Folate Status in Women of Childbearing Age Residing in Southern California after Folic Acid Fortification

Distribution of 5-Methyltetrahydrofolate and Folic Acid Levels in Maternal and Cord Blood Serum: Longitudinal Evaluation of Japanese Pregnant Women

“Total” folate in blood has usually been measured to evaluate the folate status of pregnant women. However, folate is composed of many metabolites. The main substrate is 5-methyltetrahydrofolate (5-MTHF), with folic acid (FA) representing a very small component as an unmetabolized species in blood. We longitudinally evaluated 5-MTHF, FA and total homocysteine in maternal and cord blood from Japanese pregnant women. Subjects were 146 pregnant women who participated in the Chiba study of Mother and Child Health (C-MACH) prospective cohort study. Sera were obtained in early and late pregnancy, at delivery, and from cord blood. Species levels were measured by isotope-dilution mass spectrometry. Both 5-MTHF and FA levels were lower than reported levels from pregnant women in populations from countries with mandatory FA fortification. As gestational age progressed, serum 5-MTHF levels decreased, whereas serum FA levels were slightly reduced only at delivery compared to early pregnancy. A significant negative association between serum 5-MTHF and total homocysteine was shown at all examined times, but no associations with FA were evident. At delivery, cord 5-MTHF was significantly higher than maternal levels, while FA again showed no significant correlation. These results suggest that 5-MTHF is actively transported to the fetus through placental transporters and may reflect folate status during pregnancy as a physiologically important species.

The determinants of maternal homocysteine in pregnancy: findings from the Ottawa and Kingston Birth Cohort

OBJECTIVE

Observational studies have linked elevated homocysteine to vascular conditions. Folate intake has been associated with lower homocysteine concentration, although randomised controlled trials of folic acid supplementation to decrease the incidence of vascular conditions have been inconclusive. We investigated determinants of maternal homocysteine during pregnancy, particularly in a folic acid-fortified population.

DESIGN

Data were from the Ottawa and Kingston Birth Cohort of 8085 participants. We used multivariable regression analyses to identify factors associated with maternal homocysteine, adjusted for gestational age at bloodwork. Continuous factors were modelled using restricted cubic splines. A subgroup analysis examined the modifying effect of MTHFR 677C>T genotype on folate, in determining homocysteine concentration.

SETTING

Participants were recruited in Ottawa and Kingston, Canada, from 2002 to 2009.

PARTICIPANTS

Women were recruited when presenting for prenatal care in the early second trimester.

RESULTS

In 7587 participants, factors significantly associated with higher homocysteine concentration were nulliparous, smoking and chronic hypertension, while factors significantly associated with lower homocysteine concentration were non-Caucasian race, history of a placenta-mediated complication and folic acid supplementation. Maternal age and BMI demonstrated U-shaped associations. Folic acid supplementation of >1 mg/d during pregnancy did not substantially increase folate concentration. In the subgroup analysis, MTHFR 677C>T modified the effect of folate status on homocysteine concentration.

CONCLUSIONS

We identified determinants of maternal homocysteine relevant to the lowering of homocysteine in the post-folic acid fortification era, characterised by folate-replete populations. A focus on periconceptional folic acid supplementation and improving health status may form an effective approach to lower homocysteine.

The folate status of reproductive-aged women in a randomised trial of a folate-fortified oral contraceptive: dietary and blood assessments

OBJECTIVE

To assess the folate status of US women in a study of a folate-fortified oral contraceptive (OC) using the Short Folate Food Frequency Questionnaire and plasma and red blood cell (RBC) folate samples.

DESIGN

Sub-analysis from a multi-centre, randomised, double-blind, controlled contraceptive trial with assessments at baseline and 6 months. We calculated dietary folate equivalents (DFE) consumed and the proportion of participants meeting folate adequacy benchmarks.

SETTING

Eight centres in the USA.

SUBJECTS

Healthy women aged 18-40 years requesting contraception with no contraindications for OC use.

RESULTS

Overall, 385 participants were randomised to either a novel folate-fortified OC or a marketed OC. The 262 (68 %) participants compliant with the protocol were included in the analysis set. Baseline daily DFE consumption was 529·8 (sd 342·1) μg and similar in both groups. At follow-up, the fortified OC group had higher intake than the conventional OC group (1225·9 (sd 346·2) μg compared with 500·6 (sd 361·2) μg). Mean plasma folate level increased from 44·5 (sd 17·2) to 55·8 (sd 21·1) nmol/l. Mean RBC folate level increased from 996·7 (sd 369·8) to 1311·9 (sd 436·0) nmol/l. The proportion meeting selected folate adequacy benchmarks increased in the fortified OC group (P < 0·001).

