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Background: Gestational diabetes mellitus (GDM) can adversely affect the health of the developing fetus. Women of South Asian origin are particularly at risk of developing GDM. Insulin resistance (IR) contributes to the etiology of GDM, and although studies have shown associations of vitamin B12 (B12) and folate status with GDM and IR, only a limited number of B12 and folate markers have been used.Objective: We used a comprehensive panel of B12 and folate markers to examine their association with IR in pregnant women with diet-controlled GDM and normal glucose tolerance (NGT).Methods: In this cross-sectional study, 59 British-Bangladeshi women (24 GDM and 35 NGT) with a mean age of 29 y, BMI (in kg/m2) 26.7 and gestational age 33 wk were recruited. Serum total B12, holotranscobalamin, folate, methylmalonic acid, plasma homocysteine, 5-methyltetrahydrofolate, and red cell folate (RCF) were measured along with other parameters. The independent sample t-test and chi-squared test were used to assess differences in markers between GDM and NGT women. Spearman's test was used to look for correlations. A simple multiple regression analysis was used to investigate if markers of B12 and folate status predicted IR, using the HOMA-IR and adjusting for age, GDM status, and BMI.Results: There were no differences in concentrations of B12 and folate markers between GDM and NGT women. In Spearman's analysis HOMA-IR correlated negatively with total serum B12 (P < 0.001) and holotranscobalamin (P < 0.05), and positively with BMI (P < 0.001), blood pressure (P < 0.05) and triglycerides (P < 0.05) in all women. MMA did not correlate with any of the B12 markers. In regression analysis, total B12 (β = -0.622, P = 0.004), RCF (β = 0.387, P = 0.018), and BMI (β = 0.024, P < 0.001) were the significant predictors of HOMA-IR variance.Conclusions: Significant associations between markers of B12 and folate status with HOMA-IR were found during the third trimester in British-Bangladeshi women. B12 markers correlated poorly with each other. [ABSTRACT FROM AUTHOR]

Background: Although a number of health outcomes such as CVDs, metabolic-related outcomes, neurological disorders, pregnancy outcomes, and cancers have been identified in relation to B vitamins, evidence is of uneven quality and volume, and there is uncertainty about putative causal relationships., Objectives: To explore the effects of B vitamins and homocysteine on a wide range of health outcomes based on a large biorepository linking biological samples and electronic medical records., Methods: First, we performed a phenome-wide association study (PheWAS) to investigate the associations of genetically predicted plasma concentrations (genetic component of the circulating concentrations) of folate, vitamin B6, vitamin B12, and their metabolite homocysteine with a wide range of disease outcomes (including both prevalent and incident events) among 385,917 individuals in the UK Biobank. Second, 2-sample Mendelian randomization (MR) analysis was used to replicate any observed associations and detect causality. We considered MR P <0.05 as significant for replication. Third, dose-response, mediation, and bioinformatics analyses were carried out to examine any nonlinear trends and to disentangle the underlying mediating biological mechanisms for the identified associations., Results: In total, 1117 phenotypes were tested in each PheWAS analysis. After multiple corrections, 32 phenotypic associations of B vitamins and homocysteine were identified. Two-sample MR analysis supported that 3 of them were causal, including associations of higher plasma vitamin B6 with lower risk of calculus of kidney (OR: 0.64; 95% CI: 0.42, 0.97; P = 0.033), higher homocysteine concentration with higher risk of hypercholesterolemia (OR: 1.28, 95% CI: 1.04, 1.56; P = 0.018), and chronic kidney disease (OR: 1.32, 95% CI: 1.06, 1.63; P = 0.012). Significant nonlinear dose-response relationships were observed for the associations of folate with anemia, vitamin B12 with vitamin B-complex deficiencies, anemia and cholelithiasis, and homocysteine with cerebrovascular disease., Conclusions: This study provides strong evidence for the associations of B vitamins and homocysteine with endocrine/metabolic and genitourinary disorders., (Copyright © 2023 American Society for Nutrition. All rights reserved.)

