Folic acid supplementation before and during pregnancy in the Newborn Epigenetics STudy (NEST)

Moderate levels of folic acid benefit outcomes for cilia based neural tube defects

Folic acid (FA) supplementation is a potent tool to reduce devastating birth defects known as neural tube defects (NTDs). Though effective, questions remain how FA achieves its protective effect and which gene mutations are sensitive to folic acid levels. We explore the relationship between FA dosage and NTD rates using NTD mouse models. We demonstrate that NTD rates in mouse models harboring mutations in cilia genes depend on FA dosage. Cilia mutant mouse models demonstrate reductions in NTD rates when exposed to moderate levels of FA that are not observed at higher fortified levels of FA. This trend continues with a moderate level of FA being beneficial for primary and motile cilia formation. We present a mechanism through which fortified FA levels reduce basal levels of reactive oxygen species (ROS) which in turn reduces ROS-sensitive GTPase activity required for ciliogenesis. Our data indicates that genes involved in cilia formation and function represent a FA sensitive category of mutations and a possible avenue for further reducing NTD and ciliopathy incidences.

Adverse Effects of Excessive Folic Acid Consumption and Its Implications for Individuals With the Methylenetetrahydrofolate Reductase C677T Genotype

This scoping review examines the risks of high folic acid supplementation in expectant mothers, particularly those with the methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism. While folic acid is essential for DNA synthesis and preventing neural tube defects, excessive intake may pose health risks, especially for individuals with the MTHFR variant. These individuals have a reduced ability to process folic acid, leading to the accumulation of unmetabolized folic acid (UMFA), which is associated with vitamin B12 deficiency, cognitive and psychiatric issues, and adverse pregnancy outcomes. This review emphasizes the importance of monitoring folic acid intake and explores alternative supplements such as 5-MTHF or 5-FTHF, which may mitigate these risks by bypassing MTHFR conversion. Personalized nutrition, considering genetic variations, is crucial for optimizing health and minimizing potential harm.

Creation and Validation of the First Infinium DNA Methylation Array for the Human Imprintome

Background

Differentially methylated imprint control regions (ICRs) regulate the monoallelic expression of imprinted genes. Their epigenetic dysregulation by environmental exposures throughout life results in the formation of common chronic diseases. Unfortunately, existing Infinium methylation arrays lack the ability to profile these regions adequately. Whole genome bisulfite sequencing (WGBS) is the unique method able to profile these regions, but it is very expensive and it requires not only a high coverage but it is also computationally intensive to assess those regions.

Findings

To address this deficiency, we developed a custom methylation array containing 22,819 probes. Among them, 9,757 probes map to 1,088 out of the 1,488 candidate ICRs recently described. To assess the performance of the array, we created matched samples processed with the Human Imprintome array and WGBS, which is the current standard method for assessing the methylation of the Human Imprintome. We compared the methylation levels from the shared CpG sites and obtained a mean R 2 = 0.569. We also created matched samples processed with the Human Imprintome array and the Infinium Methylation EPIC v2 array and obtained a mean R 2 = 0.796. Furthermore, replication experiments demonstrated high reliability (ICC: 0.799-0.945).

Conclusions

Our custom array will be useful for replicable and accurate assessment, mechanistic insight, and targeted investigation of ICRs. This tool should accelerate the discovery of ICRs associated with a wide range of diseases and exposures, and advance our understanding of genomic imprinting and its relevance in development and disease formation throughout the life course.

Uncovering the Hidden Dangers and Molecular Mechanisms of Excess Folate: A Narrative Review

This review delves into the intricate relationship between excess folate (vitamin B9) intake, especially its synthetic form, namely, folic acid, and its implications on health and disease. While folate plays a pivotal role in the one-carbon cycle, which is essential for DNA synthesis, repair, and methylation, concerns arise about its excessive intake. The literature underscores potential deleterious effects, such as an increased risk of carcinogenesis; disruption in DNA methylation; and impacts on embryogenesis, pregnancy outcomes, neurodevelopment, and disease risk. Notably, these consequences stretch beyond the immediate effects, potentially influencing future generations through epigenetic reprogramming. The molecular mechanisms underlying these effects were examined, including altered one-carbon metabolism, the accumulation of unmetabolized folic acid, vitamin-B12-dependent mechanisms, altered methylation patterns, and interactions with critical receptors and signaling pathways. Furthermore, differences in the effects and mechanisms mediated by folic acid compared with natural folate are highlighted. Given the widespread folic acid supplementation, it is imperative to further research its optimal intake levels and the molecular pathways impacted by its excessive intake, ensuring the health and well-being of the global population.

AHRR Hypomethylation mediates the association between maternal smoking and metabolic profiles in children

BACKGROUND

Tobacco smoking during pregnancy is associated with metabolic dysfunction in children, but mechanistic insights remain limited. Hypomethylation of cg05575921 in the aryl hydrocarbon receptor repressor (AHRR) gene is associated with in utero tobacco smoke exposure. In this study, we evaluated whether AHRR hypomethylation mediates the association between maternal smoking and metabolic dysfunction in children.

METHODS

We assessed metabolic dysfunction using liver fat content (LFC), serum, and clinical data in children aged 7-12 years (n=78) followed since birth. Maternal smoking was self-reported at 12 weeks gestation. Methylation was measured by means of pyrosequencing at 3 sequential CpG sites, including cg05575921, at birth and at ages 7-12. Regression models were used to evaluate whether AHRR methylation mediated the association between maternal smoking and child metabolic dysfunction.

RESULTS

Average AHRR methylation at birth was significantly higher among children of nonsmoking mothers compared with children of mothers who smoked (69.8% ± 4.4% vs. 63.5% ± 5.5, p=0.0006). AHRR hypomethylation at birth was associated with higher liver fat content (p=0.01), triglycerides (p=0.01), and alanine aminotransferase levels (p=0.03), and lower HDL cholesterol (p=0.01) in childhood. AHRR hypomethylation significantly mediated associations between maternal smoking and liver fat content (indirect effect=0.213, p=0.018), triglycerides (indirect effect=0.297, p=0.044), and HDL cholesterol (indirect effect = -0.413, p=0.007). AHRR methylation in childhood (n=78) was no longer significantly associated with prenatal smoke exposure or child metabolic parameters (p>0.05).

CONCLUSIONS

AHRR hypomethylation significantly mediates the association between prenatal tobacco smoke exposure and features of childhood metabolic dysfunction, despite the lack of persistent hypomethylation of AHRR into childhood. Further studies are needed to replicate these findings and to explore their causal and long-term significance.

Prenatal and Childhood Smoke Exposure Associations with Cognition, Language, and Attention-Deficit/Hyperactivity Disorder

OBJECTIVE

To assess the relationships of prenatal and childhood smoke exposure with specific neurodevelopmental and behavioral problems during early childhood.

STUDY DESIGN

A subsample (n = 386) of mother-child dyads from the Newborn Epigenetic Study (NEST) prebirth cohort participated in the study. Cotinine concentrations were used to objectively measure prenatal and childhood smoke exposure when youth were aged 3-13 years. Multivariable regression models were used to estimate associations of prenatal and childhood cotinine concentrations with performance on the National Institutes of Health (NIH) Toolbox and attention-deficit/hyperactivity disorder and behavioral symptoms, measured using the Behavior Assessment System for Children, 2nd edition (BASC-2).

RESULTS

After adjusting for confounders, childhood cotinine concentrations were associated with poorer cognitive performance on tasks measuring cognitive flexibility (B = -1.29; P = .03), episodic memory (B = -0.97; P = .02), receptive language development (B = -0.58; P = .01), and inhibitory control and attention (B = -1.59; P = .006). Although childhood cotinine concentration was associated with higher levels of attention problems (B = 0.83; P = .004) on the BASC-2, after adjustment for confounders, the association is nonsignificant. Although associations for maternal cotinine concentrations were null, an interaction was detected between prenatal and childhood cotinine concentrations on the NIH Toolbox Picture Vocabulary Task (P = .02).

CONCLUSIONS

Our findings suggest that childhood tobacco smoke exposure may lead to poorer attention regulation and language acquisition, complex visual processing ability, and attention problems.

A fully integrated nucleic acid analysis system for multiplex detection of genetic polymorphisms related to folic acid metabolism

A sufficient intake of folic acid is essential during pregnancy, but several genetic polymorphisms reduce its absorption, threaten the lives of pregnant women and cause congenital disabilities in newborns. Traditional laboratory detection of genetic variants related to folic acid metabolism is time-consuming and labor-intensive. Microfluidics-based molecular diagnosis integrates sample pre-processing and nucleic acid amplification on-chip to achieve rapid, sensitive, high-throughput, and automated detection. Here, we developed a fully integrated microfluidic system for the detection of genetic polymorphisms related to folic acid metabolism in a "sample in-answer out" style. The system consists of nucleic acid extraction and amplification modules. During nucleic acid extraction, blood cells are lysed, and DNA is captured and eluted through a silica-gel membrane. After that, multiple gene loci are detected using loop-mediated isothermal amplification (LAMP) and the color of the reaction chamber indicates whether genetic mutations are present. The experimental results demonstrate that the system can accurately detect gene polymorphisms associated with folic acid metabolism in blood samples with high sensitivity and no cross-contamination between chambers. The blood samples of five patients were tested for mutant alleles on this system, and the test results were consistent with qPCR and DNA sequencing observations. The operation is fully automated, and the detection is completed in approximately 70 minutes. The proposed system has great potential in prenatal diagnosis and other types of nucleic acid detection.

