Excess perigestational folic acid exposure induces metabolic dysfunction in post-natal life

Methyl donor micronutrients, hypothalamic development and programming for metabolic disease

Nutriture in utero is essential for fetal brain development through the regulation of neural stem cell proliferation, differentiation, and apoptosis, and has a long-lasting impact on risk of disease in offspring. This review examines the role of maternal methyl donor micronutrients in neuronal development and programming of physiological functions of the hypothalamus, with a focus on later-life metabolic outcomes. Although evidence is mainly derived from preclinical studies, recent research shows that methyl donor micronutrients (e.g., folic acid and choline) are critical for neuronal development of energy homeostatic pathways and the programming of characteristics of the metabolic syndrome in mothers and their children. Both folic acid and choline are active in one-carbon metabolism with their impact on epigenetic modification of gene expression. We conclude that an imbalance of folic acid and choline intake during gestation disrupts DNA methylation patterns affecting mechanisms of hypothalamic development, and thus elevates metabolic disease risk. Further investigation, including studies to determine translatability to humans, is required.

Fructooligosaccharide feeding during gestation to pregnant mice provided excessive folic acid decreases maternal and female fetal oxidative stress by increasing intestinal microbe-derived hydrogen gas

Fructooligosaccharide (FOS) is fermented by intestinal microbes to generate intestinal microbe-derived hydrogen gas (IMDH). Oxidative stress increases during gestation, whereas hydrogen gas has antioxidant effects with therapeutic benefits. We have previously reported that the offspring from a pregnant, excessive folic acid mouse model (PEFAM) had abnormal glucose metabolism after growth. We hypothesized that IMDH by FOS feeding during gestation in PEFAM would suppress maternal and fetal oxidative stress. C57BL/6J mice on day 1 of gestation were divided into 3 groups and dissected at gestational day 18. The control (CONT) diet was AIN-93G containing folic acid 2 mg/kg diet; PEFAM was fed with an excessive folic acid (EFA) diet containing folic acid 40 mg/kg diet, and the EFA-FOS diet was replaced half of the sucrose in the EFA diet. Hydrogen gas concentrations in maternal livers and whole fetuses in EFA-FOS were significantly higher than those in CONT and EFA, respectively (P < .05). Maternal and fetal 8-hydroxy-2'-deoxyguanosine in EFA-FOS were not significantly different from those in the CONT group, whereas those in the EFA group were significantly increased compared with CONT and EFA-FOS (P < .05). In EFA-FOS, expression of protein and mRNA of superoxide dismutase and heme oxygenase 1 in mothers and superoxide dismutase in fetuses were not significantly different from those in CONT, whereas those in EFA were significantly increased (P < .05). The protein expression of Nrf2 in mothers and fetuses were not significantly different between EFA-FOS and CONT. Therefore, FOS feeding to PEFAM during gestation decreases maternal and fetal oxidative stress through IMDH.

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.

Folic acid supplementation in a mouse model of diabetes in pregnancy alters insulin sensitivity in female mice and beta cell mass in offspring

Epidemiological studies have reported discrepant findings on the relationship between folic acid intake during pregnancy and risk for gestational diabetes mellitus (GDM). To begin to understand how folic acid impacts metabolic health during pregnancy, we determined the effects of excess folic acid supplementation (5× recommendation) on maternal and fetal offspring metabolic health. Using a mouse (female C57BL/6J) model of diet-induced diabetes in pregnancy (western diet) and control mice, we show that folic acid supplementation improved insulin sensitivity in the female mice fed the western diet and worsened insulin sensitivity in control mice. We found no unmetabolized folic acid in liver from supplemented mice suggesting the metabolic effects of folic acid supplementation are not due to unmetabolized folic acid. Male fetal (gestational day 18.5) offspring from folic acid supplemented dams (western and control) had greater beta cell mass and density than those from unsupplemented dams; this was not observed in female offspring. Differential sex-specific hepatic gene expression profiles were observed in the fetal offspring from supplemented dams but this differed between western and controls. Our findings suggest that folic acid supplementation affects insulin sensitivity in female mice, but is dependent on their metabolic phenotype and has sex-specific effects on offspring pancreas and liver.

