High prevalence of low plasma thiamine concentration in diabetes linked to a marker of vascular disease

Thiamine status and genes encoding intestinal thiamine transporters and transcription factors in obese subjects

BACKGROUND AND AIMS

The inconsistent data on thiamine status in obese subjects necessitates an examination of genes associated with intestinal absorption of thiamine. We aimed to reveal thiamine status in obese subjects and examine the expression of SLC19A2/3 genes encoding thiamine transporters and Sp1 transcription factor.

METHODS AND RESULTS

Thirty-five adult obese subjects and 11 healthy controls were included in this cross-sectional study. Small intestine epithelial cells were used for quantitative RT-PCR analysis of the gene expression. The daily thiamine and energy intake were assessed with a food frequency questionnaire. Thiamine phosphate esters were hydrolyzed to free thiamine, and liquid chromatography with a tandem mass spectrometry-based method was used to measure total thiamine in whole blood. Daily energy intake according to body weight and daily carbohydrate intake were not significantly different between groups after adjustment for sex. Although daily thiamine intake was significantly lower in the obesity group (p = 0.015), obese subjects had significantly higher whole blood thiamine levels than controls (44.96 ± 14.6 ng/mL and 33.05 ± 8.6 ng/mL, p = 0.002). There was a significant positive correlation between whole blood thiamine and BMI (r = 0.342, p = 0.020). SLC19A2 gene expression was lower in those with BMI ≥35 kg/m2 (p = 0.036). A significant positive correlation was found between SLC19A2 expression and whole blood thiamine level (r = 0.310, p = 0.038).

CONCLUSION

A possible association between intestinal thiamine intake and total thiamine in whole blood was determined. The transcriptional changes of genes encoding the high-affinity membrane thiamine transporters, especially SLC19A2, probably play a role in this relationship.

Effect of knocking out mouse Slc44a4 on colonic uptake of the microbiota-generated thiamine pyrophosphate and colon physiology

Humans and mammals obtain vitamin B1 from dietary and gut microbiota sources. A considerable amount of the microbiota-generated vitamin exists in the form of thiamine pyrophosphate (TPP), and colonocytes are capable of absorbing TPP via a specific carrier-mediated process that involves the colonic TPP transporter (cTPPT encoded by SLC44A4). Little is known about the relative contribution of the SLC44A4 transporter toward total colonic carrier-mediated TPP uptake and its role in colon physiology. To address these issues, we generated an Slc44a4 knockout (KO) mouse model (by Cre-Lox recombination) and found a near-complete inhibition in colonic carrier-mediated [3H]TPP uptake in the Slc44a4 KO compared with wild-type (WT) littermates. We also observed a significant reduction in KO mice's body weight and a shortening of their colon compared with WT. Using RNAseq and Ingenuity pathway analysis (IPA) approaches, we found that knocking out the colonic Slc44a4 led to changes in the level of expression of many genes, including upregulation in those associated with intestinal inflammation and colitis. Finally, we found that the Slc44a4 KO mice were more susceptible to the effect of the colitogenic dextran sodium sulfate (DSS) compared with WT animals, a finding that lends support to the recent prediction by multiple genome-wide association studies (GWAS) that SLC44A4 is a possible colitis susceptibility gene. In summary, the results of these investigations show that Slc44a4 is the predominant or only transporter involved in the colonic uptake of TPP, that the transporter is important for colon physiology, and that its deletion increases susceptibility to inflammation.NEW & NOTEWORTHY This study shows that Slc44a4 is the predominant or only transport system involved in the uptake of the gut microbiota-generated thiamine pyrophosphate (TPP) in the colon and that its deletion affects colon physiology and increases its susceptibility to inflammation.

Aged garlic extract preserves beta-cell functioning via modulation of nuclear factor kappa-B (NF-κB)/Toll-like receptor (TLR)-4 and sarco endoplasmic reticulum calcium ATPase (SERCA)/Ca2+ in diabetes mellitus

BACKGROUND

Peripheral insulin resistance and compromised insulin secretion from pancreatic β-cells are significant factors and pathogenic hallmarks of diabetes mellitus (DM). NF-κβ/TLR-4 and SERCA/Ca2+ pathways have been identified as potential pathways regulating insulin synthesis by preserving pancreatic β-cell functioning. The current study aimed to evaluate the therapeutic effect of aged garlic extract (AGE) against DM in a streptozotocin (STZ)-induced rat model with particular emphasis on pancreatic β-cell functioning.

METHODS

AGE was characterized by gas chromatography-mass spectrometry (GC-MS), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) to evaluate its physio-chemical characteristics followed by in-vitro anti-diabetic and antioxidant potential. This was followed by the induction of DM in laboratory animals for investigating the therapeutic action of AGE by evaluating the role of NF-κβ/TLR-4 and the SERCA/Ca2+ pathway. The parameters assessed in the present experimental setup encompassed antioxidant parameters, metabolic indicators, insulin concentration, intracellular calcium levels, apoptotic markers (CCK-8 and Caspase Glo-8), and protein expression (P-62 and APACHE-II).

RESULTS

AGE characterization by SEM, GC-MS, and X-ray diffraction (XRD) revealed the presence of phenylalanine, alliin, S-allylmercaptocysteine (SAMC), tryptophan, 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid as major bioactive constituents of AGE. Metabolic studies, including intraperitoneal glucose tolerance test (IPGTT), revealed significantly lower blood glucose levels in the AGE group compared to the disease control group. In contrast, the intraperitoneal insulin tolerance test (ITT) exhibited no significant difference in insulin sensitivity between the AGE supplementation group and the DM control group. Interestingly, AGE was found to have no significant effect on fasting glucose and serum insulin levels. In contrast, AGE supplementation was found to cause significant hypoglycaemia in postprandial blood glucose and insulin levels. Importantly, AGE causes restoration of intracellular Ca2+ levels by modulation of SERCA/Ca2 functioning and inhibition NF-κB/TLR-4 pathway. AGE was found to interact with and inhibit the DR-5/ caspase-8/3 apoptotic complex. Furthermore, microscopic studies revealed degeneration and apoptotic changes in pancreatic β-cells of the DM control group, while supplementation of AGE resulted in inhibition of apoptotic pathway and regeneration of pancreatic β-cells.

CONCLUSION

The current study suggests that AGE enhance glucose homeostasis by exerting their effects on pancreatic β-cells, without ameliorating peripheral sensitivity. Moreover, AGEs promote an increase in β-cell mass by mitigating the apoptosis of pancreatic β-cells. These findings suggest that AGE could aid in developing a viable alternative therapy for diabetes mellitus (DM).

Thiamine deficiency in diabetes, obesity and bariatric surgery: Recipes for diabetic ketoacidosis

Diabetic ketoacidosis (DKA) is a life-threatening condition affecting individuals with diabetes characterised by hyperglycaemia, metabolic acidosis and ketonemia. The incidence and financial burden of DKA is still high. Thiamine deficiency is well documented in patients with DKA and could be associated with cardiac dysfunction in those patients. Thiamine deficiency leads to cardiac dysfunction, neuronal death and worsens the prognosis of DKA. There is an existing metabolic relationship between thiamine deficiency in diabetes, obesity and bariatric surgery. Careful monitoring of thiamine, along with other vitamins, is essential for diabetic patients, obese individuals and postbariatric surgery. Further research and clinical studies are urgently needed to assess the following: (1) Whether diabetes, obesity and bariatric surgery make individuals more prone to have DKA related to thiamine deficiency and (2) Whether supplementation of thiamine can protect diabetic patients, obese subjects and individuals undergoing bariatric surgery from DKA. This review summarises the biochemistry of thiamine and the existing metabolic relationships between thiamine deficiency in DKA, diabetes, obesity and bariatric surgery. Primary and family physicians have an important role in ensuring adequate replacement of thiamine in individuals with diabetes, obesity and bariatric surgery.

Correlation of Serum Sodium and Potassium With Thiamin Levels in Type 1 and Type 2 Diabetic Patients

Introduction Chronic metabolic disorders such as diabetes mellitus (DM) are becoming a global health concern. According to recent studies, the pathophysiology of DM may involve factors other than traditional glycemic control, such as electrolyte balance and thiamin status. Therefore, this study evaluated the relationship between sodium and potassium and serum thiamin levels in patients with type 1 and type 2 DM. Methods This study was conducted in multiple diabetic outpatient clinics and centers in Karachi, Pakistan, using a non-probability convenience sampling method. The study lasted for approximately six months after the synopsis was approved. A total of 64 patients were selected, 32 of whom each had type 1 and type 2 DM. All patients who were between the ages of 25 and 46 years old and had either type 1 or type 2 DM were included in the study. A Mann-Whitney test and an independent t-test were used to compare the means between the two study groups. Pearson's correlation and chi-square tests were used to determine the variables, correlations, and associations with type 1 and type 2 DM. Results The study findings showed that the distribution of gender among diabetic patients revealed that among males, eight (25.0%) had type 1 DM, and 10 (31.2%) had type 2 DM. Among females, 24 (75.0%) had type 1 DM, and 22 (68.8%) had type 2 DM. Significant correlations were observed in the means of blood glucose levels, such as glycated hemoglobin (HbA1c), fasting blood sugar (FBS), and serum thiamin levels, among patients with type 1 and type 2 DM (p < 0.001). The HbA1c, FBS, and serum thiamin levels were significantly higher in type 2 DM patients than in type 1 DM patients. Among patients with type 1 DM, sodium levels were not substantially correlated with thiamin levels (p = 0.570, r = 0.104), whereas potassium levels were significantly correlated with thiamin levels (p = 0.005, r = 0.263). Conclusion We conclude that the sodium level was not significantly correlated with serum thiamin status in type 1 and type 2 DM, whereas a low positive correlation was observed between potassium and serum thiamin levels in type 1 DM. However, there was no significant correlation concerning potassium levels in type 2 DM.