Duration of exposure to epidural anesthesia at delivery, DNA methylation in umbilical cord blood and their association with offspring asthma in Non-Hispanic Black women

Epidural anesthesia is an effective pain relief modality, widely used for labor analgesia. Childhood asthma is one of the commonest chronic medical illnesses in the USA which places a significant burden on the health-care system. We recently demonstrated a negative association between the duration of epidural anesthesia and the development of childhood asthma; however, the underlying molecular mechanisms still remain unclear. In this study of 127 mother-child pairs comprised of 75 Non-Hispanic Black (NHB) and 52 Non-Hispanic White (NHW) from the Newborn Epigenetic Study, we tested the hypothesis that umbilical cord blood DNA methylation mediates the association between the duration of exposure to epidural anesthesia at delivery and the development of childhood asthma and whether this differed by race/ethnicity. In the mother-child pairs of NHB ancestry, the duration of exposure to epidural anesthesia was associated with a marginally lower risk of asthma (odds ratio = 0.88, 95% confidence interval = 0.76-1.01) for each 1-h increase in exposure to epidural anesthesia. Of the 20 CpGs in the NHB population showing the strongest mediation effect, 50% demonstrated an average mediation proportion of 52%, with directional consistency of direct and indirect effects. These top 20 CpGs mapped to 21 genes enriched for pathways engaged in antigen processing, antigen presentation, protein ubiquitination and regulatory networks related to the Major Histocompatibility Complex (MHC) class I complex and Nuclear Factor Kappa-B (NFkB) complex. Our findings suggest that DNA methylation in immune-related pathways contributes to the effects of the duration of exposure to epidural anesthesia on childhood asthma risk in NHB offspring.

Sex-specific DNA methylation and associations with in utero tobacco smoke exposure at nuclear-encoded mitochondrial genes

Sex-linked differences in mitochondrial ATP production, enzyme activities, and reactive oxygen species generation have been reported in multiple tissue and cell types. While the effects of reproductive hormones underlie many of these differences, regulation of sexually dimorphic mitochondrial function has not been fully characterized. We hypothesized that sex-specific DNA methylation contributes to sex-specific expression of nuclear genes that influence mitochondrial function. Herein, we analysed DNA methylation data specifically focused on nuclear-encoded mitochondrial genes in 191 males and 190 females. We found 596 differentially methylated sites (DMSs) (FDR p < 0.05), corresponding to 324 genes, with at least a 1% difference in methylation between sexes. To investigate the potential functional significance, we utilized gene expression microarray data. Of the 324 genes containing DMSs, 17 showed differences in gene expression by sex. Particularly striking was that ATP5G2, encoding subunit C of ATP synthase, contains seven DMSs and exhibits a sex difference in expression (p = 0.04). Finally, we also found that alterations in DNA methylation associated with in utero tobacco smoke exposure were sex-specific in these nuclear-encoded mitochondrial genes. Interestingly, the level of sex differences in DNA methylation at nuclear-encoded mitochondrial genes and the level of methylation changes associated with smoke exposure were less prominent than that of other genes. This suggests more conservative regulation of DNA methylation at these nuclear-encoded mitochondrial genes as compared to others. Overall, our findings suggest that sex-specific DNA methylation may help establish sex differences in expression and function and that sex-specific alterations in DNA methylation in response to exposures could contribute to sex-variable toxicological responses.

Genomic map of candidate human imprint control regions: the imprintome

Imprinted genes - critical for growth, metabolism, and neuronal function - are expressed from one parental allele. Parent-of-origin-dependent CpG methylation regulates this expression at imprint control regions (ICRs). Since ICRs are established before tissue specification, these methylation marks are similar across cell types. Thus, they are attractive for investigating the developmental origins of adult diseases using accessible tissues, but remain unknown. We determined genome-wide candidate ICRs in humans by performing whole-genome bisulphite sequencing (WGBS) of DNA derived from the three germ layers and from gametes. We identified 1,488 hemi-methylated candidate ICRs, including 19 of 25 previously characterized ICRs (https://humanicr.org/). Gamete methylation approached 0% or 100% in 332 ICRs (178 paternally and 154 maternally methylated), supporting parent-of-origin-specific methylation, and 65% were in well-described CTCF-binding or DNaseI hypersensitive regions. This draft of the human imprintome will allow for the systematic determination of the role of early-acquired imprinting dysregulation in the pathogenesis of human diseases and developmental and behavioural disorders.

Alterations in DNA methylation associate with fatty liver and metabolic abnormalities in a multi-ethnic cohort of pre-teenage children

Non-Alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in children. Epigenetic alterations, such as through DNA methylation (DNAm), may link adverse childhood exposures and fatty liver and provide non-invasive methods for identifying children at high risk for NAFLD and associated metabolic dysfunction. We investigated the association between differential DNAm and liver fat content (LFC) and liver injury in pre-adolescent children. Leveraging data from the Newborn Epigenetics Study (NEST), we enrolled 90    mother-child dyads and used linear regression to identify CpG sites and differentially methylated regions (DMRs) in peripheral blood associated with LFC and alanine aminotransferase (ALT) levels in 7-12yo children. DNAm was measured using Infinium HumanMethylationEPIC BeadChips (Illumina). LFC and fibrosis were quantified by magnetic resonance imaging proton density fat fraction and elastography. Median LFC was 1.4% (range, 0.3-13.4%) and MRE was 2.5 kPa (range, 1.5-3.6kPa). Three children had LFC ≥ 5%, while six (7.6%) met our definition of NAFLD (LFC ≥ 3.7%). All children with NAFLD were obese and five were Black. LFC was associated with 88 DMRs and 106 CpGs (FDR<5%). The top two CpGs, cg25474373 and cg07264203, mapped to or near RFTN2 and PRICKLE2 genes. These two CpG sites were also significantly associated with a NAFLD diagnosis. As higher LFC associates with an adverse cardiometabolic profile already in childhood, altered DNAm may identify these children early in disease course for targeted intervention. Larger, longitudinal studies are needed to validate these findings and determine mechanistic relevance.

Sleep onset, duration, or regularity: which matters most for child adiposity outcomes?

BACKGROUND/OBJECTIVES

Sleep measures, such as duration and onset timing, are associated with adiposity outcomes among children. Recent research among adults has considered variability in sleep and wake onset times, with the Sleep Regularity Index (SRI) as a comprehensive metric to measure shifts in sleep and wake onset times between days. However, little research has examined regularity and adiposity outcomes among children. This study examined the associations of three sleep measures (i.e., sleep duration, sleep onset time, and SRI) with three measures of adiposity (i.e., body mass index [BMI], waist circumference, and waist-to-height ratio [WHtR]) in a pediatric sample.

SUBJECTS/METHODS

Children (ages 4-13 years) who were part of the U.S. Newborn Epigenetic STudy (NEST) participated. Children (N = 144) wore an ActiGraph for 1 week. Sleep measures were estimated from actigraphy data. Weight, height, and waist circumference were measured by trained researchers. BMI and WHtR was calculated with the objectively measured waist and height values. Multiple linear regression models examined associations between child sleep and adiposity outcomes, controlling for race/ethnicity, child sex, age, mothers' BMI and sleep duration.

RESULTS

When considering sleep onset timing and duration, along with demographic covariates, sleep onset timing was not significantly associated with any of the three adiposity measures, but a longer duration was significantly associated with a lower BMI Z-score (β = -0.29, p < 0.001), waist circumference (β = -0.31, p < 0.001), and WHtR (β = -0.38, p < 0.001). When considering SRI and duration, duration remained significantly associated with the adiposity measures. The SRI and adiposity associations were in the expected direction, but were non-significant, except the SRI and WHtR association (β = -0.16, p = 0.077) was marginally non-significant.

CONCLUSIONS

Sleep duration was consistently associated with adiposity measures in children 4-13 years of age. Pediatric sleep interventions should focus first on elongating nighttime sleep duration, and examine if this improves child adiposity outcomes.

Gestational exposure to neighborhood police-reported crime and early childhood blood pressure in Durham, NC

Gestational exposure to police-reported crime is associated with adverse birth outcomes, but no previous research has evaluated the effects of gestational crime exposure on early childhood health or attempted to disentangle the health effects of neighborhood crime from the effects of neighborhood policing. Using data from 672 Newborn Epigenetics Study participants, we evaluate the effects of gestational exposure to violent crime and racialized drug policing on early childhood blood pressure. We demonstrate that violence and drug policing are consistently associated with increased blood pressure among children born to Black participants but not White or Latinx participants.

Shuffle the Decks: Children Are Sensitive to Incidental Nonrandom Structure in a Sequential-Choice Task

As children age, they can learn increasingly complex features of environmental structure-a key prerequisite for adaptive decision-making. Yet when we tested children (N = 304, 4-13 years old) in the Children's Gambling Task, an age-appropriate variant of the Iowa Gambling Task, we found that age was negatively associated with performance. However, this paradoxical effect of age was found only in children who exhibited a maladaptive deplete-replenish bias, a tendency to shift choices after positive outcomes and repeat choices after negative outcomes. We found that this bias results from sensitivity to incidental nonrandom structure in the canonical, deterministic forms of these tasks-and that it would actually lead to optimal outcomes if the tasks were not deterministic. Our results illustrate that changes in decision-making across early childhood reflect, in part, increasing sensitivity to environmental structure.