CONCLUSIONS

Lack of adequate folate intake in reproductive-aged women from dietary sources or supplements alone suggests the need for novel approaches. Use of folate-fortified OC ensures adequate folate levels and meeting of folate benchmarks.

Determinants of neural tube defect (NTD)-protective circulating concentrations of folate in women of child-bearing age in the US post-folic acid fortification era

We evaluated folate status of child-bearing age women diagnosed with abnormal pap smear in the US post-folic acid (FA) fortification era and assessed the determinants of NTD-protective and supra-physiologic (SP) concentrations of folate. The distribution of 843 women according to NTD-protective concentrations of RBC folate, plasma folate and SP concentrations of plasma folate were tested in relation to demographic and life-style factors. Logistic regression models specified NTD-protective concentrations of RBC and plasma folate or SP concentrations of plasma folate as dependent variables and demographic and life-style factors as independent predictors of interest. More than 82% reached NTD-protective concentrations of RBC and plasma folate and ~30% reached SP concentrations of plasma folate. FA supplement use was associated with having SP concentrations of plasma folate rather than NTD-protective concentrations of folate. African American (AA) women and smokers were significantly less likely to achieve NTD-protective concentrations of RBC and plasma folate. A large majority of women reached NTD-protective concentrations of folate with the current level of FA fortification without using supplementary FA. Therefore, the remaining disparities in AA women and in smokers should be addressed by targeted individual improvements in folate intake.

Methyl donor supplementation blocks the adverse effects of maternal high fat diet on offspring physiology

Maternal consumption of a high fat diet during pregnancy increases the offspring risk for obesity. Using a mouse model, we have previously shown that maternal consumption of a high fat (60%) diet leads to global and gene specific decreases in DNA methylation in the brain of the offspring. The present experiments were designed to attempt to reverse this DNA hypomethylation through supplementation of the maternal diet with methyl donors, and to determine whether methyl donor supplementation could block or attenuate phenotypes associated with maternal consumption of a HF diet. Metabolic and behavioral (fat preference) outcomes were assessed in male and female adult offspring. Expression of the mu-opioid receptor and dopamine transporter mRNA, as well as global DNA methylation were measured in the brain. Supplementation of the maternal diet with methyl donors attenuated the development of some of the adverse effects seen in offspring from dams fed a high fat diet; including weight gain, increased fat preference (males), changes in CNS gene expression and global hypomethylation in the prefrontal cortex. Notable sex differences were observed. These findings identify the importance of balanced methylation status during pregnancy, particularly in the context of a maternal high fat diet, for optimal offspring outcome.

Comprehensive evaluation of Safyral(®) 2012

The incidence of pregnancies affected with neural tube defects (NTDs) has been reduced by food fortification programs and public health campaigns promoting folic acid supplementation, but the incidence of NTDs in the USA has not achieved the full potential reduction expected with adequate periconceptional folate utilization. In seeking new ways to access sexually active women at risk for pregnancy, one option would be to link folic acid supplementation to contraceptive use. Since birth control pills are the most popular method of reversible contraception in the USA, it would seem quite logical to find a way to supplement them. To this end, a very efficient folate, levomefolate calcium salt (metafolin), has been added to drospirenone-containing oral contraceptives in equimolar concentrations to the recommended supplements of folic acid to reduce the risk for pregnancy and to reduce the risk of NTDs in pregnancies that occur while women are taking the pill or shortly after they discontinue its use. This article will focus on the need for such folate supplementation and will summarize the contraceptive and noncontraceptive benefits of the 30 µg EE/3 mg drospirenone pill (Yasmin(®), Bayer Healthcare, NJ, USA) to which has been added 451 metafolin (Safyral(®), Bayer Healthcare). The new information about thromboembolism risks associated with use of drospirenone-containing pills is also discussed.

Genetic variants in the folate pathway and risk of childhood acute lymphoblastic leukemia

OBJECTIVE

Folate is involved in the one-carbon metabolism that plays an essential role in the synthesis, repair, and methylation of DNA. We examined whether child's germline genetic variation in the folate pathway is associated with childhood acute lymphoblastic leukemia (ALL), and whether periconception maternal folate and alcohol intake modify the risk.