Maternal folate and metabolic programming of the offspring: A systematic review of the literature

There is emerging evidence suggesting that folate status during pregnancy may play a role in fetal programming of metabolic disease. Therefore, this systematic review aims to summarize and systematize the current evidence surrounding the relationship between maternal folate status during pregnancy and offspring metabolic programming, focusing on both animal and human studies. PubMed, Web of Science and Scopus databases were searched in order to identify studies conducted on pregnant women or in animals studying the association between maternal folate exposure and at least one metabolic syndrome outcome in offspring after birth (weight, blood pressure, glucose regulation parameters, triglycerides and high-density lipoprotein cholesterol (HDL-C) levels). The quality of included studies was assessed using SYRCLE Risk of Bias Tools for animal studies and NHLBI Study Quality Assessment Tools for observational studies and randomized controlled trials. Among the 10 "good" or "fair" studies that investigated excessive folate exposure during the perigestational period, 7 animal studies and 1 human study reported a positive association with development of metabolic outcomes in offspring. On the other hand, 6 of the 7 "good" or "fair" included human studies compared adequate versus low folate exposure, showing a lack of association (n = 3) or a protective effect (n = 3) regarding offspring's dysmetabolism. In conclusion, there is strong evidence from animal trials suggesting that excessive folate intake in early phases of development programs for metabolic dysfunction. While human evidence regarding excessive maternal folate exposure is currently scarce, human studies suggest that folate adequacy in pregnancy is not detrimental for metabolic function of the offspring.

High Serum Folate Concentration, Vitamin B12 Deficiency, and Anthropometric Nutritional Status in Brazilian Children Aged 6-59 Months: Data from the Brazilian National Survey of Child Nutrition

BACKGROUND

Vitamin B12 and folate are key nutrients that help children reach their full potential in growth and development; however, little is known about the status of these vitamins in Brazilian children.

OBJECTIVES

To describe the serum concentrations of vitamin B12 and folate, to investigate the association between high folate concentration (HFC) and vitamin B12 deficiency, and to evaluate the association between vitamin B12 and stunting/underweight in Brazilian children aged 6-59 mo.

METHODS

Data from 7417 children aged 6-59 mo collected during the Brazilian National Survey on Child Nutrition were used. Serum concentrations of vitamin B12 of <150 pmol/L and folate of <10 nmol/L were classified as deficient, and folate concentrations of >45.3 nmol/L were classified as HFC. Children with length/height-for-age z-score of less than -2 were considered stunted, and those with weight-for-age z-score of less than -2 were underweight. Logistic regression models were performed.

RESULTS

In Brazil, 14.2% (95% CI: 12.2, 16.1) of children aged 6-59 mo had vitamin B12 deficiency, 1.1% (95% CI: 0.5, 1.6) had folate deficiency, and 36.9% (95% CI: 33.4, 40.3) had HFC. Vitamin B12 deficiency was higher in children from the northern region of Brazil (28.5%), between 6 and 24 mo (25.3%), whose mothers had lower formal education (0-7 y; 18.7%). Children with HFC had 62% lower odds (OR: 0.38; 95% CI: 0.27, 0.54) of vitamin B12 deficiency than those with normal/deficient folate. Children with vitamin B12 deficiency and normal/deficient folate had higher odds of stunting (OR: 1.58; 95% CI: 1.02, 2.43) than children without vitamin B12 deficiency and normal/deficient folate.

CONCLUSIONS

Vitamin B12 deficiency is a public health problem among Brazilian children aged <2 y with vulnerable socioeconomic status. HFC was inversely associated with vitamin B12 deficiency, and lower odds of stunting were observed in children with HFC and vitamin B12 deficiency than in those with vitamin B12 deficiency and normal/deficient folate.

Molecular mechanisms involved in fetal programming and disease origin in adulthood

Fetal programming occurs during the gestational age when exposure to environmental stimuli can cause long-term changes in the fetus, predisposing it to develop chronic non-communicable diseases (CNCD) in adulthood. Herein, we summarized the role of low-calorie or high-fat diets during pregnancy as fetal programming agents that induce intrauterine growth restriction (IUGR), amplified de novo lipogenesis, and increased amino acid transport to the placenta, which favor the CNCD onset in the offspring. We also outlined how maternal obesity and gestational diabetes act as fetal programming stimuli by reducing iron absorption and oxygen transport to the fetus, stimulating inflammatory pathways that boost neurological disorders and CNCD in the progeny. Moreover, we reviewed the mechanisms through which fetal hypoxia elevates the offspring's risk of developing hypertension and chronic kidney disease in adult life by unbalancing the renin-angiotensin system and promoting kidney cell apoptosis. Finally, we examined how inadequate vitamin B12 and folic acid consumption during pregnancy programs the fetus to greater adiposity, insulin resistance, and glucose intolerance in adulthood. A better understanding of the fetal programming mechanisms may help us reduce the onset of insulin resistance, glucose intolerance, dyslipidemia, obesity, hypertension, diabetes mellitus, and other CNCD in the offspring during adulthood.

