South Asian Ethnicity Is Related to the Highest Risk of Vitamin B12 Deficiency in Pregnant Canadian Women

Impact of metformin treatment on cobalamin status in persons with type 2 diabetes

Over the last decades, low vitamin B12 status has been reported in individuals with type 2 diabetes mellitus (T2DM). Metformin, the first-line therapy for lowering blood glucose, is the main driving factor behind this association. Although the relationship between vitamin B12 deficiency and metformin is well established, results of studies on the exact effect of the dose and duration of the therapy remain inconsistent. Additionally, a lack of consensus on the definition of vitamin B12 deficiency adds to the conflicting literature. The objectives of this review were to analyze and synthesize the findings on the effects of metformin dose and duration on vitamin B12 status in patients with T2DM and to outline the potential mechanisms underlying metformin's effect on vitamin B12. Metformin therapy has adversely affected serum vitamin B12 concentrations, a marker of vitamin B12 status. The metformin usage index (a composite score of metformin dose and duration) might serve as a potential risk assessment tool for vitamin B12 screening in patients with T2DM. Considering the health implications of suboptimal vitamin B12 status, vitamin B12 concentrations should be monitored periodically in high-risk patients, such as vegans who are receiving metformin therapy for T2DM. Additionally, it is prudent to implement lifestyle strategies concurrent with metformin therapy in individuals with T2DM, promoting an overall synergistic effect on their glycemic control.

B12 Deficiency is the Commonest Cause of Anaemia During Pregnancy in Northern India: Study from a Tertiary Care Institute

Iron deficiency anemia is considered the leading cause of anemia during pregnancy; however, there is a lack of comprehensive studies on the etiological factors of anemia in pregnant women. The objective of this study was to systematically investigate the causes of anemia in pregnancy. Five hundred women with hemoglobin levels < 11 g/dl between 6 and 40 weeks of pregnancy underwent a complete hemogram, iron studies, serum folate, serum B12, serum copper, and serum zinc level assessments using standard methods. The median age of the patients was 26 years (range 24-29 years). The majority of patients were in the third trimester (449/500, 89.8%). Among the patients, 325 (65%) had vitamin B12 deficiency, with 159 (31.8%) having isolated B12 deficiency and 142 (28.4%) having combined B12 and iron deficiency. Isolated iron deficiency anemia was present in 74 patients (14.8%). Additionally, 28 patients (5.6%) had beta-thalassemia minor, and anemia of chronic disease was found in 17.2% (86) of the patients. Vitamin B12 deficiency was the most common cause of anemia, followed by combined B12 and iron deficiency. Further studies in diverse populations are warranted as they have broader implications for nutrient supplementation during pregnancy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12288-023-01682-x.

A Case-Control Study of the MTHFR C665T Gene Polymorphism on Macrocytic Anemia Among HIV-Infected Patients Receiving Zidovudine

Background

Methods

Results

Conclusion

DNA methylation changes in cord blood and the developmental origins of health and disease – a systematic review and replication study

Background

Environmental exposures in utero which modify DNA methylation may have a long-lasting impact on health and disease in offspring. We aimed to identify and replicate previously published genomic loci where DNA methylation changes are attributable to in utero exposures in the NutriGen birth cohort studies Alliance.

Methods

We reviewed the literature to identify differentially methylated sites of newborn DNA which are associated with the following five traits of interest maternal diabetes, pre-pregnancy body mass index (BMI), diet during pregnancy, smoking, and gestational age. We then attempted to replicate these published associations in the Canadian Healthy Infant Longitudinal Development (CHILD) and the South Asian birth cohort (START) cord blood epigenome-wide data.

Results

We screened 68 full-text articles and identified a total of 17 cord blood epigenome-wide association studies (EWAS) of the traits of interest. Out of the 290 CpG sites reported, 19 were identified in more than one study; all of them associated with maternal smoking. In CHILD and START EWAS, thousands of sites associated with gestational age were identified and maintained significance after correction for multiple testing. In CHILD, there was differential methylation observed for 8 of the published maternal smoking sites. No other traits tested (i.e., folate levels, gestational diabetes, birthweight) replicated in the CHILD or START cohorts.

Conclusions

Maternal smoking during pregnancy and gestational age are strongly associated with differential methylation in offspring cord blood, as assessed in the EWAS literature and our birth cohorts. There are a limited number of reported methylation sites associated in more than two independent studies related to pregnancy. Additional large studies of diverse populations with fine phenotyping are needed to produce robust epigenome-wide data in order to further elucidate the effect of intrauterine exposures on the infants’ methylome.