Release of Pro-Inflammatory/Angiogenic Factors by Retinal Microvascular Cells Is Mediated by Extracellular Vesicles Derived from M1-Activated Microglia

The interactions between the neuronal and vascular sides of the retina during diabetic retinopathy (DR) have gained increasing attention. Microglia is responsible for the immune response to inflammation inside the retina, which could be mediated by paracrine signals carried by extracellular vesicles (EVs). We aimed to characterize EVs released from immortalized human microglial cells in inflammation and investigate their effects on the retinal microvasculature and the anti-inflammatory potential of thiamine in this context. M1 pro-inflammatory polarization in microglia was induced through a cytokine cocktail. EVs were isolated from the supernatants, characterized, and used to stimulate human retinal endothelial cells (HRECs) and pericytes (HRPs). Microvascular cell functions and their release of pro-inflammatory/angiogenic factors were assessed. M1-derived EVs showed increased content of miR-21, miR-155, CCL2, MMP2, and MMP9, and enhanced apoptosis, proliferation, migration, and ROS production in HRPs and HRECs. IL-1β, IL-6, MMP9, CCL2, and VEGF release increased in HRPs exposed to M1-derived EVs, while HRECs showed augmented IL-6, Ang2, VEGF, and PDFG-B. Addition of thiamine to M1-microglial cultures reverted most of these effects. In conclusion, M1-derived EVs stimulate functional changes and secretion of pro-inflammatory/angiogenic molecules in microvascular cells, exacerbating inflammatory damage and retinopathy features. Thiamine added to microglia exerts anti-inflammatory effects.

Complementary Approaches to Retinal Health Focusing on Diabetic Retinopathy

Diabetes mellitus affects carbohydrate homeostasis but also influences fat and protein metabolism. Due to ophthalmic complications, it is a leading cause of blindness worldwide. The molecular pathology reveals that nuclear factor kappa B (NFκB) has a central role in the progression of diabetic retinopathy, sharing this signaling pathway with another major retinal disorder, glaucoma. Therefore, new therapeutic approaches can be elaborated to decelerate the ever-emerging "epidemics" of diabetic retinopathy and glaucoma targeting this critical node. In our review, we emphasize the role of an improvement of lifestyle in its prevention as well as the use of phytomedicals associated with evidence-based protocols. A balanced personalized therapy requires an integrative approach to be more successful for prevention and early treatment.

Thiamine and benfotiamine: Focus on their therapeutic potential

Thiamine, also known as vitamin B1, is an essential nutrient that plays a crucial role in energy metabolism and overall health. It is a water-soluble vitamin that plays an important role in the conversion of carbohydrates into energy in the body. Thiamine is essential for the proper functioning of the nervous system, heart and muscles. Thiamine deficiency is a life-threatening disease that leads to various disorders and lesions in the nerves and brain, at least in vertebrates. Several thiamine precursors with higher bioavailability have been developed to compensate for thiamine deficiency, including benfotiamine. Benfotiamine is more bioavailable and has higher tissue penetration than thiamine. Studies have shown its antioxidant and anti-inflammatory potential in activated immune and glial cells. It also improves complications observed in type 2 diabetes and has beneficial effects in mouse models of neurodegenerative disease. Benfotiamine represents an off-the-shelf agent used to support nerve health, promote healthy aging and support glucose metabolism. Accordingly, the present review aimed to provide an overview of the neuroprotective effects of thiamine/benfotiamine in the context of inflammation and oxidative stress.

Emerging Alzheimer's disease therapeutics: promising insights from lipid metabolism and microglia-focused interventions

More than 55 million people suffer from dementia, with this number projected to double every 20 years. In the United States, 1 in 3 aged individuals dies from Alzheimer's disease (AD) or another type of dementia and AD kills more individuals than breast cancer and prostate cancer combined. AD is a complex and multifactorial disease involving amyloid plaque and neurofibrillary tangle formation, glial cell dysfunction, and lipid droplet accumulation (among other pathologies), ultimately leading to neurodegeneration and neuronal death. Unfortunately, the current FDA-approved therapeutics do not reverse nor halt AD. While recently approved amyloid-targeting antibodies can slow AD progression to improve outcomes for some patients, they are associated with adverse side effects, may have a narrow therapeutic window, and are expensive. In this review, we evaluate current and emerging AD therapeutics in preclinical and clinical development and provide insight into emerging strategies that target brain lipid metabolism and microglial function - an approach that may synergistically target multiple mechanisms that drive AD neuropathogenesis. Overall, we evaluate whether these disease-modifying emerging therapeutics hold promise as interventions that may be able to reverse or halt AD progression.

Synthesis of fungal chitosan-polystyrene modified by nanoparticles of binary metals for the removal of heavy metals from waste aqueous media

The objective of this study was to assess the efficacy of fungal chitosan-polystyrene-Co-nanocomposites (FCPNC) as a material for the adsorptive removal of cadmium (Cd) ions from aqueous solutions. The synthesis and characterization of FCPNC were accomplished using various analytical techniques, including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, and dynamic light scattering (DLS). The effectiveness of this adsorbent in removing Cd(ii) species from solution matrices was systematically investigated, resulting in the achievement of a maximum adsorption capacity of approximately 112.36 mg g-1. This high adsorption capacity was detected using the following operational parameters: solution pH equals 5.0, 60 min as a contact time between the adsorbent and Cd(ii) solution, Cd initial concentration of 50 ppm, adsorbent dosage of 0.5 g L-1 and room temperature. The process of cadmium adsorption by FCPNC was found to follow the Langmuir isotherm model, suggesting that a chemical reaction occurs on the biosorbent surface. Kinetic studies have demonstrated that the cadmium removal process aligns well with the pseudo-second-order model. The thermodynamic analysis revealed the following values: ΔH° = 25.89 kJ mol-1, ΔG° = -21.58 kJ mol-1, and ΔS° = 159.30 J mol-1 K-1. These values indicate that the sorption process is endothermic, spontaneous, and feasible. These findings suggest the potential of FCPNC as an exceptionally effective biosorbent for the removal of water contaminants.

Extracellular thiamine concentration influences thermogenic competency of differentiating neck area-derived human adipocytes

Introduction

Brown adipose tissue (BAT) dissipates energy in the form of heat majorly via the mitochondrial uncoupling protein 1 (UCP1). The activation of BAT, which is enriched in the neck area and contains brown and beige adipocytes in humans, was considered as a potential therapeutic target to treat obesity. Therefore, finding novel agents that can stimulate the differentiation and recruitment of brown or beige thermogenic adipocytes are important subjects for investigation. The current study investigated how the availability of extracellular thiamine (vitamin B1), an essential cofactor of mitochondrial enzyme complexes that catalyze key steps in the catabolism of nutrients, affects the expression of thermogenic marker genes and proteins and subsequent functional parameters during ex vivo adipocyte differentiation.

Methods

We differentiated primary human adipogenic progenitors that were cultivated from subcutaneous (SC) or deep neck (DN) adipose tissues in the presence of gradually increasing thiamine concentrations during their 14-day differentiation program. mRNA and protein expression of thermogenic genes were analyzed by RT-qPCR and western blot, respectively. Cellular respiration including stimulated maximal and proton-leak respiration was measured by Seahorse analysis.

Results

Higher thiamine levels resulted in increased expression of thiamine transporter 1 and 2 both at mRNA and protein levels in human neck area-derived adipocytes. Gradually increasing concentrations of thiamine led to increased basal, cAMP-stimulated, and proton-leak respiration along with elevated mitochondrial biogenesis of the differentiated adipocytes. The extracellular thiamine availability during adipogenesis determined the expression levels of UCP1, PGC1a, CKMT2, and other browning-related genes and proteins in primary SC and DN-derived adipocytes in a concentration-dependent manner. Providing abundant amounts of thiamine further increased the thermogenic competency of the adipocytes.

Discussion

Case studies in humans reported that thiamine deficiency was found in patients with type 2 diabetes and obesity. Our study raises the possibility of a novel strategy with long-term thiamine supplementation, which can enhance the thermogenic competency of differentiating neck area-derived adipocytes for preventing or combating obesity.