Therapeutic Potential of Date Palm against Human Infertility: A Review

Male and female infertility is a global major health problem. Approximately 15% of couples of a reproductive age are unable to achieve the desired pregnancy within 12 months, despite daily unprotected sexual intercourse, and about 10% of infertilities have no specific reason worldwide. Currently, many researchers are interested to investigate the use of natural remedies for preventive and curative purposes of infertility. This review brings together some of the data on the nutritional characteristics of the date palm and its different parts on fertility outcomes and critically evaluates the past and recent literature relevant to the consumption of date fruit against infertility-related problems. Due to its antioxidant potential, dates are considered a functional treatment for reducing the risks of infertility. In males, the date palm has a potent effect on the reproductive parameters including hormonal levels and seminal vesicle parameters as well as sperm motility, count, and viability; whereas, in females, it shows a convincing effect on reproductive parameters including oogenesis process, strengthening of oocytes, regulation of hormones, strengthening of pregnancy, reduction of the need for labor augmentation, and postpartum hemorrhage prevention.

Moderate Folic Acid Supplementation in Pregnant Mice Results in Altered Methyl Metabolism and in Sex-Specific Placental Transcription Changes

SCOPE

Many pregnant women have higher folic acid (FA) intake due to food fortification and increased vitamin use. It is reported that diets containing five-fold higher FA than recommended for mice (5xFASD) during pregnancy resulted in methylenetetrahydrofolate reductase (MTHFR) deficiency and altered choline/methyl metabolism, with neurobehavioral abnormalities in newborns. The goal is to determine whether these changes have their origins in the placenta during embryonic development.

METHODS AND RESULTS

Female mice are fed control diet or 5xFASD for a month before mating and maintained on these diets until embryonic day 17.5. 5xFASD led to pseudo-MTHFR deficiency in maternal liver and altered choline/methyl metabolites in maternal plasma (increased methyltetrahydrofolate and decreased betaine). Methylation potential (S-adenosylmethionine:S-adenosylhomocysteine ratio) and glycerophosphocholine are decreased in placenta and embryonic liver. Folic acid supplemented diet results in sex-specific transcriptome profiles in placenta, with validation of dietary expression changes of 29 genes involved in angiogenesis, receptor biology or neurodevelopment, and altered methylation of the serotonin receptor 2A gene.

CONCLUSION

Moderate increases in folate intake during pregnancy result in placental metabolic and gene expression changes, particularly in angiogenesis, which may contribute to abnormal behavior in pups. These results are relevant for determining a safe upper limit for folate intake during pregnancy.

Identifying the Best Questions for Rapid Screening of Secondhand Smoke Exposure Among Children

INTRODUCTION

Many children suffer from secondhand smoke exposure (SHSe), which leads to a variety of negative health consequences. However, there is no consensus on how clinicians can best query parents for possible SHSe among children. We employed a data-driven approach to create an efficient screening tool for clinicians to quickly and correctly identify children at risk for SHSe.

METHODS

Survey data from mothers and biospecimens from children were ascertained from the Neurodevelopment and Improving Children's Health following Environmental Tobacco Smoke Exposure (NICHES) study. Included were mothers and their children whose saliva were assayed for cotinine (n = 351 pairs, mean child age = 5.6 years). Elastic net regression predicting SHSe, as indicated from cotinine concentration, was conducted on available smoking-related questions and cross-validated with 2015-2016 National Health and Nutrition Examination Survey (NHANES) data to select the most predictive items of SHSe among children (n = 1670, mean child age = 8.4 years).

RESULTS

Answering positively to at least one of the two final items ("During the past 30 days, did you smoke cigarettes at all?" and "Has anyone, including yourself, smoked tobacco in your home in the past 7 days?") showed area under the curve = .82, and good specificity (.88) and sensitivity (.74). These results were validated with similar items in the nationally representative NHANES sample, area under the curve = .82, specificity = .78, and sensitivity = .77.

CONCLUSIONS

Our data-driven approach identified and validated two items that may be useful as a screening tool for a speedy and accurate assessment of SHSe among children.

IMPLICATIONS

The current study used a rigorous data-driven approach to identify questions that could reliably predict SHSe among children. Using saliva cotinine concentration levels as a gold standard for determining SHSe, our analysis employing elastic net regression identified two questions that served as good classifier for distinguishing children who might be at risk for SHSe. The two items that we validated in the current study can be readily used by clinicians, such as pediatricians, as part of screening procedures to quickly identify whether children might be at risk for SHSe.

Estimating exposure to neighborhood crime by race and ethnicity for public health research

BACKGROUND

Police-reported crime data (hereafter "crime") is routinely used as a psychosocial stressor in public health research, yet few studies have jointly examined (a) differences in crime exposure based on participant race and ethnicity, (b) differences in measures of crime exposure, and (c) considerations for how exposure to police is captured in police-recorded crime data. We estimate neighborhood exposure to crime and discuss the implications of structural differences in exposure to crime and police based on race and ethnicity.

METHODS

Using GPS coordinates from 1188 participants in the Newborn Epigenetics Study, we estimated gestational exposure to crime provided by the Durham, North Carolina, Police Department within (a) 800 m and (b) the Census block group of residence. We controlled for non-overlapping spatial boundaries in crime, Census, residential, and police data to report crime spatial (crime per km2) and population (crime per 1000 people per km2) density.

RESULTS

We demonstrate dramatic disparities in exposure to crime based on participant race and ethnicity and highlight variability in these disparities based on the type of crime and crime measurement method chosen.

CONCLUSIONS

Public health researchers should give thoughtful consideration when using police-reported crime data to measure and model exposure to crime in the United States, as police-reported data encompasses joint exposure to police and crime in the neighborhood setting.

Choline and Folic Acid in Diets Consumed during Pregnancy Interact to Program Food Intake and Metabolic Regulation of Male Wistar Rat Offspring

BACKGROUND

North American women consume high folic acid (FA), but most are not meeting the adequate intakes for choline. High-FA gestational diets induce an obesogenic phenotype in rat offspring. It is unclear if imbalances between FA and other methyl-nutrients (i.e., choline) account for these effects.

OBJECTIVE

This study investigated the interaction of choline and FA in gestational diets on food intake, body weight, one-carbon metabolism, and hypothalamic gene expression in male Wistar rat offspring.

METHODS

Pregnant Wistar rats were fed an AIN-93G diet with recommended choline and FA [RCRF; 1-fold, control] or high (5-fold) FA with choline at 0.5-fold [low choline and high folic acid (LCHF)], 1-fold [recommended choline and high folic acid (RCHF)], or 2.5-fold [high choline and high folic acid (HCHF)]. Male offspring were weaned to an RCRF diet for 20 wk. Food intake, weight gain, plasma energy-regulatory hormones, brain and plasma one-carbon metabolites, and RNA sequencing (RNA-seq) in pup hypothalamuses were assessed.

RESULTS

Adult offspring from LCHF and RCHF, but not HCHF, gestational diets had 10% higher food intake and weight gain than controls (P < 0.01). HCHF newborn pups had lower plasma insulin and leptin compared with LCHF and RCHF pups (P < 0.05), respectively. Pup brain choline (P < 0.05) and betaine (P < 0.01) were 22-33% higher in HCHF pups compared with LCHF pups; methionine was ∼23% lower after all high FA diets compared with RCRF (P < 0.01). LCHF adult offspring had lower brain choline (P < 0.05) than all groups and lower plasma 5-methyltetrahydrofolate (P < 0.05) than RCRF and RCHF groups. HCHF adult offspring had lower plasma cystathionine (P < 0.05) than LCHF adult offspring and lower homocysteine (P < 0.01) than RCHF and RCRF adult offspring. RNA-seq identified 144 differentially expressed genes in the hypothalamus of HCHF newborns compared with controls.

CONCLUSIONS

Increased choline in gestational diets modified the programming effects of high FA on long-term food intake regulation, plasma energy-regulatory hormones, one-carbon metabolism, and hypothalamic gene expression in male Wistar rat offspring, emphasizing a need for more attention to the choline and FA balance in maternal diets.

Young children's exposure to phenols in the home: Associations between house dust, hand wipes, silicone wristbands, and urinary biomarkers

BACKGROUND

Environmental phenols, such as parabens, bisphenol A, and triclosan, are ubiquitous in indoor environments because of their use in packaging, plastics, personal care products, and as anti-microbials. The primary pathways of exposure, as well as habits and behaviors that may lead to greater exposure, are still unclear.

OBJECTIVES

Herein, we investigate the relationships between phenols found in residential environments by comparing levels in paired samples of house dust and hand wipes with children's urine. In addition, phenols were analyzed in a novel exposure tool, the silicone wristbands, to investigate which external matrix best correlates with individual exposure based on urinary phenol biomarkers.

METHODS

Children aged 3-6 years in central North Carolina, United States, provided paired hand wipe (n = 202), wristband (n = 76), and spot urine samples (n = 180), while legal guardians completed questionnaires on habits and behaviors. House dust samples (n = 186) were collected from the main living area during home visits completed between 2014 and 2016.

RESULTS

Environmental phenols were detected frequently in all matrices investigated. Ethyl, methyl, and propylparaben levels observed in hand wipes, dust, and on wristbands were significantly correlated to their associated urinary biomarkers. In addition, intra-paraben correlations were noted, with biomarkers of ethyl, methyl, and propylparabens generally positively and significantly correlated, which suggests co-application of parabens in products. Triclosan levels in dust were positive and significantly correlated with levels in hand wipes and wristbands and with urinary concentrations, suggesting non-personal care product sources may be important in children's overall triclosan exposure. Generally, chemicals on wristbands were more highly correlated with urinary biomarkers than with chemicals in hand wipes or house dust. In addition, more frequent lotion use was positively associated with urinary concentrations of paraben biomarkers.