Mitigating the detrimental developmental impact of early fetal alcohol exposure using a maternal methyl donor-enriched diet

Fetal alcohol exposure at any stage of pregnancy can lead to fetal alcohol spectrum disorder (FASD), a group of life-long conditions characterized by congenital malformations, as well as cognitive, behavioral, and emotional impairments. The teratogenic effects of alcohol have long been publicized; yet fetal alcohol exposure is one of the most common preventable causes of birth defects. Currently, alcohol abstinence during pregnancy is the best and only way to prevent FASD. However, alcohol consumption remains astoundingly prevalent among pregnant women; therefore, additional measures need to be made available to help protect the developing embryo before irreparable damage is done. Maternal nutritional interventions using methyl donors have been investigated as potential preventative measures to mitigate the adverse effects of fetal alcohol exposure. Here, we show that a single acute preimplantation (E2.5; 8-cell stage) fetal alcohol exposure (2 × 2.5 g/kg ethanol with a 2h interval) in mice leads to long-term FASD-like morphological phenotypes (e.g. growth restriction, brain malformations, skeletal delays) in late-gestation embryos (E18.5) and demonstrate that supplementing the maternal diet with a combination of four methyl donor nutrients, folic acid, choline, betaine, and vitamin B12, prior to conception and throughout gestation effectively reduces the incidence and severity of alcohol-induced morphological defects without altering DNA methylation status of imprinting control regions and regulation of associated imprinted genes. This study clearly supports that preimplantation embryos are vulnerable to the teratogenic effects of alcohol, emphasizes the dangers of maternal alcohol consumption during early gestation, and provides a potential proactive maternal nutritional intervention to minimize FASD progression, reinforcing the importance of adequate preconception and prenatal nutrition.

Elevated Maternal Folate Status and Changes in Maternal Prolactin, Placental Lactogen and Placental Growth Hormone Following Folic Acid Food Fortification: Evidence from Two Prospective Pregnancy Cohorts

Folic acid (FA) food fortification in Australia has resulted in a higher-than-expected intake of FA during pregnancy. High FA intake is associated with increased insulin resistance and gestational diabetes. We aimed to establish whether maternal one-carbon metabolism and hormones that regulate glucose homeostasis change in healthy pregnancies post-FA food fortification. Circulating folate, B12, homocysteine, prolactin (PRL), human placental lactogen (hPL) and placental growth hormone (GH2) were measured in early pregnancy maternal blood in women with uncomplicated pregnancies prior to (SCOPE: N = 604) and post (STOP: N = 711)-FA food fortification. FA food fortification resulted in 63% higher maternal folate. STOP women had lower hPL (33%) and GH2 (43%) after 10 weeks of gestation, but they had higher PRL (29%) and hPL (28%) after 16 weeks. FA supplementation during pregnancy increased maternal folate and reduced homocysteine but only in the SCOPE group, and it was associated with 54% higher PRL in SCOPE but 28% lower PRL in STOP. FA food fortification increased maternal folate status, but supplements no longer had an effect, thereby calling into question their utility. An altered secretion of hormones that regulate glucose homeostasis in pregnancy could place women post-fortification at an increased risk of insulin resistance and gestational diabetes, particularly for older women and those with obesity.

Effects of High-dose Folic Acid Supplementation on Maternal/Child Health Outcomes: Gestational Diabetes Mellitus in Pregnancy and Insulin Resistance in Offspring

OBJECTIVES

The purpose of this study was to evaluate the effects of maternal high folic acid (FA) supplementation during pregnancy on glucose intolerance in dams and insulin resistance in offspring.

METHODS

Wistar female rats (n=18) were mated and randomly divided into 3 groups: a control group and 2 experimental groups. Three different feeding protocols were administered during pregnancy: control group, 2 mg/kg FA (recommended level FA supplementation); experimental 1 group, 5 mg/kg FA (tolerable upper intake level of FA supplementation [ULFolS]); and experimental 2 group, 40 mg/kg FA (high FA supplementation [HfolS]). All dams were fed the same FA content diet (2 mg/kg FA) during the lactation period. An oral glucose tolerance test was performed on day 16 of pregnancy. After the lactation period, body weight and food intake of 36 pups were monitored. Dams were euthanized at the end of the lactation period and half of the pups were euthanized at the end of week 7 and the others at the end of week 12. Serum FA, homocysteine, vitamin B₁₂, insulin, glucose, interleukin-6, tumor necrosis factor-alpha, glycated hemoglobin (A1C), and adiponectin levels of mothers and pups were evaluated. The homeostatic model of insulin resistance (HOMA-IR) was used to determine insulin resistance in dams and offspring.