Bacterial lipopolysaccharide inhibits colonic carrier-mediated uptake of thiamin pyrophosphate: roles for TLR4 receptor and NF-κB/P38/JNK signaling pathway

This study investigated the effect of the bacterial endotoxin lipopolysaccharide (LPS) on colonic uptake of thiamin pyrophosphate (TPP), the biologically active form of vitamin B1 that is generated by gut microbiota. We used three complementary models in our study: in vitro (human-derived colonic epithelial NCM460), ex vivo (human differentiated colonoid monolayers), and in vivo (mouse colonic tissue). The results showed that exposure of NCM460 cells to LPS leads to a significant inhibition of carrier-mediated TPP uptake as well as in decreased expression of the colonic TPP transporter (cTPPT) protein, mRNA, and heterologous nuclear RNA (hnRNA) compared with untreated controls. Similarly, exposure of human differentiated colonoid monolayers and mice to LPS caused significant inhibition in colonic carrier-mediated TPP uptake and in cTPPT protein, mRNA, and hnRNA expression. The effect of LPS on colonic TPP uptake and cTTPT expression was also found to be associated with a significant reduction in activity of the SLC44A4 promoter as well as in decreased expression of the nuclear factor Elf-3 (E74-like ETS transcription factor 3), which is needed for promoter activity. Finally, we found that knocking down the Toll-like receptor 4 (TLR4) and blocking the nuclear factor kappa B (NF-κB), JNK, and p38 signaling pathways with the use of pharmacological inhibitors lead to significant abrogation in the degree of LPS-mediated inhibition in TPP uptake and cTPPT expression. These results demonstrated that exposure of colonic epithelia to LPS inhibits colonic TPP uptake via transcriptional mechanism(s) and that the effect is mediated via TLR4 receptor and NF-κB/p38/JNK signaling pathways.NEW & NOTEWORTHY This study examined the effect of the bacterial lipopolysaccharide (LPS) on the colonic uptake of thiamin pyrophosphate (TPP), the biologically active form of vitamin B1. Three complementary models were used: in vitro (human NCM460 cells), ex vivo (human colonoids), and in vivo (mice). The results showed LPS to significantly suppress TPP uptake and the expression of its transporter, and that these effects are mediated via the membrane TLR4 receptor, and involve the NF-κB/p38/JNK signaling pathways.

Correlation of Fasting Blood Sugar and Glycated Hemoglobin (HbA1c) With Thiamine Levels in Diabetic Patients

Introduction It has been discovered that low levels of thiamine reserves in the body are related to diabetes mellitus (DM) because thiamine directly influences carbohydrate metabolism. Therefore, the purpose of this study was to assess several metabolic variables and blood thiamine levels in patients with type 1 and type 2 DM and compare them with those in a control group of healthy individuals. Methods This case-control study was conducted at multiple diabetic outpatient centers in Karachi. A total of 90 participants, who were divided into three groups, each containing 30 individuals, were chosen using a convenient non-probability sampling technique. Group A served as the control group and consisted of healthy, non-diabetic individuals. Groups B and C contained subjects with type 1 and type 2 DM, respectively. Descriptive analysis was reported as mean standard deviation, whereas gender and comorbidities were expressed as frequencies and percentages. The chi-square test and Pearson's correlation coefficient were used to determine the associations of the variables with type 1 DM, type 2 DM, and controls. Results The study results revealed statistically significant differences between controls, type 1 and type 2 DM, in the means of blood glucose levels and all lipid profiles, such as glycated hemoglobin (HbA1c), fasting blood sugar (FBS), random blood sugar (RBS), serum thiamine, triglycerides (p < 0.001), high-density lipoprotein (HDL) (p = 0.014), and total cholesterol (p = 0.013). Furthermore, it was shown that among the control group, type 1 and type 2 DM, HbA1c, and FBS were insignificantly correlated with thiamine levels, whereas the HbA1c and FBS of the combined diabetic groups were significantly correlated with the thiamine level (r = 0.465, p < 0.001) and (r = 0.360, p = 0.005), respectively, where 'r' is the Pearson correlation coefficient. Additionally, HbA1c and FBS in the combined three groups were significantly correlated with the thiamine level (r = -0.626, p < 0.001) and (r = -0.561, p < 0.001), respectively. Conclusion This study concluded that patients with type 1 and type 2 DM had significantly higher levels of FBS, RBS, HbA1c, triglycerides, and total cholesterol than controls. Furthermore, both type 1 and type 2 DM patients' serum thiamine and HDL levels were observed to be considerably lower than those of controls. Additionally, among both types of DM and controls, there was a strong correlation between FBS and HbA1c. Therefore, we recommend that serum thiamine levels be routinely monitored in diabetic patients, and thiamine supplementation should be considered to avoid complications, especially vascular complications of DM.

Synthetic Thioesters of Thiamine: Promising Tools for Slowing Progression of Neurodegenerative Diseases

Thiamine (vitamin B1) is essential for the brain. This is attributed to the coenzyme role of thiamine diphosphate (ThDP) in glucose and energy metabolism. The synthetic thiamine prodrug, the thioester benfotiamine (BFT), has been extensively studied and has beneficial effects both in rodent models of neurodegeneration and in human clinical studies. BFT has no known adverse effects and improves cognitive outcomes in patients with mild Alzheimer's disease. In cell culture and animal models, BFT has antioxidant and anti-inflammatory properties that seem to be mediated by a mechanism independent of the coenzyme function of ThDP. Recent in vitro studies show that another thiamine thioester, O,S-dibenzoylthiamine (DBT), is even more efficient than BFT, especially with respect to its anti-inflammatory potency, and is effective at lower concentrations. Thiamine thioesters have pleiotropic properties linked to an increase in circulating thiamine concentrations and possibly in hitherto unidentified open thiazole ring derivatives. The identification of the active neuroprotective metabolites and the clarification of their mechanism of action open extremely promising perspectives in the field of neurodegenerative, neurodevelopmental, and psychiatric conditions. The present review aims to summarize existing data on the neuroprotective effects of thiamine thioesters and give a comprehensive account.

Availability of abundant thiamine determines efficiency of thermogenic activation in human neck area derived adipocytes

Brown/beige adipocytes express uncoupling protein-1 (UCP1) that enables them to dissipate energy as heat. Systematic activation of this process can alleviate obesity. Human brown adipose tissues are interspersed in distinct anatomical regions including deep neck. We found that UCP1 enriched adipocytes differentiated from precursors of this depot highly expressed ThTr2 transporter of thiamine and consumed thiamine during thermogenic activation of these adipocytes by cAMP which mimics adrenergic stimulation. Inhibition of ThTr2 led to lower thiamine consumption with decreased proton leak respiration reflecting reduced uncoupling. In the absence of thiamine, cAMP-induced uncoupling was diminished but restored by thiamine addition reaching the highest levels at thiamine concentrations larger than present in human blood plasma. Thiamine is converted to thiamine pyrophosphate (TPP) in cells; the addition of TPP to permeabilized adipocytes increased uncoupling fueled by TPP-dependent pyruvate dehydrogenase. ThTr2 inhibition also hampered cAMP-dependent induction of UCP1, PGC1a, and other browning marker genes, and thermogenic induction of these genes was potentiated by thiamine in a concentration dependent manner. Our study reveals the importance of amply supplied thiamine during thermogenic activation in human adipocytes which provides TPP for TPP-dependent enzymes not fully saturated with this cofactor and by potentiating the induction of thermogenic genes.

Regulation of PKC/TLR-4/NF-kB signaling by sulbutiamine improves diabetic nephropathy in rats

One of the serious complications of diabetes mellitus is diabetic nephropathy (DN) which may finally lead to renal failure. The current study aimed to explore the effect of sulbutiamine, a synthetic derivative of vitamin B1, in streptozotocin (STZ)-induced DN and related pathways. Experimental DN was successfully induced 8 weeks after a single low dose of STZ (45 mg/kg, I.P.). Four groups of rats were used in this study and divided randomly into: control group, diabetic group, sulbutiamine control (control + sulbutiamine) group, and sulbutiamine-treated (60 mg/kg) (diabetic + sulbutiamine) group. The fasting blood glucose level (BGL) and the levels of kidney injury molecule-1 (Kim-1), urea, creatinine in serum, and the renal content of malondialdehyde (MDA), protein kinase C (PKC), toll-like receptor-4 (TLR-4) and nuclear factor kappa B (NF-κB) were determined. Additionally, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and transforming growth factor-β1 (TGF-β1) contents were evaluated immunohistochemically. Sulbutiamine treatment decreased fasting BGL and improved the kidney function tests compared to diabetic rats. Moreover, TLR-4, NF-κB, MDA and PKC contents were substantially reduced following sulbutiamine treatment compared to the diabetic group. Sulbutiamine managed to obstruct the production of the pro-inflammatory TNF-α and IL-1β and suppressed TGF-β1 level, in addition to attenuating the histopathological changes associated with DN. This study revealed, for the first time, the ability of sulbutiamine to ameliorate STZ-induced diabetic nephropathy in rats. This nephroprotective outcome of sulbutiamine against DN may be attributed to glycemic control in addition to its anti-oxidative, anti-inflammatory and anti-fibrotic effects.

Association between diabetes and thiamine status - A systematic review and meta-analysis

BACKGROUND

Thiamine (vitamin B1) is an essential cofactor in glucose metabolism, but it remains unclear whether thiamine status is lower in individuals with diabetes compared to individuals with normal glucose metabolism.

AIMS

We conducted a systematic review and meta-analysis to study whether the circulating concentrations of various thiamine analytes differ between people with and those without diabetes.

METHODS

PubMed and the Cochrane Central Register of Controlled Trials were searched according to the study protocol. The standardized mean difference (SMD) and 95 % confidence intervals (CI) of thiamine markers between individuals with and without diabetes were used as effect size (random effects model). Subgroup analysis considered albuminuria as an additional variable.

RESULTS

Out of the 459 articles identified, 24 full-texts were eligible for the systematic review, 20 of which qualified for the data analysis and four were evaluated for coherence. Compared to controls, individuals with diabetes showed lower concentrations of thiamine (pooled estimate SMD [95 % CI]: -0.97 [-1.89, -0.06]), thiamine monophosphate (-1.16 [-1.82, -0.50]), and total thiamine compounds (-1.01 [-1.48, -0.54]). Thiamine diphosphate (-0.72 [-1.54, 0.11] and erythrocyte transketolase activity (-0.42 [-0.90, 0.05]) tended to be lower in persons with diabetes than in controls without reaching statistical significance. Subgroup analysis showed that individuals with diabetes and albuminuria had lower thiamine levels than the controls (-2.68 [-5.34, -0.02]).