CONCLUSIONS

Our results suggest that the home environment is an important source of exposure which has been under-investigated for some environmental phenols (e.g., triclosan in house dust). Associations between wristbands and biomarkers of exposure, which were stronger than for hand wipes and house dust, suggest that silicone wristbands may provide a suitable exposure assessment tool for some phenols.

High folic acid intake increases methylation-dependent expression of Lsr and dysregulates hepatic cholesterol homeostasis

Food fortification with folic acid and increased use of vitamin supplements have raised concerns about high folic acid intake. We previously showed that high folic acid intake was associated with hepatic degeneration, decreased levels of methylenetetrahydrofolate reductase (MTHFR), lower methylation potential, and perturbations of lipid metabolism. MTHFR synthesizes the folate derivative for methylation reactions. In this study, we assessed the possibility that high folic acid diets, fed to wild-type and Mthfr^+/- mice, could alter DNA methylation and/or deregulate hepatic cholesterol homeostasis. Digital restriction enzyme analysis of methylation in liver revealed DNA hypomethylation of a CpG in the lipolysis-stimulated lipoprotein receptor (Lsr) gene, which is involved in hepatic uptake of cholesterol. Pyrosequencing confirmed this methylation change and identified hypomethylation of several neighboring CpG dinucleotides. Lsr expression was increased and correlated negatively with DNA methylation and plasma cholesterol. A putative binding site for E2F1 was identified. ChIP-qPCR confirmed reduced E2F1 binding when methylation at this site was altered, suggesting that it could be involved in increasing Lsr expression. Expression of genes in cholesterol synthesis, transport or turnover (Abcg5, Abcg8, Abcc2, Cyp46a1, and Hmgcs1) was perturbed by high folic acid intake. We also observed increased hepatic cholesterol and increased expression of genes such as Sirt1, which might be involved in a rescue response to restore cholesterol homeostasis. Our work suggests that high folic acid consumption disturbs cholesterol homeostasis in liver. This finding may have particular relevance for MTHFR-deficient individuals, who represent ~10% of many populations.

Replicated umbilical cord blood DNA methylation loci associated with gestational age at birth

DNA methylation is highly sensitive to in utero perturbations and has an established role in both embryonic development and regulation of gene expression. The foetal genetic component has been previously shown to contribute significantly to the timing of birth, yet little is known about the identity and behaviour of individual genes. The aim of this study was to test the extent genome-wide DNA methylation levels in umbilical cord blood were associated with gestational age at birth (GA). Findings were validated in an independent sample and evidence for the regulation of gene expression was evaluated for cis gene relationships in specimens with multi-omic data. Genome-wide DNA methylation, measured by the Illumina Infinium Human Methylation 450 K BeadChip, was associated with GA for 2,372 CpG probes (5% FDR) in both the Pregnancy, Race, Environment, Genes (PREG) and Newborn Epigenetic Study (NEST) cohorts. Significant probes mapped to 1,640 characterized genes and an association with nearby gene expression measures obtained by the Affymetrix HG-133A microarray was found for 11 genes. Differentially methylated positions were enriched for actively transcribed and enhancer chromatin states, were predominately located outside of CpG islands, and mapped to genes enriched for inflammation and innate immunity ontologies. In both PREG and NEST, the first principal component derived from these probes explained approximately one-half (58.1% and 47.8%, respectively) of the variation in GA. Gene pathways identified are consistent with the hypothesis of pathogen detection and response by the immune system to elicit premature labour as a consequence of unscheduled inflammation.

Folic acid content of diet during pregnancy determines post-birth re-set of metabolism in Wistar rat dams

Maternal metabolism begins to return to homeostasis (re-set) following birth and is accelerated by lactation. Delay in metabolic re-set may contribute to postpartum weight retention and later-life metabolic consequences. Folic acid (FA) is essential during pregnancy but inadequate intakes may alter 1-carbon metabolism, consequently affecting energy homeostatic systems. Our objectives were to examine the effects of FA content 1)below and 2)above requirements during pregnancy on the re-set of body weight, markers of hepatic 1-carbon metabolism and central and peripheral energy metabolic pathways in Wistar rat mothers early post-weaning (PW) compared to pregnant controls. Pregnant Wistar rats were fed an AIN-93G diet with FA at 0X, 1X (control, 2 mg FA/kg) or a range above requirements at 2.5X, 5X or 10X recommended levels then the control diet during lactation up to 1 week PW. Dams fed below (0X) or above (5X and 10X) FA requirements had delayed weight-loss from weaning up to 1 week PW, higher plasma insulin and HOMA-IR and changes in glucose and lipid metabolism-regulating genes in muscle, but not liver or adipose tissue compared to controls. Expression of folate-related genes in liver were lower in high FA fed dams. Central food intake neurons were not affected by FA diets. In conclusion, intakes of FA below (0X) or above (5X, 10X) requirements during pregnancy delayed weight-loss, dysregulated 1-carbon pathways in the liver and peripheral energy metabolic pathways in the Wistar rat mother up to 4 weeks after dietary exposure; potentially programming long-term negative metabolic effects and that of her future offspring.

Associations between attention deficit hyperactivity disorder symptoms and eating behaviors in early childhood

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) symptoms have been linked with eating behaviors and obesity adolescence and young adulthood. Yet, little is known about whether these associations occur during early childhood and few studies have examined these associations prospectively.

OBJECTIVES

To assess magnitude and direction of associations between childhood ADHD symptoms and eating behaviors.

METHODS

Participants were from the Newborn Epigenetics Study (N = 470, M age = 4 years). Multivariable linear regression models were used to examine cross-sectional associations between ADHD symptoms and eating behaviors. Latent Change Score (LCS) modeling was performed to examine prospective association among a subset of children with available follow-up data. (N = 100, M age = 7 years).

RESULTS

The cross-sectional results showed that attention problem (AP) and hyperactivity (HY) were positively associated with food responsiveness, emotional overeating, desire to drink, and slowness in eating. AP, but not HY, was inversely associated with enjoyment of food. Results of the LCS models revealed AP and HY were both positively associated with prospective changes in emotional overeating and satiety responsiveness. AP was further positively associated with prospective changes in food responsiveness. The reverse relationship predicting changes in ADHD symptoms from earlier assessments of eating behaviors was not significant.

CONCLUSION

Results suggest a link between ADHD symptoms and obesity-related eating behaviors in early childhood, highlighting the need to address self-regulation and healthy eating behaviors in the prevention of childhood obesity.

Folic acid supplementation in Italian women during pregnancy: A cross-sectional study conducted in general practice

OBJECTIVES

The association between folate insufficiency and congenital neural tube defects has been extensively investigated since the 1990s. To reach an adequate intake of folic acid (FA), improving folate status through periconceptional supplementation with FA, promotion of the consumption of foods rich in natural folates, and appropriate use of fortified foods is recommended. The aim of the present study was to investigate the supplementation of FA in a sample of pregnant women referred to general practice services in Italy, with a focus on the quality of information received by fertile women.

METHODS

Participants were recruited from patients admitted to 44 general practice offices enrolled in the Italian Society of Preventive Medicine and Lifestyle study and located in Italy throughout the national territory. A questionnaire for the evaluation of FA supplementation was administered by the general practitioners (GPs). The interviewed subjects were asked to provide information about pregnancy characteristics, nutritional habits, lifestyle and risk factors, information sources, and knowledge about FA.

RESULTS

This study included 328 participants. The percentage of women who did not take any FA supplements was 16.8%, and 66.4% of women started FA supplementation only after finding out they were pregnant. Only 16.8% of women started FA supplementation 12 wk before the beginning of pregnancy. The lack of supplementation with FA, as well as the incorrect adherence to the existing FA supplementation protocol, is attributable to different social (e.g., immigration, place of residence, job employment) and cultural (e.g., educational level, knowledge about FA) factors, the relatively poor planning of pregnancies, and the lack of information concerning the need for FA supplementation in the prepregnancy period. Finally, GPs and gynecologists are the only sources of information on the importance of FA supplementation.

CONCLUSIONS

The adherence of women to FA supplementation before pregnancy is still insufficient. The GP role in preconception care, and the promotion of FA supplementation, needs to be emphasized and further promoted.

The association between neuraxial anesthesia and the development of childhood asthma - a secondary analysis of the newborn epigenetics study cohort

Objectives: Childhood asthma is a common chronic illness that has been associated with mode of delivery. However, the effect of cesarean delivery alone does not fully account for the increased prevalence of childhood asthma. We tested the hypothesis that neuraxial anesthesia used for labor analgesia and cesarean delivery alters the risk of developing childhood asthma.Methods: Within the Newborn Epigenetics Study birth cohort, 196 mother and child pairs with entries in the electronic anesthesia records were included. From these records, data on maternal anesthesia type, duration of exposure, and drugs administered peripartum were abstracted and combined with questionnaire-derived prenatal risk factors and medical records and questionnaire-derived asthma diagnosis data in children. Logistic regression models were used to evaluate associations between type of anesthesia, duration of anesthesia, and the development of asthma in males and females.Results: We found that longer duration of epidural anesthesia was associated with a lower risk of asthma in male children (OR = 0.80; 95% CI = 0.66-0.95) for each hour of epidural exposure. Additionally, a unit increase in the composite dose of local anesthetics and opioid analgesics administered via the spinal route was associated with a lower risk of asthma in both male (OR = 0.59, 95% CI = 0.36-0.96) and female children (OR 0.26, 95% CI 0.09-0.82).Conclusion: Our data suggest that peripartum exposure to neuraxial anesthesia may reduce the risk of childhood asthma primarily in males. Larger human studies and model systems with longer follow-up are required to elucidate these findings.