Health Outcomes of Infants with Vitamin B12 Deficiency Identified by Newborn Screening and Early Treated

OBJECTIVE

To evaluate the clinical outcomes at age 1.5 ± 0.5 years of infants with vitamin B₁₂ deficiency identified by newborn screening (NBS).

STUDY DESIGN

Prospective multicenter observational study on health outcomes of 31 infants with vitamin B₁₂ deficiency identified by NBS. Neurodevelopment was assessed by the Denver Developmental Screening Test.

RESULTS

In 285 862 newborns screened between 2016 and 2019, the estimated birth prevalence of vitamin B₁₂ deficiency was 26 in 100 000 newborns, with high seasonal variations (lowest in summer: 8 in 100 000). Infants participating in the outcome study (N = 31) were supplemented with vitamin B₁₂ for a median (range) of 5.9 (1.1-16.2) months. All achieved age-appropriate test results in Denver Developmental Screening Test at age 15 (11-23) months and did not present with symptoms characteristic for vitamin B₁₂ deficiency. Most (81%, n = 25) mothers of affected newborns had a hitherto undiagnosed (functional) vitamin B₁₂ deficiency, and, subsequently, received specific therapy.

CONCLUSIONS

Neonatal vitamin B₁₂ deficiency can be screened by NBS, preventing the manifestation of irreversible neurologic symptoms and the recurrence of vitamin B₁₂ deficiency in future pregnancies through adequate treatment of affected newborns and their mothers. The high frequency of mothers with migrant background having a newborn with vitamin B₁₂ deficiency highlights the need for improved prenatal care.

Ethnicity influences total serum vitamin B12 concentration: a study of Black, Asian and White patients in a primary care setting

AIMS

A growing body of evidence suggests that ethnicity and race influence vitamin B₁₂ metabolism and status yet clinical awareness of this is poor, causing doubts regarding diagnosis and treatment. Moreover, deficiency and insufficiency cut-offs are universally applied for this test in most diagnostic settings. The objective of this study was to assess serum vitamin B₁₂ concentrations in Black, Asian and White primary care patients in London, UK, particularly in patients of Black or Black British ethnic origin and establish if there is a need for specific reference ranges.

METHODS

Serum B₁₂ results from 49 414 patients were processed between January 2018 and November 2019 using the Architect assay (Abbott Diagnostics) at St. Thomas' Hospital, London, UK. Age, sex and ethnicity data were collected from the laboratory Health Informatics Team.

RESULTS

Black patients (n=13 806) were found to have significantly higher serum vitamin B₁₂ concentration across all age groups and both sexes, especially Nigerian patients (median B₁₂ 505 pmol/L,IQR: 362-727, n=891), compared with Asian and White ethnic groups (p<0.001). Binary logistic regression analysis revealed that the Black or Black British ethnic group had the strongest association with elevated serum B₁₂ (>652 pmol/L) (adjusted OR 3.38, 95% CI 3.17 to 3.61, p<0.0001).

CONCLUSIONS

It is likely that a combination of genetic and acquired/environmental factors are responsible for the ethnic differences in serum B₁₂. This suggests that there is a need for ethnic-specific reference ranges with indications for the incorporation of age and sex too.

Prevalence of Vitamin B12 Deficiency and Its Associated Risk Factors among Pregnant Women of Rural South India: A Community-based Cross-sectional Study

Introduction:

Vitamin B12 is essential for the normal functioning of the nervous system and for the formation of red blood cells. Vegetarian diet, low socioeconomic status, and social and religious reasons are known risk factors of its deficiency. Pregnant women, children, and the elderly are vulnerable groups. Indians have the highest prevalence, but the data among pregnant women in the rural setting is lacking.

Objectives:

The objective of this study is to assess the prevalence of Vitamin B12 deficiency and its associated factors among pregnant women of rural South India.

Materials and Methods:

A cross-sectional study was conducted to recruit consecutive 120 multigravida women with ≤20 weeks of gestation, attending the mobile doctor run clinic of Kaniyambadi block, Vellore. A structured questionnaire was administered, and blood samples were collected.

Results:

The prevalence of Vitamin B12 deficiency (<200 pgm/ml) and anemia (Hb ≤10.5 g/dL) was 55% and 17.5%, respectively. Only 11.7% were B12 deficient and anemic. Past history of abortion (odds ratio [OR] = 0.5), fatigue (OR = 0.4), and low B12 intake (OR = 2) was associated only in the bivariate analysis. First trimester (OR = 3.9) and obesity (OR = 9.6) were found to be independent risk factors of Vitamin B12 deficiency.

Conclusion:

Our study showed a high prevalence of Vitamin B12 deficiency in pregnancy in rural India. Some risk factors were identified. However, studies with a higher sample size will be beneficial to study the associated risk factors better.

