Intestinal absorption of water-soluble vitamins in health and disease

Micronutrients in Liver Disease: Roles, Risk Factors for Deficiency, and Recommendations for Supplementation

Micronutrients are essential components of the diet and are required to maintain fundamental bodily functions. Liver disease has a profound effect on nutrient intake, metabolism of nutrients, and nutrition status, often resulting in some degree of malnutrition, including micronutrient deficiency. Vitamin and mineral deficiencies can impair metabolic processes at the cellular and biochemical level even before clinical and physical alterations are seen. It is essential that micronutrient status is evaluated as part of a comprehensive nutrition assessment for all patients with chronic or advanced liver disease. Early intervention to correct suspected or confirmed deficiencies may minimize symptoms and improve clinical outcomes and quality of life. In this narrative review, different types of liver disease and associated micronutrient abnormalities are outlined, and methods of micronutrient assessment and supplementation are discussed.

Comparison of the Acute Postprandial Circulating B-Vitamin and Vitamer Responses to Single Breakfast Meals in Young and Older Individuals: Preliminary Secondary Outcomes of a Randomized Controlled Trial

B-vitamin deficiency is common in ageing populations either due to altered dietary habits or altered digestive and metabolic functions. There is limited data on the acute circulating concentrations of B-vitamins and their various forms (vitamers), following ingestion of realistic meals. This study compared the acute circulating B-vitamin and vitamer responses to either an energy-dense (ED) or a nutrient-dense (ND) breakfast meal, consumed in a randomized cross-over sequence, in older and younger adults (n = 15 and 15, aged 67.3 ± 1.5 and 22.7 ± 0.5 years (mean ± SEM), respectively). Eleven differing B-vitamins and vitamers were determined in plasma samples by ultra-high-performance liquid chromatography-tandem mass spectrometry, in the fasting and postprandial state (hourly for 5 h). While postprandial thiamine concentration increased following both meals, riboflavin increased only following a ND meal in both age groups. Many vitamins including nicotinic acid, pantothenic acid, pyridoxal, pyridoxamine, pyridoxal-5'phosphate, and 4-pyridoxic acid remained unaltered, and flavin mononucleotide (FMN), nicotinamide and nicotinuric acid concentrations reduced following both meals. Biological age and food composition had minimal impact on postprandial B-vitamin concentrations, yet the differences between the ED and ND meals for riboflavin highlight the importance of riboflavin intake to achieve adequacy.

GutSelf: Interindividual Variability in the Processing of Dietary Compounds by the Human Gastrointestinal Tract

Nutritional research is currently entering the field of personalized nutrition, to a large extent driven by major technological breakthroughs in analytical sciences and biocomputing. An efficient launching of the personalized approach depends on the ability of researchers to comprehensively monitor and characterize interindividual variability in the activity of the human gastrointestinal tract. This information is currently not available in such a form. This review therefore aims at identifying and discussing published data, providing evidence on interindividual variability in the processing of the major nutrients, i.e., protein, fat, carbohydrates, vitamins, and minerals, along the gastrointestinal tract, including oral processing, intestinal digestion, and absorption. Although interindividual variability is not a primary endpoint of most studies identified, a significant number of publications provides a wealth of information on this topic for each category of nutrients. This knowledge remains fragmented, however, and understanding the clinical relevance of most of the interindividual responses to food ingestion described in this review remains unclear. In that regard, this review has identified a gap and sets the base for future research addressing the issue of the interindividual variability in the response of the human organism to the ingestion of foods.

Enterohemorrhagic Escherichia coli infection inhibits colonic thiamin pyrophosphate uptake via transcriptional mechanism

Colonocytes possess a specific carrier-mediated uptake process for the microbiota-generated thiamin (vitamin B1) pyrophosphate (TPP) that involves the TPP transporter (TPPT; product of the SLC44A4 gene). Little is known about the effect of exogenous factors (including enteric pathogens) on the colonic TPP uptake process. Our aim in this study was to investigate the effect of Enterohemorrhagic Escherichia coli (EHEC) infection on colonic uptake of TPP. We used human-derived colonic epithelial NCM460 cells and mice in our investigation. The results showed that infecting NCM460 cells with live EHEC (but not with heat-killed EHEC, EHEC culture supernatant, or with non-pathogenic E. Coli) to lead to a significant inhibition in carrier-mediated TPP uptake, as well as in level of expression of the TPPT protein and mRNA. Similarly, infecting mice with EHEC led to a significant inhibition in colonic TPP uptake and in level of expression of TPPT protein and mRNA. The inhibitory effect of EHEC on TPP uptake by NCM460 was found to be associated with reduction in the rate of transcription of the SLC44A4 gene as indicated by the significant reduction in the activity of the SLC44A4 promoter transfected into EHEC infected cells. The latter was also associated with a marked reduction in the level of expression of the transcription factors CREB-1 and ELF3, which are known to drive the activity of the SLC44A4 promoter. Finally, blocking the ERK1/2 and NF-kB signaling pathways in NCM460 cells significantly reversed the level of EHEC inhibition in TPP uptake and TPPT expression. Collectively, these findings show, for the first time, that EHEC infection significantly inhibit colonic uptake of TPP, and that this effect appears to be exerted at the level of SLC44A4 transcription and involves the ERK1/2 and NF-kB signaling pathways.

Bioactive molecules of probiotic bacteria and their mechanism of action: a review

The bacteria residing in the gut environment do play a pivotal role in metabolic activities of the host. The metabolites produced by these bacteria affect the physiology and health of the host. The gut bacteria are exposed to environmental conditions where multiple factors such as lifestyle, stress, antibiotics, host genetics and infections have an influence on them. In case of pathogenesis of a disease, the gut bacterial composition is altered which leads to a diseased state. This stage is due to colonization of bacterial pathogens in the gut environment. The pathological condition can be alleviated by administering probiotic strains into the gut environment. The probiotic strains produce therapeutic molecules such as amino acids, vitamins, bacteriocins, enzymes, immunomodulatory compounds and short-chain fatty acids. This review discusses recent evidences of the impact of bioactive molecules produced by probiotic bacteria and their mechanism of action in the gut environment to maintain homeostasis and health of the host without any effect on beneficial bacteria sharing the same niche. In addition, the manufacturing challenges of probiotic products for various applications are discussed here.

New Oleic Acid-Capped Mesoporous Silica Particles as Surfactant-Responsive Delivery Systems

A new delivery microdevice, based on hydrophobic oleic acid-capped mesoporous silica particles and able to payload release in the presence of surfactants, has been developed. The oleic acid functionalization confers to the system a high hydrophobic character, which avoids cargo release unless surfactant molecules are present. The performance of this oleic-acid capped microdevice in the presence of different surfactants is presented and its zero-release operation in the absence of surfactants is demonstrated.

