Direct and Functional Biomarkers of Vitamin B6 Status

Nutrition biomarker assessment and exploration of the role of country foods to improve food security in the Sahtú Region, Canada

Country foods (i.e. wild traditional food) are associated with improved nutrition for northern populations. In response to community concerns, a project was implemented from 2019 to 2021 in the Sahtú region, Northwest Territories, Canada, to: 1) analyse nutrition biomarkers (vitamins A, B1, B2, B6, B12, D, E, folate, P, Na) in blood samples, in order to assess nutritional status and identify nutrient deficiencies, and 2) use a survey to document how access to country foods may improve food security in the community of Tulı́t'a. Findings from the nutritional biomarker assessments (n = 128) indicated that 94% of participants experienced clinical vitamin D deficiency (<20 ng/L of plasma 25-hydroxy-vitamin D3) and 9% had folate deficiency (<8.7 nmol/L total folate). In the previous 12 months, 71% of participants did not always have money to get more food when needed, but 92% of participants said they were not left hungry. Country foods were used to increase the quality or quantity of the diet. Increasing country food consumption, such as fatty fish and large game meat and organs could mitigate the vitamin D and folate deficiencies. Policies should be implemented to improve food security in the North by facilitating access to country food.

Gut dysbiosis-induced vitamin B6 metabolic disorder contributes to chronic stress-related abnormal behaviors in a cortisol-independent manner

Chronic stress can result in various conditions, including psychological disorders, neurodegenerative diseases, and accelerated brain aging. Gut dysbiosis potentially contributes to stress-related brain disorders in individuals with chronic stress. However, the causal relationship and key factors between gut dysbiosis and brain disorders in chronic stress remain elusive, particularly under non-sterile conditions. Here, using a repeated restraint stress (RRS) rat model, we show that sequential transplantation of the cecal contents of different RRS stages to normal rats reproduced RRS-induced core phenotypes, including abnormal behaviors, increased peripheral blood corticosterone and inflammatory cytokines, and a unique gut microbial phenotype. This core phenotypic development was effectively inhibited with probiotic supplement. The RRS-induced unique gut microbial phenotypes at the genus level were positively or negatively associated with the levels of 20 plasma metabolites, including vitamin B6 metabolites 4-pyridoxic acid and 4-pyridoxate. Vitamin B6 supplement during RRS alleviated weight loss, abnormal behaviors, peripheral inflammation, and neuroinflammation, but did not affect the peripheral corticosterone levels in chronic stressed rats. Dampening inflammatory signaling via knocking out caspase 11 or caspase 1 inhibitor abolished RRS-induced abnormal behaviors and peripheral and neuroinflammation but did not decrease peripheral corticosterone in mice. These findings show that gut dysbiosis-induced vitamin B6 metabolism disorder is a new non-hypothalamic-pituitary-adrenal axis mechanism of chronic stress-related brain disorders. Both probiotics and vitamin B6 supplement have potential to be developed as therapeutic strategies for preventing and/or treating chronic stress-related illness.

Vitamin B6 status is related to disease severity and modulated by endurance exercise in individuals with multiple sclerosis: a secondary analysis of a randomized controlled trial

BACKGROUND

Low circulating concentrations of B vitamins are linked to various chronic and neurodegenerative diseases. Notably, pyridoxal 5'-phosphate (vitamin B6) deficiency is linked to altered inflammatory responses and cellular immune function, both critical in multiple sclerosis (MS). Nevertheless, most MS research has focused on folate (vitamin B9) and vitamin B12, leaving other B vitamins understudied.

OBJECTIVES

This secondary analysis investigated B-vitamin serum concentrations and related metabolites across MS phenotypes (primary progressive MS, relapsing-remitting MS, and secondary progressive MS) and disease severity levels. Additionally, the impact of endurance exercise on B-vitamin concentrations was investigated.

METHODS

In total, 106 individuals with MS participated in a randomized controlled trial, including different endurance exercise conditions. Serum B-vitamin concentrations were analyzed in 99 participants before and after 3 wk of intervention. Before analysis, participants were dichotomized to 1 of the 2 disability groups based on their expanded disability status scale (EDSS) score: EDSS≥4.5 (n = 47, EDSS: 5.86 ± 0.56) and EDSS<4 (n = 52, EDSS: 3.59 ± 0.83).

RESULTS

Higher EDSS scores were associated with lower pyridoxal 5'-phosphate (vitamin B-6) concentrations (rs: -0.32; 95% CI: -0.49, -0.12; P = 0.011), with the EDSS≥4.5 group also showing lower baseline pyridoxal 5'-phosphate (vitamin B6) concentrations (β: -0.18; 95% CI: -0.30, -0.07; P = 0.007) than the EDSS<4 group. Significant time × EDSS group interactions were evident for pyridoxal 5'-phosphate (vitamin B6; β: 0.05; 95% CI: 0.02, 0.08; P = 0.011), pyridoxal (vitamin B6; β: 0.05; 95% CI: 0.02, 0.09; P = 0.005), and riboflavin (vitamin B2; β: 0.06; 95% CI: 0.02, 0.09; P = 0.008), showing increases in these vitamers in the EDSS≥4.5 group postexercise. N1-Methylnicotinamide (vitamin B3; β: -0.11; 95% CI: -0.15, -0.06; P < 0.001) decreased in both groups over time.

CONCLUSIONS

Disease severity is associated with distinct B-vitamin profiles in individuals with MS, although endurance exercise appears to modify specific B-vitamin concentrations. This trial was registered at clinicaltrials.gov as NCT04356248.

The potential hazards of high doses of vitamin B6 in treating nausea and vomiting in pregnancy: A systematic review

Vitamin B6 is frequently utilized as a therapeutic agent for nausea and vomiting of pregnancy (NVP). Research indicates that excessive intake of vitamin B6 can have implications on neurological function, underscoring the importance of cautious consideration when administering vitamin B6 treatment during early pregnancy. This systematic review investigates the effects of high doses of vitamin B6 on pregnant women experiencing NVP. We searched the PubMed® MEDLINE® database for articles using the following terms: "pregnancy" or "nausea and vomiting during pregnancy" and "vitamin B6." Women with nausea and vomiting symptoms during pregnancy use more than the tolerable amount of vitamin B6. A total of 136 articles were identified from the PubMed® MEDLINE® database. The etiology and treatment of NVP are briefly outlined, followed by a summary and analysis of 19 relevant literature sources. Among these sources, 12 reports detailed the adverse effects of excessive vitamin B6 intake in women; 164/1226 individuals experienced neurological symptoms such as burning, tingling, paresthesia, ataxia, or perioral numbness. Additionally, out of 245 women, four experienced miscarriages and one had an intrauterine demise. The overconsumption of vitamin B6 has the potential to impact nerve function, particularly during the critical first trimester of embryonic development. It might result in adverse outcomes such as miscarriage, intrauterine fetal demise, and congenital abnormalities.

Pyridoxal 5'-phosphate and risk of stroke: triangulation of evidence from a nationally representative cohort and bidirectional Mendelian randomization analysis

Background

Stroke is a leading cause of mortality and disability worldwide. Identifying predictive biomarkers and modifiable risk factors is crucial for stroke prevention in the context of predictive, preventive, and personalized medicine (PPPM). We aimed to investigate the association of serum pyridoxal 5'-phosphate (PLP) levels with stroke prevalence in a nationally representative cohort and to assess the causal relationship using bidirectional Mendelian randomization (MR) analysis, with a focus on the implications for PPPM strategies in stroke management.

Methods

We included 6839 participants aged ≥ 18 years from the National Health and Nutrition Examination Survey (NHANES) 2005-2013. Serum PLP levels were measured by high-performance liquid chromatography. Stroke prevalence was ascertained by self-report. We used generalized linear models, Kaplan-Meier curves, restricted cubic splines, stratified analysis, receiver operating characteristic (ROC) curves, and bidirectional two-sample MR to examine the association of PLP levels with stroke prevalence and assess the causal relationship.

Results

In the fully adjusted model, participants with low serum PLP levels had significantly higher odds of stroke compared to those with high levels (odds ratio (OR) = 6.51e-01, 95% confidence interval (CI) 4.46e-01-9.50e-01, P = 2.74E-02). Kaplan-Meier curves showed significantly lower survival probability in the low PLP group (P < 0.05). The restricted cubic spline analysis revealed a non-linear association, with the highest stroke risk at lower PLP levels. The stratified analysis showed significant associations in several subgroups. The ROC analysis indicated good predictive performance of the fully adjusted model (area under the curve (AUC) > 0.7). The MR analysis supported a protective causal effect of PLP on stroke risk (OR = 0.7723581, 95% CI 0.6388086-0.9336201, P = 0.00345), while the reverse MR analysis did not suggest a causal effect of stroke on PLP levels.

Conclusions

Low serum PLP levels are significantly associated with higher stroke prevalence in a nationally representative the United States (US) sample. Integration of observational and genetic evidence supports a protective causal role of PLP in stroke risk. Serum PLP may serve as a promising predictive biomarker for stroke risk assessment and a potential target for personalized nutritional interventions in stroke prevention, in line with PPPM strategies. Our findings highlight the importance of maintaining optimal vitamin B6 status for effective PPPM-guided stroke prevention and management.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-024-00392-2.

Chronic Oral D-Galactose Induces Oxidative Stress but Not Overt Organ Dysfunction in Male Wistar Rats

D-galactose (d-gal) plays numerous roles in the organism as an energy-providing nutrient and also an important constituent of the complex glycoconjugates. However, excessive amounts of d-gal activate alternative metabolic pathways that can lead to the development of a pro-oxidative environment. This feature is used in numerous aging studies which implied intraperitoneal (i.p.) or subcutaneous (s.c.) administration of d-gal for a prolonged time. The present study aims to investigate the systemic effects of orally administered d-gal (200 mg/kg and 500 mg/kg, dissolved in tap water, for 6 weeks) by analyzing oxidative stress parameters in the liver, kidney, and heart. For comparison with natural aging, the effects were studied in rats aged 12, 18, 24, and 30 months. In addition, histopathologic analyzes and serum biochemical measurements were performed to investigate the potential structural and functional organ damage induced by d-gal administration. Our findings show that chronic oral administration of d-gal induces oxidative stress in rat organs and mimics some aspects of natural aging similar to those of 30-month-old rats. Consistent with its primary role in galactose metabolism, the liver exhibited the most pronounced oxidative damage. However, despite the increased oxidative stress, only minor histopathological changes were observed, while organ function remained largely unaffected. Oral intake of d-gal was found to have milder effects compared to i.p. or s.c. injections, suggesting that this model may induce some features of natural aging but without overt organ dysfunction.

Association of pyridoxal 5'-phosphate (PLP) with lipid profiles: a population-based cohort study

Objectives

This study aims to explore the correlation between Pyridoxal 5'-Phosphate (PLP) levels and lipid profiles in adult individuals, utilizing data from the National Health and Nutrition Examination Survey (NHANES) database.

