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Effects of dietary fibers or probiotics on functional constipation symptoms and roles of gut microbiota: a double-blinded randomized placebo trial.
Lai, H, Li, Y, He, Y, Chen, F, Mi, B, Li, J, Xie, J, Ma, G, Yang, J, Xu, K, et al
Gut microbes. 2023;15(1):2197837
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Functional constipation is characterised by continuously difficult, incomplete, or infrequent defecation, without an organic origin. Effective intervention strategies are required to relieve the functional constipation difficulties, particularly in rapidly aging populations, such as Chinese populations. The aim of this study was to evaluate the effectiveness of three dietary fibre formulas (polydextrose, psyllium husk, and wheat bran + psyllium husk) and one probiotic supplement on the improvement of constipation symptoms among Chinese adults with functional constipation. This study was a double-blinded randomised placebo-controlled trial which enrolled 250 participants who were randomly assigned to one of the five groups. Results showed: - that daily supplement of three prebiotic formulas with dietary fibres, or a probiotic formula effectively relieved hard stool in functional constipation patients after 4 weeks intervention. - the capacity of gut microbial genera in shaping the intervention responsiveness in the improvement of bowel movement frequency, Bristol stool scale score, and degree of defecation straining. Authors conclude that the pre or probiotic interventions may modulate gut microbiota, associated with intestinal health.
Abstract
Dietary fibers/probiotics may relieve constipation via optimizing gut microbiome, yet with limited trial-based evidences. We aimed to evaluate the effects of formulas with dietary fibers or probiotics on functional constipation symptoms, and to identify modulations of gut microbiota of relevance. We conducted a 4-week double-blinded randomized placebo-controlled trial in 250 adults with functional constipation. Intervention: A: polydextrose; B: psyllium husk; C: wheat bran + psyllium husk; D: Bifidobacterium animalis subsp. lactis HN019 + Lacticaseibacillus rhamnosus HN001; Placebo: maltodextrin. Oligosaccharides were also included in group A to D. 16S rRNA sequencing was used to assess the gut microbiota at weeks 0, 2, and 4. A total of 242 participants completed the study. No time-by-group effect was observed for bowel movement frequency (BMF), Bristol stool scale score (BSS), and degree of defecation straining (DDS), while BSS showed mean increases of 0.95-1.05 in group A to D (all P < 0.05), but not significantly changed in placebo (P = 0.170), and 4-week change of BSS showed similarly superior effects of the interventions as compared placebo. Group D showed a marginal reduction in plasma 5-hydroxytryptamine. Group A resulted in a higher Bifidobacterium abundance than placebo at week 2 and 4. Fourteen genera showed intervention-specific increasing or decreasing trends continuously, among which Anaerostipes showed increasing trends in groups B and C, associated with BMF increase. Random forest models identified specific baseline microbial genera panels predicting intervention responders. In conclusion, we found that the dietary fibers or probiotics may relieve hard stool, with intervention-specific changes in gut microbiota relevant to constipation relief. Baseline gut microbiota may predispose the intervention responsiveness. ClincialTrials.gov number, NCT04667884. What is the context?Supplementation of dietary fibers, such as psyllium husk or wheat bran (10 ~ 15 g/day) may relieve constipation symptoms, but bloating and flatulence are major concerns on a high fiber intake.Functional constipation patients had alternated gut microbiota profiles, while meta-analysis suggested that multispecies probiotics may increase bowel movement frequency and relieve hard stool in functional constipation.Dietary fibers or probiotics may lead to before-after changes of gut microbiota in patients with functional constipation, but time-series continued changes of gut microbiota during the intervention are unknown.Elevation of 5-hydroxytryptamine synthesis in enterochromaffin cells may affect bowel movement. And the elevated plasma 5-hydroxytryptamine was observed in functional constipation patients.What is new? Daily supplement of three prebiotic formulas with dietary fibers (polydextrose, psyllium husk, wheat bran, together with oligosaccharides), or a probiotic formula with Bifidobacterium animalis subsp. lactis HN019 + Lacticaseibacillus rhamnosus HN001 effectively relieved hard stool in functional constipation patients after 4 weeks intervention.We identified continued increasing or decreasing gut microbial genera over the intervention. Dietary fiber – gut microbiota (Anaerostipes)—constipation relieve (bowel movement frequency) evidence axis was identified in this human trial.Probiotic supplementation marginally reduced plasma 5-hydroxytryptamine, possibly associated with changes in BMF-related gut microbial genera.Intervention-specific baseline gut microbiota well predicted the responsiveness of constipation symptom relief.What is the impact? We provided references for the dosage and duration of dietary fiber/probiotics recommendations for adults with functional constipation, and advanced the microbial genera evidences of the fibers/probiotics-microbiota-laxation theory in humans.
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Adverse Effects of Excessive Zinc Intake in Infants and Children Aged 0-3 Years: A Systematic Review and Meta-Analysis.