RESULTS

According to glucose tolerance test results of dams, blood glucose values at minutes 0, 60, 90, and 120 for the HFolS group were significantly higher compared with the control group (p<0.05). The A1C level in HFolS dams was significantly higher than in the control group (p<0.05). The mean birthweight of the pups in the HFolS group was significantly higher than that of control pups (p<0.05). HOMA-IR values for control and HFolS offspring were similar at weeks 7 and 12 and higher than in ULFolS offspring (p>0.05).

CONCLUSIONS

It was determined that high doses of FA exposure during pregnancy might be effective in the development of glucose intolerance in dams and insulin resistance in offspring in this study.

Maternal micronutrient disturbance as risks of offspring metabolic syndrome

Metabolic syndrome (MetS) is defined as a constellation of individual metabolic disturbances, including central obesity, hypertension, dyslipidemia, and insulin resistance. The established pathogenesis of MetS varies extensively with gender, age, ethnic background, and nutritional status. In terms of nutritional status, micronutrients are more likely to be discounted as essential components of required nutrition than macronutrients due to the small amount required. Numerous observational studies have shown that pregnant women frequently experience malnutrition, especially in developing and low-income countries, resulting in chronic MetS in the offspring due to the urgent and increasing demands for micronutrients during gestation and lactation. Over the past few decades, scientific developments have revolutionized our understanding of the association between balanced maternal micronutrients and MetS in the offspring. Examples of successful individual, dual, or multiple maternal micronutrient interventions on the offspring include iron for hypertension, selenium for type 2 diabetes, and a combination of folate and vitamin D for adiposity. In this review, we aim to elucidate the effects of maternal micronutrient intake on offspring metabolic homeostasis and discuss potential perspectives and challenges in the field of maternal micronutrient interventions.

Folic acid oversupplementation during pregnancy disorders lipid metabolism in male offspring via regulating arginase 1-associated NOS3-AMPKα pathway

BACKGROUND & AIMS

Folic acid supplementation is widely accepted during pregnancy, as it exerts a protective effect on neural tube defects. However, the long-term underlying effects of folic acid supplementation during pregnancy (FASDP) on offspring remain unclear.

METHODS

Thirty pregnant female rats were randomly divided into normal control group, folic acid appropriate supplementation group (2.5 × FA group) and folic acid oversupplementation group (5 × FA group) and fed with corresponding folic acid concentration AIN93G diet. UPLC-Q-TOF-MS, UPLC-TQ-MS and GC-MS were performed to detect the serum metabolites profiles in adult male offspring and explore the effects of FASDP. Moreover, molecular biology technologies were used to clarify the underlying mechanism.

RESULTS

We demonstrate that 2.5-folds folic acid leads to dyslipidemic-diabetic slightly in male offspring, while 5-folds folic acid aggravates the disorder and prominent hepatic lipid accumulations. Using untargeted and targeted metabolomics, total 63 differential metabolites and 12 significantly differential KEGG pathways are identified. Of note, arginine biosynthesis, arginine and proline metabolism are the two most significant pathways. Mechanistic investigations reveal that the increased levels of arginase-1 (Arg1) causes the lipid metabolism disorder by regulating nitric oxide synthase-3 (NOS3)-adenosine monophosphate activated protein kinase-α (AMPKα) pathway, resulting in lipid accumulation in hepatocytes.

CONCLUSIONS

Our data suggest that maternal folic acid oversupplementation during pregnancy contributes to lipid metabolism disorder in male offspring by regulating Arg1-NOS3-AMPKα pathway.

Maternal Nutritional Status and Development of Atopic Dermatitis in Their Offspring

Atopic dermatitis (AD) is the leading chronic skin inflammatory disease and the initial manifestation of atopic march. Available evidence supports the notion that primary prevention early in life leads to a decreased incidence of AD, thus possibly decreasing the subsequent occurrence of atopic march. Nutritional status is essential to a proper functioning immune system and is valued for its important role in AD. Essential nutrients, which include carbohydrates, proteins, lipids, vitamins, and minerals, are transferred from the mother to the fetus through the placenta during gestation. Various nutrients, such as polyunsaturated fatty acids (PUFAs) and vitamin D, were studied in relation to maternal status and offspring allergy. However, no strong evidence indicates that a single nutrient or food in mothers' diet significantly affects the risk of childhood AD. In the light of current evidence, mothers should not either increase nor avoid consuming these nutrients to prevent or ameliorate allergic diseases in their offspring. Each essential nutrient has an important role in fetal development, and current government recommendations suggest specific intake amounts for pregnant women. This review discusses evidence on how various nutrients, including lipids (monounsaturated fatty acids, PUFAs, saturated fatty acids, and short-chain fatty acids), carbohydrates (oligosaccharides and polysaccharides), proteins, vitamins (A, B, C, D, and E), and trace minerals (magnesium, iron, zinc, copper, selenium, and strontium) in maternal status are associated with the development of AD and their possible mechanisms.