Impact of Maternal Malnutrition on Gut Barrier Defense: Implications for Pregnancy Health and Fetal Development

Small intestinal Paneth cells, enteric glial cells (EGC), and goblet cells maintain gut mucosal integrity, homeostasis, and influence host physiology locally and through the gut-brain axis. Little is known about their roles during pregnancy, or how maternal malnutrition impacts these cells and their development. Pregnant mice were fed a control diet (CON), undernourished by 30% vs. control (UN), or fed a high fat diet (HF). At day 18.5 (term = 19), gut integrity and function were assessed by immunohistochemistry and qPCR. UN mothers displayed reduced mRNA expression of Paneth cell antimicrobial peptides (AMP; Lyz2, Reg3g) and an accumulation of villi goblet cells, while HF had reduced Reg3g and mucin (Muc2) mRNA and increased lysozyme protein. UN fetuses had increased mRNA expression of gut transcription factor Sox9, associated with reduced expression of maturation markers (Cdx2, Muc2), and increased expression of tight junctions (TJ; Cldn-7). HF fetuses had increased mRNA expression of EGC markers (S100b, Bfabp, Plp1), AMP (Lyz1, Defa1, Reg3g), and TJ (Cldn-3, Cldn-7), and reduced expression of an AMP-activator (Tlr4). Maternal malnutrition altered expression of genes that maintain maternal gut homeostasis, and altered fetal gut permeability, function, and development. This may have long-term implications for host-microbe interactions, immunity, and offspring gut-brain axis function.

Glucagon-Like Peptide-1 Receptor Agonists and Strategies To Improve Their Efficiency

Type 2 diabetes mellitus (T2DM) is increasing in global prevalence and is associated with serious health problems (e.g., cardiovascular disease). Various treatment options are available for T2DM, including the incretin hormone glucagon-like peptide-1 (GLP-1). GLP-1 is a therapeutic peptide secreted from the intestines following food intake, which stimulates the secretion of insulin from the pancreas. The native GLP-1 has a very short plasma half-life, owning to renal clearance and degradation by the enzyme dipeptidyl peptidase-4. To overcome this issue, various GLP-1 agonists with increased resistance to proteolytic degradation and reduced renal clearance have been developed, with several currently marketed. Strategies, such as controlled release delivery systems, methods to reduce renal clearance (e.g., PEGylation and conjugation to antibodies), and methods to improve proteolytic stability (e.g., stapling, cyclization, and glycosylation) provide means to further improve the ability of GLP-1 analogs. These will be discussed in this literature review.

Metabolism of Dietary and Microbial Vitamin B Family in the Regulation of Host Immunity

Vitamins are micronutrients that have physiological effects on various biological responses, including host immunity. Therefore, vitamin deficiency leads to increased risk of developing infectious, allergic, and inflammatory diseases. Since B vitamins are synthesized by plants, yeasts, and bacteria, but not by mammals, mammals must acquire B vitamins from dietary or microbial sources, such as the intestinal microbiota. Similarly, some intestinal bacteria are unable to synthesize B vitamins and must acquire them from the host diet or from other intestinal bacteria for their growth and survival. This suggests that the composition and function of the intestinal microbiota may affect host B vitamin usage and, by extension, host immunity. Here, we review the immunological functions of B vitamins and their metabolism by intestinal bacteria with respect to the control of host immunity.

Identification of transmembrane protein 237 as a novel interactor with the intestinal riboflavin transporter-3 (RFVT-3): role in functionality and cell biology

The apically localized riboflavin (RF) transporter-3 (RFVT-3) is involved in intestinal absorption of vitamin B2. Previous studies have characterized different physiological/biological aspects of the RFVT-3, but there is a lack of knowledge regarding possible existence of interacting partner(s) and consequence of interaction(s) on its function/cell biology. To address the latter, we performed yeast two-hybrid (Y2H) screening of a human colonic cDNA library and have identified transmembrane protein 237 (TMEM237) as a putative interactor with the human (h)RFVT-3; the interaction was further confirmed via "1-by-1" Y2H assay that involved appropriate positive and negative controls. TMEM237 was found to be highly expressed in human native intestine and in human intestinal epithelial cell lines; further, confocal images showed colocalization of the protein with hRFVT-3. The interaction between TMEM237 with hRFVT-3 in human intestinal epithelial HuTu-80 cells was established by coimmunoprecipitation. Expressing TMEM237 in HuTu-80 cells led to a significant induction in RF uptake, while its knockdown (with the use of gene-specific siRNA) led to a significant reduction in uptake. Transfecting TMEM237 into HuTu-80 cells also led to a marked enhancement in hRFVT-3 protein stability (reflected by an increase in the protein half-life). Interestingly, the level of expression of TMEM237 was found to be markedly reduced following treatment with TNF-α (a proinflammatory cytokine that inhibits intestinal RF uptake), while its expression was significantly upregulated following treatment with butyrate (an inducer of intestinal RF uptake). These findings identify TMEM237 as an interactor with the intestinal hRFVT-3 and show that the interaction has physiological/biological significance.

Subchronic low-dose 2,4-D exposure changed plasma acylcarnitine levels and induced gut microbiome perturbations in mice

The gut microbiota critically confers various health benefits, whereas environmental chemicals can affect its constitution and functionality thereby increasing disease risk. In the present study, we aim to evaluate the toxic effects of a wildly-used herbicide 2,4-D (2,4-dichlorophenoxyacetic acid) on the gut microbiome and host using an occupationally relevant dose. A mouse model was used combined with metagenomic sequencing and metabolomic profiling to examine the alterations induced by subchronic low-dose 2,4-D exposure in fecal and plasma samples. The metagenomics results revealed a distinct gut microbial community with profound changes in diverse microbial pathways including urea degradation, amino acid and carbohydrate metabolism in 2,4-D-treated mice. Moreover, the metabolomics results revealed that the metabolic profiles in treatment group were differentiated from control group in both fecal and plasma samples. Toxic effects on the host of 2,4-D at an occupationally relevant dose were observed indicated by decreased acylcarnitine levels in plasma. These findings indicated that 2,4-D can cause toxicity and substantially impact the gut microbiome in mice at occupationally relevant doses, inferring that the relationship between environmental contaminants and microbiota is largely underestimated calling for more comprehensive consideration of the toxicity of occupational exposures.