METHODS

Seventy-six single nucleotide polymorphisms (SNPs), including 66 haplotype-tagging SNPs in 10 genes (CBS, DHFR, FOLH1, MTHFD1, MTHFR, MTR, MTRR, SHMT1, SLC19A1, and TYMS), were genotyped in 377 ALL cases and 448 controls. Log-additive associations between genotypes and ALL risk were adjusted for age, sex, Hispanic ethnicity (when appropriate), and maternal race.

RESULTS

Single and haplotype SNPs analyses showed statistically significant associations between SNPs located in (or adjacent to) CBS, MTRR, TYMS/ENOFS, and childhood ALL. Many regions of CBS were associated with childhood ALL in Hispanics and non-Hispanics (p < 0.01). Levels of maternal folate intake modified associations with SNPs in CBS, MTRR, and TYMS.

CONCLUSION

Our data suggest the importance of genetic variability in the folate pathway and childhood ALL risk.

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

BACKGROUND

Folic acid (FA) added to foods during fortification is 70-85% bioavailable compared to 50% of folate occurring naturally in foods. Thus, if FA supplements also are taken during pregnancy, both mother and fetus can be exposed to FA exceeding the Institute of Medicine's recommended tolerable upper limit (TUL) of 1,000 micrograms per day (μg/d) for adult pregnant women. The primary objective is to estimate the proportion of women taking folic acid (FA) doses exceeding the TUL before and during pregnancy, and to identify correlates of high FA use.

METHODS

During 2005-2008, pre-pregnancy and pregnancy-related data on dietary supplementation were obtained by interviewing 539 pregnant women enrolled at two obstetrics-care facilities in Durham County, North Carolina.

RESULTS

Before pregnancy, 51% of women reported FA supplementation and 66% reported this supplementation during pregnancy. Before pregnancy, 11.9% (95% CI = 9.2%-14.6%) of women reported supplementation with FA doses above the TUL of 1,000 μg/day, and a similar proportion reported this intake prenatally. Before pregnancy, Caucasian women were more likely to take FA doses above the TUL (OR = 2.99; 95% = 1.28-7.00), compared to African American women, while women with chronic conditions were less likely to take FA doses above the TUL (OR = 0.48; 95%CI = 0.21-0.97). Compared to African American women, Caucasian women were also more likely to report FA intake in doses exceeding the TUL during pregnancy (OR = 5.09; 95%CI = 2.07-12.49).

CONCLUSIONS

Fifty-one percent of women reported some FA intake before and 66% during pregnancy, respectively, and more than one in ten women took FA supplements in doses that exceeded the TUL. Caucasian women were more likely to report high FA intake. A study is ongoing to identify possible genetic and non-genotoxic effects of these high doses.

Serum folate is a reliable indicator of hyperhomocysteinemia and borderline hyperhomocysteinemia in young adults

Serum folate has been shown to correlate well with fasting plasma homocysteine; however, erythrocyte folate concentration is a better index of tissue folate stores and probably could be a more reliable indicator for reflecting long-term supply of the vitamin and homocysteine status. The present study was undertaken to test the hypothesis that serum folate and erythrocyte folate levels had a different degree of correlation to fasting plasma homocysteine in young Taiwanese adults. This study had a cross-sectional design. Healthy young adults were divided into either a hyperhomocysteinemia (HHcy; > or =14.9 micromol/L; n = 13), borderline HHcy (BHcy; fasting homocysteine, 14.9-10.2 micromol/L; n = 52), or normohomocysteinemia (fasting homocysteine, <10.2 micromol/L; n = 65) groups based on fasting homocysteine levels. The concentrations of plasma fasting homocysteine, serum folate, erythrocyte folate, vitamin B(12), and plasma pyridoxal 5'-phosphate were measured. Fasting homocysteine was only significantly and inversely affected by serum folate (beta = -0.21, P < .05) concentration after adjusting for potential confounders. Only serum folate concentration remained to decrease the risk of fasting HHcy (odds ratio, 0.73; confidence interval, 0.56-0.95) after the other B vitamins were additionally adjusted. Serum folate also had the highest area under the receiver operating characteristic (AUC) curve to predict the risk of HHcy (AUC, 0.81) and BHcy (AUC, 0.77). Serum folate is a reliable indicator of fasting hyperhyperhomocysteinemia and BHcy in young adults.