High Intakes of [6S]-5-Methyltetrahydrofolic Acid Compared with Folic Acid during Pregnancy Programs Central and Peripheral Mechanisms Favouring Increased Food Intake and Body Weight of Mature Female Offspring

Supplementation with [6S]-5-methyltetrahydrofolic acid (MTHF) is recommended as an alternative to folic acid (FA) in prenatal supplements. This study compared equimolar gestational FA and MTHF diets on energy regulation of female offspring. Wistar rats were fed an AIN-93G diet with recommended (2 mg/kg diet) or 5-fold (5X) intakes of MTHF or FA. At weaning, female offspring were fed a 45% fat diet until 19 weeks. The 5X-MTHF offspring had higher body weight (>15%), food intake (8%), light-cycle energy expenditure, and lower activity compared to 5X-FA offspring (p < 0.05). Both the 5X offspring had higher plasma levels of the anorectic hormone leptin at birth (60%) and at 19 weeks (40%), and lower liver weight and total liver lipids compared to the 1X offspring (p < 0.05). Hypothalamic mRNA expression of leptin receptor (ObRb) was lower, and of suppressor of cytokine signaling-3 (Socs3) was higher in the 5X-MTHF offspring (p < 0.05), suggesting central leptin dysregulation. In contrast, the 5X-FA offspring had higher expression of genes encoding for dopamine and GABA- neurotransmitter receptors (p < 0.01), consistent with their phenotype and reduced food intake. When fed folate diets at the requirement level, no differences were found due to form in the offspring. We conclude that MTHF compared to FA consumed at high levels in the gestational diets program central and peripheral mechanisms to favour increased weight gain in the offspring. These pre-clinical findings caution against high gestational intakes of folates of either form and encourage clinical trials examining their long-term health effects when consumed during pregnancy.

[6S]-5-Methyltetrahydrofolic Acid and Folic Acid Pregnancy Diets Differentially Program Metabolic Phenotype and Hypothalamic Gene Expression of Wistar Rat Dams Post-Birth

[6S]-5-methyltetrahydrofolic acid (MTHF) is a proposed replacement for folic acid (FA) in diets and prenatal supplements. This study compared the effects of these two forms on maternal metabolism and hypothalamic gene expression. Pregnant Wistar rats received an AIN-93G diet with recommended FA (1X, 2 mg/kg, control), 5X-FA or equimolar levels of MTHF. During lactation they received the control diet and then a high fat diet for 19-weeks post-weaning. Body weight, adiposity, food intake, energy expenditure, plasma hormones, folate, and 1-carbon metabolites were measured. RNA-sequencing of the hypothalamus was conducted at parturition. Weight-loss from weaning to 1-week post-weaning was less in dams fed either form of the 5X vs. 1X folate diets, but final weight-gain was higher in 5X-MTHF vs. 5X-FA dams. Both doses of the MTHF diets led to 8% higher food intake and associated with lower plasma leptin at parturition, but higher leptin at 19-weeks and insulin resistance at 1-week post-weaning. RNA-sequencing revealed 279 differentially expressed genes in the hypothalamus in 5X-MTHF vs. 5X-FA dams. These findings indicate that MTHF and FA differ in their programing effects on maternal phenotype, and a potential adverse role of either form when given at the higher doses.

Knowledge gaps in understanding the metabolic and clinical effects of excess folates/folic acid: a summary, and perspectives, from an NIH workshop