Vitamin B12 Deficiency in Newborns and their Mothers-Novel Approaches to Early Detection, Treatment and Prevention of a Global Health Issue

Vitamin B₁₂ deficiency, mostly of maternal origin in newborns, is a well treatable condition but can cause severe neurologic sequelae. In women of childbearing age and pregnant women worldwide vitamin B₁₂ deficiency has been reported with frequencies of 10%-50%. Children with vitamin B₁₂ deficiency are asymptomatic at birth but may develop severe multisystemic symptoms, including irreversible developmental impairment in the second half-year of life. Early detection of vitamin B₁₂ deficiency allows for presymptomatic treatment. This article provides an overview over the function of vitamin B₁₂ and discusses causes and frequency of vitamin B₁₂ deficiency in newborns, infants, and women of childbearing age. It describes novel successful approaches to newborn screening (NBS) for vitamin B₁₂ deficiency and results of a pilot study which performed systematic NBS for vitamin B₁₂ deficiency using so-called second-tier strategies by measuring homocysteine and methylmalonic acid in dried blood spots. Recommendations for diagnostics in mothers of children with vitamin B₁₂ deficiency are described as well as results of systematic work-up in mothers and treatment and follow-up of children with vitamin B₁₂ deficiency detected by NBS. Treatment options of vitamin B₁₂ deficiency are presented including a newly developed standardized supplementation scheme with exclusively oral vitamin B₁₂ supplementation. Recommendations for preventive approaches to vitamin B₁₂ deficiency for children and mothers are stated. Many children worldwide could benefit from systematic inclusion of vitamin B₁₂ deficiency into NBS panels. In addition, preventive approaches to maternal vitamin B₁₂ deficiency should be implemented systematically during maternal care.

Reference intervals for serum total vitamin B12 and holotranscobalamin concentrations and their change points with methylmalonic acid concentration to assess vitamin B12 status during early and mid-pregnancy

Background Maternal vitamin B12 (B-12) adequacy is important for maternal health and optimal fetal growth. However, pregnancy-specific cut-offs for B-12 biomarkers are lacking. Methods Reference intervals for serum total B-12, holotranscobalamin (holoTC) and methylmalonic acid (MMA) concentrations were calculated following CLSI EP28-A3c guidelines in 723 pregnant women of European (50%) and South Asian (50%) ethnicity, residing in British Columbia, Canada, at median (range) 11.4 (8.3-13.9) and 16.1 (14.9-20.9) weeks of gestation. Change point analyses described relationships between log serum MMA concentration with serum total B-12 and holoTC concentrations, assuming linear-linear relationships. Results The central 95% reference interval limits indicated that serum total B-12 <89.9 and <84.0 pmol/L, holoTC <29.5 and <26.0 pmol/L and MMA >371 and >374 nmol/L, in the first and second trimesters, respectively, may indicate B-12 deficiency in pregnant women. The lower limits of total B-12 and holoTC and the upper limits of MMA significantly differed by ethnicity in both trimesters. According to the change point analysis, total B-12 <186 and <180 pmol/L and holoTC <62.2 and <67.5 pmol/L in the first and second trimesters, respectively, suggested an increased probability of impaired intracellular B-12 status, with no difference between ethnicities. Conclusions We present novel reference limits and change points for B-12 biomarkers, which may be employed to identify possible B-12 deficiency in women during early and mid-pregnancy. Future research is needed to validate these cut-offs and determine the predictors and functional outcomes associated with impaired B-12 status in ethnically diverse populations.

Newborn Screening for Vitamin B12 Deficiency in Germany-Strategies, Results, and Public Health Implications

OBJECTIVE

To evaluate a systematic newborn screening (NBS) strategy for vitamin B₁₂ deficiency.

STUDY DESIGN

In a prospective single-center NBS study, a systematic screening strategy for vitamin B₁₂ deficiency was developed and evaluated. Tandem-mass spectrometry screening was complemented by 2 second-tier strategies, measuring methylmalonic/3-OH-propionic/methylcitric acid, and homocysteine from dried blood spots.

RESULTS

In a cohort of 176 702 children screened over 27 months, 33 children were detected by NBS in whom (maternal) vitamin B₁₂ deficiency was confirmed. Homocysteine was the most sensitive marker for vitamin B₁₂ deficiency, but only combination with a second-tier strategy evaluating methylmalonic acid allowed for detection of all 33 children. Mothers were of various ethnic origins, and 89% adhered to a balanced diet. Treatment in children was performed predominantly by oral vitamin B₁₂ supplementation (84%), and all children remained without clinical symptoms at short-term follow-up.