Intrinsic Cisplatin Resistance in Lung and Ovarian Cancer Cells Propagating in Medium Acutely Depleted of Folate

Many tumors develop intrinsic and/or acquired resistance to cisplatin. The purpose of the present study was to examine the influence of acute extracellular folate depletion prior to cisplatin treatment on the development of intrinsic cisplatin resistance. Lung and ovarian cancer cells were propagated in medium acutely depleted of folate and subsequently treated with cisplatin. The IC50 level for cisplatin, cell viability, cell proliferation, and global DNA methylation were determined. Gene expression profiling was performed using the Atlas Cancer 1.2 Array. Acute extracellular folate depletion resulted in the development of intrinsic cisplatin resistance. Cells propagating in medium acutely depleted of folate had a survival advantage compared to control cells when exposed to cisplatin, and thymidine supplementation did not reverse the intrinsic cisplatin resistance. cDNA microarray analysis revealed some novel genes associated with the development of intrinsic cisplatin resistance. Our report is the first to demonstrate that acute extracellular folate depletion results in intrinsic cisplatin resistance. If these results are confirmed by in vivo human studies, it would suggest that the folate status of the recipient of cisplatin might have an impact on response to that chemotherapeutic agent.

Additional food folate derived exclusively from natural sources improves folate status in young women with the MTHFR 677 CC or TT genotype

The effectiveness of additional food folate in improving folate status in humans is uncertain particularly in people with the common genetic variant (677 C-->T) in the methylenetetrahydrofolate reductase (MTHFR) gene. To examine the effect of a doubling of food folate consumption on folate status response variables, women (n=32; 18-46 years) with the MTHFR 677 CC or TT genotype consumed either 400 (n=15; 7 CC and 8 TT) or 800 (n=17; 8 CC and 9 TT) microg/day of dietary folate equivalents (DFE) derived exclusively from naturally occurring food folate for 12 weeks. A repeated measures two-factor ANOVA was used to examine the effect of the dietary treatment, the MTHFR C677T genotype and their interactions on serum folate, RBC folate and plasma total homocysteine (tHcy) during the last 3 weeks of the study. Consumption of 800 microg DFE/day resulted in serum folate concentrations that were 67% (P=.005) higher than consumption of 400 microg DFE/day (18.6+/-2.9 vs. 31.0+/-2.7 nmol/L, respectively) and RBC folate concentrations that were 33% (P=.001) higher (1172+/-75 vs. 1559+/-70 nmol/L, respectively). Serum folate (P=.065) and RBC folate (P=.022) concentrations were lower and plasma tHcy was higher (P=.039) in women with the MTHFR 677 TT genotype relative to the CC genotype. However, no genotype by dietary treatment interaction was detected. These data suggest that a doubling of food folate intake will lead to marked improvements in folate status in women with the MTHFR 677 CC or TT genotype.

The effect of folate fortification of cereal-grain products on blood folate status, dietary folate intake, and dietary folate sources among adult non-supplement users in the United States

OBJECTIVE

Since January 1998, the Federal Drug Administration has required folic acid fortification of all enriched cereal-grain products in the U.S. This program intended to increase folic acid intake among women of childbearing age in order to decrease their risk of pregnancies affected by neural tube defects. The aim of this study was to explore the changes in serum and erythrocyte folate status of the adult U.S. population following folic acid fortification of enriched cereal-grain products and to explore accompanying changes in food sources and dietary total folate intake.

METHODS

We compared data from two National Health and Nutrition Examination Surveys (NHANES): NHANES III, conducted during 1988 to 1994, reflecting the time prior to folate fortification, and NHANES 1999-2000, reflecting the time period after fortification.

RESULTS

Mandatory folic acid fortification led to significant increases in both serum and erythrocyte folate concentrations in all sex and age groups. In the overall study population the mean serum folate concentration increased more than two-fold (136%), from 11.4 nmol/L to 26.9 nmol/L, and the mean erythrocyte folate concentration increased by 57 percent, from 375 nmol/L to 590 nmol/L. Less than 10% of women of childbearing age reached the recommended erythrocyte folate concentration of greater than 906 nmol/L that has been shown to be associated with a significant reduction in neural tube defect (NTD) risk. After fortification, the category "bread, rolls, and crackers" became the single largest contributor of total folate to the American diet, contributing 15.6% of total intake, surpassing vegetables, which were the number one folate food source prior to fortification. Dietary intake of total folate increased significantly in almost all sex and age groups, except in females over 60 years of age. The mean dietary total folate intake of the study population increased by 76 microg/d (28%), from 275 microg/d to 351 microg/d.

