dermatitis based on moderate-quality evidence (RR = 0.54, 95% CI 0.26-1.11).

CONCLUSION

Certain probiotic preparations demonstrate efficacy in reducing the risk of developing atopic dermatitis when administered to pregnant women, infants, or both.

The prevention effect of probiotics against eczema in children: an update systematic review and meta-analysis

Accumulated evidences support the fetus's intestinal flora unbalance is associated with the development of allergic diseases. Probiotic supplements in pregnancy and childhood might prevent atopic diseases. The aim of this systematic review and meta-analysis was to evaluate the effect of probiotic supplementation during pregnancy and early infancy in preventing eczema, atopic eczema, and other allergic diseases. We also explored whether different probiotic strains or intervention objects affected the antiallergic effect of probiotics and the prevention atopy effect of the long-term period. Fixed-effect models were used, and random-effects models where significant heterogeneity was present. Results were expressed as odds ratios (ORs) with a 95% confidence interval (CI). Twenty-one studies were included in the meta-analysis. The probiotics group had a significantly lower risk of eczema and atopic eczema compared to controls, especially those treated with probiotic combinations. Mothers' probiotics intake significantly contributed to reducing the risk of eczema as well as atopic eczema. What's more, probiotics seemed effective on eczema prevention ≤2 years of age, but against atopic eczema after 1 of age year. No significant difference in terms of prevention of asthma, rhinitis, wheeze, allergic diseases and sensation. In brief, a probiotic supplement is expected to become a novel potential strategy for infant eczema and atopic eczema.

Immunologic Strategies for Prevention of Asthma

A new understanding of factors leading to the development of asthma has pointed to potential primary, secondary, and tertiary prevention strategies. Some, such as genetic makeup, are not yet modifiable. Interventions targeting other factors such as maternal intake of vitamin D or environmental control can be used to decrease the risk of asthma development (primary prevention). The benefits of a diversified microbiome could be considered when recommending allergen avoidance and pet ownership. In addition to reducing symptoms, allergen immunotherapy is also worth considering for prevention of new sensitivities (secondary prevention) in addition to the development of asthma. Ongoing studies involving the use of bacterial vaccines and biologics may provide additional strategies for primary prevention of asthma and for reducing symptoms once it has developed (tertiary prevention). As the relative benefits of these strategies are defined, they should have an increasingly important place in the prevention and management of asthma.

Asthma in the Precision Medicine Era: Biologics and Probiotics

Asthma is a major global health issue. Over 300 million people worldwide suffer from this chronic inflammatory airway disease. Typical clinical symptoms of asthma are characterized by a recurrent wheezy cough, chest tightness, and shortness of breath. The main goals of asthma management are to alleviate asthma symptoms, reduce the risk of asthma exacerbations, and minimize long-term medicinal adverse effects. However, currently available type 2 T helper cells (Th2)-directed treatments are often ineffective due to the heterogeneity of the asthma subgroups, which manifests clinically with variable and poor treatment responses. Personalized precision therapy of asthma according to individualized clinical characteristics (phenotype) and laboratory biomarkers (endotype) is the future prospect. This mini review discusses the molecular mechanisms underlying asthma pathogenesis, including the hot sought-after topic of microbiota, add-on therapies and the potential application of probiotics in the management of asthma.

Probiotics as a Possible Strategy for the Prevention and Treatment of Allergies. A Narrative Review

Allergies are an increasing global public health concern, especially for children and people living in urban environments. Allergies impair the quality of life of those who suffer from them, and for this reason, alternatives for the treatment of allergic diseases or reduction in their symptoms are being sought. The main objective of this study was to compile the studies carried out on probiotics as a possible therapy for allergies. The most studied allergies on which probiotics have been shown to have a beneficial effect are rhinitis, asthma, and atopic dermatitis. Most studies have studied the administration of Lactobacillus and Bifidobacterium spp. in children and have shown beneficial effects, such as a reduction in hyperreactivity and inflammation caused by allergens and a decrease in cytokine release, among other beneficial effects. In the case of children, no clear beneficial effects were found in several studies, and the potential risk from the use of some opportunistic bacteria, such as probiotics, seems controversial. In the studies that reported beneficial results, these effects were found to make allergy symptoms less aggressive, thus reducing morbidity in allergy sufferers. The different effects of the same probiotic bacteria on different patients seem to reinforce the idea that the efficacy of probiotics is dependent on the microbial species or strain, its derived metabolites and byproducts, and the gut microbiota eubiosis of the patient. This study is relevant in the context of allergic diseases, as it provides a broader understanding of new alternatives for the treatment of allergies, both in children, who are the main sufferers, and adults, showing that probiotics, in some cases, reduce the symptoms and severity of such diseases.

Reporting of Perinatal Outcomes in Probiotic Randomized Controlled Trials. A Systematic Review and Meta-Analysis

The use of probiotic microorganisms in clinical practice has increased in recent years and a significant number of pregnant women are regular consumers of these products. However, probiotics might modulate the immune system, and whether or not this modulation is beneficial for perinatal outcomes is unclear. We performed a systematic review and meta-analysis to evaluate the reporting of perinatal outcomes in randomized controlled trials including women supplemented with probiotic microorganisms during pregnancy. We also analyzed the effects that the administration of probiotic microorganisms exerts on perinatal outcomes. In the review, 46 papers were included and 25 were meta-analyzed. Reporting of perinatal outcomes was highly inconsistent across the studies. Only birth weight, cesarean section, and weeks of gestation were reported in more than 50% of the studies. Random effects meta-analysis results showed that the administration of probiotic microorganisms during pregnancy did not have any a positive or negative impact on the perinatal outcomes evaluated. Subgroup analysis results at the strain level were not significantly different from main analysis results. The administration of probiotic microorganisms does not appear to influence perinatal outcomes. Nonetheless, future probiotic studies conducted in pregnant women should report probiotic strains and perinatal outcomes in order to shed light upon probiotics’ effects on pregnancy outcomes.

The Role of Probiotics in the Prevention and Treatment of Atopic Dermatitis in Children: An Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease common among infants and children. It is associated with a high risk of allergies, asthma, and mental health problems. Attempts have been made to use probiotics in clinical interventions for AD.

