Some dietary fibers increase elimination of orally administered polychlorinated biphenyls but not that of retinol in mice

Insoluble dietary fibers: structure, metabolism, interactions with human microbiome, and role in gut homeostasis

Consumption of food rich in dietary fibers (DFs) has been long recognized to exert an overall beneficial effect on human health. This review aims to provide a holistic overview on how IDFs impact human gut health either directly, or through modulation of the gut microbiome. Several databases were searched for collecting papers such as PubMed, Google Scholar, Web of Science, Scopus and Reaxys from 2000 till 2022. Firstly, an overview of the chemical structure of the various IDFs and the pathways employed by gut microbiota for their degradation is provided. The impact of IDFs on microbial community structure and pathogens colonization inside the human gut was discussed. Finally, the impact of IDFs on gut homeostasis and systemic effects at the cellular level, as well as the overall immunological benefits of IDFs consumption were analyzed. IDFs viz., cellulose, hemicellulose, resistant starch, and lignin found enriched in food are discussed for these effects. IDFs were found to induce gut immunity, improve intestinal integrity and mucosal proliferation, and favor adhesion of probiotics and hence improve human health. Also, IDFs were concluded to improve the bioavailability of plant polyphenols and improve their health-related functional roles. Ultimately, dietary fibers processing by modification shows potential to enhance fibers-based functional food production, in addition to increase the economic value and usage of food-rich fibers and their by-products.

Size-dependent concentrations and bioaccessibility of organophosphate esters (OPEs) in indoor dust: A comparative study from a megacity and an e-waste recycling site

Indoor dust ingestion is an important pathway in human exposure to environmental pollutants, and the bioaccessibility of pollutants can largely influence human exposure risk assessment. In the present study, the concentrations and compositions of organophosphate esters (OPEs) were investigated for different sizes (50 μm to 2 mm) of indoor dust collected from a megacity, Guangzhou, and an e-waste recycling site. The concentrations of total OPEs were 5360 to 6830 ng/g and 560 to 20,500 ng/g across all sizes of dust from Guangzhou and the e-waste site, respectively. The levels and compositions of OPEs were consistent in different fractions of dust from Guangzhou. The highest concentrations of OPEs were found in the finest fraction of dust from the e-waste site. OPEs in Guangzhou dust showed decreasing bioaccessibility when the log K_OW of FRs increased from 4 to 11. The bioaccessibility of most OPEs in dust from the e-waste site was much lower than those in Guangzhou dust, indicating low bioaccessibility in the components of dust, such as e-waste debris, from the e-waste site. The human exposure risks of OPEs in dust from Guangzhou were generally higher than those in dust from the e-waste site. Chitosan and montmorillonite could significantly decrease the bioaccessibility of all OPEs, except for tri-ethyl phosphate (TEP) and tris‑(2‑butoxyethyl) phosphate (TBOEP) in dust (p < 0.05), indicating chitosan and montmorillonite as promising food additives to enhance the elimination of OPEs.

Interventions to Address Environmental Metabolism-Disrupting Chemicals: Changing the Narrative to Empower Action to Restore Metabolic Health

Metabolic disease rates have increased dramatically over the last four decades. Classic understanding of metabolic physiology has attributed these global trends to decreased physical activity and caloric excess; however, these traditional risk factors insufficiently explain the magnitude and rapidity of metabolic health deterioration. Recently, the novel contribution of environmental metabolism-disrupting chemicals (MDCs) to various metabolic diseases (including obesity, diabetes, and non-alcoholic fatty liver disease) is becoming recognized. As this burgeoning body of evidence has matured, various organic and inorganic pollutants of human and natural origin have emerged as metabolic disease risk factors based on population-level and experimental data. Recognition of these heretofore underappreciated metabolic stressors now mandates that efforts to mitigate the devastating consequences of metabolic disease include dedicated efforts to address environmental drivers of disease risk; however, there have not been adequate recommendations to reduce exposures or to mitigate the effects of exposures on disease outcomes. To address this knowledge gap and advance the clinical translation of MDC science, herein discussed are behaviors that increase exposures to MDCs, interventional studies to reduce those exposures, and small-scale clinical trials to reduce the body burden of MDCs. Also, we discuss evidence from cell-based and animal studies that provide insights into MDC mechanisms of action, the influence of modifiable dietary factors on MDC toxicity, and factors that modulate MDC transplacental carriage as well as their impact on metabolic homeostasis. A particular emphasis of this discussion is on critical developmental windows during which short-term MDC exposure can elicit long-term disruptions in metabolic health with potential inter- and transgenerational effects. While data gaps remain and further studies are needed, the current state of evidence regarding interventions to address MDC exposures illuminates approaches to address environmental drivers of metabolic disease risk. It is now incumbent on clinicians and public health agencies to incorporate this knowledge into comprehensive strategies to address the metabolic disease pandemic.

The fermentation of polydextrose in the large intestine and its beneficial effects

Polydextrose is a randomly bonded glucose polymer with a highly branched and complex structure. It resists digestion in the upper gastrointestinal tract and is partially fermented in the large intestine by the colonic microbes. Due to its complex structure, a plethora of microbes is required for the catabolism of polydextrose and this process occurs slowly. This gradual fermentation of polydextrose gives rise to moderate amounts of fermentation products, such as short chain fatty acids and gas. The production of these metabolites continues in the distal part of the colon, which is usually considered to be depleted of saccharolytic fermentation substrates. The fermentation of polydextrose modifies the composition of the microbiota in the colon, and has been shown to impact appetite and satiety in humans and improve the gastrointestinal function. The purpose of this short review is to summarise the in vitro, in vivo and human studies investigating the fermentation properties of polydextrose in the large intestine.