CONCLUSIONS

Diabetes is associated with lower levels of various thiamine markers, suggesting that individuals with diabetes may have higher thiamine requirements than those without diabetes, but well-designed studies are required to confirm these findings.

Human Milk Composition and Nutritional Status of Omnivore Human Milk Donors Compared with Vegetarian/Vegan Lactating Mothers

Women of childbearing age in Western societies are increasingly adopting vegetarian diets. These women are sometimes rejected as milk donors, but little about the composition of their milk is known. The present study aimed to compare the intake, nutritional status, and nutritional composition of human milk from omnivore human milk donors (Donors) and vegetarian/vegan lactating mothers (Veg). Milk, blood, and urine samples from 92 Donors and 20 Veg were used to determine their fatty acid profiles, as well as vitamins and minerals. In a representative sample of both groups, we also determined the lipid class profile as a distribution of neutral and polar lipids, the molecular species of triacylglycerols, and the relative composition of phospholipids in their milk. A dietary assessment was conducted with a five-day dietary record (while considering the intake of supplements). We highlight the following results, expressed as the mean (SE), for the Veg vs. Donors: (1) Their docosahexaenoic acid (DHA) intake was 0.11 (0.03) vs. 0.38 (0.03) g/day; the plasma DHA was 0.37 (0.07) vs. 0.83 (0.06)%; and the milk DHA was 0.15 (0.04) vs. 0.33 (0.02)%. (2) Their milk B12 levels were 545.69 (20.49) vs. 482.89 (4.11) pM; 85% of the Veg reported taking B12 supplements (mean dose: 312.1 mcg/day); and the Veg group showed no differences with Donors in terms of total daily intake or plasma B12. (3) Their milk phosphatidylcholine levels were 26.88 (0.67) vs. 30.55 (1.10)%. (4) Their milk iodine levels were 126.42 (13.37) vs. 159.22 (5.13) mcg/L. In conclusion, the Vegs' milk was shown to be different from the Donors' milk, mainly due to its low DHA content, which is concerning. However, raising awareness and ensuring proper supplementation could bridge this gap, as has already been achieved for cobalamin.

Physiological Associations between Vitamin B Deficiency and Diabetic Kidney Disease

The number of people living with chronic kidney disease (CKD) is growing as our global population continues to expand. With aging, diabetes, and cardiovascular disease being major harbingers of kidney disease, the number of people diagnosed with diabetic kidney disease (DKD) has grown concurrently. Poor clinical outcomes in DKD could be influenced by an array of factors-inadequate glycemic control, obesity, metabolic acidosis, anemia, cellular senescence, infection and inflammation, cognitive impairment, reduced physical exercise threshold, and, importantly, malnutrition contributing to protein-energy wasting, sarcopenia, and frailty. Amongst the various causes of malnutrition in DKD, the metabolic mechanisms of vitamin B (B1 (Thiamine), B2 (Riboflavin), B3 (Niacin/Nicotinamide), B5 (Pantothenic Acid), B6 (Pyridoxine), B8 (Biotin), B9 (Folate), and B12 (Cobalamin)) deficiency and its clinical impact has garnered greater scientific interest over the past decade. There remains extensive debate on the biochemical intricacies of vitamin B metabolic pathways and how their deficiencies may affect the development of CKD, diabetes, and subsequently DKD, and vice-versa. Our article provides a review of updated evidence on the biochemical and physiological properties of the vitamin B sub-forms in normal states, and how vitamin B deficiency and defects in their metabolic pathways may influence CKD/DKD pathophysiology, and in reverse how CKD/DKD progression may affect vitamin B metabolism. We hope our article increases awareness of vitamin B deficiency in DKD and the complex physiological associations that exist between vitamin B deficiency, diabetes, and CKD. Further research efforts are needed going forward to address the knowledge gaps on this topic.

Optimization of nucleic acid extraction and amplification of a thiamine biosynthesis gene fragment from selected Malaysian seaweeds

Obtaining high-quality nucleic acid extracted from seaweeds is notoriously difficult due to contamination with polysaccharides and polyphenolic compounds after cell disruption. Specific methods need to be employed for RNA isolation in different seaweed species, and therefore studies of the thiamine biosynthesis pathway have been limited. Two selected Malaysian species which are highly abundant and underutilized, namely Gracilaria sp. and Padina sp., representing the red and brown seaweeds, respectively, were collected to develop optimized total RNA extraction methods. Prior to that, DNA was extracted, and amplification of the 18S rRNA gene and the THIC gene (encoding the first enzyme in the pyrimidine branch of the thiamine biosynthesis pathway) from the DNA template was successful in Gracilaria sp. only. RNA was then extracted from both seaweeds using three different existing methods, with some modifications, using cetyltrimethylammonium bromide, guanidine thiocyanate and sodium dodecyl sulphate. Methods I and III proved to be efficient for Padina sp. and Gracilaria sp., respectively, for the extraction of highly purified RNA, with A₂₆₀/A₂₈₀ values of 2.0 and 1.8. However, amplification of the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase and the THIC gene was successful in only Gracilaria sp. cDNA derived from extracted RNA. Further modifications are required to improve the exploitation of nucleic acids from brown seaweeds, which has been proven to be difficult. This work should pave the way for molecular studies of seaweeds generally and for the elucidation, specifically, of the thiamine biosynthesis pathway.

Effects of Interaction between SLC35F3 and Carbohydrate Intake on the Incidence of Metabolic Syndrome in Korean Middle-Aged Adults

Solute carrier family 35 member F3 (SLC35F3) mediates intracellular thiamine transport, which is crucial for carbohydrate metabolism as thiamine is required for key pathways such as glycolysis and the tricarboxylic acid cycle. This study aimed to investigate the impact of the interaction between SLC35F3 and dietary carbohydrate intake on the incidence of metabolic syndrome (MetS). The study included 3923 Korean adults over 40 years of age from the Korean Genome and Epidemiology Study. The association between dietary carbohydrate intake, SLC35F3 rs10910387 genotypes, and MetS incidence was studied using multivariable Cox proportional hazard models. Over an average of 8.5 years of follow-ups, we documented 1471 MetS cases. MetS incidence was 1.88 times greater in men with the TT genotype and the highest carbohydrate intake than in those with the CC genotype and lowest carbohydrate intake (Hazard Ratio (HR) 1.88, 95% confidence interval (CI) 1.03-3.41). MetS incidence were 2.22 and 2.53 times higher in women with the TT genotype and carbohydrate intake tertile 2 and 3, respectively, than those with the CC genotype and carbohydrate intake tertile 1 (HR 2.22, 95% CI 1.12-4.42; HR 2.53, 95% CI 1.38-4.61). In summary, we report a novel interaction between SLC35F3 rs10910387 genotypes and dietary carbohydrate intake on MetS in Koreans.

U-shaped association between dietary thiamine intake and new-onset diabetes: a nationwide cohort study

BACKGROUND

The association between dietary thiamine intake and the risk of diabetes remains unknown.

AIM

We aimed to evaluate the relation of dietary thiamine intake with new-onset diabetes and examine possible effect modifiers.

DESIGN

Prospective cohort study.

METHODS

A total of 16 272 participants who were free of diabetes at baseline were enrolled from China Health and Nutrition Survey (CHNS). Dietary nutrients intake information was collected by 3-day dietary recalls in addition to using a 3-day food-weighed method to assess cooking oil and condiment consumption. New-onset diabetes was defined as a fasting blood glucose ≥7.0 mmol/l or a glycated haemoglobin (HbA1c) ≥6.5% (48 mmol/mol) or diagnosed by a physician during the follow-up.

RESULTS

During a median follow-up duration of 9.0 years, new-onset diabetes occurred in 1101 participants. Overall, the association between dietary thiamine intake and new-onset diabetes followed a U-shape (P for non-linearity <0.001). Consistently, when thiamine intake was assessed as quartiles, compared with those in the 2-3 quartiles (0.75 to 1.10 mg/day), the significantly higher risks of new-onset diabetes were found in participants in the first quartile [adjusted hazard ratio (HR), 1.33; 95% confidence interval (CI): 1.10, 1.61] and the fourth quartile (adjusted HR, 1.39; 95% CI: 1.17, 1.67). Similar results were found when further adjusting for the intake of other major nutrients or food groups; or using the propensity score weighting to control the imbalance of covariates.

CONCLUSION

Our results suggested that there was a U-shape association between dietary thiamine intake and new-onset diabetes in general Chinese adults, with a minimal risk at 0.75-1.10 mg/day.

The Association between Maternal B Vitamins in Early Pregnancy and Gestational Diabetes Mellitus: A Prospective Cohort Study

Background: This study evaluated the association between maternal B vitamins in early pregnancy and gestational diabetes mellitus (GDM) risk. Methods: A cohort of 1265 pregnant women was recruited at 8−15 weeks of gestation in 2021−2022 (Shanghai, China). Pregnancies with both serum B vitamin measurements at recruitment and glucose measurements at 24−28 weeks of gestation were included in the final analysis. Results: Of the 1065 pregnancies, in the final analysis, GDM occurred in 121 women (11.36%). In multivariate logistic models, an increased risk trend across serum vitamin B1 quartiles with GDM was observed (p-Trend = 0.001). Compared with women in the lowest quartile of serum vitamin B6, those in the upper two quartiles had approximately twofold higher odds of GDM. Moreover, compared with women with vitamin B12 levels < 150 pmol/L, those with vitamin B12 levels > 150 pmol/L had lower odds of GDM (p = 0.005). The restricted cubic spline regression models also revealed that serum vitamin B6 and vitamin B12 were associated with an increased risk of GDM in a nonlinear fashion. Conclusions: Our study shows that higher maternal serum vitamin B1 and B6 levels in early pregnancy are associated with increased GDM risk, while sufficient vitamin B12 status is associated with lower GDM risk.