Methods

The research included individuals aged 20 years and above, extracted from the NHANES database, covering the period from 2005 to 2010. The primary objective was to scrutinize the relationship between PLP and lipid profiles. This was accomplished by employing weighted, multivariable logistic regression to ascertain these associations. Furthermore, to assess the variability within different demographic segments, interaction analyses were conducted. Additionally, restricted cubic spline (RCS) methodology was implemented to delve into potential nonlinear dynamics between PLP concentrations and lipid levels.

Results

A cohort of 6,459 individuals was included in this study. Our data indicated that 51.60% of the participants were under 50 years old, while 48.40% were over 50, comprising 48.83% males and 51.17% females. PLP levels demonstrated a negative correlation with low-density lipoprotein cholesterol (LDL-C) levels. After controlling for confounding variables, a one-unit increment in PLP correlates with a reduction of 17.7% in LDL-C concentrations (OR: 0.823, 95% CI: 0.823-0.824, p < 0.001). PLP levels exhibited a positive correlation with high-density lipoprotein cholesterol (HDL-C), which increased as PLP levels rose. After controlling for all covariates, a one-unit increase in PLP levels corresponded to a 1.952-fold enhancement in the probability of high HDL-C levels (OR: 1.952, 95% CI: 1.951-1.953, p < 0.001). The relationship between PLP and HDL-C levels was nonlinear. Subgroup analyses indicated that PLP levels and HDL-C concentrations are positively correlated, especially among diabetic patients and non-drinkers.

Conclusion

PLP levels are inversely associated with LDL-C and positively associated with HDL-C, with stronger effects observed in diabetic patients and non-drinkers. These findings underscore the potential clinical utility of PLP supplementation as a preventive measure against cardiovascular and metabolic diseases.

Vitamin B6 status, type 2 diabetes mellitus, and periodontitis: evidence from the NHANES database 2009-2010

BACKGROUND

Periodontitis is a chronic inflammatory disease that seriously affects the quality of patients' life. Diabetes mellitus (DM) is the independent risk factor of periodontitis. The association between vitamin B6 with several inflammatory diseases have been reported in previous studies. However, the effect of vitamin B6 on the association of T2DM and periodontitis remains unclear. This study aimed to explore the effect of vitamin B6 [evaluated by serum pyridoxal 5'-phosphate (PLP)] on the association of T2DM and periodontitis in American population.

METHODS

Data of this cross-sectional study were extracted from the National Health and Nutrients Examination Survey (NHANES) 2009-2010. Serum PLP level was the indicator of vitamin B6 status in vivo and measured by enzymatic assay. Covariates included demographic information, physical examination, lifestyle characteristics, laboratory parameters and complications. The weighted univariate and multivariate logistics regression models were conducted to explore the association of PLP, T2DM and periodontitis, with the odds ratios (ORs) and 95% confidence intervals (CIs). Subgroup analyses were further performed to explore these associations based on age, body mass index (BMI), cardiovascular disease (CVD) and dental decay.

RESULTS

Finally, 3,491 eligible adults with the information of periodontitis measurement, T2DM diagnosis and PLP detection were included. Among them, 1,999 (57.26%) had periodontitis. After adjusted confounders, we found adults with T2DM had high odds of periodontitis (OR = 1.45, 95%CI: 1.04-2.02); while no significant association between PLP and periodontitis was observed. Adults with low PLP level (< 67.20 nmol/L) and combined with T2DM had high odds of periodontitis (OR = 1.82, 95%CI: 1.29-2.55), no significant association was found between T2DM and periodontitis in adults with high PLP level (≥ 67.20 nmol/L). These results suggested that serum PLP levels may have the modulatory effect on the association of T2DM and periodontitis. This modulatory effect remains robust in subgroup analysis, especially in adults aged ≥ 60 years (OR = 4.54, 95%CI: 2.15-9.62), with obese (OR = 3.06, 95%CI: 1.31-7.18), without the history of CVD (OR = 2.25, 95%CI: 1.06-4.79) and without dental decay (OR = 2.93, 95%CI: 1.51-5.68) (all P < 0.05).

CONCLUSION

Our study suggested that adults with T2DM had the high odds of periodontitis, and serum PLP may plays a modulatory effect in this association. T2DM patients maintaining a higher intake of vitamin B6 may have potential benefits in reducing the periodontitis risk.

Vitamin Bs as Potent Anticancer Agents through MMP-2/9 Regulation

In recent years, the role of coenzymes, particularly those from the vitamin B group in modulating the activity of metalloenzymes has garnered significant attention in cancer treatment strategies. Metalloenzymes play pivotal roles in various cellular processes, including DNA repair, cell signaling, and metabolism, making them promising targets for cancer therapy. This review explores the complex interplay between coenzymes, specifically vitamin Bs, and metalloenzymes in cancer pathogenesis and treatment. Vitamins are an indispensable part of daily life, essential for optimal health and well-being. Beyond their recognized roles as essential nutrients, vitamins have increasingly garnered attention for their multifaceted functions within the machinery of cellular processes. In particular, vitamin Bs have emerged as a pivotal regulator within this intricate network, exerting profound effects on the functionality of metalloenzymes. Their ability to modulate metalloenzymes involved in crucial cellular pathways implicated in cancer progression presents a compelling avenue for therapeutic intervention. Key findings indicate that vitamin Bs can influence the activity and expression of metalloenzymes, thereby affecting processes such as DNA repair and cell signaling, which are critical in cancer development and progression. Understanding the mechanisms by which these coenzymes regulate metalloenzymes holds great promise for developing novel anticancer strategies. This review summarizes current knowledge on the interactions between vitamin Bs and metalloenzymes, highlighting their potential as anticancer agents and paving the way for innovative, cell-targeted cancer treatments.

Mediation of endothelial activation and stress index in the association between vitamin B6 turnover rate and diabetic retinopathy: an analysis of the National Health and Nutrition Examination Survey

Aim

This study aimed to explore the association between the ratio of 4-pyridoxine (4-PA) to pyridoxal 5'-phosphate (PLP) (4-PA/PLP) and diabetic retinopathy (DR) and further assess the mediating effect of Endothelial Activation and Stress Index (EASIX) on the association between 4-PA/PLP and DR.

Methods

In this cross-sectional study, 1,698 patients with diabetes from the National Health and Nutrition Examination Survey were included. According to the median, 4-PA/PLP was categorized into a high-level group (≥0.89) and a low-level group (<0.89). As the EASIX had a skewed distribution, it was log-transformed before analysis. Weighted logistic regression models were used to investigate the association of 4-PA/PLP with EASIX and DR and the mediating effect of EASIX on the association between 4-PA/PLP and DR. The distribution-of-product method was adopted to assess the mediating effect. Subgroup analysis was performed based on the age and duration of diabetes.

Results

A total of 362 diabetic patients were classified as having DR. After adjusting for all covariates, a higher level of 4-PA/PLP was associated with an increased level of log EASIX [odds ratio (OR) = 1.56, 95% confidence interval (CI): 1.06-2.30]. A higher ratio of 4-PA/PLP was associated with increased odds of DR compared to the reference group with lower levels of 4-PA/PLP (OR = 1.94, 95%CI: 1.40-2.67). In addition, we found that log EASIX may play a mediating role in the 4-PA/PLP and DR, with a 95% CI of distribution of product of 0.31 (95% CI: 0.02-0.67). The proportion of mediation was 69.06%. The mediating effect of log EASIX was also observed in individuals with diabetes who were aged≥60 years (proportion of mediation: 50.63%) or had a duration of diabetes ≥10 years (proportion of mediation: 71.83%).

Conclusion

This study found a positive association between high levels of 4-PA/PLP and an increased risk of DR, with the relationship being partially mediated by log EASIX.

One-carbon metabolism biomarkers and upper gastrointestinal cancer in the Golestan Cohort Study

Incidence of esophageal and gastric cancer has been linked to low B-vitamin status. We conducted matched nested case-control studies of incident esophageal squamous cell carcinoma (ESCC; 340 case-control pairs) and gastric cancer (GC; 352 case-control pairs) within the Golestan Cohort Study. The primary exposure was plasma biomarkers: riboflavin and flavin mononucleotide (FMN) (vitamin B2), pyridoxal phosphate (PLP) (B6), cobalamin (B12), para-aminobenzoylglutamate (pABG) (folate), and total homocysteine (tHcy); and indicators for deficiency: 3-hydroxykyurenine-ratio (HK-r for vitamin B6) and methylmalonic acid (MMA for B12). We estimated odds ratios (ORs) and 95% confidence intervals (CIs) using conditional logistic regression adjusting for matching factors and potential confounders. High proportions of participants had low B-vitamin and high tHcy levels. None of the measured vitamin B levels was associated with the risk of ESCC and GC, but elevated level of MMA was marginally associated with ESCC (OR = 1.42, 95% CI = 0.99-2.04) and associated with GC (OR = 1.53, 95% CI = 1.05-2.22). Risk of GC was higher for the highest versus lowest quartile of HK-r (OR = 1.95, 95%CI = 1.19-3.21) and for elevated versus non-elevated HK-r level (OR = 1.59, 95% CI = 1.13-2.25). Risk of ESCC (OR = 2.81, 95% CI = 1.54-5.13) and gastric cancer (OR = 2.09, 95%CI = 1.17-3.73) was higher for the highest versus lowest quartile of tHcy. In conclusion, insufficient vitamin B12 was associated with higher risk of ESCC and GC, and insufficient vitamin B6 status was associated with higher risk of GC in this population with prevalent low plasma B-vitamin status. Higher level of tHcy, a global indicator of OCM function, was associated with higher risk of ESCC and GC.

Association of vitamin B6 intake with the risk and prognosis of diabetic retinopathy: a NHANES-based study

CLINICAL RELEVANCE

Investigating the role of dietary vitamin B6 intake in the risk and prognosis of diabetic retinopathy (DR) could facilitate the management of DR.

BACKGROUND

This study aimed to assess the association between dietary vitamin B6 intake and the risk of DR and further explore the association between vitamin B6 intake and mortality in patients with DR.

METHODS

This retrospective cohort study gained data from the National Health and Nutrition Examination Survey (NHANES) 2005-2006 and 2007-2008. The intake of dietary vitamin B6 was assessed by two 24-h dietary recall interviews. Mortality information in the National Death Index was recorded from the date of survey participation through 31 December 2019. Multivariate regression analyses were employed to assess the association between vitamin B6 intake and the risk of DR, and the association between vitamin B6 intake and the risk of mortality in patients with DR.

RESULTS

A total of 5559 subjects were included, of which 693 (12.47%) had DR. Among these patients with DR, 429 (61.90%) were survivors. Multivariate analyses showed that the intake of vitamin B6 was negatively associated with the risk of DR (odds ratio = 0.81, 95% confidence level: 0.69-0.95, p = 0.012), and patients with DR with an increased intake of vitamin B6 had a significantly decreased risk of all-cause death (hazard ratio = 0.81, 95% confidence level: 0.66-0.99, p = 0.041) or cardiovascular disease-related death (hazard ratio = 0.76, 95% confidence level: 0.58-0.98, p = 0.037).

CONCLUSION

The intake of vitamin B6 was negatively associated with the risk of DR, and in patients with DR, a higher intake of vitamin B6 was associated with a lower risk of all-cause death and cardiovascular disease-related death, indicating the possible protective role of increased vitamin B6 intake.