CONCLUSIONS

Vitamin B₁₂ deficiency is a treatable condition but can cause severe neurologic sequelae in infants if untreated. The proposed screening strategy is feasible and effective to identify moderate and severe cases of vitamin B₁₂ deficiency. With an incidence of 1:5355 newborns, vitamin B₁₂ deficiency is more frequent than inborn errors of metabolism included in NBS panels. Treatment of vitamin B₁₂ deficiency is easy, and additional benefits can be achieved for previously undiagnosed affected mothers. This supports inclusion of vitamin B₁₂ deficiency into NBS but also stresses the need for increased awareness of vitamin B₁₂ deficiency in caregivers of pregnant women.

Serum Betaine and Dimethylglycine Are Higher in South Asian Compared with European Pregnant Women in Canada, with Betaine and Total Homocysteine Inversely Associated in Early and Midpregnancy, Independent of Ethnicity

BACKGROUND

As a methyl donor required in the folate-vitamin B-12 independent remethylation of total homocysteine (tHcy) to methionine, betaine is critical for fetal development. Pregnant South Asian women living in Canada had a higher reported prevalence of low vitamin B-12 status compared with Europeans; betaine concentrations in this population are unknown.

OBJECTIVES

We aimed to compare serum betaine concentrations between South Asian and European pregnant women, and to determine the relation between betaine and tHcy concentrations in early pregnancy.

METHODS

A retrospective cohort study was conducted using biobanked serum samples of 723 apparently healthy pregnant women of South Asian (50%) and European ethnicity residing in British Columbia, Canada. Betaine, dimethylglycine (DMG), tHcy, and related metabolites were quantified in samples collected in the first (8-13 weeks of gestation) and second (14-20 weeks of gestation) trimesters. The relation between betaine and tHcy concentrations was assessed using a generalized regression model adjusted for weeks of gestation, ethnicity, prepregnancy BMI, maternal age, neonatal sex, parity, total vitamin B-12, folate, pyridoxal 5'-phosphate, and methionine concentrations.

RESULTS

Median serum concentrations of betaine and its metabolite DMG were higher in South Asian women in the first (19.8 [IQR: 16.3-25.0] and 1.55 [IQR: 1.30-1.96] $\mu {\rm mol/L} $, respectively) and second trimesters (16.1 [IQR: 12.9-19.8] and 1.42 [IQR: 1.14-1.81] $\mu {\rm mol/L} $, respectively) compared with European women (17.6 [IQR: 13.7-22.6] and 1.38 [IQR: 1.12-1.77] $\mu {\rm mol/L} $, respectively) and (12.9 [IQR: 10.6-16.7] and 1.19 [IQR: 0.97-1.52] $\mu {\rm mol/L} $, respectively; all P values < 0.0001). Betaine was inversely associated with tHcy concentration (β = -0.0208; 95% CI: -0.0341, -0.00742; P = 0.002). Additionally, total vitamin B-12 was associated with tHcy concentration (β = -0.0312; 95% CI: -0.0401, -0.0224), after adjusting for confounding factors.

CONCLUSIONS

Pregnant South Asian women residing in Canada had higher betaine and DMG concentrations, compared with women of European ethnicity, while betaine and total vitamin B-12 predicted tHcy independent of ethnicity. Our results emphasize the role of betaine, as methyl donor, in the remethylation of tHcy in a folate-replete population.

The Effects of Vegetarian and Vegan Diet during Pregnancy on the Health of Mothers and Offspring

Vegetarian and vegan diets have increased worldwide in the last decades, according to the knowledge that they might prevent coronary heart disease, cancer, and type 2 diabetes. Althought plant-based diets are at risk of nutritional deficiencies such as proteins, iron, vitamin D, calcium, iodine, omega-3, and vitamin B12, the available evidence shows that well planned vegetarian and vegan diets may be considered safe during pregnancy and lactation, but they require a strong awareness for a balanced intake of key nutrients. A review of the scientific literature in this field was performed, focusing specifically on observational studies in humans, in order to investigate protective effects elicited by maternal diets enriched in plant-derived foods and possible unfavorable outcomes related to micronutrients deficiencies and their impact on fetal development. A design of pregestational nutrition intervention is required in order to avoid maternal undernutrition and consequent impaired fetal growth.