OBJECTIVE

Our objective was to perform an updated meta-analysis of recently published studies to evaluate the effect of probiotics in the prevention and treatment of AD in children and to further understand the role of probiotics in AD interventions in the clinic.

METHOD

We searched the PubMed/MEDLINE, Embase, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure, and Wanfang databases with prespecified selection criteria from inception of each database to 11 January 2020. No language restrictions were applied.

RESULTS

A total of 25 studies were included in our meta-analysis. Of these, 14 were prevention studies (with 3049 children enrolled) and 11 were treatment studies (with 816 children enrolled). One treatment study was excluded after the sensitivity analysis. From the 14 prevention studies included, the pooled relative risk ratio of AD in those treated with probiotics versus placebo was 0.70 [95% confidence interval (CI) 0.57-0.84; P = 0.0002]. Subgroup analyses showed that only mixed strains of probiotics had a significant effect on lowering the incidence of AD. Probiotics administered solely to infants did not prevent the development of AD, but effects were significant when probiotics were administered to both pregnant mothers and their infants or solely to pregnant mothers. In studies with treatment durations > 6 months, the incidence of AD decreased significantly; a similar effect was achieved when the treatment duration was < 6 months. Meta-analysis of the ten treatment studies showed a significant decrease in the weighted mean difference (WMD) in Scoring Atopic Dermatitis (SCORAD) index values in the probiotics group compared with the control group (WMD, - 7.23; 95% CI - 10.59 to - 3.88; P < 0.0001). Subgroup analyses showed that both single-strain and mixed-strain probiotics had a significant effect on improving SCORAD values. Studies with participants aged < 1 year (P = 0.07) reported no significant results. In studies with treatment periods > 8 weeks, SCORAD values seemed to decrease more than in studies with treatment periods < 8 weeks. However, the subgroup difference was only statistically significant when the analysis was performed according to participant age in prevention studies.

CONCLUSION

Our updated meta-analysis demonstrates that interventions with probiotics potentially lower the incidence of AD and relieve AD symptoms in children, particularly when treating infants and children aged ≥ 1 year with AD. Interventions with mixed-strain probiotics tended to have better preventive and curative effects. Probiotics administered solely to infants appeared to produce negative preventive effects. Different intervention durations might also affect clinical outcomes. However, given the insignificant subgroup differences, except for treatment by participant age, and the moderate heterogeneity among the studies, these conclusions should be interpreted with caution, and more powerful randomized controlled trials using standardized measurements should be conducted to assess the long-term effects of probiotics.

Disease managing capacities and mechanisms of host effects of lactic acid bacteria

Consumption of lactic acid bacteria (LAB) has been suggested to confer health-promoting effects on the host. However, effects of LABs have been reported to be species- and strain-specific and the mechanisms involved are subjects of discussion. Here, the possible mechanisms by which LABs induce antipathogenic, gut barrier enhancing and immune modulating effects in consumers are reviewed. Specific strains for which it has been proven that health is improved by these mechanisms are discussed. However, most strains probably act via several or combinations of mechanisms depending on which effector molecules they express. Current insight is that these effector molecules are either present on the cell wall of LAB or are excreted. These molecules are reviewed as well as the ligand binding receptors in the host. Also postbiotics are discussed. Finally, we provide an overview of the efficacy of LABs in combating infections caused by Helicobacter pylori, Salmonella, Escherichia coli, Streptococcus pneumoniae, and influenza virus, in controlling gut inflammatory diseases, in managing allergic disorders, and in alleviating cancer.

The Role of Prebiotics and Probiotics in Prevention of Allergic Diseases in Infants

Allergic diseases have been linked to genetic and/or environmental factors, such as antibiotic use, westernized high fat and low fiber diet, which lead to early intestinal dysbiosis, and account for the rise in allergy prevalence, especially in western countries. Allergic diseases have shown reduced microbial diversity, including fewer lactobacilli and bifidobacteria, within the neonatal microbiota, before the onset of atopic diseases. Raised interest in microbiota manipulating strategies to restore the microbial balance for atopic disease prevention, through prebiotics, probiotics, or synbiotics supplementation, has been reported. We reviewed and discussed the role of prebiotics and/or probiotics supplementation for allergy prevention in infants. We searched PubMed and the Cochrane Database using keywords relating to "allergy" OR "allergic disorders," "prevention" AND "prebiotics" OR "probiotics" OR "synbiotics." We limited our evaluation to papers of English language including children aged 0-2 years old. Different products or strains used, different period of intervention, duration of supplementation, has hampered the draw of definitive conclusions on the clinical impact of probiotics and/or prebiotics for prevention of allergic diseases in infants, except for atopic dermatitis in infants at high-risk. This preventive effect on eczema in high-risk infants is supported by clear evidence for probiotics but only moderate evidence for prebiotic supplementation. However, the optimal prebiotic or strain of probiotic, dose, duration, and timing of intervention remains uncertain. Particularly, a combined pre- and post-natal intervention appeared of stronger benefit, although the definition of the optimal intervention starting time during gestation, the timing, and duration in the post-natal period, as well as the best target population, are still an unmet need.

Effect of probiotic supplementation in pregnant women: a meta-analysis of randomised controlled trials

Probiotics are being used increasingly in pregnant women, whereas the efficiency on pregnancy outcomes is yet lacking. PubMed, Embase and the Cochrane Library were searched. Relative risks (RR) or weighted mean differences (WMD) with 95 % CI were employed to calculate the summary outcomes. A total of eighteen randomised controlled trials (RCT) including 4356 pregnant women were eligible. The summary RR indicated that probiotic supplementation was associated with a significant decrease in the risk of atopic eczema (RR 0·68; 95 % CI 0·58, 0·81; P < 0·001) and eczema (RR 0·79; 95 % CI 0·68, 0·91; P = 0·002) without significant heterogeneity. Probiotic supplementation was associated with a prolonged gestational age (WMD 0·09; 95 % CI 0·04, 0·15; P = 0·001) with insignificant heterogeneity, whereas no significant effect was exerted on birth weight (P = 0·851). The risks of death (RR 0·34; 95 % CI 0·13, 0·91; P = 0·031) and necrotising enterocolitis (NEC) (RR 0·38; 95 % CI 0·18, 0·81; P = 0·012) were significantly reduced in pregnant women receiving probiotics without evidence of heterogeneity. These findings suggested that probiotics in pregnant women were beneficial for atopic eczema, eczema, gestational age, death and NEC.