A Clinician's View of Wernicke-Korsakoff Syndrome

The purpose of this article is to improve recognition and treatment of Wernicke-Korsakoff syndrome. It is well known that Korsakoff syndrome is a chronic amnesia resulting from unrecognized or undertreated Wernicke encephalopathy and is caused by thiamine (vitamin B1) deficiency. The clinical presentation of thiamine deficiency includes loss of appetite, dizziness, tachycardia, and urinary bladder retention. These symptoms can be attributed to anticholinergic autonomic dysfunction, as well as confusion or delirium, which is part of the classic triad of Wernicke encephalopathy. Severe concomitant infections including sepsis of unknown origin are common during the Wernicke phase. These infections can be prodromal signs of severe thiamine deficiency, as has been shown in select case descriptions which present infections and lactic acidosis. The clinical symptoms of Wernicke delirium commonly arise within a few days before or during hospitalization and may occur as part of a refeeding syndrome. Wernicke encephalopathy is mostly related to alcohol addiction, but can also occur in other conditions, such as bariatric surgery, hyperemesis gravidarum, and anorexia nervosa. Alcohol related Wernicke encephalopathy may be identified by the presence of a delirium in malnourished alcoholic patients who have trouble walking. The onset of non-alcohol-related Wernicke encephalopathy is often characterized by vomiting, weight loss, and symptoms such as visual complaints due to optic neuropathy in thiamine deficiency. Regarding thiamine therapy, patients with hypomagnesemia may fail to respond to thiamine. This may especially be the case in the context of alcohol withdrawal or in adverse side effects of proton pump inhibitors combined with diuretics. Clinician awareness of the clinical significance of Wernicke delirium, urinary bladder retention, comorbid infections, refeeding syndrome, and hypomagnesemia may contribute to the recognition and treatment of the Wernicke-Korsakoff syndrome.

Associations between Adherence to the Taiwan Dietary Reference Intakes of Micronutrients and the Risk of Type 2 Diabetes

The dietary reference intakes (DRIs) were established as guidance for the intake of micronutrients and other nutrients. However, how DRIs affect disease status has not been thoroughly examined. The aim of this study is to examine the associations between adherence to the DRIs of selected micronutrients and type 2 diabetes. A populational and cross-sectional study was conducted using data from the Nutrition and Health Survey in Taiwan (NAHSIT) 2013-2016. A total of 14 nutrient intakes, including those for vitamin A, C, D, E, B1, B2, B3, B6, B12, iron, magnesium, zinc, calcium, and phosphorus, were evaluated using the 24 h dietary recall method. Type 2 diabetes was defined as a fasting serum HbA1c level of 6.5% or higher and excluded participants who had received treatments for type 2 diabetes or reported a diagnosis of type 2 diabetes by physicians to avoid the possible inverse association. A total of 2685 participants aged 19 and above were included in the final analysis. After adjusting for confounders, we found that adherence to the DRI of vitamin A was associated with a reduced risk of type 2 diabetes among men. The odds ratio (OR) was 0.64 (95% confidence interval (CI) = 0.42-0.99) compared with men who did not adhere to the DRI. As for women, we found that adherence to the DRI of vitamin B1 was associated with a reduced risk of type 2 diabetes. The OR was 0.59 (95% CI = 0.35-0.97) compared with that for women who did not adhere to the DRI. This study showed that adherence to Taiwan DRIs of vitamin A for men and vitamin B1 for women might have beneficial effects on type 2 diabetes.

Effect of thiamine supplementation on glycaemic outcomes in adults with type 2 diabetes: a systematic review and meta-analysis

BACKGROUND

Patients with type 2 diabetes mellitus (T2DM) have been shown to have thiamine deficiency. Dietary supplementation is an economic strategy to control blood glucose. Objective: To evaluate effectiveness of thiamine supplementation on glycaemic outcomes in patients with T2DM.

METHODS

Eligibility criteria: Studies that assessed effect of thiamine supplementation in adults with T2DM which measured glycaemic outcomes-HbA1c, fasting blood glucose (FBG) and/or postprandial blood glucose (PPG) were included. Information sources: PUBMED, Tripdatabase, the Cochrane Central Register, National Institute of Health Clinical Database and Google Scholar were searched until December 2021 for RCTs. Risk of bias: It was assessed using standardised critical appraisal instruments from the Joanna Briggs Institute for RCTs. Synthesis of results: Where possible, studies were pooled in a meta-analysis. Results were presented in a narrative format if statistical pooling was not possible.

RESULTS

Included studies: Six trials involving 364 participants. Synthesis of results: No significant beneficial effects were observed on glycaemic outcomes with 100-900 mg/day of thiamine or benfotiamine for up to 3 months (HbA1c: MD, -0.02%, 95% CI: -0.35 to 0.31; FBG: MD,-0.20 mmol/L; 95% CI: -0.69 to 0.29; PPG: MD, - 0.20 mmol/L, 95% CI: -2.05 to 1.65 (mean difference, MD)). There was a significant increase in high-density lipoprotein (HDL) (MD, 0.10; 95% CI: 0.10 to 0.20) at 3-month follow-up. Benfotiamine reduced triglyceride level (MD, -1.10; 95% CI: -1.90 to -0.30) in 120 mg/day dose as compared with placebo 150 mg/day, however this was not demonstrated in higher doses.

DISCUSSION

Limitations of evidence: Inclusion of single-centre trials published only in English, small sample sizes of included studies, lack of trials investigating outcomes for same comparisons and varying follow-up periods. Interpretation: Thiamine supplementation does not affect glycaemic outcomes, however reduces triglycerides while increasing HDL. Multicentre well-designed RCT with higher doses of thiamine and a follow-up period of 1-2 years will provide better evidence.

PROSPERO REGISTRATION NUMBER

CRD42020170520.

The role of pancreas to improve hyperglycemia in STZ-induced diabetic rats by thiamine disulfide

Background

The present study investigated the effect of thiamine disulfide (TD) on the pancreas in terms of hyperglycemia improvement and insulin sensitivity increase in diabetic male rats. We also aimed to study the function of Pdx1 (pancreatic and duodenal homeobox 1) and Glut2 (glucose transporter 2) genes in pancreatic tissue.

Methods

Type 1 diabetes was induced through injection of 60 mg/kg streptozotocin (STZ). The diabetic rats were divided into four groups, namely diabetic control (DC), diabetic treated with thiamine disulfide (D-TD), diabetic treated with insulin (D-insulin), and diabetic treated with TD and insulin (D-insulin+TD). The non-diabetic (NDC) and diabetic groups received a normal diet (14 weeks). Blood glucose level and body weight were measured weekly; insulin tolerance test (ITT) and glucagon tolerance test (GTT) were performed in the last month of the study. The level of serum insulin and glucagon were measured monthly and a hyperglycemic clamp (Insulin Infusion rate (IIR)) was done for all the groups. Pancreas tissue was isolated so that Pdx1and Glut2 genes expression could be measured.

Results

We observed that TD therapy decreased blood glucose level, ITT, and serum glucagon levels in comparison with those of the DC group; it also increased serum insulin levels, IIR, and expression of Pdx1 and Glut2 genes in comparison with those of the DC group.

Conclusion

Administration of TD could improve hyperglycemia in type 1 diabetic animals through improved pancreas function. Therefore, not only does TD have a significant effect on controlling and reducing hyperglycemia in diabetes, but it also has the potential to decrease the dose of insulin administration.

Associations of dietary intakes of vitamins B1 and B3 with risk of mortality from CVD among Japanese men and women: the Japan Collaborative Cohort study

The evidence on the association between B vitamins and the risk of CVD is inconclusive. We aimed to examine the association of dietary vitamins B1 and B3 intakes with risk of CVD mortality among 58 302 Japanese men and women aged 40-79 years participated in the Japan Collaborative Cohort (JACC) study. The Cox proportional hazard model estimated the hazard ratios (HR) and 95% CI of CVD mortality across increasing energy-adjusted quintiles of dietary vitamins B1 and B3 intakes. During 960 225 person-years of follow-up, we documented a total of 3371 CVD deaths. After adjustment for age, sex, and other CVD risk factors, HR of mortality from ischemic heart disease, myocardial infarction, and heart failure in the highest v. lowest vitamin B1 intake quintiles were 0.57 (95 % CI 0·40, 0·80; Pfor trend < 0·01), 0.56 (95 % CI 0·37, 0·82; Pfor trend < 0·01), and 0.65 (95 % CI 0·45, 0·96; Pfor trend = 0·13). The multivariable HR of myocardial infarction mortality in the highest v. lowest vitamin B3 intake quintiles was 0.66 (95 % CI 0·48, 0·90; Pfor trend = 0·02). Atendency towards a reduced risk of haemorrhagic stroke mortality was observed with a higher dietary intake of vitamin B3 (HR: 0·74 (95 % CI 0·55, 1·01)) but not vitamin B1. In conclusion, higher dietary intakes of vitamins B1 and B3 were inversely associated with mortality from ischemic heart disease and a higher dietary intake of vitamin B1 was inversely associated with a reduced risk of mortality from heart failure among Japanese men and women.

