A Practical Approach to Red Blood Cell Folate Analysis

Associations between Maternal Dietary Patterns, Biomarkers and Delivery Outcomes in Healthy Singleton Pregnancies: Multicenter Italian GIFt Study

Background: Maternal nutrition represents a critical risk factor for adverse health outcomes in both mother and offspring. We aimed to investigate associations between maternal nutritional habits, biomarker status, and pregnancy outcome among Italian healthy normal-weight pregnancies. Methods: Multicenter prospective cohort study recruiting Italian healthy normal-weight women with singleton spontaneous pregnancies at 20 ± 2 weeks (T1) in Milan and Naples. All patients underwent nutritional evaluations by our collecting a 7-day weighed dietary record at 25 ± 1 weeks (T2) and a Food Frequency Questionnaire at 29 ± 2 weeks (T3). Maternal venous blood samples were collected at T3 to assess nutritional, inflammatory and oxidative biomarker concentrations (RBCs folate, vitamin D, hepcidin, total antioxidant capacity). Pregnancy outcomes were collected at delivery (T4). General linear models adjusted for confounding factors were estimated to investigate associations between maternal dietary pattern adherence, nutrient intakes, biomarker concentrations and delivery outcomes. Results: 219 healthy normal-weight pregnant women were enrolled. Vitamin D and RBCs folate concentrations, as well as micronutrient intakes, were consistently below the recommended range. In a multi-adjusted model, maternal adherence to the most prevalent ‘high meat, animal fats, grains’ dietary pattern was positively associated with hepcidin concentrations and negatively associated with gestational age at delivery in pregnancies carrying female fetuses. Hepcidin plasma levels were further negatively associated to placental weight, whereas vitamin D concentrations were positively associated to neonatal weight. Conclusions: A high adherence to an unbalanced ‘high meat, animal fats, grains’ pattern was detected among Italian normal-weight low-risk pregnancies, further associated with maternal pro-inflammatory status and gestational age at delivery. This evidence underlines the need for a dedicated nutritional counseling even among low-risk pregnancies.

Nutritional Deficiencies, Bariatric Surgery, and Serum Homocysteine Level: Review of Current Literature

Obesity is currently one of the biggest global health problems. In the case of severe obesity, bariatric surgeries are considered to be the most important method of treatment. The 2 most commonly performed bariatric surgery procedures include Roux-en-Y gastric bypass and sleeve gastrectomy. However, these methods are not free from complications, and the most common ones (moderately long or long term) are micronutrient deficiencies. The deficiency of vitamins B6, B12, and folic acid as cofactors of the folate cycle contributes to the development of hyperhomocysteinemia. It seems that apart from nutritional factors, there are other aspects that have a significant influence on the concentration of homocysteine in blood, such as the type of conducted bariatric surgery, the post-surgical concentration of betaine and creatinine, and the clearance of methionine (i.e., the mutations of the gene that encodes the MTHFR reductase as well as other genes associated with the process of methylation, e.g., methionine synthase). Their presence might be one of the causes of the increased concentration of homocysteine after surgery despite the fact that patients take vitamin-mineral supplementation.

Assessing Volumetric Absorptive Microsampling Coupled with Stable Isotope Dilution Assay and Liquid Chromatography-Tandem Mass Spectrometry as Potential Diagnostic Tool for Whole Blood 5-Methyltetrahydrofolic Acid

Volumetric absorptive microsamplers (VAMS) have been developed recently as a promising tool for clinical blood sampling. Compared to dried blood spot samples analyzed by accurate stable isotope dilution assays (SIDAs), the new technique could provide further substantial miniaturizing of folate assays by eliminating hematocrit effects and uneven analyte distribution within the sample. Herein, we present a miniaturized SIDA coupled with LC-MS/MS measurement of 5-methyltetrahydrofolic acid as main folate vitamer in whole blood (WB) using [13C5]-5-methyltetrahydrofolic acid as internal standard. Elution and extraction of only 10.8 μL-dried WB were carried out by centrifugation followed by enzymatic treatment for polyglutamate deconjugation. Matrix separation was achieved by heating and centrifugation. To verify applicability, WB folate status of 11 volunteers was screened. Limits of detection and limits of quantitation were 9 and 26 nmol·L-1, respectively, which is sufficiently low for screening folate status. Recoveries were 97 (±5.8), 99 (±2.8), and 96 (±6.1)% for 800, 400, and 200 nmol L-1 5-methyltetrahydrofolic acid, respectively. Precision of the LC-MS/MS instrument and inter-assay precision trials revealed CVs of 8.1 and 3.5% (294 nmol L-1), respectively, thus confirming reproducible and precise quantitation. Compared to fresh WB, no significant degradation of 5-methyltetrahydrofolate was observed after 2.5 h of drying at room temperature. VAMS 5-CH3-H4folate was stable for at least 3 weeks at -20°C. In our pilot study, accurate and diagnostically conclusive determination of folate status was verified. Nevertheless, blood sampling should be performed by trained individuals to avoid substantial errors concerning the absorbed volume. Endogenous folate in rat serum and chicken pancreas caused a significant background especially at low blood 5-CH3-H4folate levels and, thus, for polyglutamate deconjugation, these background folates or alternative mixtures need to be removed. The superior feasibility of a minimized blood collection with VAMS allows further progress regarding time- and cost-effective methodologies in newborn or population screenings for 5-methyltetrahydrofolate status. Further steps toward minimization could include an automated assay coupled with UPLC-MS/MS.