Approach to the Assessment and Management of Pediatric Patients With Atopic Dermatitis: A Consensus Document. Section III: Treatment Options for Pediatric Atopic Dermatitis

Because atopic dermatitis (AD) is a chronic, relapsing disease, treatment requires the use of both active therapy to control flares and preventative maintenance therapy to promote integrity of the skin barrier. In this third of four sections, important clinical considerations for the treatment of pediatric AD are reviewed. Emerging therapies in development for pediatric AD are introduced.

Preterm Birth: A Narrative Review of the Current Evidence on Nutritional and Bioactive Solutions for Risk Reduction

Preterm birth (PTB) (<37 weeks of gestation) is the leading cause of newborn death and a risk factor for short and long-term adverse health outcomes. Most cases are of unknown cause. Although the mechanisms triggering PTB remain unclear, an inappropriate increase in net inflammatory load seems to be key. To date, interventions that reduce the risk of PTB are effective only in specific groups of women, probably due to the heterogeneity of its etiopathogenesis. Use of progesterone is the most effective, but only in singleton pregnancies with history of PTB. Thus, primary prevention is greatly needed and nutritional and bioactive solutions are a promising alternative. Among these, docosahexaenoic acid (DHA) is the most promising to reduce the risk for early PTB. Other potential nutrient interventions include the administration of zinc (possibly limited to populations with low nutritional status or poor zinc status) and vitamin D; additional preliminary evidence exists for vitamin A, calcium, iron, folic acid, combined iron-folate, magnesium, multiple micronutrients, and probiotics. Considering the public health relevance of PTB, promising interventions should be studied in large and well-designed clinical trials. The objective of this review is to describe, summarize, and discuss the existing evidence on nutritional and bioactive solutions for reducing the risk of PTB.

Cow's Milk Allergy: Immunomodulation by Dietary Intervention

Cow’s milk proteins cause allergic symptoms in 2% to 3% of all infants. In these individuals, the physiological mechanism of tolerance is broken with subsequent possible sensitization to antigens, which can lead eventually to allergic responses. The present review aims to provide an overview of different aspects of immune modulation by dietary intervention in cow’s milk allergy (CMA). It focuses on pathogenetic mechanisms of different CMA related disorders, e.g., gastroesophageal reflux and eosinophilic esophagitis, highlighting the role of dietary management on innate and adaptive immune systems. The traditional dietary management of CMA has greatly changed in the last years, moving from a passive approach, consisting of an elimination diet to relieve symptoms, to a “proactive” one, meaning the possibility to actively modulate the immune system. Thus, new insights into the role of hydrolysates and baked milk in immunomodulation are addressed here. Additionally, nutritional components, such as pre- and probiotics, may target the immune system via microbiota, offering a possible road map for new CMA prevention and treatment strategies.

Probiotic Supplementation for Prevention of Atopic Dermatitis in Infants and Children: A Systematic Review and Meta-analysis

BACKGROUND

Probiotic supplementation in early life may be effective in preventing atopic dermatitis (AD); however, results regarding efficacy have been controversial.

OBJECTIVE

The aim of our study was to investigate the effect of probiotic supplementation on the risk of AD.

METHODS

We systematically searched PubMed, EBSCO, Embase and Web of Science databases up to 8 March 2018 for potentially relevant studies regarding probiotic supplementation and AD. Included infants and children were those with probiotic exposure in utero and/or after birth who were not previously diagnosed with AD. We calculated the odds ratios (ORs) and 95% confidence intervals (CIs) and used the Jadad and Newcastle-Ottawa scales to assess methodologic quality.

RESULTS

A total of 28 studies met the inclusion criteria. Compared with controls, probiotic treatment was associated with a reduced risk of AD (OR 0.69; 95% CI 0.58-0.82, P < 0.0001). The use of probiotics during both the prenatal and the postnatal period significantly reduced the incidence of AD (OR 0.67; 95% CI 0.54-0.82); however, analysis of studies of probiotics given prenatally only or postnatally only did not reach statistical significance.

CONCLUSIONS

Our meta-analysis showed that probiotic supplementation during both the prenatal and the postnatal period reduced the incidence of AD in infants and children. Our findings suggest that starting probiotic treatment during gestation and continuing through the first 6 months of the infant's life may be of benefit in the prevention of AD.

Probiotics in late infancy reduce the incidence of eczema: A randomized controlled trial

BACKGROUND

Allergic diseases are common and represent a considerable health and economic burden worldwide. We aimed to examine the effect of a combination of two probiotic strains administered in late infancy and early childhood on the development of allergic diseases and sensitization.

METHODS

In this double-blind, placebo-controlled intervention trial, participants were randomized to receive a daily mixture of Lactobacillus rhamnosus and Bifidobacterium animalis subsp lactis or placebo-starting prior to attending day care. The intervention period was 6 months, and the parents answered web-based questionnaires on allergic symptoms and doctor's diagnosed allergic disease monthly. IgE was measured at baseline and follow-up.

RESULTS

A total of 290 participants were randomized: 144 in the probiotic group and 146 in the placebo group. Mean age at intervention start was 10.1 months. At follow-up (mean age 16.1 months), the incidence of eczema was 4.2% in the probiotic group and 11.5% in the placebo group (P = 0.036). The incidence of asthma and conjunctivitis did not differ between groups, and no children presented with rhinitis. Sensitization was equal in the two groups at intervention start (7.5% and 9.5%, respectively), and two children in each group were sensitized during the intervention.

CONCLUSIONS

We observed a significantly lower incidence of eczema in the probiotic group compared to the placebo group. The probiotics were administered in late infancy-prior to attending day care-suggesting a broader window of opportunity using probiotics in the prevention of eczema. The incidence of asthma, rhinitis, conjunctivitis, and sensitization did not differ.