Systematic Review of Gut Microbiota and Major Depression

Background: Recently discovered relationships between the gastrointestinal microbiome and the brain have implications for psychiatric disorders, including major depressive disorder (MDD). Bacterial transplantation from MDD patients to rodents produces depression-like behaviors. In humans, case-control studies have examined the gut microbiome in healthy and affected individuals. We systematically reviewed existing studies comparing gut microbial composition in MDD and healthy volunteers. Methods: A PubMed literature search combined the terms "depression," "depressive disorder," "stool," "fecal," "gut," and "microbiome" to identify human case-control studies that investigated relationships between MDD and microbiota quantified from stool. We evaluated the resulting studies, focusing on bacterial taxa that were different between MDD and healthy controls. Results: Six eligible studies were found in which 50 taxa exhibited differences (p < 0.05) between patients with MDD and controls. Patient characteristics and methodologies varied widely between studies. Five phyla-Bacteroidetes, Firmicutes, Actinobacteria, Fusobacteria, and Protobacteria-were represented; however, divergent results occurred across studies for all phyla. The largest number of differentiating taxa were within phylum Firmicutes, in which nine families and 12 genera differentiated the diagnostic groups. The majority of these families and genera were found to be statistically different between the two groups in two identified studies. Family Lachnospiraceae differentiated the diagnostic groups in four studies (with an even split in directionality). Across all five phyla, nine genera were higher in MDD (Anaerostipes, Blautia, Clostridium, Klebsiella, Lachnospiraceae incertae sedis, Parabacteroides, Parasutterella, Phascolarctobacterium, and Streptococcus), six were lower (Bifidobacterium, Dialister, Escherichia/Shigella, Faecalibacterium, and Ruminococcus), and six were divergent (Alistipes, Bacteroides, Megamonas, Oscillibacter, Prevotella, and Roseburia). We highlight mechanisms and products of bacterial metabolism as they may relate to the etiology of depression. Conclusions: No consensus has emerged from existing human studies of depression and gut microbiome concerning which bacterial taxa are most relevant to depression. This may in part be due to differences in study design. Given that bacterial functions are conserved across taxonomic groups, we propose that studying microbial functioning may be more productive than a purely taxonomic approach to understanding the gut microbiome in depression.

Microbiome as a therapeutic target in alcohol-related liver disease

Alcohol-related liver disease is associated with significant changes in gut microbial composition. The transmissibility of ethanol-induced liver disease has been demonstrated using faecal microbiota transfer in preclinical models. This technique has also led to improved survival in patients with severe alcoholic hepatitis, suggesting that changes in the composition and function of the gut microbiota are causatively linked to alcohol-related liver disease. A major mechanism by which gut microbiota influence the development of alcohol-related liver disease is through a leaky intestinal barrier. This permits translocation of viable bacteria and microbial products to the liver, where they induce and promote inflammation, as well as contribute to hepatocyte death and the fibrotic response. In addition, gut dysbiosis is associated with changes in the metabolic function of the intestinal microbiota, bile acid composition and circulation, immune dysregulation during onset and progression of alcohol-related liver disease. Findings from preclinical and human studies will be used to demonstrate how alcohol causes intestinal pathology and contributes to alcohol-related liver disease and how the latter is self-perpetuating. Additionally, we summarise the effects of untargeted treatment approaches on the gut microbiota, such as diet, probiotics, antibiotics and faecal microbial transplantation in alcohol-related liver disease. We further discuss how targeted approaches can restore intestinal homeostasis and improve alcohol-related liver disease. These approaches are likely to add to the therapeutic options for alcohol-related liver disease independently or in conjunction with steroids.

Benefits of multiple micronutrient supplementation in heart failure: A comprehensive review

BACKGROUND

Multiple micronutrient supplementation has been suggested to have a role on health outcomes in patients with heart failure (HF), but the evidence is inconclusive.

OBJECTIVE

To elucidate the role of multiple micronutrient supplementation in heart failure we performed a comprehensive review of the literature.

METHODS AND RESULTS

The search in databases included PUBMED (until June 2018) to detect randomized controlled trials (RCTs) and meta-analyzes that investigated the impact of micronutrient supplementation in HF.

RESULTS

With more than 2357 titles and abstracts reviewed, we included only the studies suitable for the final review. Whether alone or in combination, micronutrients have been found to improve the health outcomes of patients with HF by improving symptoms, work capacity and left ventricular ejection fraction (LVEF), thus increasing the quality of life in these patients.

CONCLUSION

Future studies are needed to document the effects of multiple micronutrient associations in order to include them in nutritional guidelines to increase survival and to improve quality of life in patients with heart failure.

Gut Microbiota, Short-Chain Fatty Acids, and Herbal Medicines

As an important source for traditional medical systems such as Ayurvedic medicine and traditional Chinese medicine, herbal medicines have received widespread attentions from all over the world, especially in developing countries. Over the past decade, studies on gut microbiota have generated rich information for understanding how gut microbiota shape the functioning of our body system. In view of the importance of gut microbiota, the researchers engaged in studying herbal medicines have paid more and more attention to gut microbiota and gut microbiota metabolites. Among a variety of gut microbiota metabolites, short-chain fatty acids (SCFAs) have received most attention because of their important role in maintaining the hemostasis of hosts and recovery of diseases. Herbal medicines, as an important resource provider for production of SCFAs, have been demonstrated to be able to modulate gut microbiota composition and regulate SCFAs production. In this mini-review, we summarize current knowledge about SCFAs origination, the role of SCFAs in health and disease, the influence of herbal medicine on SCFAs production and the corresponding mechanisms. At the end of this review, the strategies and suggestions for further research of SCFAs and herbal medicines are also discussed.

A Monolayer of Primary Colonic Epithelium Generated on a Scaffold with a Gradient of Stiffness for Drug Transport Studies

Animal models are frequently used for in vitro physiologic and drug transport studies of the colon, but there exists significant pressure to improve assay throughput as well as to achieve tighter control of experimental variables than can be achieved with animals. Thus, development of a primary in vitro colonic epithelium cultured as high resistance with transport protein expression and functional behavior similar to that of a native colonic would be of enormous value for pharmaceutical research. A collagen scaffold, in which the degree of collagen cross-linking was present as a gradient, was developed to support the proliferation of primary colonic cells. The gradient of cross-linking created a gradient in stiffness across the scaffold, enabling the scaffold to resist deformation by cells. mRNA expression and quantitative proteomic mass spectrometry of cells growing on these surfaces as a monolayer suggested that the transporters present were similar to those in vivo. Confluent monolayers acted as a barrier to small molecules so that drug transport studies were readily performed. Transport function was evaluated using atenolol (a substrate for passive paracellular transport), propranolol (a substrate for passive transcellular transport), rhodamine 123 (Rh123, a substrate for P-glycoprotein), and riboflavin (a substrate for solute carrier transporters). Atenolol was poorly transported with an apparent permeability ( P_app) of <5 × 10^-7 cm s^-1, while propranolol demonstrated a P_app of 9.69 × 10^-6 cm s^-1. Rh123 was transported in a luminal direction ( P_app,efflux/ P_app,influx = 7) and was blocked by verapamil, a known inhibitor of P-glycoprotein. Riboflavin was transported in a basal direction, and saturation of the transporter was observed at high riboflavin concentrations as occurs in vivo. It is anticipated that this platform of primary colonic epithelium will find utility in drug development and physiological studies, since the tissue possesses high integrity and active transporters and metabolism similar to that in vivo.

Liver Injury, Endotoxemia, and Their Relationship to Intestinal Microbiota Composition in Alcohol-Preferring Rats

BACKGROUND

There is strong evidence that alcoholism leads to dysbiosis in both humans and animals. However, it is unclear how changes in the intestinal microbiota (IM) relate to ethanol (EtOH)-induced disruption of gut-liver homeostasis. We investigated this issue using selectively bred Sardinian alcohol-preferring (sP) rats, a validated animal model of excessive EtOH consumption.