CONCLUSIONS

The fortification of enriched cereal-grain products with folic acid led to a significant improvement of blood folate status of the overall adult, non-supplement using, US population. However, women of childbearing age may take folic acid supplements to reach erythrocyte folate levels that have been associated with decreased risk of NTDs.

Population references for plasma total homocysteine concentrations for U.S. children and adolescents in the post-folic acid fortification era

Folate intake is inversely related to circulating total homocysteine (tHcy) concentrations. Elevated tHcy is a risk factor for vascular diseases. The objectives of this study were to present plasma tHcy distributions and investigate the association between tHcy and sex, age, and race-ethnicity in U.S. children and adolescents (3264 boys and 3197 girls) using data from the National Health and Nutrition Examination Surveys, 1999-2000 and 2001-2002 conducted in the post-folic acid fortification era. Plasma tHcy was higher in boys than in girls (P < 0.0001), and higher in older children (16-18 y old) than in younger children (3-15 y old) (P < 0.0001). The difference in plasma tHcy between boys and girls was greater in the 16- to 18-y-old group than in any other age group studied (P < 0.05). Age-adjusted plasma tHcy concentrations were approximately 6.8, approximately 10.5, and approximately 8.8% higher in boys than in girls in non-Hispanic White (NHW), non-Hispanic Black (NHB), and Mexican American/Hispanic (MA/H) children, respectively. Sex- and age-adjusted plasma tHcy concentrations (geometric means +/- SE) were 5.04 +/- 0.05, 5.01 +/- 0.06, and 4.99 +/- 0.06 micromol/L in the NHW, NHB, and MA/H groups, respectively. Race-ethnicity was not related to plasma tHcy in age-adjusted analysis for boys (P < 0.77) and girls (P < 0.26), and in sex- and age-adjusted analysis (P < 0.38) for all children. The plasma tHcy concentrations begin to rise between ages 8 and 11 y, and the age-related increase is greater in boys than in girls.

A long-term controlled folate feeding study in young women supports the validity of the 1.7 multiplier in the dietary folate equivalency equation

The presence of folic acid in enriched cereal grain products and the higher bioavailability of folic acid than food folate led to the expression of the 1998 folate RDA, 400 microg/d, as dietary folate equivalents (DFE). DFE are defined as: mug natural food folate + 1.7 x microg synthetic folic acid. The 1.7 multiplier was based on assumptions that added folic acid was 85% available and food folate was 50% available. The 85/50 ratio also inferred that the bioavailability of food folate was approximately 60% relative to added folic acid. The objective of this long-term controlled feeding study was to assess the dietary folate equivalency of folic acid. After a 2-wk period of folate restriction, women (n = 42, 18-45 y old) consumed either 400 or 800 microg DFE/d derived from various combinations of food folate and folic acid for 12 wk. Folic acid was converted to DFE using the 1.7 multiplier from the DFE calculation and was consumed with a meal throughout the treatment period. Folate status response to the various treatments was assessed during wk 12-14. Serum folate, RBC folate, and plasma total homocysteine did not differ among the 400 microg DFE/d groups or among the 800 microg DFE/d groups. In contrast, consumption of 800 microg DFE/d led to higher (P </= 0.05) serum and RBC folate than consumption of 400 microg DFE/d. These data support the validity of the 1.7 multiplier in the DFE equation and suggest that food folate bioavailability is approximately 60% that of added folic acid when consumed as part of a mixed diet.

Nutritional and life style determinants of plasma homocysteine in schizophrenia patients

Recently, homocysteine levels have been reported to be elevated in young male schizophrenic patients. Since smoking, obesity, low folate or low vitamin B12 and various medications can increase homocysteine levels, we studied these variables and other clinical variables in 258 schizophrenic patients. A multiple linear regression for plasma homocysteine was performed on variables that were significantly related to plasma homocysteine. Variables predicting homocysteine levels in schizophrenic patients include gender, plasma folate levels, plasma vitamin B12 levels, mean red blood cell corpuscular volume and diastolic blood pressure. Only 24% of the variance in male patients was explained by the model. The reason for elevated plasma homocysteine in some schizophrenic populations remains unclear.