The effect of chitosan on the concentration of 17β-estradiol and free triiodothyronine in mice exposed to polychlorinated biphenyls (PCBs)

The aim of this work was to examine (i) how the applied PCB mixture influences the level of 17β-estradiol (E2) and free triiodothyronine (FT3) in the blood plasma of mice (C57/BL/6J) and (ii) whether supplementation with chitosan would protect against the observed changes in the examined plasma hormone concentrations. In the study we used a mixture of indicator PCBs (CB no. 28, 52, 101, 118, 138, 153, 180) and our results showed their anti-estrogenic effects. Exposure to the mixture resulted in a significant decrease (P < 0.05) in plasma concentration of E2 relative to the control, and chitosan administration did not prevent the decrease. To the contrary, E2 concentration in the blood plasma of the mice which received both the PCB mixture and chitosan was lower compared to those which did not receive chitosan. Exposure to the PCBs also resulted in a decrease in FT3 concentration in the treatedgroup, although it was not as pronounced as for E2 and was prevented with dietary supplementation with chitosan, with the observed FT3 level in the chitosan-treated group similar to the control. In summary, supplementation with chitosan can only to a certain extent minimize the negative effects of exposure to PCBs.

Plant consumption by grizzly bears reduces biomagnification of salmon-derived polychlorinated biphenyls, polybrominated diphenyl ethers, and organochlorine pesticides

The present study characterizes the uptake and loss of persistent organic pollutants (POPs) in grizzly bears (Ursus arctos horribilis) by sampling and analyzing their terrestrial and marine foods and fecal material from a remote coastal watershed in British Columbia, Canada. The authors estimate that grizzly bears consume 341 to 1,120 µg of polychlorinated biphenyls (PCBs) and 3.9 to 33 µg of polybrominated diphenyl ethers daily in the fall when they have access to an abundant supply of returning salmon. The authors also estimate that POP elimination by grizzly bears through defecation is very low following salmon consumption (typically <2% of intake) but surprisingly high following plant consumption (>100% for PCBs and organochlorine pesticides). Excretion of individual POPs is largely driven by a combination of fugacity (differences between bear and food concentrations) and the digestibility of the food. The results of the present study are substantiated by a principal components analysis, which also demonstrates a strong role for log KOW in governing the excretion of different POPs in grizzly bears. Collectively, the present study's results reveal that grizzly bears experience a vegetation-associated drawdown of POPs previously acquired through the consumption of salmon, to such an extent that net biomagnification is reduced.

Effect of chitosan intake on fecal excretion of dioxins and polychlorinated biphenyls in healthy men

Six healthy male subjects were treated with 0 g, 1 g, 3 g, and 0 g of chitosan for the first, second, third, and fourth of four weeks, respectively. They were administered chitosan before breakfast on the second, third, and fourth days of the week, and fecal specimens were collected corresponding to the prescribed diet consumed for breakfast on the second day to breakfast on the fourth day. Fecal excretion of dioxins and polychlorinated biphenyls (PCBs) was promoted by intake of 3 g of chitosan (p=0.0589 and p<0.05 respectively), and was positively correlated with that of fat (p<0.01 for both). We found that chitosan intake increased the fecal excretion of dioxins and PCBs, as well as that of fat, suggesting that it might be useful for reducing the adverse effects of lipophilic endocrine-disrupting chemicals.

Associations between dietary intake and breast milk dioxin levels in Tokyo, Japan

BACKGROUND

The presence of dioxins in breast milk has gained much attention recently. However, in Japan the relationship between the consumption of different foods and the human breast milk dioxin concentrations is still unclear.

METHODS

Breast milk was taken from 240 mothers residing in Tokyo, Japan to measure and analyze the concentrations of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and coplanar poly-chlorinated biphenyls contained in the fat. Individual milk samples were obtained from the mothers 30 days after delivery in 1999 and 2000. The data of the mothers' diets before pregnancy were collected by means of food frequency and amount estimation. Spearman correlation analysis and stepwise multiple linear regression were used to analyze the data.

RESULTS

The concentrations of dioxins in breast milk were influenced mainly by the mother's age and history of breast-feeding. All the Spearman correlation coefficients were less than 0.20. Pork, roast ham, sausage, salt codfish and tempura had negative correlations with breast milk dioxins.

CONCLUSIONS

History of breast-feeding and the mother's age should be considered and emphasized in this kind of analysis. The cause effect relationship between dietary intake and breast milk dioxin levels were still uncertain.

Prebiotics and other microbial substrates for gut functionality

The intestinal microbiota is of great importance to our health and wellbeing. Modulation of the intestinal microbiota by exogenous and endogenous substrates can be expected to improve various physiological functions of our body, not just those in the intestine. Recently, new targets such as immune function and areas outside the colon have been considered to be influenced by the intestinal microbiota. Novel approaches might include the application of prebiotics in different combinations or the provision of nutrients to different bacterial groups and to different parts of the intestine.