BackgroundThe effects of probiotic supplementation on fecal microbiota composition in healthy adults have not been well established. We aimed to provide a systematic review of the potential evidence for an effect of probiotic supplementation on the composition of human fecal microbiota as assessed by high-throughput molecular approaches in randomized controlled trials (RCTs) of healthy adults.MethodsThe survey of peer-reviewed papers was performed on 17 August 2015 by a literature search through PubMed, SCOPUS, and ISI Web of Science. Additional papers were identified by checking references of relevant papers. Search terms included healthy adult, probiotic, bifidobacterium, lactobacillus, gut microbiota, fecal microbiota, intestinal microbiota, intervention, and (clinical) trial. RCTs of solely probiotic supplementation and placebo in healthy adults that examined alteration in composition of overall fecal microbiota structure assessed by shotgun metagenomic sequencing, 16S ribosomal RNA sequencing, or phylogenetic microarray methods were included. Independent collection and quality assessment of studies were performed by two authors using predefined criteria including methodological quality assessment of reports of the clinical trials based on revised tools from PRISMA/Cochrane and by the Jadad score.ResultsSeven RCTs investigating the effect of probiotic supplementation on fecal microbiota in healthy adults were identified and included in the present systematic review. The quality of the studies was assessed as medium to high. Still, no effects were observed on the fecal microbiota composition in terms of α-diversity, richness, or evenness in any of the included studies when compared to placebo. Only one study found that probiotic supplementation significantly modified the overall structure of the fecal bacterial community in terms of β-diversity when compared to placebo.ConclusionsThis systematic review of the pertinent literature demonstrates a lack of evidence for an impact of probiotics on fecal microbiota composition in healthy adults. Future studies would benefit from pre-specifying the primary outcome and transparently reporting the results including effect sizes, confidence intervals, and P values as well as providing a clear distinction of between-group and within-group comparisons.

BackgroundSince information about macro- and micronutrient intake among vegans is limited we aimed to determine and evaluate their dietary and supplementary intake.MethodsSeventy 18–61 years old Danish vegans completed a four-day weighed food record from which their daily intake of macro- and micronutrients was assessed and subsequently compared to an age-range-matched group of 1 257 omnivorous individuals from the general Danish population. Moreover, the vegan dietary and supplementary intake was compared to the 2012 Nordic Nutrition Recommendations (NNR).ResultsDietary intake differed significantly between vegans and the general Danish population in all measured macro- and micronutrients (p < 0.05), except for energy intake among women and intake of carbohydrates among men. For vegans the intake of macro- and micronutrients (including supplements) did not reach the NNR for protein, vitamin D, iodine and selenium. Among vegan women vitamin A intake also failed to reach the recommendations. With reference to the NNR, the dietary content of added sugar, sodium and fatty acids, including the ratio of PUFA to SFA, was more favorable among vegans.ConclusionsAt the macronutrient level, the diet of Danish vegans is in better accordance with the NNR than the diet of the general Danish population. At the micronutrient level, considering both diet and supplements, the vegan diet falls short in certain nutrients, suggesting a need for greater attention toward ensuring recommended daily intake of specific vitamins and minerals.Electronic supplementary materialThe online version of this article (doi:10.1186/s12937-015-0103-3) contains supplementary material, which is available to authorized users.

A Correction to this paper has been published: https://doi.org/10.1038/s41467-020-20412-9.

Accumulating evidence has pointed towards a role of the gut microbiota in the pathogenesis of obesity. Also, the gut microbiota is a dynamic and modifiable community offering itself as a target for therapeutic interventions potentially improving host health. This review gives an overview on effects of clinically controlled interventions with probiotics on body weight regulation in overweight or obese individuals free of co-morbidities.Literature search was performed through PubMed with the criteria 1) healthy overweight/obese adults without comorbidities as study population, 2) probiotics as intervention without limits regarding dose or duration of intervention 3) healthy overweight/obese adults receiving placebo as controls, 4) body weight-related variables as the primary outcome and 5) randomized controlled trial as the study design. Methodological quality of the included studies was assessed using the Jadad score.Seven studies from five different countries met the inclusion criteria. Three studies reported improvements in body weight-related variables after probiotic supplementation compared to that in the controls, whereas four did not find such improvements. Overall, the methodological quality of the studies was limited and ranged from three to five based on the Jadad score.In conclusion, this review failed to identify convincing evidence of a robust effect of interventions with probiotics on body weight regulation in overweight or obese individuals free of co-morbidities. Large high quality randomized controlled trials in well-phenotyped study participants on regulated and to some extent standardized diets with mixtures of probiotics known to have master-switch roles in the gut microbiota composition and function in healthy lean individuals are needed to examine the effects of probiotics on body weight in greater detail.

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