Pregnancy Metabolic Adaptation and Changes in Placental Metabolism in Preeclampsia

Pregnancy is a unique physiological state in which the maternal body undergoes a series of changes in the metabolism of glucose, lipids, amino acids, and other nutrients in order to adapt to the altered state of pregnancy and provide adequate nutrients for the fetus' growth and development. The metabolism of various nutrients is regulated by one another in order to maintain homeostasis in the body. Failure to adapt to the altered physiological conditions of pregnancy can lead to a range of pregnancy issues, including fetal growth limitation and preeclampsia. A failure of metabolic adaptation during pregnancy is linked to the emergence of preeclampsia. The treatment of preeclampsia by focusing on metabolic changes may provide new therapeutic alternatives.

Serum Pyridoxal 5'-Phosphate and Pyridoxic Acid Ratio Index with Prognosis of Colorectal Cancer: A Prospective Cohort Study

BACKGROUND

Studies on the association between serum vitamin B6 status and colorectal cancer prognosis are limited and have yielded inconsistent results. This study investigated the association of pyridoxal 5'-phosphate (PLP) and pyridoxic acid ratio (PAr) index with colorectal cancer survival.

METHODS

A total of 1286 colorectal cancer patients diagnosed since 2010 were selected from the Guangdong Colorectal Cancer Cohort study. Serum levels of PLP, pyridoxal, and 4-pyridoxic acid were measured using ultra-high-performance liquid chromatography-tandem mass spectrometry. The study followed overall mortality and colorectal cancer-specific mortality until December 2023. Multivariable Cox proportional hazards regression models were applied to calculate hazard ratios (HRs) and 95% confidence intervals (95% CIs). Restricted cubic spline and stratified analysis were performed.

RESULTS

During a median follow-up of 77.36 months, 331 deaths were recorded, with 293 specifically attributed to colorectal cancer. Higher PLP levels were associated with a longer overall survival (HRQ4 vs. Q1, 0.63; 95% CI: 0.46, 0.87; p for trend = 0.008) and colorectal cancer-specific survival (HRQ4 vs. Q1, 0.62; 95% CI: 0.44, 0.87; p for trend = 0.006). Non-linear associations were observed between serum PLP and overall and colorectal cancer-specific survival (p for non-linear < 0.05). However, PAr was not significantly associated with either overall survival (HRQ4 vs. Q1, 1.03; 95% CI: 0.75, 1.41) or colorectal cancer-specific survival (HRQ4 vs. Q1, 1.01; 95% CI: 0.72, 1.42). The association between serum PLP and both overall survival and colorectal cancer-specific survival (p for interaction < 0.05) varied by alcohol drinking status.

CONCLUSIONS

Higher serum PLP levels, but not PAr, may be associated with improved overall and colorectal cancer-specific survival.

Vitamin B6 status and chronic chemotherapy-induced peripheral neuropathy: a prospective cohort study among patients with non-metastatic colorectal cancer receiving oxaliplatin-based chemotherapy

Objective

Chronic chemotherapy-induced peripheral neuropathy (CIPN) is a long-lasting side-effect of oxaliplatin. Vitamin B6 might play a role in the pathogenesis of CIPN. Therefore, we investigated associations between plasma vitamin B6 markers and the occurrence and severity of chronic CIPN in patients with non-metastatic colorectal cancer (CRC).

Methods and analysis

242 patients with CRC receiving oxaliplatin-based chemotherapy were included. Blood samples were collected at diagnosis (ie, before chemotherapy), and 6 and 12 months after diagnosis (ie, during and after chemotherapy, respectively). Pyridoxal 5'-phosphate (PLP), pyridoxal (PL) and xanthurenic acid:3-hydroxykynurenine (XA:HK) ratio were measured as vitamin B6 markers using liquid chromatography tandem mass spectrometry. Chronic CIPN was assessed 12 months after diagnosis using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-CIPN twenty-item scale questionnaire. Prevalence ratios (PRs) and restricted cubic splines (RCSs) were used to assess associations with chronic CIPN occurrence, and linear regressions were used to assess associations with chronic CIPN severity. Analyses were adjusted for age, sex, smoking, alcohol consumption, diabetes and timing of chemotherapy (neoadjuvant/adjuvant/both).

Results

Chronic CIPN was found in 80% (n=194) of patients. Higher PLP levels and XA:HK ratios during chemotherapy were associated with lower occurrence of chronic CIPN (PRperdoubling 0.75, 95% CI 0.62 to 0.91 and PRCS<0.05, respectively) and lower chronic CIPN severity (βperdoubling -4.54, 95% CI -7.12 to -1.96 and βperdoubling -6.30, 95% CI -9.53 to -3.07, respectively). No associations between PL levels and chronic CIPN were observed.

Conclusion

Within this population, merely having PLP levels within the normal range, higher vitamin B6 status during chemotherapy was associated with lower occurrence and severity of chronic CIPN. Future research is warranted to investigate causality and the optimal vitamin B6 status during chemotherapy.

Vitamin B6 Cofactor Pyridoxal 5'-phosphate Conjugated Papain-Stabilized Fluorescent Gold Nanoclusters for Switch-on Detection of Zinc(II)

In this study, fluorescent gold nanoclusters (AuNCs) conjugated with pyridoxal-5-phosphate (PLP) were synthesized, characterized, and used for Zn2+ fluorescence turn-on sensing. PLP was conjugated over the surface of papain-stabilized fluorescent gold nanoclusters (pap-AuNCs; λex = 380 nm, λem = 670 nm) by forming imine linkage. Due to this modification, the red color emitting pap-AuNCs changed to orange color emitting nanoclusters PLP_pap-AuNCs. The nano-assembly PLP_pap-AuNCs detect Zn2+ selectively by showing a notable fluorescence enhancement at 477 nm. Zn2+ detection with PLP_pap-AuNCs was quick and easy, with an estimated detection limit of 0.14 µM. Further, paper strips and cotton buds coated with PLP_pap-AuNCs were developed for affordable on-site visual detection of Zn2+. Finally, the detection of Zn2+ in actual environmental water samples served as validation of the usefulness of PLP_pap-AuNCs.

The Mediating Role of Kynurenine Pathway Metabolites on the Relationship Between Inflammation and Muscle Mass in Oldest-Old Men

Tryptophan (TRP) metabolites along the kynurenine (KYN) pathway (KP) have been found to influence muscle. Proinflammatory cytokines are known to stimulate the degradation of TRP down the KP. Given that both inflammation and KP metabolites have been connected with loss of muscle, we assessed the potential mediating role of KP metabolites on inflammation and muscle mass in older men. Five hundred and five men (85.0 ± 4.2 years) from the Osteoporotic Fractures in Men cohort study with measured D3-creatine dilution (D3Cr) muscle mass, KP metabolites, and inflammation markers (C-reactive protein [CRP], alpha-1-acid glycoprotein [AGP] and a subsample [n = 305] with interleukin [IL-6, IL-1β, IL-17A] and tumor necrosis factor-α [TNF-α]) were included in the analysis. KP metabolites and inflammatory markers were measured using liquid chromatography-tandem mass spectrometry and immunoassays, respectively. 23%-92% of the inverse relationship between inflammatory markers and D3Cr muscle mass was mediated by KP metabolites (indirect effect p < .05). 3-hydroxyanthranilic acid (3-HAA), quinolinic acid (QA), TRP, xanthurenic acid (XA), KYN/TRP, 3-hydroxykynurenine (3-HK)/3-HAA, QA/3-HAA, and nicotinamide (NAM)/QA mediated the AGP relationship. 3-HAA, QA, KYN/TRP, 3-HK/XA, HKr ratio, 3-HK/3-HAA, QA/3-HAA, and NAM/QA mediated the CRP. KYN/TRP, 3-HK/XA, and NAM/QA explained the relationship for IL-6 and 3-HK/XA and QA/3-HAA for TNF-α. No mediation effect was observed for the other cytokines (indirect effect p > .05). KP metabolites, particularly higher ratios of KYN/TRP, 3-HK/XA, 3-HK/3-HAA, QA/3-HAA, and a lower ratio of NAM/QA, mediated the relationship between inflammation and low muscle mass. Our preliminary cross-sectional data suggest that interventions to alter D3Cr muscle mass may focus on KP metabolites rather than inflammation per se.

Human-derived fecal microbiota transplantation alleviates social deficits of the BTBR mouse model of autism through a potential mechanism involving vitamin B6 metabolism

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental condition characterized by social communication deficiencies and stereotypic behaviors influenced by hereditary and/or environmental risk factors. There are currently no approved medications for treating the core symptoms of ASD. Human fecal microbiota transplantation (FMT) has emerged as a potential intervention to improve autistic symptoms, but the underlying mechanisms are not fully understood. In this study, we evaluated the effects of human-derived FMT on behavioral and multi-omics profiles of the BTBR mice, an established model for ASD. FMT effectively alleviated the social deficits in the BTBR mice and normalized their distinct plasma metabolic profile, notably reducing the elevated long-chain acylcarnitines. Integrative analysis linked these phenotypic changes to specific Bacteroides species and vitamin B6 metabolism. Indeed, vitamin B6 supplementation improved the social behaviors in BTBR mice. Collectively, these findings shed new light on the interplay between FMT and vitamin B6 metabolism and revealed a potential mechanism underlying the therapeutic role of FMT in ASD.IMPORTANCEAccumulating evidence supports the beneficial effects of human fecal microbiota transplantation (FMT) on symptoms associated with autism spectrum disorder (ASD). However, the precise mechanism by which FMT induces a shift in the microbiota and leads to symptom improvement remains incompletely understood. This study integrated data from colon-content metagenomics, colon-content metabolomics, and plasma metabolomics to investigate the effects of FMT treatment on the BTBR mouse model for ASD. The analysis linked the amelioration of social deficits following FMT treatment to the restoration of mitochondrial function and the modulation of vitamin B6 metabolism. Bacterial species and compounds with beneficial roles in vitamin B6 metabolism and mitochondrial function may further contribute to improving FMT products and designing novel therapies for ASD treatment.