METHODS

Independent groups of male adult sP rats were exposed to the standard, home-cage 2-bottle "EtOH (10% v/v) versus water" choice regimen with unlimited access for 24 h/d (Group Et) for 3 (T1), 6 (T2), and 12 (T3) consecutive months. Control groups (Group Ct) were composed of matched-age EtOH-naïve sP rats. We obtained samples from each rat at the end of each experimental time, and we used blood and colon tissues for intestinal barrier integrity and/or liver pathology assessments and used stool samples for IM analysis with 16S ribosomal RNA gene sequencing.

RESULTS

Rats in Group Et developed hepatic steatosis and elevated serum transaminases and endotoxin/lipopolysaccharide (LPS) levels but no other liver pathological changes (i.e., necrosis/inflammation) or systemic inflammation. While we did not find any apparent alteration of the intestinal colonic mucosa, we found that rats in Group Et exhibited significant changes in IM composition compared to the rats in Group Ct. These changes were sustained throughout T1, T2, and T3. In particular, Ruminococcus, Coprococcus, and Streptococcus were the differentially abundant microbial genera at T3. The KEGG Ortholog profile revealed that IM functional modules, such as biosynthesis, transport, and export of LPS, were also enriched in Group Et rats at T3.

CONCLUSIONS

We showed that chronic, voluntary EtOH consumption induced liver injury and endotoxemia together with dysbiotic changes in sP rats. This work sets the stage for improving our knowledge of the prevention and treatment of EtOH-related diseases.

Characterization of the Functional Changes in Mouse Gut Microbiome Associated with Increased Akkermansia muciniphila Population Modulated by Dietary Black Raspberries

Gut microbiome plays an essential role in host health through host-gut microbiota metabolic interactions. Desirable modulation of beneficial gut bacteria, such as Akkermansia muciniphila, can confer health benefits by altering microbiome-related metabolic profiles. The purpose of this study is to examine the effects of a black raspberry-rich diet to reshape the gut microbiome by selectively boosting A. muciniphila population in C57BL/6J mice. Remarkable changes of the mouse gut microbiome were revealed at both compositional and functional levels with an expected increase of A. muciniphila in concert with a profound impact on multiple gut microbiome-related functions, including vitamin biosynthesis, aromatic amino acid metabolism, carbohydrate metabolism, and oxidative stress. These functional alterations in the gut microbiome by an easily accessed freeze-dried black raspberry-supplemented diet may provide novel insights on the improvement of human health via gut microbiome modulation.

Effects of Metabolites Derived From Gut Microbiota and Hosts on Pathogens

Intestinal metabolites participate in various physiological processes, including energy metabolism, cell-to-cell communication, and host immunity. These metabolites mainly originate from gut microbiota and hosts. Although many host metabolites are dominant in intestines, such as free fatty acids, amino acids and vitamins, the metabolites derived from gut microbiota are also essential for intestinal homeostasis. In addition, some metabolites are only generated and released by gut microbiota, such as bacteriocins, short-chain fatty acids, and quorum-sensing autoinducers. In this review, we summarize recent studies regarding the crosstalk between pathogens and metabolites from different sources, including the influence on bacterial development and the activation/inhibition of immune responses of hosts. All of these functions would affect the colonization of and infection by pathogens. This review provides clear ideas and directions for further exploring the regulatory mechanisms and effects of metabolites on pathogens.

Gastrointestinal Handling of Water-Soluble Vitamins

Nine compounds are classified as water-soluble vitamins, eight B vitamins and one vitamin C. The vitamins are mandatory for the function of numerous enzymes and lack of one or more of the vitamins may lead to severe medical conditions. All the vitamins are supplied by food in microgram to milligram quantities and in addition some of the vitamins are synthesized by the intestinal microbiota. In the gastrointestinal tract, the vitamins are liberated from binding proteins and for some of the vitamins modified prior to absorption. Due to their solubility in water, they all require specific carriers to be absorbed. Our current knowledge concerning each of the vitamins differs in depth and focus and is influenced by the prevalence of conditions and diseases related to lack of the individual vitamin. Because of that we have chosen to cover slightly different aspects for the individual vitamins. For each of the vitamins, we summarize the physiological role, the steps involved in the absorption, and the factors influencing the absorption. In addition, for some of the vitamins, the molecular base for absorption is described in details, while for others new aspects of relevance for human deficiency are included. © 2018 American Physiological Society. Compr Physiol 8:1291-1311, 2018.

Effect of the proinflammatory cytokine TNF-α on intestinal riboflavin uptake: inhibition mediated via transcriptional mechanism(s)

Riboflavin (RF), is essential for normal cellular metabolism/function. Intestinal RF absorption occurs via a specific carrier-mediated process that involves the apical transporter RFVT-3 ( SLC52A3) and the basolateral RFVT-1 (SLC52A1). Previously, we characterized different cellular/molecular aspects of the intestinal RF uptake process, but nothing is known about the effect of proinflammatory cytokines on the uptake event. We addressed this issue using in vitro, ex vivo, and in vivo models. First, we determined the level of mRNA expression of the human (h)RFVT-3 and hRFVT-1 in intestinal tissue of patients with inflammatory bowel disease (IBD) and observed a markedly lower level compared with controls. In the in vitro model, exposing Caco-2 cells to tumor necrosis factor-α (TNF-α) led to a significant inhibition in RF uptake, an effect that was abrogated upon knocking down TNF receptor 1 (TNFR1). The inhibition in RF uptake was associated with a significant reduction in the expression of hRFVT-3 and -1 protein and mRNA levels, as well as in the activity of the SLC52A3 and SLC52A1 promoters. The latter effects appear to involve Sp1 and NF-κB sites in these promoters. Similarly, exposure of mouse small intestinal enteroids and wild-type mice to TNF-α led to a significant inhibition in physiological and molecular parameters of intestinal RF uptake. Collectively, these findings demonstrate that exposure of intestinal epithelial cells to TNF-α leads to inhibition in RF uptake and that this effect is mediated, at least in part, via transcriptional mechanism(s). These findings may explain the significantly low RF levels observed in patients with IBD.

Biotin and pantothenic acid oversupplementation to conditional SLC5A6 KO mice prevents the development of intestinal mucosal abnormalities and growth defects

Intestinal absorption of the water-soluble vitamins biotin and pantothenic acid is carrier mediated and involves the sodium-dependent multivitamin transporter (SMVT; product of the SLC5A6 gene). We recently observed that intestinal-specific (conditional) knockout of the mouse Slc5a6 gene (SMVT-cKO) is associated with growth retardation, the development of spontaneous and severe inflammation, abnormal histology in the large intestine, altered gut permeability, and early death. Our aim in this study was to examine the possibility that biotin and pantothenic acid oversupplementation (BPS) of the SMVT-cKO mice could reverse the above-described abnormalities. BPS was provided in the drinking water to mice before conception, to dams during pregnancy and lactation, and to the SMVT-cKO mice throughout their life. Our findings showed that such a regimen prevents early death, as well as normalizes the growth rate, intestinal integrity, pathology, and inflammation in SMVT-cKO mice. These findings provide clear evidence for a role for biotin and/or pantothenic acid in the maintenance of normal intestinal integrity and health.

