Foodborne Titanium Dioxide Nanoparticles Induce Stronger Adverse Effects in Obese Mice than Non-Obese Mice: Gut Microbiota Dysbiosis, Colonic Inflammation, and Proteome Alterations.

The recent ban of titanium dioxide (TiO2 ) as a food additive (E171) in France intensified the controversy on safety of foodborne-TiO2 nanoparticles (NPs). This study determines the biological effects of TiO2 NPs and TiO2 (E171) in obese and non-obese mice. Oral consumption (0.1 wt% in diet for 8 weeks) of TiO2 (E171, 112 nm) and TiO2 NPs (33 nm) does not cause severe toxicity in mice, but significantly alters composition of gut microbiota, for example, increased abundance of Firmicutes phylum and decreased abundance of Bacteroidetes phylum and Bifidobacterium and Lactobacillus genera, which are accompanied by decreased cecal levels of short-chain fatty acids. Both TiO2 (E171) and TiO2 NPs increase abundance of pro-inflammatory immune cells and cytokines in the colonic mucosa, indicating an inflammatory state. Importantly, TiO2 NPs cause stronger colonic inflammation than TiO2 (E171), and obese mice are more susceptible to the effects. A microbiota transplant study demonstrates that altered fecal microbiota by TiO2 NPs directly mediate inflammatory responses in the mouse colon. Furthermore, proteomic analysis shows that TiO2 NPs cause more alterations in multiple pathways in the liver and colon of obese mice than non-obese mice. This study provides important information on the health effects of foodborne inorganic nanoparticles.

Modeling the degradation kinetics of ascorbic acid.

Most published reports on ascorbic acid (AA) degradation during food storage and heat preservation suggest that it follows first-order kinetics. Deviations from this pattern include Weibullian decay, and exponential drop approaching finite nonzero retention. Almost invariably, the degradation rate constant's temperature-dependence followed the Arrhenius equation, and hence the simpler exponential model too. A formula and freely downloadable interactive Wolfram Demonstration to convert the Arrhenius model's energy of activation, Ea, to the exponential model's c parameter, or vice versa, are provided. The AA's isothermal and non-isothermal degradation can be simulated with freely downloadable interactive Wolfram Demonstrations in which the model's parameters can be entered and modified by moving sliders on the screen. Where the degradation is known a priori to follow first or other fixed order kinetics, one can use the endpoints method, and in principle the successive points method too, to estimate the reaction's kinetic parameters from considerably fewer AA concentration determinations than in the traditional manner. Freeware to do the calculations by either method has been recently made available on the Internet. Once obtained in this way, the kinetic parameters can be used to reconstruct the entire degradation curves and predict those at different temperature profiles, isothermal or dynamic. Comparison of the predicted concentration ratios with experimental ones offers a way to validate or refute the kinetic model and the assumptions on which it is based.

Kinetic parameters of thiamine degradation in NASA spaceflight foods determined by the endpoints method for long-term storage.

Retention of labile vitamins such as thiamine (vitamin B1) in NASA spaceflight foods intended for extended-duration missions is critical for the health of the crew. In this study, the degradation kinetics of thiamine in three NASA spaceflight foods (brown rice, split pea soup, BBQ beef brisket) during storage was determined for the first time, using an interactive isothermal model developed by our group. Results showed that brown rice and split pea soup demonstrated resistance to thiamine degradation, while thiamine in beef brisket was less stable. Model-predicted thiamine retention in brown rice stored at 20 °C for 720 days was 55% of the original thiamine content after thermal processing, 42% for split pea soup, and 3% for beef brisket. Water activity, moisture content, and pH differences did not sufficiently explain the variation in the degradation kinetics of thiamine among these foods.

Dietary cranberry suppressed colonic inflammation and alleviated gut microbiota dysbiosis in dextran sodium sulfate-treated mice.

Increased consumption of fruits may decrease the risk of chronic inflammatory diseases including inflammatory bowel disease (IBD). Gut microbiota dysbiosis plays an important etiological role in IBD. However, the mechanisms of action underlying the anti-inflammatory effects of dietary cranberry (Vaccinium macrocarpon) in the colon and its role on gut microbiota were unclear. In this study, we determined the anti-inflammatory efficacy of whole cranberry in a mouse model of dextran sodium sulfate (DSS)-induced colitis, as well as its effects on the structure of gut microbiota. The results showed that dietary cranberry significantly decreased the severity of colitis in DSS-treated mice, evidenced by increased colon length, and decreased disease activity and histologic score of colitis in DSS-treated mice compared to the positive control group (p < 0.05). Moreover, the colonic levels of pro-inflammatory cytokine (IL-1ß, IL-6 and TNF-α) were significantly reduced by cranberry supplementation (p < 0.05). Analysis of the relative abundance of fecal microbiota in phylum and genus levels revealed that DSS treatment significantly altered the microbial structure of fecal microbiota in mice. α diversity was significantly decreased in the DSS group, compared to the healthy control group. But, cranberry treatment significantly improved DSS-induced decline in α-diversity. Moreover, cranberry treatment partially reversed the change of gut microbiota in colitic mice by increasing the abundance of potential beneficial bacteria, for example, Lactobacillus and Bifidobacterium, and decreasing the abundance of potential harmful bacteria, such as Sutterella and Bilophila. Overall, our results for the first time demonstrated that modification of gut microbiota by dietary whole cranberry might contribute to its inhibitory effects against the development of colitis in DSS-treated mice.