Thirty Years of Lactobacillus rhamnosus GG: A Review

Lactobacillus rhamnosus GG (LGG) was the first strain belonging to the genus Lactobacillus to be patented in 1989 thanks to its ability to survive and to proliferate at gastric acid pH and in medium containing bile, and to adhere to enterocytes. Furthermore LGG is able to produces both a biofilm that can mechanically protect the mucosa, and different soluble factors beneficial to the gut by enhancing intestinal crypt survival, diminishing apoptosis of the intestinal epithelium, and preserving cytoskeletal integrity. Moreover LGG thanks to its lectin-like protein 1 and 2 inhibits some pathogens such as Salmonella species. Finally LGG is able to promote type 1 immune-responsiveness by reducing the expression of several activation and inflammation markers on monocytes and by increasing the production of interleukin-10, interleukin-12 and tumor necrosis factor-α in macrophages. A large number of research data on Lactobacillus GG is the basis for the use of this probiotic for human health. In this review we have considered predominantly randomized controlled trials, meta-analysis, Cochrane Review, guide lines of Scientific Societies and anyway studies whose results were evaluated by means of relative risk, odds ratio, weighted mean difference 95% confidence interval. The effectiveness of LGG in gastrointestinal infections and diarrhea, antibiotic and Clostridium difficile associated diarrhea, irritable bowel syndrome, inflammatory bowel disease, respiratory tract infections, allergy, cardiovascular diseases, nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, cystic fibrosis, cancer, elderly end sport were analyzed.

Association between probiotic supplementation and asthma incidence in infants: a meta-analysis of randomized controlled trials

Objective: The increased social and economic burdens for asthma in infants make the prevention of asthma a major public health goal. Probiotics may reduce the risk of asthma in infants. However, randomized controlled trials (RCTs) have shown mixed efficacy outcomes. We performed a meta-analysis of RCTs to investigate whether probiotics are associated with a lower asthma incidence in infants. Methods: The PubMed, Cochrane library, and EMBASE databases were systematically searched from the inception dates to August 2018. RCTs comparing the effects of probiotic supplements with a placebo for asthma or wheeze incidence in infants were included. A meta-analysis was performed to calculate risk ratio (RR) and 95% confidence interval (CI) using the Mantel-Haenszel statistical method. Results: A total of 19 randomized trials involving 5157 children fulfilled the inclusion criteria. There was no significant association of probiotics with risk of asthma (RR, 0.94 [95% CI, 0.82-1.09]) or wheeze (RR, 0.97 [95% CI, 0.88-1.06]) compared with placebo. Subgroup analysis by asthma risk showed that probiotics significantly reduced wheeze incidence among infants with atopy disease (RR, 0.61 [95% CI, 0.42-0.90]), but no significant associations were found in the other subgroup analyses by participants receiving the intervention, timing of intervention, prevention regimen, probiotic organism, duration of intervention, and duration of follow-up. Conclusions: The use of probiotic supplementation compared with placebo was not associated with a lower risk of asthma in infants. These findings do not support recommendation to use probiotics in the prevention of asthma in infants.

[Effect of probiotic supplementation during pregnancy and infancy in preventing atopic dermatitis in children: a Meta analysis]

OBJECTIVE

To systematically review the effect of probiotic supplementation during pregnancy and infancy in preventing atopic dermatitis in children.

METHODS

RevMan5.3 was used to perform a Meta analysis of randomized controlled trials on the effect of probiotic supplementation during pregnancy and infancy in preventing atopic dermatitis in children published between January 2008 and May 2018 across the world. A subgroup analysis was conducted according to the type of probiotics for intervention, follow-up time, time of probiotic supplementation, and study areas.

RESULTS

A total of 22 articles were selected, with 3 280 cases in the intervention group and 3 281 cases in the control group. The results of pooled effect size showed that probiotic supplementation during pregnancy and/or infancy significantly reduced the incidence rate of atopic dermatitis (RR=0.81, 95%CI: 0.70-0.93, P<0.05). According to the subgroup analysis, the intervention with Lactobacillus and Bifidobacterium had a significant effect (RR=0.68, 95%CI: 0.52-0.90, P<0.05); probiotic supplementation during both pregnancy and infancy also had a significant effect (RR=0.77, 95%CI: 0.66-0.90, P<0.05); probiotic supplementation during pregnancy and/or infancy had a better effect in preventing atopic dermatitis in children aged ≤2 years than in those aged >2 years (RR=0.74, 95%CI: 0.61-0.90, P<0.05); probiotic supplementation had a significant effect in Australia (RR=0.83, 95%CI: 0.73-0.96, P<0.05) and Europe/the United States (RR=0.74, 95%CI: 0.61-0.91, P<0.05). Heterogeneity was mainly due to follow-up time (I²=62.7%) and time of probiotic supplementation (I²=53.5%).

CONCLUSIONS

Probiotic supplementation during pregnancy and infancy helps to prevent atopic dermatitis in children, and mixed Lactobacillus-Bifidobacterium intervention has a better effect.

Maternal probiotic supplementation for prevention of morbidity and mortality in preterm infants

BACKGROUND

Inflammation may contribute to preterm birth and to morbidity of preterm infants. Preterm infants are at risk for alterations in the normal protective microbiome. Oral probiotics administered directly to preterm infants have been shown to decrease the risk for severe necrotizing enterocolitis (NEC) as well as the risk of death, but there are safety concerns about administration of probiotics directly to preterm infants. Through decreasing maternal inflammation, probiotics may play a role in preventing preterm birth and/or decreasing the inflammatory milieu surrounding delivery of preterm infants, and may alter the microbiome of the preterm infant when given to mothers during pregnancy. Probiotics given to mothers after birth of preterm infants may effect infant bacterial colonization, which could potentially reduce the incidence of NEC.

OBJECTIVES

1. To compare the efficacy of maternal probiotic administration versus placebo or no intervention in mothers during pregnancy for the prevention of preterm birth and the prevention of morbidity and mortality of infants born preterm.2. To compare the efficacy of maternal probiotic administration versus placebo, no intervention, or neonatal probiotic administration in mothers of preterm infants after birth on the prevention of mortality and preterm infant morbidities such as NEC.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL 2017, Issue 2), MEDLINE via PubMed (1966 to 21 March 2017), Embase (1980 to 21 March 2017), and CINAHL (1982 to 21 March 2017). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomized controlled trials and quasi-randomized trials.