The Drosophila melanogaster Gut Microbiota Provisions Thiamine to Its Host

The microbiota of Drosophila melanogaster has a substantial impact on host physiology and nutrition. Some effects may involve vitamin provisioning, but the relationships between microbe-derived vitamins, diet, and host health remain to be established systematically. We explored the contribution of microbiota in supplying sufficient dietary thiamine (vitamin B₁) to support D. melanogaster at different stages of its life cycle. Using chemically defined diets with different levels of available thiamine, we found that the interaction of thiamine concentration and microbiota did not affect the longevity of adult D. melanogaster. Likewise, this interplay did not have an impact on egg production. However, we determined that thiamine availability has a large impact on offspring development, as axenic offspring were unable to develop on a thiamine-free diet. Offspring survived on the diet only when the microbiota was present or added back, demonstrating that the microbiota was able to provide enough thiamine to support host development. Through gnotobiotic studies, we determined that Acetobacter pomorum, a common member of the microbiota, was able to rescue development of larvae raised on the no-thiamine diet. Further, it was the only microbiota member that produced measurable amounts of thiamine when grown on the thiamine-free fly medium. Its close relative Acetobacter pasteurianus also rescued larvae; however, a thiamine auxotrophic mutant strain was unable to support larval growth and development. The results demonstrate that the D. melanogaster microbiota functions to provision thiamine to its host in a low-thiamine environment.

There has been a long-standing assumption that the microbiota of animals provides their hosts with essential B vitamins; however, there is not a wealth of empirical evidence supporting this idea, especially for vitamin B₁ (thiamine). To determine whether this assumption is true, we used Drosophila melanogaster and chemically defined diets with different thiamine concentrations as a model. We found that the microbiota does provide thiamine to its host, enough to allow the development of flies on a thiamine-free diet. The power of the Drosophila-microbiota system allowed us to determine that one microbiota member in particular, Acetobacter pomorum, is responsible for the thiamine provisioning. Thereby, our study verifies this long-standing hypothesis. Finally, the methods used in this work are applicable for interrogating the underpinnings of other aspects of the tripartite interaction between diet, host, and microbiota.

Determinants of folate and vitamin B12 plasma levels in the French E3N-EPIC cohort

PURPOSE

Impaired B vitamin status has been identified as a risk factor for major chronic diseases. This study aims at examining the determinants of plasma folate and vitamin B12 concentrations, considering lifestyle factors and MTHFR polymorphisms.

METHODS

A total of 988 women aged 40-65 years from the French E3N cohort were investigated. Intakes of folate and vitamin B12 were assessed using food frequency questionnaires, and plasma concentrations were measured by microbiological assay. Dietary scores were computed to summarize folate and vitamin B12 dietary sources. MTHFR-C677T and MTHFR-A1298C were determined by Kaspar assay. Pearson's partial correlation coefficients and multivariable linear regression models were used to assess correlations between main determinants and plasma folate and vitamin B12 levels.

RESULTS

The partial correlation coefficient between dietary intakes and plasma folate was 0.19 (p value <0.001) and 0.08 (p value = 0.008) for vitamin B12. Dietary scores were the main determinant of B vitamin plasma concentrations with a percent change per unit increase of 12.64% (p value <0.001) for folate and 7.6% (p value <0.001) for vitamin B12. Homozygous (T/T) or heterozygous (C/T) women for MTHFR-C677T had lower plasma folate concentrations [C/T: -6.48% (p value = 0.038) and T/T: -15.89% (p value <0.001)] compared to women carrying the C/C genotype. Other determinants of B vitamin plasma concentration include: smoking status for folate, and age and hormone replacement therapy for vitamin B12.

CONCLUSIONS

We confirmed previous findings on the role of diet as main determinant of folate and vitamin B12 plasma concentrations. However, the impact of genetic polymorphisms and lifestyle factors on plasma B vitamin concentrations should not be neglected.

Recent Developments in Folate Nutrition

The term folate (vitamin B9) refers to a group of water-soluble compounds that are nutritionally essential for the support of optimal human health and development. Folates participate in numerous one-carbon transfer reactions, including the methylation of important biomolecules (lipids, amino acids, DNA). A deficiency of folate leads to pathological outcomes including anemia and impairments in reproductive health and fetal development. Due to the linkage of impaired folate status with an increased prevalence of neural tube defects (NTDs) in babies, several jurisdictions required the fortification of the food supply with folic acid, a synthetic and stable form of folate. Data from the postfortification era have provided strong evidence for the reduction of NTDs due to folic acid fortification. However, concern is now growing with respect to the amount of synthetic folic acid within the human food supply. Excess folic acid intake has been linked to a masking of vitamin B12 deficiency, and concerns regarding the promotion of folate-sensitive cancers, including colorectal cancer. New strategies to ensure the supply of optimal folate to at-risk populations may be needed, including the use of biofortification approaches, in order to address recent concerns.

Riboflavin and health: A review of recent human research

There has lately been a renewed interest in Riboflavin owing to insight into its recognition as an essential component of cellular biochemistry. The knowledge of the mechanisms and regulation of intestinal absorption of riboflavin and its health implications has significantly been expanded in recent years. The purpose of this review is to provide an overview of the importance of riboflavin, its absorption and metabolism in health and diseased conditions, its deficiency and its association with various health diseases, and metabolic disorders. Efforts have been made to review the available information in literature on the relationship between riboflavin and various clinical abnormalities. The role of riboflavin has also been dealt in the prevention of a wide array of health diseases like migraine, anemia, cancer, hyperglycemia, hypertension, diabetes mellitus, and oxidative stress directly or indirectly. The riboflavin deficiency has profound effect on iron absorption, metabolism of tryptophan, mitochondrial dysfunction, gastrointestinal tract, brain dysfunction, and metabolism of other vitamins as well as is associated with skin disorders. Toxicological and photosensitizing properties of riboflavin make it suitable for biological use, such as virus inactivation, excellent photosensitizer, and promising adjuvant in chemo radiotherapy in cancer treatment. A number of recent studies have indicated and highlighted the cellular processes and biological effects associated with riboflavin supplementation in metabolic diseases. Overall, a deeper understanding of these emerging roles of riboflavin intake is essential to design better therapies for future.