The gastrointestinal fate of limonin and its effect on gut microbiota in mice.

The gut microbiota plays a critical role in human health. Diets could modulate the gut microbiota, which in turn may contribute to altered health outcomes by way of changing the relative risk of chronic diseases. Limonin, widely found in citrus fruits, has been reported to possess multiple beneficial health effects. However, the gastrointestinal fate of limonin and its effect on gut microbiota remain unknown. Herein, mice were fed a diet containing 0.05% limonin (w/w) for 9 weeks. Liquid chromatography-mass spectrum analysis showed that limonin was concentrated along the gastrointestinal tract and reached 523.14 nmol g-1 in the colon lumen. Compared to control mice, colonic microbiota richness was significantly increased by limonin. Gut microbiota community was also clearly distinct from the control group as shown by Principle Coordinate Analysis. Additionally, the relative abundance of 22 genera (relative abundance >0.1%) was altered significantly. Among these, generally regarded probiotics (Lactobacillus and Bifidobacterium) were reduced, which was not due to direct inhibitory effect of limonin. According to the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, amino acid metabolism, lipid, metabolism and immune system function were predicted to be upregulated, and immune system disease and infectious disease markers were predicted to be suppressed dramatically by limonin based on gut microbiota composition. Within the infectious disease category, bacterial toxin and Staphylococcus aureus infection markers were suppressed significantly with limonin treatment. Collectively, our study provides the first line of evidence that oral intake of limonin could shift gut microbiota composition and its functions, which warrants further investigation to determine its implication in human health.

Dietary Intake of Whole Strawberry Inhibited Colonic Inflammation in Dextran-Sulfate-Sodium-Treated Mice via Restoring Immune Homeostasis and Alleviating Gut Microbiota Dysbiosis.

Strawberry (Fragaria chiloensis) is a major edible berry with various potential health benefits. This study determined the protective effects of whole strawberry (WS) against dextran-sulfate-sodium-induced colitis in mice. In colitic mice, dietary WS reduced the disease activity index, prevented the colon shortening and spleen enlargement, and alleviated the colonic tissue damages. The abundance of proinflammatory immune cells was reduced by dietary WS in the colonic mucosa, which was accompanied by the suppression of overproduction of proinflammatory cytokines. Western blotting and immunohistochemical analysis revealed that dietary WS decreased the expression of proinflammatory proteins in the colonic mucosa. Moreover, dietary WS partially reversed the alteration of gut microbiota in the colitic mice by increasing the abundance of potential beneficial bacteria, e.g., Bifidobacterium and Lactobacillus, and decreasing the abundance of potential harmful bacteria, e.g., Dorea and Bilophila. Dietary WS also restored the decreased production of short-chain fatty acids in the cecum of the colitic mice. The results revealed the anti-inflammatory effects and mechanisms of dietary WS in the colon, which is critical for the rational utilization of strawberry for the prevention of inflammation-driven diseases.

Mechanism of Different Stereoisomeric Astaxanthin in Resistance to Oxidative Stress in Caenorhabditis elegans.

As a potent antioxidant in human diet, astaxanthin (AST) may play important roles in alleviating oxidative stress-driven adverse physiological effects. This study examined the effects of different stereoisomers of AST in protecting Caenorhabditis elegans from chemically induced oxidative stress. Three stereoisomers of AST investigated herein included 3S,3´S (S) AST, 3R,3´R (R) AST, and a statistical mixture (S: meso: R = 1:2:1) (M) AST. Under paraquat-induced oxidative conditions, all three types of AST significantly enhanced survival rate of C. elegans. The accumulation levels of ROS in the worms were reduced by 40.12%, 30.05%, and 22.04% by S, R, and M AST, respectively (P < 0.05). Compared with R and M AST, S significantly enhanced the expression levels of SOD-3. The results of RNA-Seq analysis demonstrated that AST protected C. elegans from oxidative damage potentially by modulating genes involved in the insulin/insulin-like growth factor (IGF) signaling (IIS) pathway and the oxidoreductase system. It is noteworthy that different stereoisomers of AST showed different effects on the expression levels of various genes related with oxidative stress. This study revealed important information on the in vivo antioxidative effects of AST stereoisomers, which might provide useful information for better utilization of AST.