Plasma folate, vitamin B-6, and vitamin B-12 and breast cancer risk in BRCA1- and BRCA2-mutation carriers: a prospective study

BACKGROUND

B vitamins [vitamins B-6, B-9 (folate), and B-12] play important roles in nucleotide biosynthesis and biological methylation reactions, aberrancies of which have all been implicated in carcinogenesis. In the general population, evidence has suggested that high circulating folate and folic acid (synthetic form of folate) supplement use may increase breast cancer risk, but the role of folate in BRCA-associated breast cancer is not clear.

OBJECTIVE

We prospectively evaluated the relation between plasma folate, pyridoxal 5'-phosphate (PLP; the biologically active form of vitamin B-6), and vitamin B-12 and breast cancer risk in women with a BRCA1/2 mutation.

DESIGN

Baseline blood samples and biennial follow-up questionnaires were available for 164 BRCA1/2-mutation carriers with no previous history of cancer other than nonmelanoma skin cancer. Plasma folate, PLP, and vitamin B-12 concentrations were categorized dichotomously as high compared with low based on the upper 25% and the lower 75% of distribution, respectively. Cox proportional hazards were used to estimate the HR and 95% CI for the association between plasma biomarkers of each B vitamin and incident breast cancer.

RESULTS

Over a mean follow-up of 6.3 y, 20 incident primary invasive breast cancers were observed. Women with high plasma folate concentrations (>24.4 ng/mL) were associated with significantly increased breast cancer risk (HR: 3.20; 95% CI: 1.03, 9.92; P = 0.04, P-trend across quintiles = 0.07) compared with that of women with low plasma folate concentrations (≤24.4 ng/mL). Plasma PLP and vitamin B-12 concentrations were not associated with breast cancer risk.

CONCLUSIONS

Our data suggest that elevated plasma folate concentrations may be associated with increased risk of breast cancer in women with a BRCA1/2 mutation. Additional studies with a larger sample size and longer follow-up periods are warranted to clarify the relation between folate status and breast cancer risk in high-risk women.

Potential role of folate in pre-eclampsia

Dietary deficiencies of folate and other B vitamin cofactors involved in one-carbon metabolism, together with genetic polymorphisms in key folate-methionine metabolic pathway enzymes, are associated with increases in circulating plasma homocysteine, reduction in DNA methylation patterns, and genome instability events. All of these biomarkers have also been associated with pre-eclampsia. The aim of this review was to explore the literature and identify potential knowledge gaps in relation to the role of folate at the genomic level in either the etiology or the prevention of pre-eclampsia. A systematic search strategy was designed to identify citations in electronic databases for the following terms: folic acid supplementation AND pre-eclampsia, folic acid supplementation AND genome stability, folate AND genome stability AND pre-eclampsia, folic acid supplementation AND DNA methylation, and folate AND DNA methylation AND pre-eclampsia. Forty-three articles were selected according to predefined selection criteria. The studies included in the present review were not homogeneous, which made pooled analysis of the data very difficult. The present review highlights associations between folate deficiency and certain biomarkers observed in various tissues of women at risk of pre-eclampsia. Further investigation is required to understand the role of folate in either the etiology or the prevention of pre-eclampsia.

Maternal cadmium, iron and zinc levels, DNA methylation and birth weight

Background

Cadmium (Cd) is a ubiquitous and environmentally persistent toxic metal that has been implicated in neurotoxicity, carcinogenesis and obesity and essential metals including zinc (Zn) and iron (Fe) may alter these outcomes. However mechanisms underlying these relationships remain limited.