Association between dietary macronutrient composition and plasma one-carbon metabolites and B-vitamin cofactors in patients with stable angina pectoris

Elevated plasma concentrations of several one-carbon metabolites are associated with increased CVD risk. Both diet-induced regulation and dietary content of one-carbon metabolites can influence circulating concentrations of these markers. We cross-sectionally analysed 1928 patients with suspected stable angina pectoris (geometric mean age 61), representing elevated CVD risk, to assess associations between dietary macronutrient composition (FFQ) and plasma one-carbon metabolites and related B-vitamin status markers (GC-MS/MS, LC-MS/MS or microbiological assay). Diet-metabolite associations were modelled on the continuous scale, adjusted for age, sex, BMI, smoking, alcohol and total energy intake. Average (geometric mean (95 % prediction interval)) intake was forty-nine (38, 63) energy percent (E%) from carbohydrate, thirty-one (22, 45) E% from fat and seventeen (12, 22) E% from protein. The strongest associations were seen for higher protein intake, i.e. with higher plasma pyridoxal 5'-phosphate (PLP) (% change (95 % CI) 3·1 (2·1, 4·1)), cobalamin (2·9 (2·1, 3·7)), riboflavin (2·4 (1·1, 3·7)) and folate (2·1 (1·2, 3·1)) and lower total homocysteine (tHcy) (-1·4 (-1·9, -0·9)) and methylmalonic acid (MMA) (-1·4 (-2·0, -0·8)). Substitution analyses replacing MUFA or PUFA with SFA demonstrated higher plasma concentrations of riboflavin (5·0 (0·9, 9·3) and 3·3 (1·1, 5·6)), tHcy (2·3 (0·7, 3·8) and 1·3 (0·5, 2·2)) and MMA (2·0 (0·2, 3·9) and 1·7 (0·7, 2·7)) and lower PLP (-2·5 (-5·3, 0·3) and -2·7 (-4·2, -1·2)). In conclusion, a higher protein intake and replacing saturated with MUFA and PUFA were associated with a more favourable metabolic phenotype regarding metabolites associated with CVD risk.

Treatment of patients with carcinomas in advanced stages with 5-fluorouracil, folinic acid and pyridoxine in tandem

The effect of high-dose pyridoxine (PN) on activity of 5-fluorouracil (FUra) and folinic acid (FA)-containing regimens was studied in 50 patients including 14 with digestive tract, and 36 with breast carcinomas (BC) in advanced stages with poor prognostic characteristics. Patients with colorectal, and pancreas adenocarcinoma received oxaliplatin, irinotecan, FUra, FA (Folfirinox), and patients with squamous cell carcinoma of the esophagus had paclitaxel, carboplatin, FUra, FA (TCbF). Patients with BC received AVCF (doxorubicin, vinorelbine, cyclophosphamide, FUra, FA) followed by TCbF or TCbF only, and patients who overexpressed HER2 received TCbF plus trastuzumab and pertuzumab. PN (1000-3000 mg/day iv) preceded each administration of FUra and FA. 47 patients (94%) responded, including 16 (32%) with CR. Median tumor reduction was 93%. Median event-free survival (EFS) was 37.7 months. The 25 patients with tumor shrinkage ≥ 91% had EFS of 52% from 42 months onwards. Unexpected toxicity did not occur. PN enhances potency of chemotherapy regimens comprising FUra and FA.

Trimethylamine N-oxide, β-alanine, tryptophan index, and vitamin B6-related dietary patterns in association with stroke risk

BACKGROUND AND AIMS

The aim of this study was to examine the associations of dietary patterns derived by reduced-rank regression (RRR) model reflecting variation in novel biomarkers (trimethylamine N-oxide, β-alanine, tryptophan index, and vitamin B6) with stroke risk.

METHODS AND RESULTS

We performed analyses based on a community-based cohort study "the Prospective Follow-up Study on Cardiovascular Morbidity and Mortality in China (PFS-CMMC)". Factor loadings were calculated by RRR using 11 food groups collected via a validated food frequency questionnaire and the four response variables based on its nested case-control data (393 cases of stroke vs. 393 matched controls). Dietary pattern scores were derived by applying the factor loadings to the food groups in the entire cohort (n = 15,518). The associations of dietary pattern with the stroke risk were assessed using Cox proportional hazards models. The dietary pattern characterized with higher intakes of red meat and poultry but lower intakes of fresh vegetables, fresh fruits, and fish/seafoods were identified for further analyses. The hazard ratios (HR) for the highest vs. lowest quartile was 1.55 [95 % confidence interval (CI): 1.18-2.03, P trend = 0.001] for total stroke, 2.96 [95 % CI: 1.53-5.71, P trend <0.001] for non-ischemic stroke, after adjustment for sex, age, educational attainment, current smoking, current drinking, body mass index, total energy intake, family history of stroke, hypertension, diabetes, hyperlipidemia, and estimated glomerular filtration rate.

CONCLUSION

Our findings highlight the importance of limited meat intake and increased intakes of fresh vegetables, fruits, and fish/seafoods in the prevention of stroke among Chinese adults.

Effects of Excessive High-fructose Corn Syrup Drink Intake in Middle-aged Mice

BACKGROUND/AIM

The global prevalence of type 2 diabetes (T2D) continues to increase, necessitating the need for understanding the causes of its development. The widespread use of high-fructose corn syrup (HFCS) in drinks and diets is suspected to play a role in metabolic disorders. Although many studies have reported on the effects of excessive HFCS and excessive energy intakes in middle-aged individuals, few have focused on energy restriction. This study aimed to investigate the effects of excessive HFCS drink intake under energy restriction on developing T2D in early middle-aged mice.

MATERIALS AND METHODS

Early middle-aged mice were divided in HFCS and control groups; they were provided either 10% HFCS water or deionized water ad libitum for 12 weeks, respectively. Total energy intake was controlled using a standard rodent diet. Oral glucose tolerance test (OGTT), insulin tolerance test (ITT), tissue weight measurements, serum parameter analyses, and mRNA expression assessments were performed.

RESULTS

No increase in body and adipose tissue weight was observed with excessive HFCS intake under energy restriction. Moreover, serum lipid parameters did not differ from those of controls. However, in the OGTT and ITT, the HFCS group showed higher blood glucose levels than the control group. Moreover, the pancreatic weight and insulin II mRNA expression were reduced.

CONCLUSION

The excessive HFCS drink intake under energy restriction did not induce obesity; however, it induced impaired glucose tolerance, indicating its negative effects on the pancreas in early middle-aged mice. When translated in human physiology, our results show that even if one does not become obese, excessive HFCS may affect the overall metabolic mechanism; these effects may vary depending on age.

Longitudinal associations of plasma kynurenines and ratios with anxiety and depression scores in colorectal cancer survivors up to 12 months post-treatment

INTRODUCTION

Colorectal cancer (CRC) survivors often experience neuropsychological symptoms, including anxiety and depression. Mounting evidence suggests a role for the kynurenine pathway in these symptoms due to potential neuroprotective and neurotoxic roles of involved metabolites. However, evidence remains inconclusive and insufficient in cancer survivors. Thus, we aimed to explore longitudinal associations of plasma tryptophan, kynurenines, and their established ratios with anxiety and depression in CRC survivors up to 12 months post-treatment.

METHODS

In 249 stage I-III CRC survivors, blood samples were collected at 6 weeks, 6 months, and 12 months post-treatment to analyze plasma concentrations of tryptophan and kynurenines using liquid-chromatography tandem-mass spectrometry (LC/MS-MS). At the same timepoints, anxiety and depression were assessed using the Hospital Anxiety and Depression Scale (HADS). Confounder-adjusted linear mixed models were used to analyze longitudinal associations. Sensitivity analyses with false discovery rate (FDR) correction were conducted to adjust for multiple testing.

RESULTS

Higher plasma tryptophan concentrations were associated with lower depression scores (β as change in depression score per 1 SD increase in the ln-transformed kynurenine concentration: -0.31; 95%CI: -0.56,-0.05), and higher plasma 3-hydroxyanthranilic acid concentrations with lower anxiety scores (-0.26; -0.52,-0.01). A higher 3-hydroxykynurenine ratio (HKr; the ratio of 3-hydroxykynurenine to the sum of kynurenic acid, xanthurenic acid, anthranilic acid, and 3-hydroxyanthranilic acid) was associated with higher depression scores (0.34; 0.04,0.63) and higher total anxiety and depression scores (0.53; 0.02,1.04). Overall associations appeared to be mainly driven by inter-individual associations, which were statistically significant for tryptophan with depression (-0.60; -1.12,-0.09), xanthurenic acid with total anxiety and depression (-1.04; -1.99,-0.10), anxiety (-0.51; -1.01,-0.01), and depression (-0.56; -1.08,-0.05), and kynurenic-acid-to-quinolinic-acid ratio with depression (-0.47; -0.93,-0.01). In sensitivity analyses, associations did not remain statistically significant after FDR adjustment.

CONCLUSION

We observed that plasma concentrations of tryptophan, 3-hydroxyanthranilic acid, xanthurenic acid, 3-hydroxykynurenine ratio, and kynurenic-acid-to-quinolinic-acid ratio tended to be longitudinally associated with anxiety and depression in CRC survivors up to 12 months post-treatment. Future studies are warranted to further elucidate the association of plasma kynurenines with anxiety and depression.

Associations of serum vitamin B6 status with the risks of cardiovascular, cancer, and all-cause mortality in the elderly

Background

There are few studies investigating the relationship between serum vitamin B6 and mortality risk in the elderly. This study hereby evaluated the associations between biomarkers of serum vitamin B6 status and cardiovascular, cancer, and all-cause mortality risks in the elderly.

Methods

Our study included a total of 4,881 participants aged 60 years or older from the National Health and Nutrition Examination Survey (NHANES) 2005-2010. Serum vitamin B6 status was estimated based on levels of pyridoxal 5'-phosphate (PLP), 4-pyridoxic acid (4-PA), and vitamin B6 turnover rate (4-PA/PLP) detected by high-performance liquid chromatography. Survival status and corresponding causes of death were matched through the National Death Index records through December 31, 2019. Multivariate Cox regression model was adopted to assess the relationships between serum vitamin B6 status and the risk of mortality.

Results

During a median follow-up period of 10.33 years, 507 cardiovascular deaths, 426 cancer deaths, and 1995 all-cause deaths were recorded, respectively. In the multivariate-adjusted Cox model, the hazard ratios (HRs) and 95% confidence intervals (CIs) for the highest versus the lowest quartiles of PLP, 4-PA, and 4-PA/PLP were 0.70(0.54-0.90), 1.33(0.88-2.02), and 2.01(1.41-2.79) for cardiovascular mortality, 0.73(0.52-1.02), 1.05(0.71-1.57), and 1.95(1.25-3.05) for cancer mortality, and 0.62(0.53-0.74), 1.05(0.82-1.34), and 2.29(1.87-2.79) for all-cause mortality, respectively.

Conclusion

Our study found that lower serum PLP levels were associated with increased risks of cardiovascular and all-cause mortality among the elderly population. And higher vitamin B6 turnover rate was associated with increased risks of cardiovascular, cancer, and all-cause mortality.