Screening, diagnosis and management of diabetic sensorimotor polyneuropathy in clinical practice: International expert consensus recommendations

Diabetic sensorimotor polyneuropathy (DSPN) affects around one third of people with diabetes and accounts for considerable morbidity, increased risk of mortality, reduced quality of life, and increased health care costs resulting particularly from neuropathic pain and foot ulcers. Painful DSPN is encountered in 13-26% of diabetes patients, while up to 50% of patients with DSPN may be asymptomatic. Unfortunately, DSPN still remains inadequately diagnosed and treated. Herein we provide international expert consensus recommendations and algorithms for screening, diagnosis, and treatment of DSPN in clinical practice derived from a Delphi process. Typical neuropathic symptoms include pain, paresthesias, and numbness particularly in the feet and calves. Clinical diagnosis of DSPN is based on neuropathic symptoms and signs (deficits). Management of DSPN includes three cornerstones: (1) lifestyle modification, optimal diabetes treatment aimed at near-normoglycemia, and multifactorial cardiovascular risk intervention, (2) pathogenetically oriented pharmacotherapy (e.g. α-lipoic acid and benfotiamine), and (3) symptomatic treatment of neuropathic pain including analgesic pharmacotherapy (antidepressants, anticonvulsants, opioids, capsaicin 8% patch and combinations, if required) and non-pharmacological options. Considering the individual risk profile, pain management should not only aim at pain relief, but also allow for improvement in quality of sleep, functionality, and general quality of life.

Association Between Blood Biochemical Factors Contributing to Cognitive Decline and B Vitamins in Patients With Alzheimer's Disease

Background

Malnutrition, metabolism stress, inflammation, peripheral organs dysfunction, and B vitamins deficiency significantly contribute to the progression and mortality of Alzheimer's disease (AD). However, it is unclear which blood biochemical indicators are most closely related to cognitive decline and B vitamins deficiency (thiamine, folate, vitamin B12) in patients with AD.

Methods

This was a cross-sectional study of 206 AD patients recruited from six hospitals in China. Thiamine diphosphate (TDP), the bioactive form of thiamine, was measured by high-performance liquid chromatography fluoroscopy (HPLC) at a single center. Levels of biochemical indicators (except TDP) were measured by regular and standard laboratory tests in each hospital. Pearson's rank correlation analysis was used to assess relationships between B vitamins and biochemical indicators. T-test was used to compare the difference between ApoE ε4 and non-ApoE ε4 groups. Differences were considered statistically significant as P < 0.05.

Results

Among the biochemical results, in AD population, malnutrition indicators (erythrocyte, hemoglobin, serum albumin, and total protein) were most significantly associated with cognitive function, as was free triiodothyronine (FT3) levels which had been observed in previous study. Malnutrition and FT3 levels depend on age but not apolipoprotein E (ApoE) genotype. Meanwhile, Among the B vitamins, TDP was the most significantly associated with malnutrition indicators and FT3.

Conclusion

Our results indicated that TDP reduction could be a modifiable risk factor for malnutrition and FT3 that contributed to cognitive decline in AD patients. Correcting thiamine metabolism could serve as an optional therapy target for AD treatment.

A case of Wernicke encephalopathy in a dementia caregiver: The need for nutritional evaluation in family caregivers

A 63-year-old woman had started caring for her mother with dementia 6 months previously. A loss of appetite had appeared 2 months prior to her visit. Neurologically, she experienced mild unsteadiness, but she was fully conscious and had no ocular symptoms. MRI examination of her head did not reveal any notable findings. From these symptoms, the possibility of thiamine deficiency was considered, and her unsteadiness disappeared within a few days after an intravenous injection of thiamine. The burden of caring for a dementia patient may affect the nutritional status of the family caregiver.

An increased intake of thiamine diminishes the risk of metabolic syndrome in the Korean population with various comorbidities

BACKGROUND AND AIMS

There is growing evidence that thiamine supplementation could reverse non-communicable diseases such as diabetes and cardiovascular diseases. However, the role of thiamine in metabolic syndrome (MetS) remains unclear. We hypothesized whether an increased intake of thiamine diminishes the risk of MetS in the Korean population with various comorbidities. This study aimed to assess the association between thiamine intake and MetS among adults with comorbidities.

METHODS

57,523 eligible participants aged over 18 years between 2009 and 2019 were recruited to obtain data on sociodemographic characteristics, medical history, current medications, lifestyle, and family history. A 24-h recall was used to determine thiamine intake. Odds ratio (OR) for MetS was calculated for log2-transformed thiamine intake values, subsequently predicting the risk of MetS based on the marginal effect.

RESULTS

The risk of MetS was significantly higher in subjects with comorbidities than in those without comorbidities. A doubling of daily thiamine intake was significantly associated with a decrease in MetS among adults with comorbidities by 7% (OR 0.93; 95%CI 0.89-0.97).

CONCLUSIONS

The potential health benefits result from the intake of thiamine through an ordinary diet in the clinical management of MetS. Therefore, there is an ongoing need to look into these links between thiamine supplementation and MetS in well-characterized cohorts of participants with comorbidities.

Gut microbiota and vitamin status in persons with obesity: A key interplay

There are numerous factors involved in obesity progression and maintenance including systemic low-grade inflammation, adipose tissue dysfunction, or gut microbiota dysbiosis. Recently, a growing interest has arisen for vitamins' role in obesity and related disorders, both at the host and gut bacterial level. Indeed, vitamins are provided mostly by food, but some, from the B and K groups in particular, can be synthesized by the gut bacterial ecosystem and absorbed in the colon. Knowing that vitamin deficiency can alter many important cellular functions and lead to serious health issues, it is important to carefully monitor the vitamin status of patients with obesity and potentially already existing comorbidities as well as to examine the dysbiotic gut microbiota and thus potentially altered bacterial metabolism of vitamins. In this review, we examined both murine and human studies, to assess the prevalence of sub-optimal levels of several vitamins in obesity and metabolic alterations. This review also examines the relationship between vitamins and the gut microbiota in terms of vitamin production and the modulation of the gut bacterial ecosystem in conditions of vitamin shortage or supplementation. Furthermore, some strategies to improve vitamin status of patients with severe obesity are proposed within this review.

Synthesis, physico-chemical properties and effect of adenosine thiamine triphosphate on vitamin B1 metabolism in the liver of alloxan diabetic rats

BACKGROUND

Adenosine thiamine triphosphate (AThTP) is a nucleotide discovered in bacteria and some other living organisms more than a decade ago. No biochemical function for AThTP has been established yet, however, experimental data available indicate its possible involvement in metabolic regulation or cell signaling. Metabolism of AThTP in mammals, as well as the feasibility of its pharmacological application, is essentially unstudied.

METHODS

Preparative low-pressure chromatography was employed to purify chemically synthesized AThTP with its further analysis by mass spectrometry, HPLC, UV and fluorescence spectroscopy. Enzyme activity assays along with HPLC were used to examine the effects of AThTP and thiamine on vitamin B₁ metabolism in the liver of alloxan-induced diabetic rats.

RESULTS

An improved procedure for AThTP synthesis and purification is elaborated. Solution stability, optical spectral properties and the molar absorption coefficient for AThTP were determined. The levels of thiamine compounds were found to be increased in the liver of diabetic rats. Neither AThTP nor thiamine treatment affected hepatic vitamin B₁ metabolism. Fasting blood glucose concentration was also unchangeable after AThTP or thiamine administration.

GENERAL SIGNIFICANCE

Contrast to the widespread view about thiamine deficiency in diabetes, our results clearly shows an adaptive increase in the level of B₁ vitamers in the liver of alloxan diabetic rats with no further rising after AThTP or thiamine treatment at a moderate dose. Neither AThTP nor thiamine is effective in glycaemic control. These findings are to be considered in future studies dealing with thiamine or its analogues application to correct metabolic disturbances in diabetes.

Diagnostic Tools, Biomarkers, and Treatments in Diabetic polyneuropathy and Cardiovascular Autonomic Neuropathy

The various manifestations of diabetic neuropathy, including distal symmetric sensorimotor polyneuropathy (DSPN) and cardiovascular autonomic neuropathy (CAN), are among the most prevalent chronic complications of diabetes. Major clinical complications of diabetic neuropathies, such as neuropathic pain, chronic foot ulcers, and orthostatic hypotension, are associated with considerable morbidity, increased mortality, and diminished quality of life. Despite the substantial individual and socioeconomic burden, the strategies to diagnose and treat diabetic neuropathies remain insufficient. This review provides an overview of the current clinical aspects and recent advances in exploring local and systemic biomarkers of both DSPN and CAN assessed in human studies (such as biomarkers of inflammation and oxidative stress) for better understanding of the underlying pathophysiology and for improving early detection. Current therapeutic options for DSPN are (I) causal treatment, including lifestyle modification, optimal glycemic control, and multifactorial risk intervention, (II) pharmacotherapy derived from pathogenetic concepts, and (III) analgesic treatment against neuropathic pain. Recent advances in each category are discussed, including non-pharmacological approaches, such as electrical stimulation. Finally, the current therapeutic options for cardiovascular autonomic complications are provided. These insights should contribute to a broader understanding of the various manifestations of diabetic neuropathies from both the research and clinical perspectives.