Folate, an essential nutrient found naturally in foods in a reduced form, is present in dietary supplements and fortified foods in an oxidized synthetic form (folic acid). There is widespread agreement that maintaining adequate folate status is critical to prevent diseases due to folate inadequacy (e.g., anemia, birth defects, and cancer). However, there are concerns of potential adverse effects of excess folic acid intake and/or elevated folate status, with the original concern focused on exacerbation of clinical effects of vitamin B-12 deficiency and its role in neurocognitive health. More recently, animal and observational studies have suggested potential adverse effects on cancer risk, birth outcomes, and other diseases. Observations indicating adverse effects from excess folic acid intake, elevated folate status, and unmetabolized folic acid (UMFA) remain inconclusive; the data do not provide the evidence needed to affect public health recommendations. Moreover, strong biological and mechanistic premises connecting elevated folic acid intake, UMFA, and/or high folate status to adverse health outcomes are lacking. However, the body of evidence on potential adverse health outcomes indicates the need for comprehensive research to clarify these issues and bridge knowledge gaps. Three key research questions encompass the additional research needed to establish whether high folic acid or total folate intake contributes to disease risk. 1) Does UMFA affect biological pathways leading to adverse health effects? 2) Does elevated folate status resulting from any form of folate intake affect vitamin B-12 function and its roles in sustaining health? 3) Does elevated folate intake, regardless of form, affect biological pathways leading to adverse health effects other than those linked to vitamin B-12 function? This article summarizes the proceedings of an August 2019 NIH expert workshop focused on addressing these research areas.

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.

Excess Folic Acid Supplementation Before and During Pregnancy and Lactation Activates Fos Gene Expression and Alters Behaviors in Male Mouse Offspring

Periconceptional folic acid (FA) supplementation is recommended to prevent neural tube defects and other birth defects. After 20 years mandate food fortification with FA, serum concentration of folate and unmetabolized FA increased significantly in the North American population. But whether excess FA intake impairs neurodevelopment and behavior is still controversial. Here, we treated mice with approximately 2.5-fold (moderate dose of FA, MFA) or 10-fold (high dose of FA, HFA) the dietary requirement of FA 1 week before mating and throughout pregnancy and lactation, and examined behaviors in adult male offspring using open field test, three-chamber sociability and social novelty test, elevated plus maze, rotarod and Morris water maze. We found that early life MFA supplementation increased long-term body weight gain in adults, elevated anxiety-like behavior, and impaired social preference, motor learning and spatial learning ability without modifying motor ability and spatial memory. In contrast, HFA supplementation only induced mild behavioral abnormality. RNA sequencing revealed that FA supplementation altered the expression of brain genes at weaning, among which Fos and related genes were significantly up-regulated in MFA mice compared with control and HFA mice. Quantitative real time-PCR (qRT-PCR) and western blots confirmed the increase of these genes. Our results suggested that FA supplementation during early life stage affected gene expression in weaning mice, and exhibited long-term impairments in adult behaviors in a dose-sensitive manner.

Perigestational high folic acid: impact on offspring's peripheral metabolic response

Perigestational excess folic acid programmed offspring to increased weight gain, but also to adipocyte hypertrophy, associated with Lpl upregulation, and to hyperglycemia, possibly due to VAT and skeletal muscle Glut4 downregulation.

Determinants of folic acid supplement use outside national recommendations for pregnant women: results from the Growing Up in New Zealand cohort study

OBJECTIVE

To evaluate the sociodemographic and lifestyle factors associated with insufficient and excessive use of folic acid supplements (FAS) among pregnant women.

DESIGN

A pregnancy cohort to which multinomial logistic regression models were applied to identify factors associated with duration and dose of FAS use.

SETTING

The Growing Up in New Zealand child study, which enrolled pregnant women whose children were born in 2009-2010.

SUBJECTS

Pregnant women (n 6822) enrolled into a nationally generalizable cohort.

RESULTS

Ninety-two per cent of pregnant women were not taking FAS according to the national recommendation (4 weeks before until 12 weeks after conception), with 69 % taking insufficient FAS and 57 % extending FAS use past 13 weeks' gestation. The factors associated with extended use differed from those associated with insufficient use. Consistent with published literature, the relative risks of insufficient use were increased for younger women, those with less education, of non-European ethnicities, unemployed, who smoked cigarettes, whose pregnancy was unplanned or who had older children, or were living in more deprived households. In contrast, the relative risks of extended use were increased for women of higher socio-economic status or for whom this was their first pregnancy and decreased for women of Pacific v. European ethnicity.

CONCLUSIONS

In New Zealand, current use of FAS during pregnancy potentially exposes pregnant women and their unborn children to too little or too much folic acid. Further policy development is necessary to reduce current socio-economic inequities in the use of FAS.