Methods

We examined whether maternal Cd levels during early pregnancy were associated with offspring DNA methylation at regulatory sequences of genomically imprinted genes and weight at birth, and whether Fe and Zn altered these associations. Cd, Fe and Zn were measured in maternal blood of 319 women ≤12 weeks gestation. Offspring umbilical cord blood leukocyte DNA methylation at regulatory differentially methylated regions (DMRs) of 8 imprinted genes was measured using bisulfite pyrosequencing. Regression models were used to examine the relationships among Cd, Fe, Zn, and DMR methylation and birth weight.

Results

Elevated maternal blood Cd levels were associated with lower birth weight (p = 0.03). Higher maternal blood Cd levels were also associated with lower offspring methylation at the PEG3 DMR in females (β = 0.55, se = 0.17, p = 0.05), and at the MEG3 DMR in males (β = 0.72, se = 0.3, p = 0.08), however the latter association was not statistically significant. Associations between Cd and PEG3 and PLAGL1 DNA methylation were stronger in infants born to women with low concentrations of Fe (p < 0.05).

Conclusions

Our data suggest the association between pre-natal Cd and offspring DNA methylation at regulatory sequences of imprinted genes may be sex- and gene-specific. Essential metals such as Zn may mitigate DNA methylation response to Cd exposure. Larger studies are required.

More than 50% of pregnant Japanese women with an intake of 150 μg dietary folate per 1,000 kcal can maintain values above the cut-off

Most Japanese pregnant women do not take the estimated average requirement (EAR) of folate for pregnant women, which is 400 μg/d. Nevertheless, folate deficiencies have not been reported. We examined biomarkers for evaluating the status of folate in pregnant Japanese women. Apparently healthy pregnant Japanese women were cross-sectionally recruited from a private obstetric hospital. We measured nutritional biomarkers of folate in these women, as well as their folate intake. The numbers of subjects were 230 (49, 62, and 81, and 38 in the first (up to 15 wk), second (16-30 wk), and third (over 31 wk) trimesters of pregnancy, and 1 mo after delivery, respectively). Folate intakes (medians) in the first, second, and third trimesters, and 1 mo after delivery were 235±147 (194), 226±83 (218), and 256±85 (254), and 300±105 (305) μg/d, respectively. Folate concentrations in plasma and erythrocytes appeared to be valid indicators for assessing folate status, with cut-off values of 7 nmol/L and 300 nmol/L, respectively. Plasma folate concentrations (medians) in the first, second, and third trimesters, and 1 mo after delivery were 17.6±9.6 (16.7), 12.4±8.3 (9.4), and 12.1±8.4 (9.4), and 10.7±8.9 (7.9) nmol/L, respectively. Each of the folate values was over the cut-off value. Erythrocyte folate concentrations (medians) in the first, second, and third trimesters, and 1 mo after delivery were 358±108 (365), 389±154 (365), and 325±150 (315), and 308±158 (276) nmol/L, respectively. Each of the folate values was near or over the cut-off value. In conclusion, the data obtained demonstrated that the estimated average requirement of folate for pregnant Japanese women was ≍250 μg/d.

Erythrocyte folate concentrations, CpG methylation at genomically imprinted domains, and birth weight in a multiethnic newborn cohort

Epigenetic mechanisms are proposed to link maternal concentrations of methyl group donor nutrients with the risk of low birth weight. However, empirical data are lacking. We have examined the association between maternal folate and birth weight and assessed the mediating role of DNA methylation at nine differentially methylated regions (DMRs) of genomically imprinted genes in these associations. Compared with newborns of women with folate levels in the lowest quartile, birth weight was higher in newborns of mothers in the second (β = 143.2, se = 63.2, P = 0.02), third (β = 117.3, se = 64.0, P = 0.07), and fourth (β = 133.9, se = 65.2, P = 0.04) quartiles, consistent with a threshold effect. This pattern of association did not vary by race/ethnicity but was more apparent in newborns of non-obese women. DNA methylation at the PLAGL1, SGCE, DLK1/MEG3 and IGF2/H19 DMRs was associated with maternal folate levels and also birth weight, suggestive of threshold effects. MEG3 DMR methylation mediated the association between maternal folate levels and birth weight (P =0.06). While the small sample size and partial scope of examined DMRs limit our conclusions, our data suggest that, with respect to birth weight, no additional benefits may be derived from increased maternal folate concentrations, especially in non-obese women. These data also support epigenetic plasticity as a key mechanistic response to folate availability during early fetal development.