Comparing the Use of Silicone Wristbands, Hand Wipes, And Dust to Evaluate Children's Exposure to Flame Retardants and Plasticizers

Organophosphate esters (OPEs) are applied as additive flame retardants, and along with phthalates, are also used as plasticizers in consumer products. As such, human exposure is common and chronic. Deployed as personal passive samplers, silicone wristbands have been shown to detect over a thousand industrial and consumer product chemicals; however, few studies have evaluated chemical concentrations with their corresponding biomarkers of exposure, especially in children. Further, little is known about how well the wristbands predict individual exposure compared to existing validated external exposure tools such as indoor air, dust, and hand wipes. Here, we analyzed wristbands worn by children (ages 3-6) for 18 OPEs and 10 phthalates and compared them to corresponding urinary biomarkers. In wristbands, 13 of 18 OPEs and all phthalates were detected in >80% of wristbands, and 6 OPEs and 4 phthalates were significantly associated with corresponding urinary metabolites (r_s = 0.2-0.6, p < 0.05). When compared to paired hand wipes and house dust, wristbands were found to have similar or greater correlation coefficients with respective urinary biomarkers. These results suggest that wristbands can serve as effective and quantitative assessment tools for evaluating personal exposure to some OPEs and phthalates, and for certain chemicals, may provide a better exposure estimate than indoor dust.

Folic Acid Supplement Intake and Risk of Colorectal Cancer in Women; A Case Control Study

Background

An ongoing controversy exists on the role of folic acid supplementation in colorectal cancer risk among epidemiological studies.

Objective

To assess the association between maternal folic acid supplementation and colorectal cancer risk.

Methods

A paired matched case control study of 405 subjects was performed, including women residing in 135 villages of East Azerbaijan, Iran. Per area, subjects were followed regularly in local healthcare centers, where health- and social-related information have been collected prospectively in face to face interviews by well-trained health workers. We extracted folic acid supplement intake, baseline characteristics, and confounders from healthcare records. The data for study participants were linked to national cancer registry repositories, from which we retrieved the data of 135 women diagnosed with colorectal cancer between 2005 to 2015. Two hundred seventy controls were individually matched with cases in terms of residing village, age, and gender. We applied multivariate conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

Findings

There was no significant association between folic acid supplementation and colorectal cancer risk in those with history of folic acid intake compared to those with no history of intake (OR 0.95; 95% CI 0.59 to 1.53), in those with less than five years of folic acid (0.79; 0.45 to 1.39) or in those with ≥5 years intake (1.09; 0.52 to 2.26). This risk did not change after adjustment for covariates or further stratification.

Conclusions

Maternal folic acid supplementation did not affect colorectal cancer risk in a population where supplemental folic acid is prescribed with regular intervals for women of child-bearing age.

Effect of Prenatal Smoke Exposure on Birth Weight: The Moderating Role of Maternal Depressive Symptoms

INTRODUCTION

Both prenatal smoke exposure and depression have been linked to lower birth weight, a risk factor for morbidity and mortality. Few studies have looked at the interaction between these risk factors and none have used a biomarker to objectively measure prenatal smoke exposure. The current study sought to examine independent and interactive effects of cotinine and depression on birth weight. The effect of race was also explored.

METHOD

Data were drawn from a prospective study of pregnant women (N = 568) in the southeastern United States. Maternal demographic, health information, depressive symptoms, and birth data were collected via self-report and medical record abstraction. Prenatal blood samples were assayed for cotinine.

RESULTS

Controlling for covariates, multiple regression analyses indicated that both cotinine and depressive symptoms independently predicted lower birth weight and a significant interaction was also observed. Upon probing the interaction, a negative association between cotinine levels and birth weight was found in the context of higher depression but not lower depression scores. Similarly, logistic regression analyses revealed a significant interaction between cotinine and depression, such that cotinine predicted having a baby less than 2500 g among women who fell above the indicated cutoff score. African American women had the highest levels of cotinine and lowest weight babies; however, race was not a significant moderator.

CONCLUSIONS

Results suggest prenatal smoke exposure has a greater negative effect on birth weight for women endorsing co-occurring depressive symptoms. Findings can inform targeted interventions and assist medical providers with identifying women at increased risk for poor perinatal outcomes.

IMPLICATIONS

Despite the common occurrence of smoking during pregnancy and prenatal depression, the interaction between these risk factors on birth weight has rarely been examined. Further, the extant results have been mixed, likely due in part to difficulties in measurement. The current study was the first to use prenatal cotinine to assess bias-free, continuous levels of prenatal smoke exposure. Results indicate that prenatal cotinine was a significant predictor of birth weight only in the context of maternal depressive symptoms. These findings have important implications for mitigating negative perinatal outcomes for pregnant women and their children.

Children's exposure to phthalates and non-phthalate plasticizers in the home: The TESIE study

BACKGROUND

Phthalates and their potential replacements, including non-phthalate plasticizers, are ubiquitous in home environments due to their presence in building materials, plastics, and personal care products. As a result, exposure to these compounds is universal. However, the primary pathways of exposure and understanding which products in the home are associated most strongly with particular exposures are unclear.

OBJECTIVES

We sought to investigate the relationships between phthalates and non-phthalate plasticizers in paired samples of house dust, hand wipes, and their corresponding metabolites in children's urine samples (n = 180). In addition, we compared product use or presence of materials in the household against all compounds to investigate the relationship between product use or presence and exposure.

METHODS

Children aged 3-6 years provided hand wipe and urine samples. Questionnaires were completed by mothers or legal guardians to capture product use and housing characteristics, and house dust samples were collected from the main living area during home visits.

RESULTS

Phthalates and non-phthalate replacements were detected frequently in the environmental matrices. All urine samples had at least 13 of 19 phthalate or non-phthalate replacement metabolites present. Hand wipe mass and dust concentrations of diisobutyl phthalate, benzyl butyl phthalate (BBP), bis(2-ethylhexyl) phthalate, and di-isononyl phthalate were significantly associated with their corresponding urinary metabolites (r_s = 0.18-0.56, p < 0.05). Bis(2-ethylhexyl) terephthalate (DEHTP) in dust was also significantly and positively correlated with its urinary metabolites (r_s = 0.33, p < 0.001). Vinyl flooring was most significantly and positively associated with particular phthalate exposures (indicated by concentrations in environmental matrices and urinary biomarkers). In particular, children who lived in homes with 100% vinyl flooring had urinary concentrations of monobenzyl phthalate, a BBP metabolite, that were 15 times higher than those of children who lived in homes with no vinyl flooring (p < 0.0001). Levels of BBP in hand wipes and dust were 3.5 and 4.5 times higher, respectively, in those homes with 100% vinyl flooring (p < 0.0001 for both).

CONCLUSIONS

This paper summarizes one of the most comprehensive phthalate and non-phthalate plasticizer investigation of potential residential exposure sources conducted in North America to date. The data presented herein provide evidence that dermal contact and hand-to-mouth behaviors are important sources of exposure to phthalates and non-phthalate plasticizers. In addition, the percentage of vinyl flooring is an important consideration when examining residential exposures to these compounds.

Maternal oversupplementation with folic acid and its impact on neurodevelopment of offspring

Folic acid, a B vitamin, is vital for early neurodevelopment and is well known for its protective effect against neural tube defects. Various national health agencies worldwide recommend that women of childbearing age take approximately 0.4 to 1 mg of supplemental folic acid daily to reduce the risk of neural tube defects in offspring. Several countries have tried to promote folic acid intake through mandatory fortification programs to reduce neural tube defects. Supplementation combined with mandatory fortification of foods has led to high levels of folic acid and related metabolites in women of childbearing age. Recent studies have reported that oversupplementation, defined as exceeding either the recommended dietary allowance or the upper limit of the daily reference intake of folic acid, may have negative effects on human health. This review examines whether maternal oversupplementation with folic acid affects the neurodevelopment of offspring. Data from animal studies suggest there are behavioral, morphological, and molecular changes in the brain of offspring. Additional studies are required to determine both the dosage of folic acid and the timing of folic acid intake needed for optimal neurodevelopment in humans.

Maternal pre-pregnancy obesity, offspring cord blood DNA methylation, and offspring cardiometabolic health in early childhood: an epigenome-wide association study

Pre-pregnancy obesity is an established risk factor for adverse sex-specific cardiometabolic health in offspring. Epigenetic alterations, such as in DNA methylation (DNAm), are a hypothesized link; however, sex-specific epigenomic targets remain unclear. Leveraging data from the Newborn Epigenetics Study (NEST) cohort, linear regression models were used to identify CpG sites in cord blood leukocytes associated with pre-pregnancy obesity in 187 mother-female and 173 mother-male offsprings. DNAm in cord blood was measured using the Illumina HumanMethylation450k BeadChip. Replication analysis was conducted among the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort. Associations between pre-pregnancy obesity-associated CpG sites and offspring BMI z-score (BMIz) and blood pressure (BP) percentiles at 4-5-years of age were also examined. Maternal pre-pregnacy obesity was associated with 876 CpGs in female and 293 CpGs in male offspring (false discovery rate <5%). Among female offspring, 57 CpG sites, including the top 18, mapped to the TAPBP gene (range of effect estimates: -0.83% decrease to 4.02% increase in methylation). CpG methylation differences in the TAPBP gene were also observed among males (range of effect estimates: -0.30% decrease to 2.59% increase in methylation). While technically validated, none of the TAPBP CpG sites were replicated in ALSPAC. In NEST, methylation differences at CpG sites of the TAPBP gene were associated with BMI z-score (cg23922433 and cg17621507) and systolic BP percentile (cg06230948) in female and systolic (cg06230948) and diastolic (cg03780271) BP percentile in male offspring. Together, these findings suggest sex-specific effects, which, if causal, may explain observed sex-specific effects of maternal obesity.