SELECTION CRITERIA

We included randomized controlled trials in the review if they administered oral probiotics to pregnant mothers at risk for preterm birth, or to mothers of preterm infants after birth. Quasi-randomized trials were eligible for inclusion, but none were identified. Studies enrolling pregnant women needed to administer probiotics at < 36 weeks' gestation until the trimester of birth. Probiotics considered were of the genera Lactobacillus, Bifidobacterium or Saccharomyces.

DATA COLLECTION AND ANALYSIS

We used the standard methods of the Cochrane Collaboration and Cochrane Neonatal to determine the methodologic quality of studies, and for data collection and analysis.

MAIN RESULTS

We included 12 eligible trials with a total of 1450 mothers and 1204 known infants. Eleven trials administered probiotics to mothers during pregnancy and one trial administered probiotics to mothers after birth of their preterm infants. No studies compared maternal probiotic administration directly with neonatal administration. Included prenatal trials were highly variable in the indication for the trial, the gestational age and duration of administration of probiotics, as well as the dose and formulation of the probiotics. The pregnant women included in these trials were overall at low risk for preterm birth. In a meta-analysis of trial data, oral probiotic administration to pregnant women did not reduce the incidence of preterm birth < 37 weeks (typical risk ratio (RR) 0.92, 95% confidence interval (CI) 0.32 to 2.67; 4 studies, 518 mothers and 506 infants), < 34 weeks (typical risk difference (RD) 0.00, 95% CI -0.02 to 0.02; 2 studies, 287 mothers and infants), the incidence of infant mortality (typical RD 0.00, 95% CI -0.02 to 0.02; 2 studies, 309 mothers and 298 infants), or the gestational age at birth (mean difference (MD) 0.15, 95% CI -0.33 to 0.63; 2 studies, 209 mothers with 207 infants).One trial studied administration of probiotics to mothers after preterm birth and included 49 mothers and 58 infants. There were no significant differences in the risk of any NEC (RR 0.44, 95% CI 0.13 to 1.46; 1 study, 58 infants), surgery for NEC (RR 0.15, 95% CI 0.01 to 2.58; 1 study, 58 infants), death (RR 0.66, 95% CI 0.06 to 6.88; 1 study, 58 infants), and death or NEC (RR 0.53, 95% CI 0.19 to 1.49; 1 study, 58 infants). There was an improvement in time to reach 50% enteral feeds in infants whose mothers received probiotics, but the estimate is imprecise (MD -9.60 days, 95% CI -19.04 to -0.16 days; 58 infants). No other improvement in any neonatal outcomes were reported. The estimates were imprecise and do not exclude the possibility of meaningful harms or benefits from maternal probiotic administration. There were no cases of culture-proven sepsis with the probiotic organism. The GRADE quality of evidence was judged to be low to very low due to inconsistency and imprecision.

AUTHORS' CONCLUSIONS

There is insufficient evidence to conclude whether there is appreciable benefit or harm to neonates of either oral supplementation of probiotics administered to pregnant women at low risk for preterm birth or oral supplementation of probiotics to mothers of preterm infants after birth. Oral supplementation of probiotics to mothers of preterm infants after birth may decrease time to 50% enteral feeds, however, this estimate is extremely imprecise. More research is needed for post-natal administration of probiotics to mothers of preterm infants, as well as to pregnant mothers at high risk for preterm birth.

Probiotics for treating eczema

BACKGROUND

Eczema is a common chronic skin condition. Probiotics have been proposed as an effective treatment for eczema; their use is increasing, as numerous clinical trials are under way. This is an update of a Cochrane Review first published in 2008, which suggested that probiotics may not be an effective treatment for eczema but identified areas in which evidence was lacking.

OBJECTIVES

To assess the effects of probiotics for treating patients of all ages with eczema.

SEARCH METHODS

We updated our searches of the following databases to January 2017: the Cochrane Skin Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), in the Cochrane Library, the Global Resource of Eczema Trials (GREAT) database, MEDLINE, Embase, PsycINFO, the Allied and Complementary Medicine Database (AMED), and Latin American Caribbean Health Sciences Literature (LILACS). We searched five trials registers and checked the reference lists of included studies and relevant reviews for further references to relevant randomised controlled trials (RCTs). We also handsearched a number of conference proceedings. We updated the searches of the main databases in January 2018 and of trials registries in March 2018, but we have not yet incorporated these results into the review.

SELECTION CRITERIA

Randomised controlled trials of probiotics (live orally ingested micro-organisms) compared with no treatment, placebo, or other active intervention with no probiotics for the treatment of eczema diagnosed by a doctor.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures as expected by Cochrane. We recorded adverse events from the included studies and from a separate adverse events search conducted for the first review. We formally assessed reporting bias by preparing funnel plots, and we performed trial sequential analysis for the first primary outcome - eczema symptoms at the end of active treatment.We used GRADE to assess the quality of the evidence for each outcome (in italic font).