Ceballos-Rasgado, M, Lowe, NM, Mallard, S, Clegg, A, Moran, VH, Harris, C, Montez, J, Xipsiti, M
Advances in nutrition (Bethesda, Md.). 2022;13(6):2488-2518
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The upper limit of a nutrient’s intake has been defined as the maximum intake from food, water, and supplements that is unlikely to pose risk of adverse health effects to most individuals in the general population. The aim of this study was to determine the levels of zinc intake at which adverse effects are observed in children aged 0–3 years. This study is a systematic review and meta-analysis of fifty-eight articles from fifty-five studies. Almost all studies were randomised controlled studies (n=52) and the rest were quasi-experimental studies. Results show: - that zinc supplementation had a significant adverse effect on serum ferritin, plasma/serum copper concentration, serum transferrin receptor, haemoglobin, haematocrit, and the odds of anaemia in ≥1 of the subgroups of pooled data. - a significant reduction of the lactulose:mannitol ratio. - that there weren’t significant effects of zinc supplementation on c-reactive protein, erythrocyte superoxide dismutase [antioxidant enzyme], zinc protoporphyrin [chemical compound], blood cholesterol, or iron deficiency anaemia Authors conclude that the recommended maximum zinc doses might need to be adjusted for children at risk or recovering from iron or copper deficiency. Additionally, the study’s findings may be used to undertake dose–response modelling to estimate tolerable upper intake levels of zinc in children aged 0–3 years.
Abstract
Zinc supplementation reduces morbidity, but evidence suggests that excessive intakes can have negative health consequences. Current guidelines of upper limits (ULs) of zinc intake for young children are extrapolated from adult data. This systematic review (PROSPERO; registration no. CRD42020215187) aimed to determine the levels of zinc intake at which adverse effects are observed in young children. Studies reporting potential adverse effects of zinc intake in children aged 0-3 y were identified (from inception to August 2020) in MEDLINE, Embase, and the Cochrane Library, with no limits on study design. Adverse clinical and physical effects of zinc intake were synthesized narratively, and meta-analyses of biochemical outcomes were conducted. Random effects models were used to generate forest plots to examine the evidence by age category, dose, dose duration, chemical formula of zinc, and zinc compared with placebo. The Joanna Briggs Institute Critical Appraisal Checklist, Cochrane Risk of Bias 2, and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) guideline were employed to assess risk of bias and to appraise the certainty of evidence. Fifty-eight studies assessed possible adverse effects of zinc doses ranging from 3 to 70 mg/d. Data from 39 studies contributed to meta-analyses. Zinc supplementation had an adverse effect on serum ferritin, plasma/serum copper concentration, serum transferrin receptor, hemoglobin, hematocrit, and the odds of anemia in ≥1 of the subgroups investigated. Lactulose:mannitol ratio was improved with zinc supplementation, and no significant effect was observed on C-reactive protein, erythrocyte superoxide dismutase, zinc protoporphyrin, blood cholesterol, and iron deficiency anemia. The certainty of the evidence, as assessed using GRADE, was very low to moderate. Although possible adverse effects of zinc supplementation were observed in some subgroups, it is unclear whether these findings are clinically important. The synthesized data can be used to undertake a dose-response analysis to update current guidelines of ULs of zinc intake for young children.
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Systematic review: probiotics in the management of lower gastrointestinal symptoms - an updated evidence-based international consensus.
Hungin, APS, Mitchell, CR, Whorwell, P, Mulligan, C, Cole, O, Agréus, L, Fracasso, P, Lionis, C, Mendive, J, Philippart de Foy, JM, et al
Alimentary pharmacology & therapeutics. 2018;47(8):1054-1070
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The role of the gut microbiota in health and disease is far reaching and there is a growing body of evidence on the therapeutic potential of probiotics in gastrointestinal (GI) disease. Patients with GI disease present with a variety of symptoms and current evidence suggests probiotics may play a role in ameliorating these adverse symptoms. The purpose of this review is to update the previous systematic review and incorporate new findings on the role of probiotics in adult patients presenting with a variety of GI symptoms. Based on the updated evidence, this study confirms the finding that specific probiotics are beneficial for certain lower GI problems. According to this review, the author deems this study useful for clinicians when recommending probiotics to patients.
Abstract
BACKGROUND In 2013, a systematic review and Delphi consensus reported that specific probiotics can benefit adult patients with irritable bowel syndrome (IBS) and other gastrointestinal (GI) problems. AIM: To update the consensus with new evidence. METHODS A systematic review identified randomised, placebo-controlled trials published between January 2012 and June 2017. Evidence was graded, previously developed statements were reassessed by an 8-expert panel, and agreement was reached via Delphi consensus. RESULTS A total of 70 studies were included (IBS, 34; diarrhoea associated with antibiotics, 13; diarrhoea associated with Helicobacter pylori eradication therapy, 7; other conditions, 16). Of 15 studies that examined global IBS symptoms as a primary endpoint, 8 reported significant benefits of probiotics vs placebo. Consensus statements with 100% agreement and "high" evidence level indicated that specific probiotics help reduce overall symptom burden and abdominal pain in some patients with IBS and duration/intensity of diarrhoea in patients prescribed antibiotics or H. pylori eradication therapy, and have favourable safety. Statements with 70%-100% agreement and "moderate" evidence indicated that, in some patients with IBS, specific probiotics help reduce bloating/distension and improve bowel movement frequency/consistency. CONCLUSIONS This updated review indicates that specific probiotics are beneficial in certain lower GI problems, although many of the new publications did not report benefits of probiotics, possibly due to inclusion of new, less efficacious preparations. Specific probiotics can relieve lower GI symptoms in IBS, prevent diarrhoea associated with antibiotics and H. pylori eradication therapy, and show favourable safety. This study will help clinicians recommend/prescribe probiotics for specific symptoms.