Low ALT Is Associated with IBD and Disease Activity: Results from a Nationwide Study

Background: Sarcopenia is underdiagnosed in patients with inflammatory bowel disease (IBD). Low alanine transaminase (ALT) is associated with sarcopenia. We evaluated the association between low ALT and the presence of IBD and disease activity. Methods: Data were collected from a national Israeli health insurer cohort comprising 976,615 patients. Patients with a diagnosis of IBD were compared to healthy controls. After exclusion of patients with liver disease, ALT > 40 IU/L and age < 18, a total of 233,451 patients were included in the analysis. Low ALT was defined as <10 IU/L. Results: Low ALT was more common amongst patients with IBD than in healthy controls (7.76% vs. 5.7% p < 0.001). Low ALT was found in 148 (7.9%) of the patients with CD and 69 (6.9%) of the patients with UC. For CD, low ALT was associated with increased fecal calprotectin (FC) and CRP (223.00 μg/mg [63.45-631.50] vs. 98.50 [31.98-324.00], p < 0.001, 9.10 mg/L [3.22-19.32] vs. 3.20 [1.30-8.30], p < 0.001) and decreased albumin and hemoglobin (3.90 g/dL [3.60-4.20] vs. 4.30 [4.00-4.50], p < 0.001,12.20 g/dL [11.47-13.00] vs. 13.60 [12.60-14.70], p < 0.001). For UC, low ALT was associated with higher FC and CRP (226.50 μg/mg [143.00-537.00] vs. 107.00 [40.85-499.50], p = 0.057, 4.50 mg/L [1.90-11.62] vs. 2.30 [1.00-6.20], p < 0.001) and with lower albumin and hemoglobin (4.00 g/dL [3.62-4.18] vs. 4.30 [4.10-4.40], p < 0.001, 12.40 g/dL [11.60-13.20] vs. 13.60 [12.60-14.60], p < 0.001). These findings remained consistent following multivariate regression and in a propensity score-matched cohort. Conclusions: Low ALT is more common in patients with IBD and is associated with biochemical disease activity indices.

Inflammation, the kynurenines, and mucosal injury during human experimental enterotoxigenic Escherichia coli infection

Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea in children and travelers, especially in low- and middle-income countries. ETEC is a non-invasive gut pathogen colonizing the small intestinal wall before secreting diarrhea-inducing enterotoxins. We sought to investigate the impact of ETEC infection on local and systemic host defenses by examining plasma markers of inflammation and mucosal injury as well as kynurenine pathway metabolites. Plasma samples from 21 volunteers experimentally infected with ETEC were collected before and 1, 2, 3, and 7 days after ingesting the ETEC dose, and grouped based on the level of intestinal ETEC proliferation: 14 volunteers experienced substantial proliferation (SP) and 7 had low proliferation (LP). Plasma markers of inflammation, kynurenine pathway metabolites, and related cofactors (vitamins B2 and B6) were quantified using targeted mass spectrometry, whereas ELISA was used to quantify the mucosal injury markers, regenerating islet-derived protein 3A (Reg3a), and intestinal fatty acid-binding protein 2 (iFABP). We observed increased concentrations of plasma C-reactive protein (CRP), serum amyloid A (SAA), neopterin, kynurenine/tryptophan ratio (KTR), and Reg3a in the SP group following dose ingestion. Vitamin B6 forms, pyridoxal 5'-phosphate and pyridoxal, decreased over time in the SP group. CRP, SAA, and pyridoxic acid ratio correlated with ETEC proliferation levels. The changes following experimental ETEC infection indicate that ETEC, despite causing a non-invasive infection, induces systemic inflammation and mucosal injury when proliferating substantially, even in cases without diarrhea. It is conceivable that ETEC infections, especially when repeated, contribute to negative health impacts on children in ETEC endemic areas.

Nutrient Metabolites Associated With Low D3Cr Muscle Mass, Strength, and Physical Performance in Older Men

BACKGROUND

The relationship between amino acids, B vitamins, and their metabolites with D3-creatine (D3Cr) dilution muscle mass, a more direct measure of skeletal muscle mass, has not been investigated. We aimed to assess associations of plasma metabolites with D3Cr muscle mass, as well as muscle strength and physical performance in older men from the Osteoporotic Fractures in Men cohort study.

METHODS

Out of 1 425 men (84.2 ± 4.1 years), men with the lowest D3Cr muscle mass (n = 100), slowest walking speed (n = 100), lowest grip strength (n = 100), and a random sample (n = 200) serving as a comparison group to the low groups were included. Metabolites were analyzed using liquid chromatography-tandem mass spectrometry. Metabolite differences between the low groups and random sample and their relationships with the muscle outcomes adjusted for confounders and multiple comparisons were assessed using t-test/Mann-Whitney-Wilcoxon and partial correlations, respectively.

RESULTS

For D3Cr muscle mass, significant biomarkers (p < .001) with ≥10% fold difference and largest partial correlations were tryptophan (Trp; r = 0.31), kynurenine (Kyn)/Trp; r = -0.27), nicotinamide (Nam)/quinolinic acid (Quin; r = 0.21), and alpha-hydroxy-5-methyl-tetrahydrofolate (hm-THF; r = -0.25). For walking speed, hm-THF, Nam/Quin, and Quin had the largest significance and fold difference, whereas valine (r = 0.17), Trp (r = 0.17), HKyn/Xant (r = -0.20), neopterin (r = -0.17), 5-methyl-THF (r = -0.20), methylated folate (r = -0.21), and thiamine (r = -0.18) had the strongest correlations. Only hm-THF was correlated with grip strength (r = -0.21) and differed between the low group and the random sample.

CONCLUSIONS

Future interventions focusing on how the Trp metabolic pathway or hm-THF influences D3Cr muscle mass and physical performance declines in older adults are warranted.

Diet-Induced Severe Hyperhomocysteinemia Promotes Atherosclerosis Progression and Dysregulates the Plasma Metabolome in Apolipoprotein-E-Deficient Mice

Atherosclerosis and resulting cardiovascular disease are the leading causes of death in the US. Hyperhomocysteinemia (HHcy), or the accumulation of the intermediate amino acid homocysteine, is an independent risk factor for atherosclerosis, but the intricate biological processes mediating this effect remain elusive. Several factors regulate homocysteine levels, including the activity of several enzymes and adequate levels of their coenzymes, including pyridoxal phosphate (vitamin B6), folate (vitamin B9), and methylcobalamin (vitamin B12). To better understand the biological influence of HHcy on the development and progression of atherosclerosis, apolipoprotein-E-deficient (apoE-/- mice), a model for human atherosclerosis, were fed a hyperhomocysteinemic diet (low in methyl donors and B vitamins) (HHD) or a control diet (CD). After eight weeks, the plasma, aorta, and liver were collected to quantify methylation metabolites, while plasma was also used for a broad targeted metabolomic analysis. Aortic plaque burden in the brachiocephalic artery (BCA) was quantified via 14T magnetic resonance imaging (MRI). A severe accumulation of plasma and hepatic homocysteine and an increased BCA plaque burden were observed, thus confirming the atherogenic effect of the HHD. Moreover, a decreased methylation capacity in the plasma and aorta, indirectly assessed by the ratio of S-adenosylmethionine to S-adenosylhomocysteine (SAM:SAH) was detected in HHD mice together with a 172-fold increase in aortic cystathionine levels, indicating increased flux through the transsulfuration pathway. Betaine and its metabolic precursor, choline, were significantly decreased in the livers of HHD mice versus CD mice. Widespread changes in the plasma metabolome of HHD mice versus CD animals were detected, including alterations in acylcarnitines, amino acids, bile acids, ceramides, sphingomyelins, triacylglycerol levels, and several indicators of dysfunctional lipid metabolism. This study confirms the relevance of severe HHcy in the progression of vascular plaque and suggests novel metabolic pathways implicated in the pathophysiology of atherosclerosis.

Human Milk Micronutrients and Child Growth and Body Composition in the First 2 years: A Systematic Review

Human milk (HM) provides a plethora of nutritional and non-nutritional compounds that support infant development. For many compounds, concentrations vary substantially among mothers and across lactation, and their impact on infant growth is poorly understood. We systematically searched MEDLINE, Embase, the Cochrane Library, Scopus, and Web of Science to synthesize evidence published between 1980 and 2022 on HM components and anthropometry through 2 y of age among term-born infants. Outcomes included weight-for-length, length-for-age, weight-for-age, body mass index (in kg/m2)-for-age, and growth velocity. From 9992 abstracts screened, 144 articles were included and categorized based on their reporting of HM micronutrients, macronutrients, or bioactive components. Micronutrients (vitamins and minerals) are reported here, based on 28 articles involving 2526 mother-infant dyads. Studies varied markedly in their designs, sampling times, geographic and socioeconomic settings, reporting practices, and the HM analytes and infant anthropometrics measured. Meta-analysis was not possible because data were sparse for most micronutrients. The most-studied minerals were zinc (15 articles, 1423 dyads) and calcium (7 articles, 714 dyads). HM iodine, manganese, calcium, and zinc concentrations were positively associated with several outcomes (each in ≥2 studies), whereas magnesium (in a single study) was negatively associated with linear growth during early lactation. However, few studies measured HM intake, adjusted for confounders, provided adequate information about complementary and formula feeding, or adequately described HM collection protocols. Only 4 studies (17%) had high overall quality scores. The biological functions of individual HM micronutrients are likely influenced by other HM components; yet, only 1 study analyzed data from multiple micronutrients simultaneously, and few addressed other HM components. Thus, available evidence on this topic is largely inconclusive and fails to address the complex composition of HM. High-quality research employing chronobiology and systems biology approaches is required to understand how HM components work independently and together to influence infant growth and to identify new avenues for future maternal, newborn, or infant nutritional interventions.

Vitamin B6: a scoping review for Nordic Nutrition Recommendations 2023

Pyridoxal 5´-phosphate (PLP) is the main form of vitamin B6 in animal tissue and functions as a coenzyme for more than 160 different enzymatic reactions in the metabolism of amino acids, carbohydrates, lipids, and neurotransmitters. Estimated dietary intake of vitamin B6 and plasma PLP values differ a lot between studies, something which may be due to variable use of supplements, variations in dietary assessment and analytical methods. These factors make it difficult to achieve precise data for setting a correct recommended intake of vitamin B6. In addition, a plasma PLP concentration of 30 nmol/L is considered to be sufficient and the current recommendations for vitamin B6 intake is based on this concept. However, the metabolic marker for vitamin B6 status, HK ratio (HKr), starts to increase already when plasma PLP falls below 100 nmol/L and increases more steeply below 50 nmol/L, indicating biochemical deficiency. Consequently, a plasma PLP concentration of 30 nmol/L, may be too low as a marker for an adequate vitamin B6 status.

Nutritional peripheral neuropathies

Nutritional peripheral neuropathies are a global problem, heavily influenced by geopolitical, cultural and socioeconomic factors. Peripheral neuropathy occurs most frequently secondary to B-vitamin deficiencies, which is suspected to increase in years to come due to the popularity of vegan and vegetarian diets and increased use of bariatric surgery.This review will focus on the common B-vitamins for which a causal link to peripheral neuropathy is more established (vitamins B1, B2, B6, B9 and B12). We will review the historical human and animal data on which much of the clinical descriptions of vitamin deficiencies are based and summarise current available tools for accurately diagnosing a nutritional deficiency. We will also review recently described genetic diseases due to pathogenic variants in genes involved in B-vitamin metabolism that have helped to inform the phenotypes and potential causality of certain B-vitamins in peripheral neuropathy (B2 and B9).Endemic outbreaks of peripheral neuropathy over the last two centuries have been linked to food shortages and nutritional deficiency. These include outbreaks in Jamaican sugar plantation workers in the nineteenth century (Strachan's syndrome), World War two prisoners of war, Cuban endemic neuropathy and also Tanzanian endemic optic neuropathy, which remains a significant public health burden today. An improved understanding of lack of which vitamins cause peripheral neuropathy and how to identify specific deficiencies may lead to prevention of significant and irreversible disability in vulnerable populations.