Status of plasma folate after folic acid fortification of the food supply in pregnant African American women and the influences of diet, smoking, and alcohol consumption

BACKGROUND

African American women and socioeconomically challenged women are at risk of compromised folate status and, thus, of folate-related birth defects. Data are limited on circulating folate concentrations in pregnant African American women after folic acid fortification of the food supply was implemented.

OBJECTIVE

The objective was to determine the influence of smoking and alcohol consumption on plasma 5-methyltetrahydrofolic acid (5-MTHFA) concentrations in pregnant African American women.

DESIGN

Alcohol consumption, smoking exposure, and other characteristics of pregnant African American women reporting to an inner-city antenatal clinic were assessed. At 24 wk of gestation, blood samples and food-frequency intake data were collected. Plasma 5-MTHFA concentrations were determined by liquid chromatography-mass spectrometry for 116 subjects and examined in a correlational study design.

RESULTS

Dietary folate and markers of alcohol consumption were positively associated, whereas exposure to smoke was negatively associated with plasma 5-MTHFA. More than one-half of the participants in this population failed to meet the recommended dietary allowance for dietary folate equivalents of 600 microg/d during pregnancy.

CONCLUSIONS

Most inner-city African American women are not meeting the recommended dietary allowance for dietary folate during pregnancy, and smoking may further compromise their folate status. Programs to reduce smoking and raise awareness about the importance of folate and multivitamin supplementation during pregnancy need to target this population.

Erythrocyte folate and its response to folic acid supplementation is assay dependent in women

Optimizing folate status requires continued monitoring of erythrocyte (RBC) folate and folate intake. The accuracy of RBC folate assays remains a concern. Therefore, we measured RBC folate with 4 different assays, examined the interassay correlations, and compared RBC folate with folate intake as measured by an abbreviated folate-targeted food/supplement screener. The screener had 21 questions (19 diet, 2 supplement) and measured usual and customary intakes of dietary folate equivalents (DFEs). Our design was a 4 x 2 x 2 factorial, 4 assays in pregnant and nonpregnant women before and after each group received a folic acid supplement (1814 nmol/d) for 30-60 d. Folate assays included L. casei, chemiluminescence, GC-MS, and radioassay (RA). Baseline RBC folate levels ranked low to high by assay (mean +/- SE) were as follows: 1155 +/- 44 nmol/L (L. casei) < 1390 +/- 43 nmol/L (chemiluminescence) < 1531 +/- 39 nmol/L (GC-MS) < 1727 +/- 55 nmol/L (RA) (P < 0.0001). Supplementation raised RBC folate levels (mean +/- SE) as follows: 138 +/- 63 nmol/L (chemiluminescence) < 267 +/- 64 nmol/L (GC-MS) = 285 +/- 75 nmol/L (L. casei) < 351 +/- 87 nmol/L (RA). Pregnant women had higher RBC folate than nonpregnant women using chemiluminescence and RA. Interassay correlations (r) ranged from 0.4679 to 0.8261 (P < 0.001). Correlations of RBC folate with folate intake ranged from 0.2676 to 0.4622 (P < 0.0004). We conclude that RBC folate levels are assay dependent, as is the definition of optimized status; there continues to be a need for an accurate assay of RBC folate. RBC folate correlated with total folate intake using a folate-targeted food/supplement screener.

Modeling the level of fortification and post-fortification assessments: U.S. experience

Mandatory fortification of enriched cereal-grain products became effective in the United States on January 1, 1998. This fortification was undertaken to assist women of child-bearing age in increasing their intake of folic acid to reduce their risk of having a pregnancy affected by a neural tube birth defect. The process by which the Food and Drug Administration modeled the level of fortification with folic acid illustrates the complex issues and general principles that emerge when fortification of a nation's food supply is evaluated as a means of addressing a public health concern. The effectiveness of fortification for a target population and safety for the much larger general population impose conflicting challenges that must be considered concurrently when making decisions regarding fortification. Recent data show improved folate status and apparent decreases in risk of neural tube birth defects in the U.S. Much about the long-term effects of the fortification program remains unknown and careful monitoring over time will be necessary to ensure that the program functions as intended.

Effect of folic acid fortification of foods on folate intake in female smokers with cervical dysplasia

OBJECTIVE

We investigated the effect of folic acid fortification of enriched cereal grains on folate intake in women of predominantly childbearing age at high risk for cervical cancer.

