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Background & Aims: Epidemiologic and murine studies suggest that dietary emulsifiers promote development of diseases associated with microbiota dysbiosis. Although the detrimental impact of these compounds on the intestinal microbiota and intestinal health have been demonstrated in animal and in vitro models, impact of these food additives in healthy humans remains poorly characterized., Methods: To examine this notion in humans, we performed a double-blind controlled-feeding study of the ubiquitous synthetic emulsifier carboxymethylcellulose (CMC) in which healthy adults consumed only emulsifier-free diets (n = 9) or an identical diet enriched with 15 g per day of CMC (n = 7) for 11 days., Results: Relative to control subjects, CMC consumption modestly increased postprandial abdominal discomfort and perturbed gut microbiota composition in a way that reduced its diversity. Moreover, CMC-fed subjects exhibited changes in the fecal metabolome, particularly reductions in short-chain fatty acids and free amino acids. Furthermore, we identified 2 subjects consuming CMC who exhibited increased microbiota encroachment into the normally sterile inner mucus layer, a central feature of gut inflammation, as well as stark alterations in microbiota composition., Conclusions: These results support the notion that the broad use of CMC in processed foods may be contributing to increased prevalence of an array of chronic inflammatory diseases by altering the gut microbiome and metabolome (ClinicalTrials.gov, number NCT03440229)., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Trends in nutritional science are rapidly shifting as information regarding the value of eating unprocessed foods and its salutary effect on the human microbiome emerge. Unravelling the evolution and ecology by which humans have harboured a microbiome that participates in every facet of health and disease is daunting. Most strikingly, the host habitat has sought out naturally occurring foodstuff that can fulfil its own metabolic needs and also the needs of its microbiota, each of which remain inexorably connected to one another. With the introduction of modern medicine and complexities of critical care, came the assumption that the best way to feed a critically ill patient is by delivering fibre-free chemically defined sterile liquid foods (that is, total enteral nutrition). In this Perspective, we uncover the potential flaws in this assumption and discuss how emerging technology in microbiome sciences might inform the best method of feeding malnourished and critically ill patients., (© 2021. Springer Nature Limited.)

Background: A processed diet, high in fat and low in fiber, is associated with differences in the gut microbiota and adverse health outcomes in humans; however, little is known about the diet-microbiota relation and its impact on pregnancy. Spontaneous preterm birth (SPTB), a pregnancy outcome with serious short- and long-term consequences, occurs more frequently in black and in obese women in the United States., Objectives: In a prospective, case-control sample matched for race and obesity (cases = 16, controls = 32), we compared the fecal gut microbiota, fecal and plasma metabolites, and diet in the late second trimester. We hypothesized that a Western diet would be associated with reduced microbiota richness and a metabolic signature predicting incidence of SPTB., Methods: The fecal microbiota was characterized by 16S-tagged sequencing and untargeted metabolomics was used to analyze both plasma and fecal metabolites. Wilcoxon's rank-sum test was used for the comparison of microbiota genera, α-diversity, fecal and plasma metabolites, and dietary variables between term and SPTB. β-Diversity was analyzed using permutational multivariate ANOVA, and metabolite associations were assessed by module analysis., Results: A decrease in α-diversity was strongly associated with the development of SPTB, especially in the taxonomic class of Betaproteobacteria. Of 824 fecal metabolites, 22 metabolites (mostly lipids) differed between cases and controls (P < 0.01), with greater DHA (22:6n-3) and EPA (20:5n-3) in cases [false discovery rate (FDR) < 0.2]. The most significant fecal metabolite module (FDR-adjusted P = 0.008) was dominated by DHA and EPA. Dietary saturated fat (primarily palmitate) intake was greater in cases (31.38 ± 7.37 compared with 26.08 ± 8.62 g, P = 0.045) and was positively correlated with fecal DHA and EPA (P < 0.05)., Conclusions: Reduced α-diversity of the gut microbiota and higher excretion of omega-3 (n-3) fatty acids in stool may provide a novel biomarker signature predicting SPTB in women with a low-fiber, high-fat diet. Further investigation of these markers in a larger sample is needed for validation., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition.)