Maternal folic acid supplementation with vitamin B12 deficiency during pregnancy and lactation affects the metabolic health of adult female offspring but is dependent on offspring diet

Epidemiologic studies have reported relationships between maternal high folate and/or low B₁₂ status during pregnancy and greater adiposity and insulin resistance in children. The goal of this study was to determine the effects of maternal folic acid supplementation (10 mg/kg diet), with (50 μg/kg diet) and without B₁₂, on adult female offspring adiposity and glucose homeostasis. Female C57BL/6J mice were fed 1 of 3 diets from weaning and throughout breeding, pregnancy, and lactation: control (2 mg/kg diet folic acid, 50 μg/kg diet B₁₂), supplemental folic acid with no B₁₂ (SFA-B₁₂), or supplemental folic acid with adequate B₁₂ (SFA+B₁₂). Female offspring were weaned onto the control diet or a Western diet (45% energy fat, 2 mg/kg diet folic acid, 50 μg/kg diet B₁₂) for 35 wk. After weaning, control diet-fed offspring with SFA-B₁₂ dams had fasting hyperglycemia, glucose intolerance, lower β cell mass, and greater islet hepatocyte nuclear factor 1 homeobox α and nuclear receptor subfamily 1 group H member 3 mRNA than did offspring from control dams. In Western diet-fed offspring, those with SFA-B₁₂ dams had lower fasting blood glucose and plasma insulin concentrations, and were smaller than control offspring. Our findings suggest that maternal folic acid supplementation with B₁₂ deficiency during pregnancy/lactation programs the metabolic health of adult female offspring but is dependent on offspring diet.-Henderson, A. M., Tai, D. C., Aleliunas, R. E., Aljaadi, A. M., Glier, M. B., Xu, E. E., Miller, J. W., Verchere, C. B., Green, T. J., Devlin, A. M. Maternal folic acid supplementation with vitamin B₁₂ deficiency during pregnancy and lactation affects the metabolic health of adult female offspring but is dependent on offspring diet.

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.

The effect of oxidative stress induced by tert-butylhydroperoxide under distinct folic acid conditions: An in vitro study using cultured human trophoblast-derived cells

Preeclampsia is a pregnancy disorder characterized by high maternal blood pressure, fetal growth restriction and intrauterine hypoxia. Folic acid is a vitamin required during pregnancy. In this work, we investigated the relationship between preeclampsia and the intake of distinct doses of folic acid during pregnancy. Considering that preeclampsia is associated with increased placental oxidative stress levels, we investigated the effect of oxidative stress induced by tert-butylhydroperoxide (TBH) in human trophoblast-derived cells cultured upon deficient/low, physiological and supra-physiological folic acid levels. The negative effect of TBH upon thiobarbituric acid reactive substances (TBARS), total, reduced and oxidized glutathione, cell viability, cell proliferation, culture growth and cell migration was more marked under folic acid excess. This study suggests more attention on the dose administered, and ultimately, on the overall folic acid levels during pregnancy, in the context of preeclampsia risk.

High-dose maternal folic acid supplementation before conception impairs reversal learning in offspring mice

Maternal folic acid (FA) supplementation prior to and during gestation is recommended for the prevention of neural tube closure defects in the developing embryo. Prior studies, however, suggested that excessive FA supplementation during gestation can be associated with toxic effects on the developing organism. Here, we address whether maternal dietary folic acid supplementation at 40 mg/kg chow (FD), restricted to a period prior to conception, affects neurobehavioural development in the offspring generation. Detailed behavioural analyses showed reversal learning impairments in the Morris water maze in offspring derived from dams exposed to FD prior to conceiving. Furthermore, offspring of FD dams showed minor and transient gene expression differences relative to controls. Our data suggest that temporary exposure of female germ cells to FD is sufficient to cause impaired cognitive flexibility in the subsequent generation.

The adverse effects of an excessive folic acid intake

Folate is a vital component of a healthy diet, being essential for numerous bodily functions. Deficiency of folate is common, with studies suggesting prevalence of deficiencyas high as 85.5% as was shown in women between the ages of 16 and 49, living in the UK. Causes of folate deficiency range from diet and lifestyle, to pathological and pharmacological processes. Because of the well-known role of folate in prevention of neural tube defects, numerous countries have implemented strategies to increase folate intake, with programs such as mandatory grain fortification. As a result, the intake of folate in these countries is often higher than the recommended dietary allowance for many groups of people. Although folate is believed to be non-toxic, the potential adverse effects of excessive intake of folic acid (synthetic form of folate) have not been highlighted well by authorities to people taking supplements; despite this, many studies have addressed this issue. However, the results of these studies provide discrepant results, leading to confusion as to whether mandatory folic acid fortification should be introduced in other countries. The purpose of this review was to provide a summary of evidence related to high folic acid ingestion and to look at the unwanted effects it may have on the certain groups within the general population.

Responses of bovine early embryos to S-adenosyl methionine supplementation in culture

AIM

There is a growing concern about the potential adverse effects of high dose folic acid (FA) supplementation before and during pregnancy. FA metabolism generates S-adenosyl methionine (SAM) which is an important cofactor of epigenetic programming. We sought to assess the impact of a large dose of SAM on early embryo development.