Case Report: Severe Edema and Marked Weight Gain Induced by Marginal Thiamine Deficiency in a Patient With Alcohol Dependency and Type 2 Diabetes Mellitus

Background: Patients with alcohol use disorder (AUD) may develop peripheral edema due to alcohol-related liver, renal, or heart disease. Thiamine deficiency is reported to occur in AUD and type 2 diabetes mellitus (T2DM). Thiamine deficiency may also cause peripheral edema. Thiamine is essential for optimal glucose metabolism through its role as an essential co-factor for key enzymes in intermediary metabolism. Since glucose metabolism worsens under diabetic conditions, it seems that a relative shortage of thiamine may occur more easily in patients with diabetes mellitus.

Case Presentation: A 59-year-old Japanese man was admitted to the hospital with severe peripheral edema. His background history included alcohol liver disease (ALD), chronic renal failure (CRF), and T2DM. His body mass index (BMI) at admission was 37.7 kg/m² and this represented a 30 kg increase in body weight over 2 months. Laboratory investigations showed anemia, liver and renal injury, hyperglycemia, and marginal hypothyroidism. The plasma thiamine diphosphate concentration was 20 ng/mL (reference range: 24–66 ng/mL). Diet therapy of 1,600 kcal/day and intravenous fursultiamine hydrochloride therapy (50 mg/once a day, seven days) was commenced in combination with intravenous diuretics. After one week, the plasma thiamine concentration was 853 ng/mL, and the patient's body weight had reduced by 18 kg.

Conclusions: Patients with T2DM and AUD may develop severe peripheral edema in the context of marginal thiamine deficiency. Fursultiamine hydrochloride (50 mg/once a day, seven days) restored normal plasma thiamine concentrations and may have contributed to the rapid resolution of severe peripheral edema in this case. Empirical treatment with thiamine should be considered in patients with severe peripheral edema in the context of AUD and T2DM.

Thiamine and diabetes: back to the future?

The first reports of a link between thiamine and diabetes date back to the 1940s. Some years later, a role for thiamine deficiency in diabetic neuropathy became evident, and some pilot studies evaluated the putative effects of thiamine supplementation. However, the administration of thiamine and its lipophilic derivative benfotiamine for the treatment of this complication gained consensus only at the end of the '90 s. The first evidence of the beneficial effects of thiamine on microvascular cells involved in diabetic complications dates to 1996: from then on, several papers based on in vitro and animal models have addressed the potential use of this vitamin in counteracting diabetic microangiopathy. A few pilot studies in humans reported beneficial effects of thiamine administration on diabetic nephropathy, but, despite all promising proofs-of-concept, the possible role of thiamine in counteracting development or progression of retinopathy has not been addressed until now. Thiamine is a water-soluble vitamin, rapidly expelled from the body, with no issues of over-dosage or accumulation; unfortunately, it is non-patentable, and neither industry nor independent donors are interested in investing in large-scale randomized controlled clinical trials to investigate its potential in diabetes and its complications. Consequently, science will not be able to disprove a promising hypothesis and, more importantly, diabetic people remain deprived of a possible way to ameliorate their condition.

Hiding in Plain Sight: Modern Thiamine Deficiency

Thiamine or vitamin B1 is an essential, water-soluble vitamin required for mitochondrial energetics—the production of adenosine triphosphate (ATP). It is a critical and rate-limiting cofactor to multiple enzymes involved in this process, including those at the entry points and at critical junctures for the glucose, fatty acid, and amino acid pathways. It has a very short half-life, limited storage capacity, and is susceptible to degradation and depletion by a number of products that epitomize modern life, including environmental and pharmaceutical chemicals. The RDA for thiamine is 1.1–1.2 mg for adult females and males, respectively. With an average diet, even a poor one, it is not difficult to meet that daily requirement, and yet, measurable thiamine deficiency has been observed across multiple patient populations with incidence rates ranging from 20% to over 90% depending upon the study. This suggests that the RDA requirement may be insufficient to meet the demands of modern living. Inasmuch as thiamine deficiency syndromes pose great risk of chronic morbidity, and if left untreated, mortality, a more comprehensive understanding thiamine chemistry, relative to energy production, modern living, and disease, may prove useful.

Pediatric thiamine deficiency disorders in high-income countries between 2000 and 2020: a clinical reappraisal

Often thought to be a nutritional issue limited to low- and middle-income countries (LMICs), pediatric thiamine deficiency (PTD) is perceived as being eradicated or anecdotal in high-income countries (HICs). In HICs, classic beriberi cases in breastfed infants by thiamine-deficient mothers living in disadvantaged socioeconomic conditions are thought to be rare. This study aims to assess PTD in HICs in the 21st century. Literature searches were conducted to identify case reports of PTD observed in HICs and published between 2000 and 2020. The analyzed variables were age, country, underlying conditions, clinical manifestations of PTD, and response to thiamine supplementation. One hundred and ten articles were identified, totaling 389 PTD cases that were classified into four age groups: neonates, infants, children, and adolescents. Eleven categories of PTD-predisposing factors were identified, including genetic causes, lifestyle (diabetes, obesity, and excessive consumption of sweetened beverages), eating disorders, cancer, gastrointestinal disorders/surgeries, critical illness, and artificial nutrition. TD-associated hyperlactatemia and Wernicke encephalopathy were the most frequent clinical manifestations. The circumstances surrounding PTD in HICs differ from classic PTD observed in LMICs and this study delineates its mutiple predisposing factors. Further studies are required to estimate its magnitude. Awareness is of utmost importance in clinical practice.

The role of biofactors in the prevention and treatment of age-related diseases

The present demographic changes toward an aging society caused a rise in the number of senior citizens and the incidence and burden of age-related diseases (such as cardiovascular diseases [CVD], cancer, nonalcoholic fatty liver disease [NAFLD], diabetes mellitus, and dementia), of which nearly half is attributable to the population ≥60 years of age. Deficiencies in individual nutrients have been associated with increased risks for age-related diseases and high intakes and/or blood concentrations with risk reduction. Nutrition in general and the dietary intake of essential and nonessential biofactors is a major determinant of human health, the risk to develop age-related diseases, and ultimately of mortality in the older population. These biofactors can be a cost-effective strategy to prevent or, in some cases, even treat age-related diseases. Examples reviewed herein include omega-3 fatty acids and dietary fiber for the prevention of CVD, α-tocopherol (vitamin E) for the treatment of biopsy-proven nonalcoholic steatohepatitis, vitamin D for the prevention of neurodegenerative diseases, thiamine and α-lipoic acid for the treatment of diabetic neuropathy, and the role of folate in cancer epigenetics. This list of potentially helpful biofactors in the prevention and treatment of age-related diseases, however, is not exhaustive and many more examples exist. Furthermore, since there is currently no generally accepted definition of the term biofactors, we here propose a definition that, when adopted by scientists, will enable a harmonization and consistent use of the term in the scientific literature.

Effects of Antioxidant Vitamins, Curry Consumption, and Heavy Metal Levels on Metabolic Syndrome with Comorbidities: A Korean Community-Based Cross-Sectional Study

The burden of metabolic syndrome (MetS) has increased worldwide, especially during the COVID-19 pandemic, and this phenomenon is related to environmental, dietary, and lifestyle risk factors. We aimed to determine the association between the levels of serum heavy metals, hs-CRP, vitamins, and curry intake and to predict risks of MetS based on marginal effects. A data set of 60,256 Koreans aged ≥ 15 years between 2009 and 2017 was used to obtain information on sociodemographic, lifestyle, family history characteristics, MetS, food intake survey, and serum heavy metals. Daily intake of vitamins was measured by a one-day 24 h recall, and curry consumption was calculated using a food frequency questionnaire. Serum heavy metal levels were quantified by graphite furnace atomic absorption spectrometry and using a mercury analyzer. We found that vitamin B1, B2, B3, C, and A intakes were significantly lower in subjects with than without MetS. In contrast, serum levels of Pb, Hg, Cd, vitamin A, E, and hs-CRP were significantly higher in subjects with MetS. The risk of MetS was significantly lower for high curry consumers than low curry consumers (adjusted odds ratio 0.85, 95%CI 0.74-0.98). The risks of MetS were reduced by 12% and 1%, when vitamin B1 and C intakes increased by one mg, respectively, but were increased by 14%, 3%, and 9%, when serum levels of Pb, Hg, and hs-CRP increased by one unit. These results show that the potential health benefits resulting from vitamin and curry intakes could protect the public against the dual burden of communicable and non-communicable diseases. Further studies are required to reduce risk factors associated with serum heavy metal levels and to determine whether interactions between vitamin and curry consumption influence the presence of MetS.

Insight into the In Vitro Antiglycation and In Vivo Antidiabetic Effects of Thiamine: Implications of Vitamin B1 in Controlling Diabetes

Hyperglycemia is considered to be a driving factor for advanced glycated end products (AGEs) formation. Inhibition of this process plays a vital role in reducing the problems of diabetes. This study aimed to explore the in vitro antiglycation and in vivo antidiabetic effect of thiamine. Human serum albumin (HSA) was used as a model protein to delineate the antiglycation potential of thiamine. Fructosamine levels were low in the presence of thiamine, implying the inhibition of early stages of glycation by thiamine. Furthermore, HSA-glucose assays depict the inhibition of post-Amadori products by thiamine. CD spectroscopy suggested fewer alterations in the secondary structure in the presence of thiamine. It was found that the administration of thiamine to diabetic rats leads to an increase in hexokinase activity and increased insulin secretion coupled with glycolysis utilization of glucose. Moreover, the activity of glucose-6-phosphatase and fructose- 1-6-phosphatase (increased in the liver and kidney of diabetic rats) is restored to near-normal levels upon thiamine administration. Histopathological studies also advocated that thiamine supplementation decreases the pathological abnormalities associated with diabetes in the liver and kidney. This study provides a rationale that vitamins can be implicated in controlling diabetes.

