Elsevier

Nutrition

Volume 32, Issue 5, May 2016, Pages 609-614
Nutrition

Nutrition and food
A glance at … dietary emulsifiers, the human intestinal mucus and microbiome, and dietary fiber

https://doi.org/10.1016/j.nut.2015.12.036Get rights and content

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Human intestinal mucus

Human intestinal mucus contains >1300 identifiable proteins, most of which are O-glycosylated mucin (MUC) proteins (predominantly MUC2) that share similar large domains enriched in proline, threonine, and serine (PTS domains) [4], [5], [6], [7], [8], [9]. Although O-glycosylation tends to confer a rodlike conformation to the glycosylated mucins [4], the hydroxyls, carboxyl, and sulfate groups of the O-glycans form hydrogen bonds with water, forming complex cross-linked branching structures [5]

Mucus–microbiome ecological equilibrium

The relative balance between the rates of mucin protein replacement and glycosylation and the rates of microbial mucus proteolysis, hydrolysis, and digestion determines the degree of homeostatic mucus maintenance and the functional balance between protection against bacterial invasion and facilitation of nutrient penetration and absorption. This balance determines the status of the human intestinal microbial-epithelial system, or “microbiome,” consisting of the intestinal epithelial tissues,

Human microbiome, intestinal mucus, and soluble dietary fiber

The normal microbiologic residents of the healthy human gut generate and sustain conditions in the gut that disfavor colonization by enteric pathogenic organisms (“colonization resistance”). The composition of the microbiota determines, in part, the level of resistance to specific infections and the susceptibility to specific inflammatory diseases of the intestinal tract [33]. The very dense beneficial human commensal gut microbiota exhibits more variability in species and abundance between

Emulsifiers and the microbiome—case in point: carboxymethylcellulose

Carboxymethylcellulose is one of the principal cellulose ethers manufactured worldwide (especially in India and China). It is an artificial hydrophilic, water-soluble, cellulose-based emulsifier that is used in the food and beverage (e.g., dry pet foods, frozen dairy foods, diet soft drinks, white and sparkling wines, and tortillas), paper, pharmaceutical, personal care cosmetics, oil drilling, mineral ore mining, wallpaper, paper bag, textile, and detergent industries [63], [64], [65], [66].

Human intestinal mucus and inflammatory bowel disease

A possible causal association between human intestinal mucus deficiency and inflammatory bowel disease (IBD) is suggested by the results of early studies that reported that patients with symptomatic IBD exhibited decreased glycosylation of intestinal mucus that was accompanied by thinning of the inner mucus layer of the colon [86]. Consistent with these reports, children diagnosed with IBD exhibit reductions in goblet cell density, hypoglycosylation of the intestinal mucus, and thinning of the

Emulsifiers, phytochemicals, and IBD

Interestingly, there is interest in exploiting the mucus-degrading properties of emulsifiers to increase the accessibility of the intestinal epithelium to putatively health-promoting dietary phytochemicals. In one such investigation, the ability of the phytochemical curcumin to penetrate the intestinal mucus was nearly doubled in the presence of the emulsifier, Tween-80 (polysorbate 80) [94]. In the face of concern that dietary emulsifiers may potentiate the initiation or progression of IBD [90]

Conclusions

Dietary emulsifiers contribute to the desirable characteristics of many processed foods and beverages, while remaining indigestible, unabsorbable, and unfermentable, thereby conferring no benefits on the human digestive tract. Furthermore, the consumption of emulsifiers (such as carboxymethylcellulose) weakens the mucus barrier of the intestinal epithelium and facilitates bacterial translocation into the intestinal tissues. In contrast, the consumption of soluble dietary fiber supports the

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