METHODS

Subjects in this cross-sectional study were 77 women randomized between November 1999 and December 2000 in the Women's Intervention to Stay Healthy (WISH), a clinical trial evaluating the effect of a tobacco control intervention on the progression of cervical dysplasia. All subjects were cigarette smokers, had a previously abnormal Papanicolaou test, and were positive for high-risk human papillomavirus at entry. Dietary intake was assessed with food-frequency questionnaires completed at the baseline visit for WISH. The effect of folic acid fortification on folate intake was assessed by using pre- and postfortification folate databases to estimate folate intake.

RESULTS

Mean folate intake assessed with the postfortification database was 63% higher than intake assessed with the prefortification database: 417 versus 256 microg/d of dietary folate equivalents (P < 0.0001). The proportion of subjects below the estimated average requirement for folate was smaller after fortification than before fortification: 40.3% versus 75.3% (P < 0.0001). Several foods, including white bread, cheese dishes, spaghetti, and rice, became major sources of folate as a result of fortification.

CONCLUSIONS

Folic acid fortification resulted in an increased intake of folate in these subjects. However, even with fortification, folate intake in a large proportion of these women remained below recommended levels. These results should be considered before decisions regarding future levels of folic acid fortification are made.

Determination of folate vitamers in human serum by stable-isotope-dilution tandem mass spectrometry and comparison with radioassay and microbiologic assay

BACKGROUND

Current clinical methods for folate give different results and cannot measure the various forms of folate. We developed an isotope-dilution tandem mass spectrometric method coupled to liquid chromatography (LC/MS/MS) as a candidate reference method for 5-methyltetrahydrofolic acid (5MeTHF), 5-formyltetrahydrofolic acid (5FoTHF), and folic acid (FA) in human serum.

METHODS

We quantitatively isolated folates from 275 microL of serum with a phenyl solid-phase extraction cartridge, then detected and quantified them in stabilized serum extracts by positive-ion electrospray ionization LC/MS/MS. We used an isocratic mobile phase of acetic acid in organic solvent on a C(8) analytical column. (13)C-labeled folates were used as internal standards.

RESULTS

Limits of detection in serum were 0.13 (5MeTHF), 0.05 (5FoTHF), and 0.07 (FA) nmol/L. Within- and between-run imprecision (CV) was <7% for 5MeTHF and <10% for 5FoTHF at concentrations >0.5 nmol/L, and <10% for FA at concentrations >2.0 nmol/L. Total folate (TFOL) concentrations determined by competitive protein binding radioassay were approximately 9% lower than results obtained with LC/MS/MS. The microbiologic assay gave approximately 15% higher TFOL results with FA calibrator and no difference with 5MeTHF calibrator. The mean (SD) [range] TFOL in 42 sera was 35.5 (17.8) [6.5-75.6] nmol/L. Thirty-two samples with TFOL <50 nmol/L had, on average, 93.3% 5MeTHF, 2.3% FA, and 4.4% 5FoTHF. Ten samples with TFOL >50 nmol/L had, on average, 81.7% 5MeTHF, 15.7% FA, and 2.5% 5FoTHF.

CONCLUSIONS

This stable-isotope-dilution LC/MS/MS method can quantify 5MeTHF, 5FoTHF, and FA in serum. Currently used clinical assays agree with this candidate reference method.

Epidemiology of neural tube defects

Neural tube defects (NTDs)-malformations secondary to abnormal neural tube closure between the third and fourth weeks of gestational age-have a complex and imperfectly understood etiology in which both genetic and environmental factors appear to be involved. A number of specific chromosomal or single-gene disorders, presumably not affected by environmental influences, are associated with the development of NTDs, but such syndromal cases account for a small proportion of NTDs in live-born infants. Analysis of recurrence patterns within families and of twin-concordance data provides evidence of a genetic influence in nonsyndromal cases, but factors such as socioeconomic status and geographic area (independent of race or ethnicity) are also associated with variations in the incidence of NTDs. The prevalence at birth of both anencephaly and spina bifida has decreased, but the advent of antenatal diagnosis and elective termination of affected pregnancies has undermined the reliability of birth prevalence rate as an estimate of incidence. Some occupational and other exposures, including maternal use of antiepileptic drugs (AEDs), are associated with increased risk for NTDs. Among women who have had an NTD-affected pregnancy, recurrence risk is markedly higher than the risk for a first NTD-affected pregnancy in the general population. There is strong evidence, overall, for a protective effect of adequate folate consumption. In some high-risk groups, however, such as women taking AEDs, folate supplementation has not been proven to reduce NTD risk.