Developmental maturation of the colonic uptake process of the microbiota-generated thiamin pyrophosphate

The water-soluble vitamin B1 is essential for normal human health and physiology. In its main biologically active form, i.e., thiamin pyrophosphate (TPP), the vitamin plays many critical roles in cell metabolism; thus, its deficiency leads to a variety of adverse effects. Humans/mammals obtain vitamin B1 from two exogenous sources: diet and gut microbiota. Considerable amount of the microbiota-generated vitamin B1 exists in the form of TPP, and colonocytes can efficiently absorb this TPP via a high-affinity and specific carrier-mediated mechanism that involves the recently cloned colonic TPP transporter (cTPPT; product of SLC44A4 gene). There is nothing currently known about colonic uptake of TPP during early stages of life and whether the process undergoes developmental regulation. We addressed this issue using the mouse as animal model. Our results showed that colonic uptake of TPP undergoes developmental upregulation as the animal moves from the suckling period to weanling and adulthood. This upregulation in uptake was found to be associated with a parallel induction in level of expression of the cTPPT protein, mRNA, and heterogeneous nuclear RNA, suggesting possible involvement of transcriptional mechanism(s). We also found a parallel upregulation in the level of expression of the two nuclear factors that drive activity of the SLC44A4 promoter (i.e., CREB-1 and Elf-3) with maturation. These results demonstrate, for the first time, to our knowledge, that colonic TPP uptake process and cTPPT expression are developmentally upregulated and that this upregulation is likely driven via transcriptional mechanism(s).NEW & NOTEWORTHY The colonic carrier-mediated uptake process of the microbiota-generated and phosphorylated form of vitamin B1, i.e., thiamin pyrophosphate, undergoes ontogenic changes that parallel the development of the gut microbiota (and their ability to generate vitamins) during early stages of life.

Association between levels of thiamine intake, diabetes, cardiovascular diseases and depression in Korea: a national cross-sectional study

The present study aimed to determine thiamine intake levels and the association between thiamine intake, diabetes, cardiovascular diseases and mental health. Participants were interviewed to obtain data on socio-demographic characteristics, lifestyle, current medications, medical and family history. The daily intake of thiamine was assessed by a 24-h recall. The mean age of the 34 700 study subjects was 42⋅9 years (sd 22⋅8, min-max: 1-80) and 19 342 (55⋅7 %) were women. The levels of thiamine intake were 1⋅126 mg (2016), 1⋅115 mg (2017) and 1⋅087 mg (2018) for women, which were equal to or only slightly above the recommended intake of 1⋅10 mg/d for women. The levels of thiamine intake from 2014-15 and 2016-18 significantly decreased. The estimated percentage of insufficient thiamine intake was 37⋅8 % (95 % CI 37⋅3, 38⋅4). Multivariable regression analysis adjusted for potential confounders showed that thiamine intake was critically associated with lower risks of hypertension, MI or angina, type 2 diabetes, depression and dyslipidemia. The daily thiamine intake from food can reversal the risks of hypertension (OR 0⋅95; 95 % CI 0⋅90, 0⋅99), MI or angina (OR 0⋅84; 95 % CI 0⋅74, 0⋅95), type 2 diabetes (OR 0⋅86; 95 % CI 0⋅81, 0⋅93), depression (OR 0⋅90; 95 % CI 0⋅83, 0⋅97) and dyslipidemia (OR 0⋅90; 95 % CI 0⋅86, 0⋅95), respectively. Further works are needed to identify the effects of thiamine and non-communicable diseases (NCDs) and mental health. A preventive thiamine supplementation strategy should be adopted to target NCDs and mental health and risk factors associated with thiamine deficiency. The optimisation of NCD control and mental health protection is also a vital integral part of Korea's public health system.

Reduced Thiamine Availability and Hyperglycemia Impair Thiamine Transport in Renal Glomerular Cells through Modulation of Thiamine Transporter 2

Thiamine helps transketolase in removing toxic metabolites, counteracting high glucose-induced damage in microvascular cells, and progression of diabetic retinopathy/nephropathy in diabetic animals. Diabetic subjects show reduced thiamine levels. Hyperglycemia and reduced thiamine availability concur in impairing thiamine transport inside the blood-retinal barrier, with thiamine transporter-2 (THTR2) primarily involved. Here, we examined the behavior of thiamine transporter-1 (THTR1), THTR2, and their transcription factor Sp1 in response to high glucose and altered thiamine availability in renal cells involved in diabetic nephropathy. Human proximal tubule epithelial cells, podocytes, glomerular endothelial, and mesangial cells were exposed to high glucose and/or thiamine deficiency/oversupplementation. Localization and modulation of THTR1, THTR2, and Sp1; intracellular thiamine; transketolase activity; and permeability to thiamine were examined. Reduced thiamine availability and hyperglycemia impaired thiamine transport and THTR2/Sp1 expression. Intracellular thiamine, transketolase activity, and permeability were strongly dependent on thiamine concentrations and, partly, excess glucose. Glomerular endothelial cells were the most affected by the microenvironmental conditions. Our results confirmed the primary role of THTR2 in altered thiamine transport in cells involved in diabetic microvascular complications. Lack of thiamine concurs with hyperglycemia in impairing thiamine transport. Thiamine supplementation could represent a therapeutic option to prevent or slow the progression of these complications.

Gut microbiota compositions and metabolic functions in type 2 diabetes differ with glycemic durability to metformin monotherapy

AIMS

The metabolic derangements in type 2 diabetes have been attributed to compositional changes in the gut microbiota. Metformin, the first-line treatment for type 2 diabetes, has been found to modulate the gut microbiota. However, no literature has reported the associations between the composition of the gut microbiota and glycemic durability to metformin monotherapy.

METHODS

A total of 375 patients with type 2 diabetes were recruited, among which 14 and 11 patients were eligible as the metformin durable group and nondurable group, respectively. Fecal samples were collected to analyze the gut microbiota by Illumina sequencing of the 16S rRNA gene, and PICRUSt2 was adopted to infer microbial functional differences.

RESULTS

Although the two groups had similar biochemical profiles and microbial metabolites, the pattern of microbiota clustering was different. The intra-group diversity was significantly reduced in the durable group. For the microbial metabolic pathways, the biosynthesis of thiamine and lipopolysaccharide was dominant in the durable group.

CONCLUSIONS

There were different compositions of gut microbiota with unique microbial metabolic pathways between type 2 diabetes with and without glycemic durability to metformin monotherapy. Microbial salvage by increasing thiamine biosynthesis might be beneficial for the metformin durable group to maintain optimal glycemic control.

High-dose vitamin B1 therapy prevents the development of experimental fatty liver driven by overnutrition

Fatty liver is an abnormal metabolic condition of excess intrahepatic fat. This condition, referred to as hepatic steatosis, is tightly associated with chronic liver disease and systemic metabolic morbidity. The most prevalent form in humans, i.e. non-alcoholic fatty liver, generally develops due to overnutrition and sedentary lifestyle, and has as yet no approved drug therapy. Previously, we have developed a relevant large-animal model in which overnourished sheep raised on a high-calorie carbohydrate-rich diet develop hyperglycemia, hyperinsulinemia, insulin resistance, and hepatic steatosis. Here, we tested the hypothesis that treatment with thiamine (vitamin B1) can counter the development of hepatic steatosis driven by overnutrition. Remarkably, the thiamine-treated animals presented with completely normal levels of intrahepatic fat, despite consuming the same amount of liver-fattening diet. Thiamine treatment also decreased hyperglycemia and increased the glycogen content of the liver, but it did not improve insulin sensitivity, suggesting that steatosis can be addressed independently of targeting insulin resistance. Thiamine increased the catalytic capacity for hepatic oxidation of carbohydrates and fatty acids. However, at gene-expression levels, more-pronounced effects were observed on lipid-droplet formation and lipidation of very-low-density lipoprotein, suggesting that thiamine affects lipid metabolism not only through its known classic coenzyme roles. This discovery of the potent anti-steatotic effect of thiamine may prove clinically useful in managing fatty liver-related disorders.This article has an associated First Person interview with the joint first authors of the paper.

B vitamins as a treatment for diabetic pain and neuropathy

WHAT IS KNOWN AND OBJECTIVE

B vitamin therapy is a common treatment for diabetic pain and neuropathy, yet its use remains controversial in patients lacking B vitamin deficiencies. The aim of this review was to summarize the current evidence for the efficacy of B vitamin therapy in diabetic patients with neuropathy.

COMMENT

We screened the English literature for clinical studies evaluating B vitamins as a therapy for pain and neuropathy in diabetic patients. We selected 43 relevant studies for qualitative analysis based on our selection criteria. Our survey of the literature revealed substantive heterogeneity with respect to efficacies of reported outcomes, as well as study design. Most beneficial outcomes were reported against baseline measures, with few positive comparisons against placebo. This highlights the need for larger, placebo-controlled studies.

WHAT IS NEW AND CONCLUSION

B vitamins should be considered a plausible therapy for diabetic neuropathy, but its overall efficacy remains uncertain and requires further study.