Racial and ethnic differences in predictors of vitamin D among pregnant women in south-eastern USA

Insufficient vitamin D during pregnancy increases risk of adverse outcomes, with known differences by race/ethnicity. We sought to determine whether predictors of vitamin D insufficiency vary by race/ethnicity in an ethnically diverse pregnancy cohort. Plasma 25-hydroxyvitamin D concentrations and patient characteristics were measured at first prenatal visit to prenatal clinics in south-eastern USA between 2009 and 2011 (n 504). Prevalence ratios (PR) and 95 % CI were estimated using multivariable regression to quantify predictors of vitamin D insufficiency, overall and by race/ethnicity. In race/ethnicity-stratified models, season was most associated with vitamin D insufficiency among non-Hispanic white women; PR for winter v. summer were 3·58 (95 % CI 1·64, 7·81) for non-Hispanic white, 1·52 (95 % CI 1·18, 1·95) for Hispanic and 1·14 (95 % CI 0·99, 1·30) for non-Hispanic black women. Although women with darker skin tones are most vulnerable to prenatal vitamin D insufficiency, season may be more strongly associated with insufficiency among women with lighter skin tones.

Associations between imprinted gene differentially methylated regions, appetitive traits and body mass index in children

BACKGROUND

Knowledge regarding genetic influences on eating behaviours is expanding; yet less is known regarding contributions of epigenetic variation to appetitive traits and body mass index (BMI) in children.

OBJECTIVE

The purpose of this study was to explore relationships between methylation at differentially methylated regions (DMRs) of imprinted genes (insulin-like growth factor 2/H19 and Delta-like, Drosophila, homolog 1/maternally expressed gene 3) using DNA extracted from umbilical cord blood leucocytes, two genetically influenced appetitive traits (food responsiveness and satiety responsiveness) and BMI.

METHODS

Data were obtained from participants (N = 317; mean age = 3.6 years; SD = 1.8 years) from the Newborn Epigenetic STudy. Conditional process models were implemented to investigate the associations between DMRs of imprinted genes and BMI, and test whether this association was mediated by appetitive traits and birthweight and moderated by sex.

RESULTS

Appetitive traits and birthweight did not mediate the relationship between methylation at DMRs. Increased insulin-like growth factor 2 DMR methylation was associated with higher satiety responsiveness. Higher satiety responsiveness was associated with lower BMI. Associations between methylation at DMRs, appetitive traits and BMI differed by sex.

CONCLUSIONS

This is one of the first studies to demonstrate associations between epigenetic variation established prior to birth with appetitive traits and BMI in children, providing support for the need to uncover genetic and epigenetic mechanisms for appetitive traits predisposing some individuals to obesity.

Subacute oral administration of folic acid elicits anti-inflammatory response in a mouse model of allergic dermatitis

Folic acid (FA) deficiency is associated with several health problems, including megaloblastic anemia and fetal neural tube defects. Therefore, supplementation with FA is strongly recommended by governments worldwide. Recent published reports indicate that FA functions in immune system maintenance. The main objective of this study is to examine possible anti-inflammatory and antipruritic effects of FA using a mouse model of allergic dermatitis. The mouse model was developed by repetitive sensitization to the Th2-type hapten toluene-2,4-diisocyanate (TDI). During the development of allergic dermatitis, FA was orally administered to the mice at doses of 8, 160, 1000 or 10,000 μg/day for 5 weeks. The ear swelling response and scratching behavior were monitored after the TDI challenge. Serum, ear tissue and auricular lymph node samples were isolated for further analysis 24 h after the TDI challenge. The ear swelling response was reduced in a dose-dependent manner by FA administration, and a significant change was observed at a concentration of 10,000-μg/day group. Comparable results were obtained through histological evaluation and cytokine level measurement in the ear tissue samples. Oral administration of FA exhibited the inhibitory effect on T-cell infiltration and T-cell-related cytokine production in auricular lymph nodes. Scratching behavior was not altered by FA administration. The in vivo evidence was corroborated by in vitro results, which showed that FA treatment significantly interfered with T-cell proliferation in a dose-dependent manner. Our findings imply that subacute oral administration of FA elicits an anti-inflammatory response, mainly through inhibition of T-cell proliferation.

Elevated metabolites of acetaminophen in cord blood of children with obesity

BACKGROUND

High-throughput metabolomics has been used cross-sectionally to evaluate differential metabolic profiles associated with human obesity.

OBJECTIVES

This study longitudinally assessed the cord blood metabolome to explore if metabolic signatures of obesity at age 3-5 are apparent at birth.

METHODS

In a nested case-control design, metabolomics analysis was performed on umbilical cord blood of 25 children who developed obesity by age 3-5 years, compared with 25 sex-matched non-obese children enrolled as part of an ongoing birth cohort. Logistic regression models were used to identify significant metabolites, adjusting for maternal pre-pregnancy obesity.

RESULTS

Children who had obesity by age 3-5 years had elevated levels of medium and long chain fatty acids including stearate, oleate and palmitate at birth. Children with obesity were also more likely to have elevated levels of acetaminophen metabolites at birth, specifically: 3-(N-acetyl-L-cystein-S-yl) acetaminophen, 2-hydroxyacetaminophen sulfate, 2-methoxyacetaminophen glucuronide and p-acetamidophenyl glucuronide.

CONCLUSION

Although the observed increases in lipids are consistent with previous metabolomic studies of obesity, this study is the first to report associations between acetaminophen metabolites and obesity in children; however, we lack mechanistic insights for this link. Larger human studies with longer follow-up and laboratory-controlled animal experiments are needed to clarify associations.

Biomarkers of exposure to SVOCs in children and their demographic associations: The TESIE Study

Semi-volatile organic compounds (SVOCs) are used extensively in consumer and personal care products; electronics; furniture; and building materials and are detected in most indoor environments. As a result, human exposure to mixtures of SVOCs is wide-spread. However, very few studies have measured biomarkers of exposure to multiple SVOC classes, and exposure determinants have not been thoroughly explored, particularly for young children. In this study, we investigated biomarkers of exposure to SVOCs among children (age 3-6 years), who may experience higher exposures and be more susceptible to adverse health outcomes than other age groups. We enrolled 203 participants in the Toddlers Exposure to SVOCs in Indoor Environments (TESIE) study (181 provided urine samples and 90 provided serum samples).We quantified 44 biomarkers of exposure to phthalates, organophosphate esters (OPEs), parabens, phenols, antibacterial agents and per- and polyfluoroalkyl substances (PFASs); we detected 29 of the 44 biomarkers in >95% of samples, and many biomarkers were detected at higher median concentrations than those previously reported in the U.S. general population. Demographic characteristics were associated with differences in concentrations. In general, non-Hispanic white race and higher maternal education were associated with lower concentrations, even after adjusting for other potential confounding variables. Our results suggest that outdoor temperature at the time of biospecimen collection may be a particularly important and under-evaluated predictor of biomarker concentrations; statistically significant relationships were observed between 10 biomarkers and outdoor temperature at the time of collection. A complex correlation structure was also observed among the biomarkers assessed. By and large, statistically significant correlations between biomarkers of exposure to phthalates, parabens, phenols, and OPEs were positive. Conversely, although PFASs were positively correlated with one another, they tended to be negatively correlated with other biomarkers where significant associations were observed. Taken together, our results provide evidence that the assessments of SVOC-associated health impacts should focus on chemical mixtures.

Self-reported prenatal tobacco smoke exposure, AXL gene-body methylation, and childhood asthma phenotypes

BACKGROUND

Epigenetic modifications, including DNA methylation, act as one potential mechanism underlying the detrimental effects associated with prenatal tobacco smoke (PTS) exposure. Methylation in a gene called AXL was previously reported to differ in response to PTS.

METHODS

We investigated the association between PTS and epigenetic changes in AXL and how this was related to childhood asthma phenotypes. We tested the association between PTS and DNA methylation at multiple CpG loci of AXL at birth using Pyrosequencing in two separate study populations, the Children's Health Study (CHS, n = 799) and the Newborn Epigenetic Study (NEST, n = 592). Plasma cotinine concentration was used to validate findings with self-reported smoking status. The inter-relationships among AXL mRNA and miR-199a1 expression, PTS, and AXL methylation were examined. Lastly, we evaluated the joint effects of AXL methylation and PTS on the risk of asthma and related symptoms at age 10 years old.

RESULTS

PTS was associated with higher methylation level in the AXL gene body in both CHS and NEST subjects. In the pooled analysis, exposed subjects had a 0.51% higher methylation level in this region compared to unexposed subjects (95% CI 0.29, 0.74; p < 0.0001). PTS was also associated with 21.2% lower expression of miR-199a1 (95% CI - 37.9, - 0.1; p = 0.05), a microRNA known to regulate AXL expression. Furthermore, the combination of higher AXL methylation and PTS exposure at birth increased the risk of recent episodes of bronchitic symptoms in childhood.

CONCLUSIONS

PTS was associated with methylation level of AXL and the combination altered the risk of childhood bronchitic symptoms.