MAIN RESULTS

We included 39 randomised controlled trials involving 2599 randomised participants. We included participants of either gender, aged from the first year of life through to 55 years (only six studies assessed adults), who had mild to severe eczema. Trials were undertaken in primary and secondary healthcare settings, mainly in Europe or Asia. Duration of treatment ranged from four weeks to six months, and duration of follow-up after end of treatment ranged from zero to 36 months. We selected no standard dose: researchers used a variety of doses and concentrations of probiotics. The probiotics used were bacteria of the Lactobacillus and Bifidobacteria species, which were taken alone or combined with other probiotics, and were given with or without prebiotics. Comparators were no treatment, placebo, and other treatments with no probiotics.For all results described in this abstract, the comparator was no probiotics. Active treatment ranged from six weeks to three months for all of the following results, apart from the investigator-rated eczema severity outcome, for which the upper limit of active treatment was 16 weeks. With regard to score, the higher the score, the more severe were the symptoms. All key results reported in this abstract were measured at the end of active treatment, except for adverse events, which were measured during the active treatment period.Probiotics probably make little or no difference in participant- or parent-rated symptoms of eczema (13 trials; 754 participants): symptom severity on a scale from 0 to 20 was 0.44 points lower after probiotic treatment (95% confidence interval (CI) -1.22 to 0.33; moderate-quality evidence). Trial sequential analysis shows that target sample sizes of 258 and 456, which are necessary to demonstrate a minimum mean difference of -2 and -1.5, respectively, with 90% power, have been exceeded, suggesting that further trials with similar probiotic strains for this outcome at the end of active treatment may be futile.We found no evidence suggesting that probiotics make a difference in QoL for patients with eczema (six studies; 552 participants; standardised mean difference (SMD) 0.03, 95% CI -0.36 to 0.42; low-quality evidence) when measured by the participant or the parent using validated disease-specific QoL instruments.Probiotics may slightly reduce investigator-rated eczema severity scores (24 trials; 1596 participants). On a scale of 0 to 103 for total Severity Scoring of Atopic Dermatitis (SCORAD), a score combining investigator-rated eczema severity score and participant scoring for eczema symptoms of itch and sleep loss was 3.91 points lower after probiotic treatment than after no probiotic treatment (95% CI -5.86 to -1.96; low-quality evidence). The minimum clinically important difference for SCORAD has been estimated to be 8.7 points.We noted significant to extreme levels of unexplainable heterogeneity between the results of individual studies. We judged most studies to be at unclear risk of bias; six studies had high attrition bias, and nine were at low risk of bias overall.We found no evidence to show that probiotics make a difference in the risk of adverse events during active treatment (risk ratio (RR) 1.54, 95% CI 0.90 to 2.63; seven trials; 402 participants; low-quality evidence). Studies in our review that reported adverse effects described gastrointestinal symptoms.

AUTHORS' CONCLUSIONS

Evidence suggests that, compared with no probiotic, currently available probiotic strains probably make little or no difference in improving patient-rated eczema symptoms. Probiotics may make little or no difference in QoL for people with eczema nor in investigator-rated eczema severity score (combined with participant scoring for eczema symptoms of itch and sleep loss); for the latter, the observed effect was small and of uncertain clinical significance. Therefore, use of probiotics for the treatment of eczema is currently not evidence-based. This update found no evidence of increased adverse effects with probiotic use during studies, but a separate adverse events search from the first review revealed that probiotic treatment carries a small risk of adverse events.Results show significant, unexplainable heterogeneity between individual trial results. Only a small number of studies measured some outcomes.Future studies should better measure QoL scores and adverse events, and should report on new probiotics. Researchers should also consider studying subgroups of patients (e.g. patients with atopy or food allergies, adults) and standardising doses/concentrations of probiotics given.

Rationale of Probiotic Supplementation during Pregnancy and Neonatal Period

Probiotics are living microorganisms that confer a health benefit when administered in adequate amounts. It has been speculated that probiotics supplementation during pregnancy and in the neonatal period might reduce some maternal and neonatal adverse outcomes. In this narrative review, we describe the rationale behind probiotic supplementation and its possible role in preventing preterm delivery, perinatal infections, functional gastrointestinal diseases, and atopic disorders during early life.

Effectiveness of Multistrain Versus Single-strain Probiotics: Current Status and Recommendations for the Future

Probiotics are investigated as single-strain and multistrain products. In the market, however, there is an increasing tendency to work with multistrain probiotics, in particular, products with a high number of different strains. There are some thoughts behind this: more strains imply more chances of success; it can mean a broader spectrum of efficacy, and there is often the hope that there are at least additive and, potentially, even synergistic effects. The present review did not find convincing evidence that these assumptions are valid. There is, however, also no strong evidence that the assumptions are incorrect and/or that there is antagonistic activity between strains in a combination. We suggest that, to answer these questions, structured research is conducted. Starting with a systematic review of meta-analyses that have compared single-strain and multistrain probiotic efficacy, dedicated human studies need to be performed, comparing single-strain and multistrain probiotics to each other and placebo. In vitro and animal studies can provide indications and may help understand mechanisms. For human, animal, and in vitro studies, it is recommended to work with the simple setup of 2 single strains, a 2-strain combination, and placebo. It is also important in such research to take into consideration the doses, as a combination product will have a higher total dose.

Lactobacillus rhamnosus GG in the Primary Prevention of Eczema in Children: A Systematic Review and Meta-Analysis

Current guidelines recommend the use of probiotics to reduce the risk of eczema. It remains unclear which strain(s) to use. We systematically evaluated data on the efficacy of Lactobacillus rhamnosus GG (LGG) supplementation prenatally and/or postnatally for the primary prevention of eczema. The Cochrane Library, MEDLINE, and EMBASE databases were searched up to August 2018, with no language restrictions, for systematic reviews of randomized controlled trials (RCTs) and RCTs published afterwards. The primary outcome was eczema. For dichotomous outcomes, we calculated the risk ratio (RR) and 95% confidence interval (CI). A random-effects model was used to pool data. Heterogeneity was explored using the I² statistics. The GRADE criteria were used to assess the overall quality of evidence supporting the primary outcome. Seven publications reporting 5 RCTs (889 participants) were included. High to moderate certainty in the body of evidence suggests that LGG supplementation (regardless of the timing of administration) did not reduce the risk of eczema. There was also no consistent effect on other allergic outcomes. This meta-analysis shows that LGG was ineffective in reducing eczema. It does not support the general recommendation to use probiotics for preventing eczema, unless specific strains would be indicated.

Probiotics against airway allergy: host factors to consider

The worldwide prevalence of allergic diseases has drastically increased in the past decades. Recent studies underline the importance of microbial exposure for the development of a balanced immune system. Consequently, probiotic bacteria are emerging as a safe and natural strategy for allergy prevention and treatment. However, clinical probiotic intervention studies have so far yielded conflicting results. There is increasing awareness about the importance of host-associated factors that determine whether an individual will respond to a specific probiotic treatment, and it is therefore crucial to promote a knowledge-based instead of an empirical selection of promising probiotic strains and their administration regimen.In this Review, we summarize the insights from animal model studies of allergic disease, which reveal how host-related factors - such as genetic makeup, sex, age and microbiological status - can impact the outcomes of preventive or curative probiotic treatment. We explore why and how these factors can influence the results of probiotic studies and negatively impact the reproducibility in animal experiments. These same factors might profoundly influence the outcomes of human clinical trials, and can potentially explain the conflicting results from probiotic intervention studies. Therefore, we also link these host-related factors to human probiotic study outcomes in the context of airway allergies.