Approaches to improving micronutrient status assessment at the population level

Optimising micronutrient status globally is a major health priority. Nutritional biomarkers are critical for the identification of nutrient inadequacies in light of the limitations of dietary assessment methods. Early diagnosis and prevention of nutrient inadequacies require sensitive, validated and harmonised methods to determine and monitor micronutrient status in individual healthcare and population-based surveys. Important criteria in the identification, validation and implementation of nutritional biomarkers include the testing of biomarker specificity and sensitivity, and their response to dietary as well as physiologic changes, e.g. age or pregnancy. Nutritional status can be categorised into deficient, suboptimal, adequate and excess status, where appropriate, and provided cut-offs are available. Cut-offs are quantitative measures to reflect health outcomes and are important in validating nutritional surveys, interventions and monitoring of populations. For many biomarkers, available cut-offs have limited interpretability and are most commonly derived in adult populations only. For the comparison of studies from across the globe, the harmonisation of analytical methods is essential and can be realised with the use of internationally available reference material and interlaboratory comparison studies. This narrative review describes current efforts on identifying and validating existing and new biomarkers, the derivation of biomarker cut-offs, and international efforts on harmonisation of laboratory methods for biomarker quantitation and their interpretation, in the example of B-vitamins. Establishing sensitive, reliable and cost-efficient biomarkers and related cut-offs for use in populations across the globe are critical to facilitating the early diagnosis of micronutrient inadequacies on the clinical and community-based level for timely intervention and disease prevention.

High incidence of maternal vitamin B12 deficiency detected by newborn screening: first results from a study for the evaluation of 26 additional target disorders for the German newborn screening panel

BACKGROUND

Newborn screening (NBS) in Germany currently includes 15 target disorders. Recent diagnostic improvements suggest an extension of the screening panel.

METHODS

Since August 2016, a prospective study evaluating 26 additional target disorders (25 metabolic disorders and vitamin B₁₂-deficiency) in addition to the German screening panel is performed at the Newborn Screening Center Heidelberg. First-tier results from tandem-MS screening are complemented by second-tier strategies for 15 of the additional target disorders. NBS results of seven patients diagnosed symptomatically with one of the additional target disorders by selective screening since August 2016 are retrospectively evaluated.

RESULTS

Over a 13-month period, 68,418 children participated in the study. Second-tier analyses were performed in 5.4% of samples. Only 59 (0.1%) of study participants had abnormal screening results for one of the additional target disorders. Target disorders from the study panel were confirmed in 12 children: 1 3-hydroxy-3-methylglutaryl coenzyme A (CoA)-lyase deficiency, 1 citrullinemia type I, 1 multiple acyl-CoA dehydrogenase-deficiency, 1 methylenetetrahydrofolate reductase-deficiency, and 8 children with maternal vitamin B₁₂-deficiency. In addition, six of seven patients diagnosed symptomatically outside the study with one of the target disorders would have been identified by the study strategy in their NBS sample.

CONCLUSIONS

Within 13 months, the study "Newborn Screening 2020" identified additional 12 children with treatable conditions while only marginally increasing the recall rate by 0.1%. Maternal vitamin B₁₂-deficiency was the most frequent finding. Even more children could benefit from screening for the additional target disorders by extending the NBS panel for Germany and/or other countries.

Pregnant women of South Asian ethnicity in Canada have substantially lower vitamin B12 status compared with pregnant women of European ethnicity

Maternal vitamin B12 (B12) status has been inversely associated with adverse pregnancy outcomes and positively with fetal growth and infant development. South Asians, Canada's largest ethnic minority, are prone to B12 deficiency. Yet, data are lacking on B12 status in South Asian pregnant women in North America. We sought to determine B12 status, using multiple biomarkers, in 1st and 2nd trimester pregnant women of South Asian and, for comparison, European ethnicity living in Vancouver, Canada. In this retrospective cohort study, total B12, holotranscobalamin (holoTC), methylmalonic acid (MMA), and total homocysteine concentrations were quantified in two routinely collected (mean gestational week: 11·5 (range 8·3-13·9) and 16·5 (range 14·9-20·9)), banked serum samples of 748 healthy pregnant South Asian (n 371) and European (n 377) women. South Asian pregnant women had significantly lower B12 status than European pregnant women at both time points, as indicated by lower serum total B12 and holoTC concentrations, and higher MMA concentrations (all P≤0·001). The largest difference, which was substantial (Cohen's d≥0·5), was observed in mean serum total B12 concentrations (1st trimester: 189 (95 % CI 180, 199) v. 246 (95 % CI 236, 257) pmol/l; 2nd trimester: 176 (95 % CI 168, 185) v. 226 (95 % CI 216, 236) pmol/l). Further, South Asian ethnicity was a significant negative predictor of B12 status during pregnancy. South Asian women living in Vancouver have substantially lower B12 status during early pregnancy. Future research identifying predictors and health consequences of this observed difference is needed to allow for targeted interventions.