Development of 4-Pyridoxic Acid PBPK Model to Support Biomarker-Informed Evaluation of OAT1/3 Inhibition and Effect of Chronic Kidney Disease

Monitoring endogenous biomarkers is increasingly used to evaluate transporter-mediated drug-drug interactions (DDIs) in early drug development and may be applied to elucidate changes in transporter activity in disease. 4-pyridoxic acid (PDA) has been identified as the most sensitive plasma endogenous biomarker of renal organic anion transporters (OAT1/3). Increase in PDA baseline concentrations was observed after administration of probenecid, a strong clinical inhibitor of OAT1/3 and also in patients with chronic kidney disease (CKD). The aim of this study was to develop and verify a physiologically-based pharmacokinetic (PBPK) model of PDA, to predict the magnitude of probenecid DDI and predict the CKD-related changes in PDA baseline. The PBPK model for PDA was first developed in healthy population, building on from previous population pharmacokinetic modeling, and incorporating a mechanistic kidney model to consider OAT1/3-mediated renal secretion. Probenecid PBPK model was adapted from the Simcyp database and re-verified to capture its dose-dependent pharmacokinetics (n = 9 studies). The PBPK model successfully predicted the PDA plasma concentrations, area under the curve, and renal clearance in healthy subjects at baseline and after single/multiple probenecid doses. Prospective simulations in severe CKD predicted successfully the increase in PDA plasma concentration relative to healthy (within 2-fold of observed data) after accounting for 60% increase in fraction unbound in plasma and additional 50% decline in OAT1/3 activity beyond the decrease in glomerular filtration rate. The verified PDA PBPK model supports future robust evaluation of OAT1/3 DDI in drug development and increases our confidence in predicting exposure and renal secretion in patients with CKD.

Maternal B-vitamin and vitamin D status before, during, and after pregnancy and the influence of supplementation preconception and during pregnancy: Prespecified secondary analysis of the NiPPeR double-blind randomized controlled trial

BACKGROUND

Maternal vitamin status preconception and during pregnancy has important consequences for pregnancy outcome and offspring development. Changes in vitamin status from preconception through early and late pregnancy and postpartum have been inferred from cross-sectional data, but longitudinal data on vitamin status from preconception throughout pregnancy and postdelivery are sparse. As such, the influence of vitamin supplementation on vitamin status during pregnancy remains uncertain. This study presents one prespecified outcome from the randomized controlled NiPPeR trial, aiming to identify longitudinal patterns of maternal vitamin status from preconception, through early and late pregnancy, to 6 months postdelivery, and determine the influence of vitamin supplementation.

METHODS AND FINDINGS

In the NiPPeR trial, 1,729 women (from the United Kingdom, Singapore, and New Zealand) aged 18 to 38 years and planning conception were randomized to receive a standard vitamin supplement (control; n = 859) or an enhanced vitamin supplement (intervention; n = 870) starting in preconception and continued throughout pregnancy, with blinding of participants and research staff. Supplement components common to both treatment groups included folic acid, β-carotene, iron, calcium, and iodine; components additionally included in the intervention group were riboflavin, vitamins B6, B12, and D (in amounts available in over-the-counter supplements), myo-inositol, probiotics, and zinc. The primary outcome of the study was glucose tolerance at 28 weeks' gestation, measured by oral glucose tolerance test. The secondary outcome reported in this study was the reduction in maternal micronutrient insufficiency in riboflavin, vitamin B6, vitamin B12, and vitamin D, before and during pregnancy. We measured maternal plasma concentrations of B-vitamins, vitamin D, and markers of insufficiency/deficiency (homocysteine, hydroxykynurenine-ratio, methylmalonic acid) at recruitment, 1 month after commencing intervention preconception, in early pregnancy (7 to 11 weeks' gestation) and late pregnancy (around 28 weeks' gestation), and postdelivery (6 months after supplement discontinuation). We derived standard deviation scores (SDS) to characterize longitudinal changes among participants in the control group and measured differences between the 2 groups. At recruitment, the proportion of patients with marginal or low plasma status was 29.2% for folate (<13.6 nmol/L), 7.5% and 82.0% for riboflavin (<5 nmol/L and ≤26.5 nmol/L, respectively), 9.1% for vitamin B12 (<221 pmol/L), and 48.7% for vitamin D (<50 nmol/L); these proportions were balanced between the groups. Over 90% of all participants had low or marginal status for one or more of these vitamins at recruitment. Among participants in the control group, plasma concentrations of riboflavin declined through early and late pregnancy, whereas concentrations of 25-hydroxyvitamin D were unchanged in early pregnancy, and concentrations of vitamin B6 and B12 declined throughout pregnancy, becoming >1 SDS lower than baseline by 28 weeks gestation. In the control group, 54.2% of participants developed low late-pregnancy vitamin B6 concentrations (pyridoxal 5-phosphate <20 nmol/L). After 1 month of supplementation, plasma concentrations of supplement components were substantially higher among participants in the intervention group than those in the control group: riboflavin by 0.77 SDS (95% CI 0.68 to 0.87, p < 0.0001), vitamin B6 by 1.07 SDS (0.99 to 1.14, p < 0.0001), vitamin B12 by 0.55 SDS (0.46 to 0.64, p < 0.0001), and vitamin D by 0.51 SDS (0.43 to 0.60, p < 0.0001), with higher levels in the intervention group maintained during pregnancy. Markers of vitamin insufficiency/deficiency were reduced in the intervention group, and the proportion of participants with vitamin D insufficiency (<50 nmol/L) during late pregnancy was lower in the intervention group (35.1% versus 8.5%; p < 0.0001). Plasma vitamin B12 remained higher in the intervention group than in the control group 6 months postdelivery (by 0.30 SDS (0.14, 0.46), p = 0.0003). The main limitation is that generalizability to the global population is limited by the high-resource settings and the lack of African and Amerindian women in particular.

CONCLUSIONS

Over 90% of the trial participants had marginal or low concentrations of one or more of folate, riboflavin, vitamin B12, or vitamin D during preconception, and many developed markers of vitamin B6 deficiency in late pregnancy. Preconception/pregnancy supplementation in amounts available in over-the-counter supplements substantially reduces the prevalence of vitamin deficiency and depletion markers before and during pregnancy, with higher maternal plasma vitamin B12 maintained during the recommended lactational period.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02509988; U1111-1171-8056.

Association between Vitamin B6 and Risk of Gastric Cancer: A Systematic Review and Meta-Analysis of Epidemiological Studies

Inconsistent findings have emerged from epidemiological research investigating the association between vitamin B6 and the risk of gastric cancer. To obtain a more precise assessment, we conducted a comprehensive search of published data and performed a meta-analysis. PubMed, Web of Science, EMBASE and Cochrane Library databases were systematically searched. A total of 12 studies (5 prospective cohort and 7 case-control studies) involving 5,692 cases and 814,157 participants were included in the meta-analysis. The results showed that high intake of vitamin B6 may reduce the odds of gastric cancer (OR = 0.83, 95% CI: 0.73-0.95, p = 0.006). However, this association was only observed in the case-control studies (OR = 0.68, 95% CI: 0.51-0.89, p = 0.006) but not in the cohort studies (RR = 1.01, 95% CI: 0.94-1.08, p = 0.819). Additionally, the negative association between vitamin B6 intake and gastric cancer risk was found in the United States of America (OR = 0.71, 95% CI: 0.62-0.82, p = 10-4), but not in Europe (OR = 0.88, 95% CI: 0.74-1.05, p = 0.169) or the other regions (OR = 0.86, 95% CI: 0.66-1.13, p = 0.280). In conclusion, there is not sufficient evidence to assume that vitamin B6 intake is associated with gastric cancer risk, which needs further confirmation.

Micronutrient Deficiency in Inherited Metabolic Disorders Requiring Diet Regimen: A Brief Critical Review

Many inherited metabolic disorders (IMDs), including disorders of amino acid, fatty acid, and carbohydrate metabolism, are treated with a dietary reduction or exclusion of certain macronutrients, putting one at risk of a reduced intake of micronutrients. In this review, we aim to provide available evidence on the most common micronutrient deficits related to specific dietary approaches and on the management of their deficiency, in the meanwhile discussing the main critical points of each nutritional supplementation. The emerging concepts are that a great heterogeneity in clinical practice exists, as well as no univocal evidence on the most common micronutrient abnormalities. In phenylketonuria, for example, micronutrients are recommended to be supplemented through protein substitutes; however, not all formulas are equally supplemented and some of them are not added with micronutrients. Data on pyridoxine and riboflavin status in these patients are particularly scarce. In long-chain fatty acid oxidation disorders, no specific recommendations on micronutrient supplementation are available. Regarding carbohydrate metabolism disorders, the difficult-to-ascertain sugar content in supplementation formulas is still a matter of concern. A ketogenic diet may predispose one to both oligoelement deficits and their overload, and therefore deserves specific formulations. In conclusion, our overview points out the lack of unanimous approaches to micronutrient deficiencies, the need for specific formulations for IMDs, and the necessity of high-quality studies, particularly for some under-investigated deficits.

Longitudinal associations of macronutrient and micronutrient intake with plasma kynurenines in colorectal cancer survivors up to 12 months posttreatment

BACKGROUND

The tryptophan-kynurenine pathway is increasingly recognized to play a role in health-related quality of life (HRQoL) after cancer. Because tryptophan is an essential amino acid, and vitamins and minerals act as enzymatic cofactors in the tryptophan-kynurenine pathway, a link between diet and kynurenines is plausible.

OBJECTIVES

This study aimed to investigate the longitudinal associations of macronutrient and micronutrient intake with metabolites of the kynurenine pathway in colorectal cancer (CRC) survivors up to 12 mo posttreatment.

METHODS

In a prospective cohort of stage I-III CRC survivors (n = 247), repeated measurements were performed at 6 wk, 6 mo, and 12 mo posttreatment. Macronutrient and micronutrient intake was measured by 7-d dietary records. Plasma concentrations of tryptophan and kynurenines were analyzed using liquid chromatography tandem mass spectrometry (LC/MS-MS). Longitudinal associations were analyzed using linear mixed models adjusted for sociodemographic, clinical, and lifestyle factors.