Background/objectives: The evidence of relationship between dietary intake of folate, vitamin B6 and vitamin B12 and cardiovascular diseases (CVD) in UK populations is limited. We aimed to analyze the association of dietary intake of folate, vitamin B6, and vitamin B12 with CVD events [stroke, myocardial infarction (MI)] and CVD mortality., Methods: We included 115,664 participants, aged 40-70 years, with no CVD events or cancer at baseline, enrolled between 2006 and 2010 and followed up to the end of 2018. Dietary intake was measured with an online 24-h dietary assessment. Multivariable Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the associations., Results: After multivariate adjustment, higher dietary folate intake was inversely associated with CVDs with hazard ratios of 0.99, 0.92, and 0.88 in groups 2-4 compared with group 1 (the lowest group); inversely associated with stroke with hazard ratios of 0.94, 0.90, and 0.86 groups 2-4 compared to group 1 (lowest group); inversely associated with MI with hazard ratios of 1.01, 0.90 and 0.86 groups 2-4 compared to group 1 (lowest group); inversely associated with CVD mortality with hazard ratios of 0.95, 0.80 and 0.74 Groups 2-4 compared to group 1 (lowest group). Each tablespoon/day higher intake of raw vegetable intake, pieces/day higher intake of fresh fruit intake bowls/week higher intake of cereal intake, and g/day higher intake of dietary fiber were associated with higher intakes of folate every 0.02,0.06,0.05, and 0.08 SD, respectively. E-value analysis suggested robustness to unmeasured confounding., Conclusions: Each increase in folate intakes was related to 5% lower risks of total CVD events and 10% lower risks of CVD mortality. Our findings support that strengthening dietary folate intake as a primary prevention strategy for CVD events and CVD mortality., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Cobalamin concentration is often assessed in clinical practice but little is known about the significance of hypercobalaminemia. The objective of this retrospective study was to identify the conditions associated with hypercobalaminemia in dogs and to investigate association with clinicopathological variables. Medical records of dogs having serum cobalamin measured between 2016 and 2018 were reviewed. One hundred sixty dogs were included and 47 (29%) showed hypercobalaminemia. Dogs with hypercobalaminemia had gastrointestinal (57%), hepatic (11%), neurological (11%), endocrine (9%), renal (4%), pancreatic (2%), and miscellaneous (6%) diseases. Overall, 11% had neoplasia. This distribution was not significantly different from that for hypocobalaminemic and normocobalaminemic dogs. There were significantly more dogs with hyperfolatemia in the hypercobalaminemia group. These results suggest that in clinical practice hypercobalaminemia is commonly identified in gastrointestinal and hepatic disease in dogs, but can also be seen with endocrine and neurological conditions. The frequency of hyperfolatemia alongside hypercobalaminemia may reflect common metabolic pathways., (Copyright and/or publishing rights held by the Canadian Veterinary Medical Association.)

The first epigenome-wide association study of BMI identified DNA methylation at an HIF3A locus associated with BMI. We tested the hypothesis that DNA methylation variants are associated with BMI according to intake of B vitamins. In two large cohorts, we found significant interactions between the DNA methylation-associated HIF3A single nucleotide polymorphism (SNP) rs3826795 and intake of B vitamins on 10-year changes in BMI. The association between rs3826795 and BMI changes consistently increased across the tertiles of total vitamin B2 and B12 intake (all P for interaction <0.01). The differences in the BMI changes per increment of minor allele were -0.10 (SE 0.06), -0.01 (SE 0.06), and 0.12 (SE 0.07) within subgroups defined by increasing tertiles of total vitamin B2 intake and -0.10 (SE 0.06), -0.01 (SE 0.06), and 0.10 (SE 0.07) within subgroups defined by increasing tertiles of total vitamin B12 intake. In two independent cohorts, a DNA methylation variant in HIF3A was associated with BMI changes through interactions with total or supplemental vitamin B2, vitamin B12, and folate. These findings suggest a potential causal relation between DNA methylation and adiposity., (© 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.)