Role of Water Soluble Vitamins in the Reduction Diet of an Amateur Sportsman

This study is aimed at determining the content of water soluble vitamins in amateur sportsmen before and after the use of reduction diet. Twenty adult male amateur sportsmen aged between 20 and 43 qualified for this study. The participants adhered to individually adjusted reduction diets for 3 months. Diet supplements were excluded from the diet during that time. Vitamins were analyzed before and after the reduction diet using HPLC. The following vitamins were analyzed: B1, B2, B3, PP, B5, B6, B7, B9, B12 and vitamin C. Statistically significant increase of riboflavin in blood plasma (p=0.0254) and statistically significant (p=0.048) decrease in the concentration of niacin was found when compared to the period before the diet. Appropriate level of riboflavin can be obtained by the consumption of proper amount of diary in the diet. Supplementation with PP is advised and, in case of improper diet, the supplementation of B1, B7 and B12 may also be considered.

Role of MicroRNA-423-5p in posttranscriptional regulation of the intestinal riboflavin transporter-3

Riboflavin (RF) is essential for normal cellular functions and health. Humans obtain RF from exogenous sources via intestinal absorption that involves a highly specific carrier-mediated process. We have recently established that the riboflavin transporter-3 (RFVT3) is vital for the normal intestinal RF uptake process and have characterized certain aspects of its transcriptional regulation. Little is known, however, about how this transporter is regulated at the posttranscriptional level. We address this issue by focusing on the role of microRNAs. Using bioinformatics, we identified two potential interacting miRNAs with the human (h) RFVT3-3'-UTR, and showed (using pmirGLO-hRFVT3-3'-UTR) that the hRFVT3-3'-UTR is, indeed, a target for miRNA effect. Of the two putative miRNAs identified, miR-423-5p was found to be highly expressed in intestinal epithelial cells and that its mimic affected luciferase reporter activity of the pmirGLO-hRFVT3-3'-UTR construct, and also led to inhibition in RF uptake by intestinal epithelial Caco-2 and HuTu-80 cells. Furthermore, cells transfected with mutated seed sequences for miR-423-5p showed an abrogation in inhibitory effect of the miR-423-5p mimic on luciferase activity. While miR-423-5p did not affect the level of expression of the hRFVT3 mRNA, it did lead to a significant inhibition in the level of expression of its protein. Similarly, miR-423-5p was found to affect the level of expression of the mouse RFVT3 in cultured intestinal enteroids. These findings demonstrate, for the first time, that the RFVT3 is a target for posttranscriptional regulation by miRNAs in intestinal epithelial cells and that this regulation has functional consequences on intestinal RF uptake.NEW & NOTEWORTHY Our findings show for the first time that RFVT3 is a target for posttranscriptional regulation by miR-423-5p in intestinal epithelial cells, and this regulation has functional consequences on intestinal riboflavin (RF) uptake process.

The Role of Thiamine and Effects of Deficiency in Dogs and Cats

Recent pet food recalls for insufficient dietary thiamine have highlighted the importance of adequate thiamine intake in dogs and cats, as thiamine is an essential dietary nutrient with a critical role in energy metabolism. Prolonged thiamine deficiency leads to clinical signs that can span several organ systems, and deficiency can be fatal if not reversed. In this review, the current knowledge of thiamine metabolism will be summarized. Dietary recommendations for dogs and cats will be discussed, and the risk factors and clinical signs associated with thiamine deficiency will be examined.

Dietary pyridoxine deficiency reduced growth performance and impaired intestinal immune function associated with TOR and NF-κB signalling of young grass carp (Ctenopharyngodon idella)

The objective of this study was to evaluate the effects of dietary pyridoxine (PN) deficiency on growth performance, intestinal immune function and the potential regulation mechanisms in young grass carp (Ctenopharyngodon idella). Fish were fed six diets containing graded levels of PN (0.12-7.48 mg/kg) for 70 days. After that, a challenge test was conducted by infection of Aeromonas hydrophila for 14 days. The results showed that compared with the optimal PN level, PN deficiency: (1) reduced the production of innate immune components such as lysozyme (LZ), acid phosphatase (ACP), complements and antimicrobial peptides and adaptive immune components such as immunoglobulins in three intestinal segments of young grass carp (P < 0.05); (2) down-regulated the mRNA levels of anti-inflammatory cytokines such as transforming growth factor β (TGF-β), interleukin 4/13A (IL-4/13A) (rather than IL-4/13B), IL-10 and IL-11 partly relating to target of rapamycin (TOR) signalling [TOR/ribosomal protein S6 kinases 1 (S6K1) and eIF4E-binding proteins (4E-BP)] in three intestinal segments of young grass carp; (3) up-regulated the mRNA levels of pro-inflammatory cytokines such as tumour necrosis factor α (TNF-α) [not in the proximal intestine (PI) and distal intestine (DI)], IL-1β, IL-6, IL-8, IL-12p35, IL-12p40, IL-15 and IL-17D [(rather than interferon γ2 (IFN-γ2)] partly relating to nuclear factor kappa B (NF-κB) signalling [IκB kinase β (IKKβ) and IKKγ/inhibitor of κBα (IκBα)/NF-κB (p65 and c-Rel)] in three intestinal segments of young grass carp. These results suggest that PN deficiency could impair the intestinal immune function, and the potential regulation mechanisms were partly associated with TOR and NF-κB signalling pathways. In addition, based on percent weight gain (PWG), the ability against enteritis and LZ activity, the dietary PN requirements for young grass carp were estimated to be 4.43, 4.75 and 5.07 mg/kg diet, respectively.

Sugar industry sponsorship of germ-free rodent studies linking sucrose to hyperlipidemia and cancer: An historical analysis of internal documents

In 1965, the Sugar Research Foundation (SRF) secretly funded a review in the New England Journal of Medicine that discounted evidence linking sucrose consumption to blood lipid levels and hence coronary heart disease (CHD). SRF subsequently funded animal research to evaluate sucrose's CHD risks. The objective of this study was to examine the planning, funding, and internal evaluation of an SRF-funded research project titled "Project 259: Dietary Carbohydrate and Blood Lipids in Germ-Free Rats," led by Dr. W.F.R. Pover at the University of Birmingham, Birmingham, United Kingdom, between 1967 and 1971. A narrative case study method was used to assess SRF Project 259 from 1967 to 1971 based on sugar industry internal documents. Project 259 found a statistically significant decrease in serum triglycerides in germ-free rats fed a high sugar diet compared to conventional rats fed a basic PRM diet (a pelleted diet containing cereal meals, soybean meals, whitefish meal, and dried yeast, fortified with a balanced vitamin supplement and trace element mixture). The results suggested to SRF that gut microbiota have a causal role in carbohydrate-induced hypertriglyceridemia. A study comparing conventional rats fed a high-sugar diet to those fed a high-starch diet suggested that sucrose consumption might be associated with elevated levels of beta-glucuronidase, an enzyme previously associated with bladder cancer in humans. SRF terminated Project 259 without publishing the results. The sugar industry did not disclose evidence of harm from animal studies that would have (1) strengthened the case that the CHD risk of sucrose is greater than starch and (2) caused sucrose to be scrutinized as a potential carcinogen. The influence of the gut microbiota in the differential effects of sucrose and starch on blood lipids, as well as the influence of carbohydrate quality on beta-glucuronidase and cancer activity, deserve further scrutiny.