RESULTS

After adjustment for multiple testing, higher total protein intake was positively associated with kynurenic acid (KA) (β as standard deviation [SD] change in KA concentration per 1 SD increase in total protein intake: 0.12; 95% CI: 0.04, 0.20), xanthurenic acid (XA) (standardized β: 0.22; 95% CI: 0.11, 0.33), 3-hydroxyanthranilic acid (HAA) (standardized β: 0.15; 95% CI: 0.04, 0.27) concentrations, and the kynurenic acid-to-quinolinic acid ratio (KA/QA) (standardized β: 0.12; 95% CI: 0.02,0.22). In contrast, higher total carbohydrate intake was associated with lower XA concentrations (standardized β: -0.18; 95% CI: -0.30, -0.07), a lower KA/QA (standardized β: -0.23; 95% CI: -0.34, -0.13), and a higher kynurenine-to-tryptophan ratio (KTR) (standardized β: 0.20; 95% CI: 0.10, 0.30). Higher fiber intake was associated with a higher KA/QA (standardized β: 0.11; 95% CI: 0.02, 0.21) and a lower KTR (standardized β: -0.12; 95% CI: -0.20, -0.03). Higher total fat intake was also associated with higher tryptophan (Trp) concentrations (standardized β: 0.18; 95% CI: 0.06, 0.30) and a lower KTR (standardized β: -0.13; 95% CI: -0.22, -0.03). For micronutrients, positive associations were observed for zinc with XA (standardized β: 0.13; 95% CI: 0.04, 0.21) and 3-hydroxykynurenine (HK) (standardized β: 0.12; 95% CI: 0.03, 0.20) concentrations and for magnesium with KA/QA (standardized β: 0.24; 95% CI: 0.13, 0.36).

CONCLUSIONS

Our findings show that intake of several macronutrients and micronutrients is associated with some metabolites of the kynurenine pathway in CRC survivors up to 12 mo posttreatment. These results may be relevant for enhancing HRQoL after cancer through potential diet-induced changes in kynurenines. Further studies are necessary to confirm our findings.

New Insights Into Pyridoxal Kinase Inhibitors and Their Antileukemic Effects

Pyridoxal kinase (PDXK) plays a pivotal role as an essential enzyme in cellular processes. It catalyzes the phosphorylation of pyridoxal, pyridoxamine, and pyridoxine to generate pyridoxal 5'-phosphate (PLP), the bioactive form of vitamin B6. An intriguing link has emerged between elevated expression levels of PDXK and PLP and various types of carcinomas, including leukemia. Leukemic cells have an increased need for vitamin B6 to sustain their survival and rapid growth, highlighting the potential of targeting PDXK-PLP as a promising therapeutic target in cancer treatment. To discover a novel and promising PDXK inhibitor, we conducted a comprehensive screening of compounds derived from both natural sources and drug-like databases. Our approach involved employing structure-based virtual screening and molecular docking techniques to attenuate the phosphorylation of PLP. Among the top six compounds, ZINC095099376 (referred to as C03) emerged as the most potent inhibitor of PDXK, primarily due to its exceptional binding affinity and remarkable specificity for the target protein. Furthermore, our investigation revealed that compound C03 establishes crucial interactions with key residues within the substrate binding site, indicating that it binds at the same site as the co-crystallized ligand. Remarkably, compound C03 inhibited the endogenous PDXK expression, showed anti-proliferative activity, and triggered an intrinsic pathway for apoptosis via the activation of key apoptotic factors in leukemic cells. In summary, these findings strongly indicate that compound C03 holds promise as a novel inhibitor of PDXK, offering the potential for the development of effective treatments for leukemia.

How vitamins act as novel agents for ameliorating diabetic peripheral neuropathy: A comprehensive overview

Diabetic peripheral neuropathy (DPN) is a pervasive and incapacitating sequela of diabetes, affecting a significant proportion of those diagnosed with the disease, yet an effective treatment remains elusive. Vitamins have been extensively studied, emerging as a promising target for diagnosing and treating various systemic diseases, but their role in DPN is not known. This review collates and synthesizes knowledge regarding the interplay between vitamins and DPN, drawing on bibliographies from prior studies and relevant articles, and stratifying the therapeutic strategies from prophylactic to interventional. In addition, the clinical evidence supporting the use of vitamins to ameliorate DPN is also evaluated, underscoring the potential of vitamins as putative therapeutic agents. We anticipate that this review will offer novel insights for developing and applying vitamin-based therapies for DPN.

Lower Intakes of Key Nutrients Are Associated with More School and Workplace Absenteeism in US Children and Adults: A Cross-Sectional Study of NHANES 2003-2008

The influence of individual macro- and micronutrients on absenteeism in the United States is largely unknown. The objective of this study was to determine whether nutritional status or nutrient intake were associated with absenteeism from school and work due to illness or injury. Data from NHANES 2003-2008 were used to assess nutrient intake from food and food plus supplements, nutritional biomarker levels, and school and work absenteeism per year in children and adults. Negative binomial regression models were used to predict mean days of missed work per year and to estimate incidence rate ratios (IRRs) of absenteeism by nutrient biomarker status. Of 7429 children, 77% reported missing school days (mean 4.0 days). Of 8252 adults, 51% reported missing work days (mean 4.9 days). Children and adults who reported more absent days had a significantly lower intake of protein and several essential micronutrients from the diet. When nutrients from supplements were included, this negative association was retained for protein, selenium, choline, and DHA in children and for protein, selenium, vitamin K, choline, potassium, fiber, octadecatrienoic acid, and lycopene in adults. Future studies are needed to ascertain whether dietary interventions, such as access to healthier food options and/or dietary supplements, can reduce absenteeism.

Clinical and biochemical impact of vitamin B6 deficiency in primary sclerosing cholangitis before and after liver transplantation

BACKGROUND AND AIMS

We previously demonstrated that people with primary sclerosing cholangitis (PSC) had reduced gut microbial capacity to produce active vitamin B6 (pyridoxal 5'-phosphate [PLP]), which corresponded to lower circulating PLP levels and poor outcomes. Here, we define the extent and biochemical and clinical impact of vitamin B6 deficiency in people with PSC from several centers before and after liver transplantation (LT).

METHODS

We used targeted liquid chromatography-tandem mass spectrometry to measure B6 vitamers and B6-related metabolic changes in blood from geographically distinct cross-sectional cohorts totaling 373 people with PSC and 100 healthy controls to expand on our earlier findings. Furthermore, we included a longitudinal PSC cohort (n = 158) sampled prior to and serially after LT, and cohorts of people with inflammatory bowel disease (IBD) without PSC (n = 51) or with primary biliary cholangitis (PBC) (n = 100), as disease controls. We used Cox regression to measure the added value of PLP to predict outcomes before and after LT.

RESULTS

In different cohorts, 17-38% of people with PSC had PLP levels below the biochemical definition of a vitamin B6 deficiency. The deficiency was more pronounced in PSC than in IBD without PSC and PBC. Reduced PLP was associated with dysregulation of PLP-dependent pathways. The low B6 status largely persisted after LT. Low PLP independently predicted reduced LT-free survival in both non-transplanted people with PSC and in transplant recipients with recurrent disease.

CONCLUSIONS

Low vitamin B6 status with associated metabolic dysregulation is a persistent feature of PSC. PLP was a strong prognostic biomarker for LT-free survival both in PSC and recurrent disease. Our findings suggest that vitamin B6 deficiency modifies the disease and provides a rationale for assessing B6 status and testing supplementation.

IMPACT AND IMPLICATIONS

We previously found that people with PSC had reduced gut microbial potential to produce essential nutrients. Across several cohorts, we find that the majority of people with PSC are either vitamin B6 deficient or have a marginal deficiency, which remains prevalent even after liver transplantation. Low vitamin B6 levels strongly associate with reduced liver transplantation-free survival as well as deficits in biochemical pathways dependent on vitamin B6, suggesting that the deficiency has a clinical impact on the disease. The results provide a rationale for measuring vitamin B6 and to investigate whether vitamin B6 supplementation or modification of the gut microbial community can help improve outcomes for people with PSC.

The Influence of Preanalytical Biospecimen Handling on the Measurement of B Vitamers, Amino Acids, and Other Metabolites in Blood

Introduction: Sample handling can influence biomarker measurement and introduce variability when combining data from multiple studies or study sites. To inform the development of blood collection protocols within a multisite cohort study, we directly quantified concentrations of 54 biomarkers in blood samples subjected to different handling conditions. Materials and Methods: We obtained serum, lithium heparin plasma, and EDTA plasma from 20 adult volunteers. Tubes of chilled whole blood were either centrifuged and processed within 2 hours of collection (the "reference standard") or were stored with cool packs for 24 or 48 hours; centrifuged before and/or after this delay; or collected in tubes with/without gel separators. We used linear mixed models with random intercepts to estimate geometric mean concentrations and relative percent differences across the conditions. Results: Compared to the reference standard tubes, concentrations of many biomarkers changed after processing delays, but changes were often small. In serum, we observed large differences for B vitamers, glutamic acid (37% and 73% increases with 24- and 48-hour delays, respectively), glycine (12% and 23% increases), serine (16% and 27% increases), and acetoacetate (-19% and -26% decreases). Centrifugation timing and separator tube use did not affect concentrations of most biomarkers. Conclusion: Sample handling should be consistent across samples within an analysis. The length of processing delays should be recorded and accounted for when this is not feasible.

Pyridoxamine protects human granulosa cells against advanced glycation end-products-induced steroidogenesis disturbances

BACKGROUND

Ovarian advanced glycation end-products (AGEs) accumulation is associated with ovarian granulosa cells (GCs) dysfunction. Vitamin B6 derivatives positively affected reproduction. The current study was conducted to elucidate the AGEs effects on human luteinized mural GCs steroidogenesis in the presence or absence of pyridoxamine (PM).

METHODS AND RESULTS

Isolated GCs of 50 healthy women were divided into four parts and treated with media alone (Control), PM alone, or human glycated albumin (HGA) with/without PM. Main steroidogenic enzymes and hormones were assessed by qRT-PCR and ELISA. The AGE receptor (RAGE) protein was also determined using Western blotting. The non-toxic concentration of HGA increased the expression of RAGE, StAR, 3β-HSD, and 17β-HSD (P < 0.0001 for all) but decreased the expression of CYP19A1 at mRNA levels. The increased RAGE protein expression was also confirmed by western blot analysis. These effects resulted in declined estradiol (E2), slightly, and a sharp rise in progesterone (P4) and testosterone (T) levels, respectively. PM, on its own, ameliorated the HGA-altered enzyme expression and, thereby, corrected the aberrant levels of E2, P4, and T. These effects are likely mediated by regulating the RAGE gene and protein expression.

CONCLUSION

This study indicates that hormonal dysfunctions induced by the AGEs-RAGE axis in luteinized GCs are likely rectified by PM treatment. This effect is likely acquired by reduced expression of RAGE. A better understanding of how AGEs and PM interact in ovarian physiology and pathology may lead to more targeted therapy for treating ovarian dysfunction.

Lower levels of the neuroprotective tryptophan metabolite, kynurenic acid, in users of estrogen contraceptives

Changes in kynurenine metabolites are reported in users of estrogen containing contraception. We have assessed kynurenines, vitamin B6, vitamin B2 and the inflammation markers, C-reactive protein (CRP) and neopterin, in healthy, never-pregnant women between 18 and 40 years (n = 123) and related this to their use of hormonal contraception. The population included 58 women, who did not use hormonal contraceptives (non-users), 51 users of estrogen-containing contraceptives (EC-users), and 14 users of progestin only contraceptives (PC-users). EC-users had significantly lower plasma kynurenic acid (KA) and higher xanthurenic acid (XA) levels compared to non-users. Serum CRP was significantly higher and negatively associated with both vitamin B6 and B2 status in EC-user compared to non-users. No significant differences in any parameters were seen between PC-users and non-users (p > 0.1). The low KA and high XA concentration in users of estrogen containing contraception resemble the biochemical profile observed in vitamin B6 deficiency. The hormonal effect may result from interference with the coenzyme function of vitamin B6 and B2 for particular enzymes in the kynurenine metabolism. KA has been suggested to be neuroprotective and the significantly reduced concentration in EC-users may be of importance in the observed increased risk of mood disorders among users of oral contraceptives.