Guidance on the use of probiotics in clinical practice in children with selected clinical conditions and in specific vulnerable groups

AIM

The use of probiotics has been covered by many guidelines, position papers and evidence-based recommendations, but few have referred to specific patient groups or clinical indications. This review summarises recommendations and scientifically credited guidelines on the use of probiotics for children with selected clinical conditions and provides practice points.

METHODS

An expert panel was convened by the European Paediatric Association in June 2017 to define the relevant clinical questions for using probiotics in paediatric health care and review and summarise the guidelines, recommendations, position papers and high-quality evidence.

RESULTS

The panel found that specific probiotic strains were effective in preventing antibiotic-associated and nosocomial diarrhoea, treating acute gastroenteritis and treating infantile colic in breastfed infants. However, special caution is indicated for premature infants, immunocompromised and critically ill patients and those with central venous catheters, cardiac valvular disease and short-gut syndrome. This review discusses the safety of using probiotics in selected groups of paediatric patients and the quality of the available products providing practice points based on proved findings.

CONCLUSION

Efficacy of probiotics is strain specific. Their benefits are currently scientifically proven for their use in selected clinical conditions in children and not recommended for certain patient groups.

Pregnancy outcomes in women taking probiotics or prebiotics: a systematic review and meta-analysis

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).

Electronic supplementary material

The online version of this article (10.1186/s12884-017-1629-5) contains supplementary material, which is available to authorized users.

Pre- and probiotics for allergy prevention: time to revisit recommendations?

Reduced intensity and diversity of microbial exposure is considered a major factor driving abnormal postnatal immune maturation and increasing allergy prevalence, particularly in more affluent regions. Quantitatively, the largest important source of early immune-microbial interaction, the gut microbiota, is of particular interest in this context, with variations in composition and diversity in the first months of life associated with subsequent allergy development. Attempting to restore the health consequences of the 'dysbiotic drift' in modern society, interventions modulating gut microbiota for allergy prevention have been evaluated in several randomized placebo-controlled trials. In this review, we provide an overview of these trials and discuss recommendations from international expert bodies regarding prebiotic, probiotic and synbiotic interventions. Recent guidelines from the World Allergy Organization recommend the use of probiotics for the primary prevention of eczema in pregnant and breastfeeding mothers of infants at high risk for developing allergy and in high-risk infants. It is however stressed that these recommendations are conditional, based on very low-quality evidence and great heterogeneity between studies, which also impedes specific and practical advice to consumers on the most effective regimens. We discuss how the choice of probiotic strains, timing and duration of administration can critically influence the outcome due to different effects on immune modulation and gut microbiota composition. Furthermore, we propose strategies to potentially improve allergy-preventive effects and enable future evidence-based implementation.

Bugging allergy; role of pre-, pro- and synbiotics in allergy prevention

Large-scale biodiversity loss and complex changes in social behaviors are altering human microbial ecology. This is increasingly implicated in the global rise in inflammatory diseases, most notably the "allergy epidemic" in very early life. Colonization of human ecological niches, particularly the gastrointestinal tract, is critical for normal local and systemic immune development and regulation. Disturbances in composition, diversity and timing of microbial colonization have been associated with increased allergy risk, indicating the importance of strategies to restore a dysbiotic gut microbiota in the primary prevention of allergic diseases, including the administration of probiotics, prebiotics and synbiotics. Here, we summarize and discuss findings of randomized clinical trials that have examined the effects of these microbiome-related strategies on short and long-term allergy preventative effects - including new guidelines from the World Allergy Organization which now recommend probiotics and prebiotics for allergy prevention under certain conditions. The relatively low quality evidence, limited comparative studies and large heterogeneity between studies, have collectively hampered recommendations on specific probiotic strains, specific timing and specific conditions for the most effective preventive management. At the same time the risk of using available products is low. While further research is needed before specific practice guidelines on supplement probiotics and prebiotics, it is equally important that the underlying dietary and lifestyle factors of dysbiosis are addressed at both the individual and societal levels.

The Maternal Diet, Gut Bacteria, and Bacterial Metabolites during Pregnancy Influence Offspring Asthma

This review focuses on the current evidence that maternal dietary and gut bacterial exposures during pregnancy influence the developing fetal immune system and subsequent offspring asthma. Part 1 addresses exposure to a farm environment, antibiotics, and prebiotic and probiotic supplementation that together indicate the importance of bacterial experience in immune programming and offspring asthma. Part 2 outlines proposed mechanisms to explain these associations including bacterial exposure of the fetoplacental unit; immunoglobulin-related transplacental transport of gut bacterial components; cytokine signaling producing fetomaternal immune alignment; and immune programming via metabolites produced by gut bacteria. Part 3 focuses on the interplay between diet, gut bacteria, and bacterial metabolites. Maternal diet influences fecal bacterial composition, with dietary microbiota-accessible carbohydrates (MACs) selecting short-chain fatty acid (SCFA)-producing bacteria. Current evidence from mouse models indicates an association between increased maternal dietary MACs, SCFA exposure during pregnancy, and reduced offspring asthma that is, at least in part, mediated by the induction of regulatory T lymphocytes in the fetal lung. Part 4 discusses considerations for future studies investigating maternal diet-by-microbiome determinants of offspring asthma including the challenge of measuring dietary MAC intake; limitations of the existing measures of the gut microbiome composition and metabolic activity; measures of SCFA exposure; and the complexities of childhood respiratory health assessment.

Oral administration of Saccharomyces cerevisiae UFMG A-905 prevents allergic asthma in mice

BACKGROUND AND OBJECTIVE

The prevalence of asthma has increased in communities that adopt a Western lifestyle and become more urbanized. Probiotics may be effective in the prevention of allergic diseases, such as asthma. The aim of the current study was to examine the effects of Saccharomyces cerevisiae UFMG A-905 in an allergic model of asthma.

METHODS

Balb/c mice were sensitized twice with ovalbumin (OVA) intraperitoneally, 1 week apart and challenged with OVA intranasally for 3 days. Mice were daily treated with S. cerevisiae UFMG A-905 via gavaging needle 10 days before OVA sensitization and during challenges. After challenge, in vivo lung function was measured, and bronchoalveolar lavage (BAL) and lung inflammation were assessed.