MATERIALS & METHODS

In vitro cultured bovine embryos were treated with SAM from the eight-cell stage to the blastocyst stage. In addition to the phenotype, the genome-wide epigenetic and transcription profiles were analyzed.

RESULTS

Treatment significantly improved embryo hatching and caused a shift in sex ratio in favor of males. SAM caused genome-wide hypermethylation mainly in exonic regions and in CpG islands. Although differentially expressed genes were associated with response to nutrients and developmental processes, no correspondence was found with the differentially methylated regions, suggesting that cellular responses to SAM treatment during early embryo development may not require DNA methylation-driven changes.

CONCLUSION

Since bovine embryos were not indifferent to SAM, effects of large-dose FA supplements on early embryonic development in humans cannot be ruled out.

Canadian Consensus on Female Nutrition: Adolescence, Reproduction, Menopause, and Beyond

OBJECTIVES

To provide health care professionals in Canada with the basic knowledge and tools to provide nutrition guidance to women through their lifecycle.

OUTCOMES

Optimal nutrition through the female lifecycle was evaluated, with specific focus on adolescence, pre-conception, pregnancy, postpartum, menopause, and beyond. The guideline begins with an overview of guidance for all women, followed by chapters that examine the evidence and provide recommendations for the promotion of healthy nutrition and body weight at each life stage. Nutrients of special concern and other considerations unique to each life stage are discussed in each chapter.

EVIDENCE

Published literature, governmental and health agency reports, clinical practice guidelines, grey literature, and textbook sources were used in supporting the recommendations made in this document.

VALUES

The quality of evidence was rated using the criteria described in the report of the Canadian Task Force on Preventive Health Care. CHAPTER 2: GENERAL FEMALE NUTRITION: Summary Statements Recommendations CHAPTER 3: ADOLESCENCE NUTRITION: Summary Statements Recommendations CHAPTER 4: PRE-CONCEPTUAL NUTRITION: Summary Statement Recommendations CHAPTER 5: NUTRITION IN PREGNANCY: Summary Statements Recommendations CHAPTER 6: POSTPARTUM NUTRITION AND LACTATION: Summary Statements Recommendations CHAPTER 7: NUTRITION DURING MENOPAUSE AND BEYOND: Summary Statement Recommendations.

Folic Acid Supplementation of Female Mice, with or without Vitamin B-12, before and during Pregnancy and Lactation Programs Adiposity and Vascular Health in Adult Male Offspring

BACKGROUND

The developmental origins of health and disease theory suggest that disturbances in the fetal and early postnatal environment contribute to chronic adulthood diseases, such as type 2 diabetes and cardiovascular disease. Greater adiposity and insulin resistance have been reported in children of women with high erythrocyte folate but poor vitamin B-12 status during pregnancy. The mechanisms underlying this relation are not known.

OBJECTIVE

The objective of this study was to investigate the effects of maternal supplemental folic acid, with or without vitamin B-12, on adiposity, glucose homeostasis, and vascular health in adult male offspring mice.

METHODS

Female C57BL/6J mice were fed a control diet (M-CON, 2 mg folic acid/kg, 50 μg vitamin B-12/kg) or a folic acid-supplemented diet with [10 mg folic acid/kg, 50 μg vitamin B-12/kg (SFA+B12)] or without [10 mg folic acid/kg, no vitamin B-12 (SFA-B12)] vitamin B-12 for 6 wk before mating and during pregnancy and lactation. The offspring were weaned onto a control diet (16% energy from fat) or a western diet (45% energy from fat) until 23 wk of age. The effects of maternal diet on adiposity, vascular function, and glucose tolerance were assessed in 6 groups of adult male offspring: control diet-fed M-CON, SFA+B12, and SFA-B12 and western diet-fed M-CON, SFA+B12, and SFA-B12.

RESULTS

Control and western diet-fed SFA-B12 and SFA+B12 offspring had smaller visceral and subcutaneous adipose tissue than M-CON offspring (P < 0.05). Control SFA-B12 and SFA+B12 offspring had lower serum total adiponectin and vitamin B-12 concentrations and lower NADPH oxidase 2 expression in aorta compared with M-CON offspring (P < 0.05). These effects were not observed in western diet-fed offspring.

CONCLUSIONS

Folic acid supplementation of female mice before and during pregnancy and lactation, with or without dietary vitamin B-12, affects adult male offspring adiposity, vascular function, and one-carbon metabolism in those fed a control diet but not a western diet.