Vitamin B6 is governed by the local compartmentalization of metabolic enzymes during growth

Vitamin B6 is a vital micronutrient across cell types and tissues, and dysregulated B6 levels contribute to human disease. Despite its importance, how B6 vitamer levels are regulated is not well understood. Here, we provide evidence that B6 dynamics are rapidly tuned by precise compartmentation of pyridoxal kinase (PDXK), the rate-limiting B6 enzyme. We show that canonical Wnt rapidly led to the accumulation of inactive B6 by shunting cytosolic PDXK into lysosomes. PDXK was modified with methyl-arginine Degron (MrDegron), a protein tag for lysosomes, which enabled delivery via microautophagy. Hyperactive lysosomes resulted in the continuous degradation of PDXK and B6 deficiency that promoted proliferation in Wnt-driven colorectal cancer (CRC) cells. Pharmacological or genetic disruption of the coordinated MrDegron proteolytic pathway was sufficient to reduce CRC survival in cells and organoid models. In sum, this work contributes to the repertoire of micronutrient-regulated processes that enable cancer cell growth and provides insight into the functional impact of B6 deficiencies for survival.

Inflammation, sex, blood pressure changes and hypertension in midlife: the Hordaland Health Study

Our aim was to test sex-specific associations of circulating markers of inflammation with blood pressure (BP) and incident hypertension in midlife. Participants in the Hordaland Health study (n = 3280, 56% women, mean age 48 years) were examined at baseline and followed for 6 years. Circulating levels of inflammatory markers including high-sensitive C-reactive protein (hs-CRP), neopterin, and pyridoxic acid ratio (PAr) index were measured at follow-up. The associations with systolic/diastolic BP and incident hypertension were tested in sex-specific linear- or logistic-regression analyses adjusted for body mass index, serum triglycerides, creatinine, physical activity, smoking and diabetes. At follow-up, women had lower mean BP than men (124/72 vs. 130/78 mmHg, p < 0.001). Higher hs-CRP was significantly associated with greater systolic and diastolic BP (standardized β = 0.07 and β = 0.09, both p < 0.01) in women, but not in men. Higher neopterin was associated with higher diastolic BP in women and higher PAr index was associated with higher diastolic BP in women and higher systolic and diastolic BP in men (all p < 0.01). Compared to hs-CRP < 1 mg/l, higher levels of hs-CRP 1-<3 mg/l and hs-CRP ≥ 3 mg/l were associated with new-onset hypertension only in women (odds ratio (OR) 1.74, 95% CI 1.20-2.53 and OR 1.87, 95% CI 1.20-2.90). Sex-interactions were found for hs-CRP and neopterin in models on incident hypertension and diastolic BP, respectively (both p < 0.05). Higher levels of circulating markers of inflammation were associated with higher BP and incident hypertension in a sex-specific manner. Our results suggest a sex-specific interaction between cardiovascular inflammation and BP in midlife.

Inadequate Niacin Intake Disrupts Growth and Retinol Homeostasis Resulting in Higher Liver and Lower Serum Retinol Concentrations in Male Rats

BACKGROUND

Niacin-derived nicotinamide adenine dinucleotide is an essential cofactor for many dehydrogenase enzymes involved in vitamin A (VA) metabolism. Several countries with high prevalence of VA deficiency rely on maize, a poor source of available niacin, as a dietary staple.

OBJECTIVES

This study evaluated the interaction of dietary niacin on VA homeostasis using male Sprague-Dawley rats, aged 21 d (baseline body weight 88.3 ± 6.6 g).

METHODS

After 1 wk of acclimation, baseline samples were collected (n = 4). Remaining rats (n = 54) were split into 9 groups to receive low tryptophan, VA-deficient feed with 3 different amounts of niacin (0, 15, or 30 mg/kg) and 3 different oral VA doses (50, 350, or 3500 nmol/d) in a 3 × 3 design. After 4 wk, the study was terminated. Serum, livers, and small intestine were analyzed for retinoids using high-performance liquid chromatography. Niacin and metabolites were evaluated with nuclear magnetic resonance. Plasma pyridoxal-P (PLP) was measured with high-performance liquid chromatography.

RESULTS

Niacin intake correlated with serum retinol concentrations (r = 0.853, P < 0.001). For rats receiving the highest VA dose, liver retinol concentrations were lower in the 30-mg/kg niacin group (5.39 ± 0.27 μmol/g) than those in the 0-mg/kg and 15-mg/kg groups (9.18 ± 0.62 and 8.75 ± 0.07 μmol/g, respectively; P ≤ 0.05 for both). This phenomenon also occurred in the lower VA doses (P ≤ 0.05 for all). Growth and tissue weight at endline were associated with niacin intake (P ≤ 0.001 for all). Plasma PLP correlated with estimated niacin intake (r = 0.814, P < 0.001).

CONCLUSIONS

Optimal niacin intake is associated with lower liver VA and higher serum retinol and plasma PLP concentrations. The extent to which vitamin B intake affects VA homeostasis requires further investigation to determine if the effects are maintained in humans.

Evaluation of vitamin B6 supplementation in Wilson's disease patients treated with D-penicillamine

INTRODUCTION

Wilson's disease (WD) is a copper metabolism disorder characterised by a progressive accumulation of this metal mainly in the liver and the brain. Treatment is based on the removal of copper operated by the chelators, among which, D-penicillamine (DP) is prescribed as a first-line treatment in most situations. There is some evidence in linking the use of DP with a risk of vitamin B6; therefore, vitamin supplementation is sometimes recommended, although non-consensually. The objective of our study was to evaluate the level of vitamin B6 in WD patients treated with DP with and without associated supplementation.

METHODOLOGY

All WD patients followed at the National Reference Centre for WD in Lyon between January 2019 and December 2020 treated with DP for more than 1 year were included and separated in two groups according to vitamin B6 supplementation. The level of vitamin B6 was measured by the determination of pyridoxal phosphate (PLP).

RESULTS

A total of 37 patients were included. Average age of 23.3±14.8 years, 15 patients with <18 years. Median duration of treatment was 51 (55.8) months. 15 patients were under vitamin B6 supplementation and 22 had interrupted it for more than 1 year. The median PLP level was significantly higher in the group with supplementation, 137.2 (86.7) nmol/L vs 64.9 (30.8) nmol/(p<0.01). No patient had a PLP level<35 nmol/L.

CONCLUSION

Long-term stable WD patients under DP treatment probably do not need vitamin B6 supplementation.

Rapid Diagnostic Platform for Personalized Vitamin B6 Detection in Erythrocytes via PLP Cofactor Mimics

Personalized assessment of vitamin levels in point-of-care (POC) devices is urgently needed to advance the recognition of diseases associated with malnutrition and unbalanced diets. We here introduce a diagnostic platform, which showcases an easy and rapid readout of vitamin B6 (pyridoxal phosphate, PLP) levels in erythrocytes as a first step toward a home-use POC. The technology is based on fluorescent probes, which bind to PLP-dependent enzymes (PLP-DEs) and thereby indirectly report their occupancy with endogenous B6. For example, low vitamin levels result in high probe binding, yielding a strong signal and vice versa. Antibodies against signature human PLP-DEs were immobilized on microarrays to capture probe labeled enzymes for fluorescent detection. Calibrating the system with defined B6 levels revealed a concentration-depended readout as well as sufficient sensitivity for its detection in erythrocytes. To account for individual differences in protein expression, a second antibody was used to normalize protein abundance. This sandwiched assay correctly reported relative B6 levels in human erythrocyte samples, as confirmed by classical laboratory diagnostics. In principle, the platform layout can be easily expanded to other crucial vitamins beyond B6 via an analogous probe strategy.

Different Aspects of the Voltammetric Detection of Vitamins: A Review

Vitamins comprise a group of organic chemical compounds that contribute significantly to the normal functioning of living organisms. Although they are biosynthesized in living organisms, some are also obtained from the diet to meet the needs of organisms, which is why they are characterized as essential chemical compounds. The lack, or low concentrations, of vitamins in the human body causes the development of metabolic dysfunctions, and for this reason their daily intake with food or as supplements, as well as the control of their levels, are necessary. The determination of vitamins is mainly accomplished by using analytical methods, such as chromatographic, spectroscopic, and spectrometric methods, while studies are carried out to develop new and faster methodologies and techniques for their analysis such as electroanalytical methods, the most common of which are voltammetry methods. In this work, a study is reported that was carried out on the determination of vitamins using both electroanalytical techniques, the common significant of which is the voltammetry technique that has been developed in recent years. Specifically, the present review presents a detailed bibliographic survey including, but not limited to, both electrode surfaces that have been modified with nanomaterials and serve as (bio)sensors as well as electrochemical detectors applied in the determination of vitamins.

Associations of vitamin B6 turnover rate with the risk of cardiovascular and all-cause mortality in hypertensive adults

BACKGROUND AND AIM

This study was to assess the association between vitamin B6 turnover rate and mortality in hypertensive adults.

METHODS AND RESULTS

Vitamin B6 status including serum pyridoxal-5'-phosphate (PLP) levels, serum 4-pyridoxal acid (4-PA) levels, and vitamin B6 turnover rate (4-PA/PLP) were obtained from the 2005-2010 National Health and Nutrition Examination Survey (NHANES) dataset of hypertensive adults with follow-up through December 30, 2019. Using Cox proportional risk regression models, Hazard ratios (HRs) and 95% confidence intervals (CIs) were analyzed for PLP, 4-PA and 4-PA/PLP quartiles in relation to cardiovascular and all-cause mortality. A total of 5434 participants were included in this study (mean age, 58.48 years; 50.4% men), and the median 4-PA/PLP was 0.75. The median follow-up time was 11.0 years, with 375 and 1387 cardiovascular and all-cause deaths, respectively. In multivariate COX regression models, PLP was negatively associated with cardiovascular mortality (HR [95% CI] quartile 4 vs. 1: 0.66 [0.47-0.94], P_trend = 0.03) and 4-PA/PLP was positively associated with cardiovascular mortality (HR [95% CI] quartile 4 vs.1: 1.80 [1.21-2.67], P_trend = 0.01). Similarly, the higher the quartile of PLP, the lower the risk of all-cause mortality (HR [95% CI] quartile 4 vs. 1: 0.67 [0.56-0.80], P_trend < 0.01). The higher the quartile of 4-PA and 4-PA/PLP, the higher the risk of all-cause mortality (HR [95% CI] quartile 4 vs. 1: 1.22 [1.01-1.48], P_trend < 0.01; and 2.09 [1.71-2.55], P_trend < 0.01).

CONCLUSION

The findings suggested that higher vitamin B6 turnover rate was associated with an increased risk of cardiovascular and all-cause mortality in hypertensive adults.