Multi-micronutrient supplementation during pregnancy for prevention of maternal anaemia and adverse birth outcomes in a high-altitude area: a prospective cohort study in rural Tibet of China

Anaemia during pregnancy, characterised by Hb <110 g/l, is a specific risk factor for adverse maternal and perinatal outcomes in developing countries. The objective of this study was to determine the effectiveness of daily antenatal supplementation with multiple micronutrients (MMN) compared with folic acid (FA) on the occurrence of anaemia among pregnant women and their infants’ health in a high-altitude area. A prospective cohort study was carried out in two rural counties in Tibet from 2007 to 2012. A total of 1149 eligible pregnant women were allocated daily supplementation with FA in one county and MMN containing a recommended allowance of twenty-three vitamins and minerals in another county starting ≤24 weeks of gestation and continuing until delivery. Compared with the FA group, prenatal supplementation with MMN was significantly associated with reduced odds of anaemia in the third trimester. This was demonstrated in the primary outcome, with an adjusted OR (AOR) of 0·63; 95 % CI 0·45, 0·88 and P=0·007 and also reduced odds of preterm delivery (AOR: 0·31; 95 % CI 0·15, 0·61; P=0·001). There was no difference between MMN and FA groups in mean birth weight (adjusted mean difference: 36·78; 95 % CI −19·42, 92·98 g; P=0·200), whereas MMN supplementation significantly reduced the odds of low-birth weight (LBW) babies (AOR: 0·58; 95 % CI 0·36, 0·91; P=0·019). In conclusion, the antenatal MMN supplementation in rural Tibet is associated with a reduction of maternal anaemia in the third trimester, and may potentially decrease the risk of preterm delivery and LBW babies.

Amino acid supplements and metabolic health: a potential interplay between intestinal microbiota and systems control

Dietary supplementation of essential amino acids (EAAs) has been shown to promote healthspan. EAAs regulate, in fact, glucose and lipid metabolism and energy balance, increase mitochondrial biogenesis, and maintain immune homeostasis. Basic science and epidemiological results indicate that dietary macronutrient composition affects healthspan through multiple and integrated mechanisms, and their effects are closely related to the metabolic status to which they act. In particular, EAA supplementation can trigger different and even opposite effects depending on the catabolic and anabolic states of the organisms. Among others, gut-associated microbial communities (referred to as gut microbiota) emerged as a major regulator of the host metabolism. Diet and host health influence gut microbiota, and composition of gut microbiota, in turn, controls many aspects of host health, including nutrient metabolism, resistance to infection, and immune signals. Altered communication between the innate immune system and the gut microbiota might contribute to complex diseases. Furthermore, gut microbiota and its impact to host health change largely during different life phases such as lactation, weaning, and aging. Here we will review the accumulating body of knowledge on the impact of dietary EAA supplementation on the host metabolic health and healthspan from a holistic perspective. Moreover, we will focus on the current efforts to establish causal relationships among dietary EAAs, gut microbiota, and health during human development.

Thiamine Acquisition Strategies Impact Metabolism and Competition in the Gut Microbe Bacteroides thetaiotaomicron

Thiamine (vitamin B₁) is an essential cofactor for all organisms. Humans primarily acquire thiamine through their diet, and thiamine deficiencies have adverse neurological effects. However, the role gut microbes play in modulating thiamine availability is poorly understood, and little is known about how thiamine impacts the stability of microbial gut communities. To investigate thiamine's role in the gut, we utilized the model gut microbe Bacteroides thetaiotaomicron. Transcriptome sequencing (RNA-seq) revealed a global downregulation of thiamine and amino acid biosynthesis, glycolysis, and purine metabolism when thiamine was present. Using genetic mutants with thiamine biosynthesis and transport locus mutations, we determined both systems were critical for growth in thiamine-deficient medium. The defect in the double transport mutant suggests an uncharacterized feedback mechanism between thiamine transport and biosynthesis in B. thetaiotaomicron. Mutant phenotypes were recapitulated during pairwise competitions, reinforcing the importance of encoding versatile thiamine acquisition mechanisms when thiamine concentrations are variable. In addition, liquid chromatography-mass spectrometry (LC-MS) analyses corroborate that exogenous thiamine levels affect the internal thiamine pool of B. thetaiotaomicron. Furthermore, we computationally examined the ability of other gut microbes to acquire thiamine and identified lineage-specific differences in thiamine acquisition strategies. Among the Bacteroidetes, the capacities for both thiamine transport and biosynthesis are common. Together, these data show that thiamine acquisition mechanisms used by B. thetaiotaomicron not only are critical for its physiology and fitness but also provide the opportunity to model how other gut microbes may respond to the shifting availability of thiamine in the gut. IMPORTANCE Variation in the ability of gut microbes to transport, synthesize, and compete for vitamin B₁ (thiamine) is expected to impact the structure and stability of the microbiota, and ultimately this variation may have both direct and indirect effects on human health. Our study identifies the diverse strategies employed by gut Bacteroidetes to acquire thiamine. We demonstrate how the presence or absence of thiamine biosynthesis or transport dramatically affects the abundance of B. thetaiotaomicron in a competitive environment. This study adds further evidence that altering the presence or concentrations of water-soluble vitamins such as thiamine may be an effective method for manipulating gut community composition. In turn, targeted thiamine delivery could be used therapeutically to alter dysbiotic communities linked to disease. Author Video: An author video summary of this article is available.

Molecular mechanisms involved in the adaptive regulation of the colonic thiamin pyrophosphate uptake process

A considerable amount of the thiamin generated by gut microbiota exists in the form of thiamin pyrophosphate (TPP). We have previously shown that human colonocytes possess an efficient carrier-mediated uptake process for TPP that involves the SLC44A4 system and this uptake process is adaptively regulated by prevailing extracellular TPP level. Little is known about the molecular mechanisms that mediate this adaptive regulation. We addressed this issue using human-derived colonic epithelial NCM460 cells and mouse colonoids as models. Maintaining NCM460 cells in the presence of a high level of TPP (1 mM) for short (2 days)- and long-term (9 days) periods was found to lead to a significant reduction in [³H] TPP uptake compared with cells maintained in its absence. Short-term exposure showed no changes in level of expression of SLC44A4 protein in total cell homogenate (although there was a decreased expression in the membrane fraction), mRNA, and promoter activity. However, a significant reduction in the level of expression of the SLC44A4 protein, mRNA, and promoter activity was observed upon long-term maintenance with the substrate. Similar changes in Slc44a4 mRNA expression were observed when mouse colonoids were maintained with TPP for short- and long-term periods. Expression of the transcription factors ELF3 and CREB-1 (which drive the SLC44A4 promoter) following long-term exposure was unchanged, but their binding affinity to the promoter was decreased and specific histone modifications were also observed. These studies demonstrate that, depending on the period of exposure, different mechanisms are involved in the adaptive regulation of colonic TPP uptake by extracellular substrate level.