Children's residential exposure to organophosphate ester flame retardants and plasticizers: Investigating exposure pathways in the TESIE study

BACKGROUND

Following the phase-out of polybrominated diphenyl ethers (PBDEs), organophosphate esters (OPEs) have been increasingly used in consumer products and building materials for their flame retardant and plasticizing properties. As a result, human exposure to these chemicals is widespread as evidenced by common detection of their metabolites in urine. However, little is known about the major exposure pathways, or factors that influence children's exposure to OPEs. Furthermore, little data is available on exposure to the novel aryl OPEs.

OBJECTIVES

To examine predictors of children's internal exposure, we assessed relationships between OPEs in house dust and on hand wipes and levels of their corresponding metabolites in paired urine samples (n = 181). We also examined associations between urinary metabolites and potential covariates, including child's age and sex, mother's educational attainment and race, and average outdoor air temperature.

METHODS

Children aged 3 to 6 years provided urine and hand wipe samples. Mothers or legal guardians completed questionnaires, and a house dust sample was taken from the main living area during home visits. Alkyl chlorinated and aryl OPEs were measured in dust and hand wipes, and composite urine samples were analyzed for several metabolites.

RESULTS

Tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), 2-ethylhexyl diphenyl phosphate (EHDPHP), triphenyl phosphate (TPHP), and 2-isopropylphenyl diphenyl phosphate (2IPPDPP) were detected frequently in hand wipes and dust (>80%), indicating that these compounds were near-ubiquitous in indoor environments. Additionally, bis(1-chloro-2-propyl) 1-hydroxy-2-propyl phosphate (BCIPHIPP), bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), diphenyl phosphate (DPHP), mono-isopropyl phenyl phenyl phosphate (ip-PPP), and mono-tert-butyl phenyl phenyl phosphate (tb-PPP) were detected in >94% of tested urine samples, signifying that TESIE participants were widely exposed to OPEs. Contrary to PBDEs, house dust OPE concentrations were generally not correlated with urinary OPE metabolite levels; however, hand wipe levels of OPEs were associated with internal dose. For example, children with the highest mass of TDCIPP on hand wipes had BDCIPP levels that were 2.73 times those of participants with the lowest levels (95% CI: 1.67, 4.48, p < 0.0001). Of the variables examined, hand wipe level was the most consistent and strongest predictor of OPE urinary metabolite concentrations. Outdoor air temperature was also a significant predictor of urinary BDCIPP concentrations, with a 1 °C increase in temperature corresponding to a 4% increase in urinary BDCIPP (p < 0.0001).

CONCLUSIONS

OPE exposures are highly prevalent, and data provided herein further substantiate hand-to-mouth contact and dermal absorption as important pathways of OPE exposure, especially for young children.

Associations between maternal cytokine levels during gestation and measures of child cognitive abilities and executive functioning

Preclinical studies demonstrate that environmentally-induced alterations in inflammatory cytokines generated by the maternal and fetal immune system can significantly impact fetal brain development. Yet, the relationship between maternal cytokines during gestation and later cognitive ability and executive function remains understudied. Children (n = 246) were born of mothers enrolled in the Newborn Epigenetic Study - a prospective pre-birth cohort in the Southeastern US. We characterized seven cytokines [IL-1β, IL-4,IL-6, IL-12p70, IL-17A, tumor necrosis factor-α (TNFα), and interferon-γ (IFNγ)] and one chemokine (IL-8) from maternal plasma collected during pregnancy. We assessed children's cognitive abilities and executive functioning at a mean age of 4.5 (SD = 1.1) years. Children's DAS-II and NIH toolbox scores were regressed on cytokines and the chemokine, controlling for maternal age, race, education, body mass index, IQ, parity, smoking status, delivery type, gestational weeks, and child birth weight and sex. Higher IL-12p70 (β_IL-12p70 = 4.26, p = 0.023) and IL-17A (β_IL-17A = 3.70, p = 0.042) levels were related to higher DAS-II GCA score, whereas higher IL-1β (β_IL-1B = -6.07, p = 0.003) was related to lower GCA score. Higher IL-12p70 was related to higher performance on NIH toolbox measures of executive functions related to inhibitory control and attention (β_IL-12p70 = 5.20, p = 0.046) and cognitive flexibility (β_IL-12p70 = 5.10, p = 0.047). Results suggest that dysregulation in gestational immune activity are associated with child cognitive ability and executive functioning.

Low Dietary Folate Interacts with MTHFD1 Synthetase Deficiency in Mice, a Model for the R653Q Variant, to Increase Incidence of Developmental Delays and Defects

Background

Suboptimal folate intake, a risk factor for birth defects, is common even in areas with folate fortification. A polymorphism in methylenetetrahydrofolate dehydrogenase 1 (MTHFD1), R653Q (MTHFD1 c.1958 G > A), has also been associated with increased birth defect risk, likely through reduced purine synthesis.

Objective

We aimed to determine if the interaction of MTHFD1 synthetase deficiency and low folate intake increases developmental abnormalities in a mouse model for MTHFD1 R653Q.

Methods

Female Mthfd1S+/+ and Mthfd1S+/- mice were fed control or low-folate diets (2 and 0.3 mg folic acid/kg diet, respectively) before mating and during pregnancy. Embryos and placentas were examined for anomalies at embryonic day 10.5. Maternal 1-carbon metabolites were measured in plasma and liver.

Results

Delays and defects doubled in litters of Mthfd1S+/- females fed low-folate diets compared to wild-type females fed either diet, or Mthfd1S+/- females fed control diets [P values (defects): diet 0.003, maternal genotype 0.012, diet × maternal genotype 0.014]. These adverse outcomes were associated with placental dysmorphology. Intrauterine growth restriction was increased by embryonic Mthfd1S+/- genotype, folate deficiency, and interaction of maternal Mthfd1S+/- genotype with folate deficiency (P values: embryonic genotype 0.045, diet 0.0081, diet × maternal genotype 0.0019). Despite a 50% increase in methylenetetrahydrofolate reductase expression in low-folate maternal liver (P diet = 0.0007), methyltetrahydrofolate concentration decreased 70% (P diet <0.0001) and homocysteine concentration doubled in plasma (P diet = 0.0001); S-adenosylmethionine decreased 40% and S-adenosylhomocysteine increased 20% in low-folate maternal liver (P diet = 0.002 and 0.0002, respectively).

Conclusions

MTHFD1 synthetase-deficient mice are more sensitive to low folate intake than wild-type mice during pregnancy. Reduced purine synthesis due to synthetase deficiency and altered methylation potential due to low folate may increase pregnancy complications. Further studies and individualized intake recommendations may be required for women homozygous for the MTHFD1 R653Q variant.

Annual Research Review: DNA methylation as a mediator in the association between risk exposure and child and adolescent psychopathology

BACKGROUND

DNA methylation (DNAm) is a potential mechanism for propagating the effects of environmental exposures on child and adolescent mental health. In recent years, this field has experienced steady growth.

METHODS

We provide a strategic review of the current child and adolescent literature to evaluate evidence for a mediating role of DNAm in the link between environmental risks and psychopathological outcomes, with a focus on internalising and externalising difficulties.

RESULTS

Based on the studies presented, we conclude that there is preliminary evidence to support that (a) environmental factors, such as diet, neurotoxic exposures and stress, influence offspring DNAm, and that (b) variability in DNAm, in turn, is associated with child and adolescent psychopathology. Overall, very few studies have examined DNAm in relation to both exposures and outcomes, and almost all analyses have been correlational in nature.

CONCLUSIONS

DNAm holds potential as a biomarker indexing both environmental risk exposure and vulnerability for child psychopathology. However, the extent to which it may represent a causal mediator is not clear. In future, collection of prospective risk exposure, DNAm and outcomes - as well as functional characterisation of epigenetic findings - will assist in determining the role of DNAm in the link between risk exposure and psychopathology.

High-Dose Perinatal Folic-Acid Supplementation Alters Insulin Sensitivity in Sprague-Dawley Rats and Diminishes the Expression of Adiponectin

The possible intake of folate in excess of the recommended upper levels is a matter of critical importance. This study was conducted to investigate the effects of prenatal and postnatal high folic acid supplementation (FAS) on glucose tolerance, insulin sensitivity, lipid metabolism, and expression of adiponectin in rats. The study included 20 female rats divided into two groups: control group and FAS group (receiving high folic acid supplemented diet). Both groups of female rats were mated and pregnancy confirmed. At parturition, the diet of 5 dams that were fed with control diet during gestation and their litters was changed to FAS diet and continued throughout lactation. Similarly, half of the dams that were previously fed with FAS diet during gestation and their litters were also changed to control diet. The remaining 5 dams in each group continued on their respective diets throughout lactation with their litters. Other dams remained on their respective diets throughout lactation. Food and water intake, body weight, lipid concentrations, insulin, and the expression of adiponectin were determined. Glucose tolerance and insulin sensitivity were also measured to evaluate glucose homeostasis. FAS significantly increased the postweaning food, water intake, triglyceride, and insulin levels but diminished insulin sensitivity in adult offspring. The expression of adiponectin in insulin-sensitive tissues was also significantly decreased and these were consistent with insulin resistance of FAS offspring. High-dose FAS may promote insulin resistance and dyslipidemia and disrupt glucose metabolism possibly by depressing adiponectin expression. Although this is an animal model and the effects of the diets cannot be directly transposed to humans, this study provides indications of the possible adverse effects of FAS maternal diet on glucose metabolism in the offspring.