RESULTS

Oral treatment with S. cerevisiae UFMG A-905 significantly decreased airway hyperresponsiveness, total cell number and the influx of eosinophils to the airway, inflammatory cell in the lung, mucus expression in epithelial cells and the levels of IL-4, IL-5 and IL-13. Additionally, S. cerevisiae UFMG A-905 restored the levels of IL-10 and interferon (IFN)-gamma, and increased the levels of IL-17A.

CONCLUSION

Oral administration of S. cerevisiae UFMG A-905 prevented the development of major asthma-like characteristics in a mouse model.

Probiotics for treatment and primary prevention of allergic diseases and asthma: looking back and moving forward

Microbial ecosystems cover the surface of the human body and it is becoming increasingly clear that our modern environment has profound effects on microbial composition and diversity. A dysbiotic gut microbiota has been associated with allergic diseases and asthma in cross-sectional and observational studies. In an attempt to restore this dysbiosis, probiotics have been evaluated in randomized controlled trials. Here, we review treatment and primary prevention studies, recent meta-analyses, and discuss the current understanding of the role of probiotics in this context. Many meta-analyses have shown a moderate benefit of probiotics for eczema prevention, whereas there is less evidence of a benefit for other allergic manifestations. Because of very low quality evidence and heterogeneity between studies, specific advice on the most effective regimens cannot yet be given - not even for eczema prevention. To be able to adopt results into specific recommendations, international expert organizations stress the need for well-designed studies.

Probiotics for Prevention of Atopy and Food Hypersensitivity in Early Childhood: A PRISMA-Compliant Systematic Review and Meta-Analysis of Randomized Controlled Trials

Most studies investigated probiotics on food hypersensitivity, not on oral food challenge confirmed food allergy in children. The authors systematically reviewed the literature to investigate whether probiotic supplementation prenatally and/or postnatally could reduce the risk of atopy and food hypersensitivity in young children.PubMed, Embase, the Cochrane Central Register of Controlled Trials, and 4 main Chinese literature databases (Wan Fang, VIP, China National Knowledge Infrastructure, and SinoMed) were searched for randomized controlled trials regarding the effect of probiotics on the prevention of allergy in children. The last search was conducted on July 11, 2015.Seventeen trials involving 2947 infants were included. The first follow-up studies were analyzed. Pooled analysis indicated that probiotics administered prenatally and postnatally could reduce the risk of atopy (relative risk [RR] 0.78; 95% confidence interval [CI] 0.66-0.92; I = 0%), especially when administered prenatally to pregnant mother and postnatally to child (RR 0.71; 95% CI 0.57-0.89; I = 0%), and the risk of food hypersensitivity (RR 0.77; 95% CI 0.61-0.98; I = 0%). When probiotics were administered either only prenatally or only postnatally, no effects of probiotics on atopy and food hypersensitivity were observed.Probiotics administered prenatally and postnatally appears to be a feasible way to prevent atopy and food hypersensitivity in young children. The long-term effects of probiotics, however, remain to be defined in the follow-up of existing trials. Still, studies on probiotics and confirmed food allergy, rather than surrogate measure of food hypersensitivity, are warranted.

Probiotics for allergy prevention

Probiotics, given either as a supplement or in infant foods, have been evaluated in randomised controlled trials for allergy prevention. Here, the aim is to give an overview of the results from these primary prevention studies and to discuss current strategies. In most studies, single strains or a mixture of strains of lactic acid bacteria and bifidobacteria have been used--prenatally, postnatally or perinatally. Several meta-analyses have reported a moderate benefit of probiotics for eczema prevention, and the most consistent effect has been observed with a combined perinatal intervention in infants at high risk of allergic disease due to familial predisposition. In a recent meta-analysis, the use of multi-strain probiotics appeared to be most effective for eczema prevention. No preventive effect has been shown for other allergic manifestations. As long-term follow-up data on later onset allergic conditions (asthma and allergic rhinitis) are available only from a few of the initiated studies, reports from ongoing follow-up studies that are adequately powered to examine long-term outcomes are anticipated to provide more insight. Arguably, the differences in many aspects of study design and the use of different probiotic strains and combinations have made direct comparison difficult. To date, expert bodies do not generally recommend probiotics for allergy prevention, although the World Allergy Organization (WAO) in their recently developed guidelines suggests considering using probiotics in pregnant women, during breastfeeding and/or to the infant if at high risk of developing allergic disease (based on heredity). However, in concordance with other expert bodies, the WAO guideline panel stressed the low level of evidence and the need for adequately powered randomised controlled trials and a more standardised approach before clinical recommendations on specific strains, dosages and timing can be given.

Probiotics for prevention of atopic diseases in infants: systematic review and meta-analysis

Growing evidence underlines the pivotal role of infant gut colonization in the development of the immune system. The possibility to modify gut colonization through probiotic supplementation in childhood might prevent atopic diseases. The aim of the present systematic review and meta-analysis was to evaluate the effect of probiotic supplementation during pregnancy and early infancy in preventing atopic diseases. PubMed, Embase and Cochrane Library were searched for randomized controlled trials evaluating the use of probiotics during pregnancy or early infancy for prevention of allergic diseases. Fixed-effect models were used, and random-effects models where significant heterogeneity was present. Results were expressed as risk ratio (RR) with 95% confidence interval (CI). Seventeen studies, reporting data from 4755 children (2381 in the probiotic group and 2374 in the control group), were included in the meta-analysis. Infants treated with probiotics had a significantly lower RR for eczema compared to controls (RR 0.78 [95% CI: 0.69-0.89], P = 0.0003), especially those supplemented with a mixture of probiotics (RR 0.54 [95% CI: 0.43-0.68], P < 0.00001). No significant difference in terms of prevention of asthma (RR 0.99 [95% CI: 0.77-1.27], P = 0.95), wheezing (RR 1.02 [95% CI: 0.89-1.17], P = 0.76) or rhinoconjunctivitis (RR 0.91 [95% CI: 0.67-1.23], P = 0.53) was documented. The results of the present meta-analysis show that probiotic supplementation prevents infantile eczema, thus suggesting a new potential indication for probiotic use in pregnancy and infancy.