Thiamine content of F-75 therapeutic milk for complicated severe acute malnutrition: time for a change?

Since community-based management of severe acute malnutrition has become the standard of care, the clinical profile of severe acutely malnourished patients admitted to hospitals or inpatient therapeutic feeding centers has changed significantly. These patients are usually very ill and often present with several comorbidities, such as shock, sepsis, and pneumonia. Complicated severe acute malnutrition patients are at risk of thiamine insufficiency, and critically ill patients have higher thiamine requirements. The thiamine content of F-75, the therapeutic milk formula used in the early stabilization phase of refeeding in patients with severe acute malnutrition, seems insufficient. Here, we discuss the need and rationale for a substantial increase in the thiamine content of F-75.

Nutritional and Micronutrient Care of Bariatric Surgery Patients: Current Evidence Update

PURPOSE OF REVIEW

The continued success of bariatric surgery to treat obesity and obesity-associated metabolic conditions creates a need for a strong understanding of clinical nutrition both before and after these procedures.

RECENT FINDINGS

Surgically induced alteration of gastrointestinal physiology can affect the nutrition of individuals, especially among those who have undergone malabsorptive procedures. While uncommon, a subset of patients may develop protein-calorie malnutrition. In these cases, nutrition support should be tailored to the severity of malnutrition. Among all patients who undergo bariatric surgery, high rates of micronutrient deficiencies have been observed. To mitigate these deficiencies, empiric supplementation with multivitamins, calcium citrate, and vitamin D is generally recommended. Periodic surveillance should be performed for commonly deficient micronutrients, including thiamin (B1), folate (B9), cobalamin (B12), iron, and vitamin D. Following Roux-en-Y gastric bypass, serum levels of copper and zinc should also be monitored. In addition, lipid-soluble vitamins should be monitored following biliopancreatic diversion with/without duodenal switch.

Does Vitamin C Influence Neurodegenerative Diseases and Psychiatric Disorders?

Vitamin C (Vit C) is considered to be a vital antioxidant molecule in the brain. Intracellular Vit C helps maintain integrity and function of several processes in the central nervous system (CNS), including neuronal maturation and differentiation, myelin formation, synthesis of catecholamine, modulation of neurotransmission and antioxidant protection. The importance of Vit C for CNS function has been proven by the fact that targeted deletion of the sodium-vitamin C co-transporter in mice results in widespread cerebral hemorrhage and death on post-natal day one. Since neurological diseases are characterized by increased free radical generation and the highest concentrations of Vit C in the body are found in the brain and neuroendocrine tissues, it is suggested that Vit C may change the course of neurological diseases and display potential therapeutic roles. The aim of this review is to update the current state of knowledge of the role of vitamin C on neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis and amyotrophic sclerosis, as well as psychiatric disorders including depression, anxiety and schizophrenia. The particular attention is attributed to understanding of the mechanisms underlying possible therapeutic properties of ascorbic acid in the presented disorders.

Inhibition of Intestinal Thiamin Transport in Rat Model of Sepsis

OBJECTIVES

Thiamin deficiency is highly prevalent in patients with sepsis, but the mechanism by which sepsis induces thiamin deficiency is unknown. This study aimed to determine the influence of various severity of sepsis on carrier-mediated intestinal thiamin uptake, level of expressions of thiamin transporters (thiamin transporter-1 and thiamin transporter-2), and mitochondrial thiamin pyrophosphate transporter.

DESIGN

Randomized controlled study.

SETTING

Research laboratory at a Veterans Affairs Medical Center.

SUBJECTS

Twenty-four Sprague-Dawley rats were randomized into controls, mild, moderate, and severe sepsis with equal number of animals in each group.

INTERVENTIONS

Sepsis was induced by cecal ligation and puncture with the cecum ligated below the cecal valve at 25%, 50%, and 75% of cecal length, defined as severe, moderate, and mild sepsis, respectively. Control animals underwent laparotomy only.

MEASUREMENTS AND MAIN RESULTS

After 2 days of induced sepsis, carrier-mediated intestinal thiamin uptake was measured using [H]thiamin. Expressions of thiamin transporter-1, thiamin transporter-2, and mitochondrial thiamin pyrophosphate transporter proteins and messenger RNA were measured. Proinflammatory cytokines (interleukin-1β and interleukin-6) and adenosine triphosphate were also measured. Sepsis inhibited [H]thiamin uptake, and the inhibition was a function of sepsis severity. Both cell membrane thiamin transporters and mitochondrial thiamin pyrophosphate transporter expression levels were suppressed; also levels of adenosine triphosphate in the intestine of animals with moderate and severe sepsis were significantly lower than that of sham-operated controls.

CONCLUSIONS

For the first time, we demonstrated that sepsis inhibited carrier-mediated intestinal thiamin uptake as a function of sepsis severity, suppressed thiamin transporters and mitochondrial thiamin pyrophosphate transporter, leading to adenosine triphosphate depletion.

High Throughput and Quantitative Measurement of Microbial Metabolome by Gas Chromatography/Mass Spectrometry Using Automated Alkyl Chloroformate Derivatization

The ability to identify and quantify small molecule metabolites derived from gut microbial-mammalian cometabolism is essential for the understanding of the distinct metabolic functions of the microbiome. To date, analytical protocols that quantitatively measure a complete panel of microbial metabolites in biological samples have not been established but are urgently needed by the microbiome research community. Here, we report an automated high-throughput quantitative method using a gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) platform to simultaneously measure over one hundred microbial metabolites in human serum, urine, feces, and Escherichia coli cell samples within 15 min per sample. A reference library was developed consisting of 145 methyl and ethyl chloroformate (MCF and ECF) derivatized compounds with their mass spectral and retention index information for metabolite identification. These compounds encompass different chemical classes including fatty acids, amino acids, carboxylic acids, hydroxylic acids, and phenolic acids as well as benzoyl and phenyl derivatives, indoles, etc., that are involved in a number of important metabolic pathways. Within an optimized range of concentrations and sample volumes, most derivatives of both reference standards and endogenous metabolites in biological samples exhibited satisfactory linearity (R² > 0.99), good intrabatch reproducibility, and acceptable stability within 6 days (RSD < 20%). This method was further validated by examination of the analytical variability of 76 paired human serum, urine, and fecal samples as well as quality control samples. Our method involved using high-throughput sample preparation, measurement with automated derivatization, and rapid GC/TOFMS analysis. Both techniques are well suited for microbiome metabolomics studies.

Water soluble vitamins and peritoneal dialysis - State of the art

This review presents the results of a systematic literature search concerning water soluble vitamins and peritoneal dialysis modality. We provide an overview of the data available on vitamin requirements, dietary intake, dialysis related losses, metabolism and the benefits of supplementation. We also summarise the current recommendations concerning the supplementation of vitamins in peritoneal dialysis and discuss the safety of an administration of vitamins in pharmacological doses.