Impact of Smoking Ban on Passive Smoke Exposure in Pregnant Non-Smokers in the Southeastern United States

Prenatal passive smoke exposure raises risk for negative birth outcomes. Legislation regulating public smoking has been shown to impact exposure levels, though fewer studies involving pregnant women have been conducted within the U.S. where bans are inconsistent across regions. This study examined the effect of a ban enacted in the southeastern U.S. on pregnant women's cotinine levels. Additional analyses compared self-reported exposure to cotinine and identified characteristics associated with passive exposure. Pregnant women (N = 851) were recruited prospectively between 2005 and 2011 in North Carolina. Sociodemographic and health data were collected via surveys; maternal blood samples were assayed for cotinine. Among non-active smokers who provided self-report data regarding passive exposure (N = 503), 20% were inconsistent with corresponding cotinine. Among all non-smokers (N = 668), being unmarried, African American, and less educated were each associated with greater passive exposure. Controlling for covariates, mean cotinine was higher prior to the ban compared to after, F(1, 640) = 24.65, p < 0.001. Results suggest that banning smoking in public spaces may reduce passive smoke exposure for non-smoking pregnant women. These data are some of the first to examine the impact of legislation on passive smoke exposure in pregnant women within the U.S. using a biomarker and can inform policy in regions lacking comprehensive smoke-free legislation.

Chemical and non-chemical stressors affecting childhood obesity: a systematic scoping review

Childhood obesity in the United States has doubled over the last three decades and currently affects 17% of children and adolescents. While much research has focused on individual behaviors impacting obesity, little research has emphasized the complex interactions of numerous chemical and non-chemical stressors found in a child's environment and how these interactions affect a child's health and well-being. The objectives of this systematic scoping review were to (1) identify potential chemical stressors in the context of non-chemical stressors that impact childhood obesity; and, (2) summarize our observations for chemical and non-chemical stressors in regards to child-specific environments within a community setting. A review was conducted to identify chemical and non-chemical stressors related to childhood obesity for the childhood life stages ranging from prenatal to adolescence. Stressors were identified and grouped into domains: individual behaviors, family/household behaviors, community stressors, and chemical exposures. Stressors were related to the child and the child's everyday environments and used to characterize child health and well-being. This review suggests that the interactions of chemical and non-chemical stressors are important for understanding a child's overall health and well-being. By considering these relationships, the exposure science research community can better design and implement strategies to reduce childhood obesity.

Early prenatal vitamin D concentrations and social-emotional development in infants

BACKGROUND

Many pregnant women in the United States have suboptimal vitamin D, but the impact on infant development is unclear. Moreover, no pregnancy-specific vitamin D recommendations have been widely accepted.

AIMS

Given the ubiquitous expression of vitamin D receptors in the brain, we investigated the association between early prenatal plasma 25-hydroxyvitamin D (25(OH)D) concentrations and children's social and emotional development in the Newborn Epigenetic Study, a prospective study of pregnancies from 2009 to 2011 in Durham, North Carolina.

METHODS

We measured 25(OH)D concentrations in first or second trimester plasma samples and categorized 25(OH)D concentrations into quartiles. Covariates were derived from maternal questionnaires. Mothers completed the Infant Toddler Social-Emotional Development Assessment when children were 12-24 months of age. We used multivariable linear regression to evaluate associations between 25(OH)D and specific behavior scores, adjusted for season of blood draw, maternal age, education, parity, smoking, marital status, prepregnancy BMI, and infant gender. We investigated effect-measure modification by race/ethnicity.

RESULTS

Of the 218 mother-infant pairs with complete data, Black mothers had much lower 25(OH)D concentrations as compared to White and Hispanic mothers. After adjustment, lower prenatal 25(OH)D was associated with slightly higher (less favorable) Internalizing scores among White children, but lower (more favorable) Internalizing scores among Black and Hispanic children. Lower prenatal 25(OH)D also appears to be associated with higher (less favorable) dysregulation scores, though only among White and Hispanic children.

CONCLUSIONS

Though imprecise, preliminary results warrant further investigation regarding a role for prenatal vitamin D on children's early social and emotional development.

Is High Folic Acid Intake a Risk Factor for Autism?-A Review

Folate is required for metabolic processes and neural development. Insuring its adequate levels for pregnant women through supplementation of grain-based foods with synthetic folic acid (FA) in order to prevent neural tube defects has been an ongoing public health initiative. However, because women are advised to take multivitamins containing FA before and throughout pregnancy, the supplementation together with natural dietary folates has led to a demographic with high and rising serum levels of unmetabolized FA. This raises concerns about the detrimental effects of high serum synthetic FA, including a rise in risk for autism spectrum disorder (ASD). Some recent studies have reported a protective effect of FA fortification against ASD, but others have concluded there is an increased risk for ASD and other negative neurocognitive development outcomes. These issues are accompanied by further health questions concerning high, unmetabolized FA levels in serum. In this review, we outline the reasons excess FA supplementation is a concern and review the history and effects of supplementation. We then examine the effects of FA on neuronal development from tissue culture experiments, review recent advances in understanding of metabolic functional blocks in causing ASD and treatment for these with alternative forms such as folinic acid, and finally summarize the conflicting epidemiological findings regarding ASD. Based on the evidence evaluated, we conclude that caution regarding over supplementing is warranted.

Epigenetic regulation of AXL and risk of childhood asthma symptoms

Background

AXL is one of the TAM (TYRO3, AXL and MERTK) receptor tyrosine kinases and may affect numerous immune-related health conditions. However, the role for AXL in asthma, including its epigenetic regulation, has not been extensively studied.

Methods

We investigated the association between AXL DNA methylation at birth and risk of childhood asthma symptoms at age 6 years. DNA methylation of multiple CpG loci across the regulatory regions of AXL was measured in newborn bloodspots using the Illumina HumanMethylation450 array on a subset of 246 children from the Children's Health Study (CHS). Logistic regression models were fitted to assess the association between asthma symptoms and DNA methylation. Findings were evaluated for replication in a separate population of 1038 CHS subjects using Pyrosequencing on newborn bloodspot samples. AXL genotypes were extracted from genome-wide data.

Results

Higher average methylation of CpGs in the AXL gene at birth was associated with higher risk of parent-reported wheezing, and the association was stronger in girls than in boys. This relationship reflected the methylation status of the gene-body region near the 5' end, for which a 1% higher methylation level was significantly associated with a 72% increased risk of ever having wheezed by 6 years. The association of one CpG locus, cg00360107 was replicated using Pyrosequencing. Increased AXL methylation was also associated with lower mRNA expression level of this gene in lung tissue from the Cancer Genome Atlas (TCGA) dataset. Furthermore, AXL DNA methylation was strongly linked to underlying genetic polymorphisms.

Conclusions

AXL DNA methylation at birth was associated with higher risk for asthma-related symptoms in early childhood.

Maternal BMI at the start of pregnancy and offspring epigenome-wide DNA methylation: findings from the pregnancy and childhood epigenetics (PACE) consortium

Pre-pregnancy maternal obesity is associated with adverse offspring outcomes at birth and later in life. Individual studies have shown that epigenetic modifications such as DNA methylation could contribute. Within the Pregnancy and Childhood Epigenetics (PACE) Consortium, we meta-analysed the association between pre-pregnancy maternal BMI and methylation at over 450,000 sites in newborn blood DNA, across 19 cohorts (9,340 mother-newborn pairs). We attempted to infer causality by comparing the effects of maternal versus paternal BMI and incorporating genetic variation. In four additional cohorts (1,817 mother-child pairs), we meta-analysed the association between maternal BMI at the start of pregnancy and blood methylation in adolescents. In newborns, maternal BMI was associated with small (<0.2% per BMI unit (1 kg/m2), P < 1.06 × 10-7) methylation variation at 9,044 sites throughout the genome. Adjustment for estimated cell proportions greatly attenuated the number of significant CpGs to 104, including 86 sites common to the unadjusted model. At 72/86 sites, the direction of the association was the same in newborns and adolescents, suggesting persistence of signals. However, we found evidence for acausal intrauterine effect of maternal BMI on newborn methylation at just 8/86 sites. In conclusion, this well-powered analysis identified robust associations between maternal adiposity and variations in newborn blood DNA methylation, but these small effects may be better explained by genetic or lifestyle factors than a causal intrauterine mechanism. This highlights the need for large-scale collaborative approaches and the application of causal inference techniques in epigenetic epidemiology.

Folate dietary insufficiency and folic acid supplementation similarly impair metabolism and compromise hematopoiesis

While dietary folate deficiency is associated with increased risk for birth defects and other diseases, evidence suggests that supplementation with folic acid can contribute to predisposition to some diseases, including immune dysfunction and cancer. Herein, we show that diets supplemented with folic acid both below and above the recommended levels led to significantly altered metabolism in multiple tissues in mice. Surprisingly, both low and excessive dietary folate induced similar metabolic changes, which were particularly evident for nucleotide biosynthetic pathways in B-progenitor cells. Diet-induced metabolic changes in these cells partially phenocopied those observed in mice treated with anti-folate drugs, suggesting that both deficiency and excessive levels of dietary folic acid compromise folate-dependent biosynthetic pathways. Both folate deficiency and excessive dietary folate levels compromise hematopoiesis, resulting in defective cell cycle progression, persistent DNA damage, and impaired production of lymphocytes. These defects reduce the reconstitution potential in transplantation settings and increase radiation-induced mortality. We conclude that excessive folic acid supplementation can metabolically mimic dietary folate insufficiency, leading to similar functional impairment of hematopoiesis.