Validation of a semiquantitative food frequency questionnaire to assess folate status. Results discriminate a high-risk group of women residing on the Mexico-US border

BACKGROUND

The purpose of the study was to estimate dietary intake of folate in two groups of women from different economic backgrounds and to evaluate validity of the 5-day-weighed food registry (5-d-WFR) and Food Frequency Questionnaire (FFQ) using biological markers.

METHODS

A cross-sectional study was conducted in two samples of urban Mexican women: one represented the middle socioeconomic status (middle SES) and the other, low socioeconomic status (low SES). Middle SES included 34 women recruited from 1998 to 1999. Participants were between the ages of 18 and 32 years and were employed in the banking industry (middle SES) in the US-Mexican border city of Tijuana, Baja California. Low SES included 70 women between the ages of 18 and 35 years recruited during the year 2000. These women were receiving care at a primary health care center in Ensenada, Baja California Norte State, Mexico (low SES). Pearson correlations were calculated between folate intake among 5-day diet registry, FFQ, and biochemical indices. FFQ reproducibility was performed by Spearman correlation of each food item daily and of weekly intake.

RESULTS

Average folate intake in middle SES from 5-d-WFR was 210 microg +/- 171. Fifty four percent of participants had intakes <200 microg/daily. Average folate intake from FFQ was 223 +/- 78 microg/day. Pearson correlation between log transformed and within individually adjusted 5-d-WFR folate intakes and serum folate was 0.40 (p=0.02).

DISCUSSION

Mexican women of reproductive age living in the US-Mexican border State of Baja California are at very high risk of NTDs as a result of low folate intake and low serum folate and RBC folate concentrations.

Periconceptional use of folic acid supplements in Oslo

BACKGROUND

Periconceptional supplementation with folic acid has been shown to decrease the occurrence of neural tube defects (NTD). A daily supplement of 400 micro g folic acid from the month before pregnancy and the first 2 to 3 months of pregnancy is recommended in Norway. We wanted to evaluate the use of folic acid supplements among pregnant women in Oslo, and to explore demographic factors that were associated with periconceptional intake.

METHODS

All women attending antenatal ultrasound screening at the two main obstetric departments in Oslo during 3 months in 2001 were invited to answer questions regarding folic acid supplementation before and during their present pregnancy.

RESULTS

A total of 1541 women (91, 5%) participated in the study, of which 26% were nonwestern immigrants. Only 17% of all women had started the folic acid supplementation preconceptionally (22% of the nonimmigrant vs. 2% of the immigrant population). Folic acid had been used by 58% at some time during the present pregnancy (73% of the nonimmigrant vs. 19% of the immigrant population). Regression analysis demonstrated that the difference in periconceptional use of folic acid between the two population groups could not be explained by registered demographic factors other than immigrant status.

CONCLUSIONS

Most pregnant women in Oslo do not use folic acid as recommended and a dramatically low usage is seen among the immigrant population, indicating that more widespread information is necessary. Furthermore, fortification of cereals with folic acid should be considered to secure a sufficient intake of folic acid in all fertile women.

Heterogeneity in the prevalence of methylenetetrahydrofolate reductase gene polymorphisms in women of different ethnic groups

OBJECTIVE

To determine the prevalence of methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms in women of different ethnic groups and to relate these common mutations to plasma homocysteine, red cell folate, and serum folate.

DESIGN

A one-time fasting blood sample was obtained for MTHFR genotype (C677T and A1298C) determinations (n=433). Serum folate, red cell folate, and homocysteine analyses were performed in nonfolic acid supplement users (n=215).

SUBJECTS/SETTING

This study involved 433 women from four ethnic groups, including 193 Hispanic women of Mexican descent, 139 white women, 53 Asian women of mixed descent, and 48 African American women. STATISTICAL ANALYSIS PREFORMED: Chi;(2), t Test, and analysis of variance were used.

RESULTS

Mexican women (18.1%) had a higher frequency of the 677 TT genotype compared with white (7.2%), Asian (3.8%), and African American (0%) women. White women (7.9%) had a higher frequency of the 1298 CC genotype than the other ethnic groups (range=1.9% to 2.6%). The frequency of compound heterozygosity (677 CT + 1298 AC) was higher in Mexican (17.6%) and white (15.1%) women than Asian and African American ( approximately 4% to 6%) women. In the era of folic acid fortification, neither genotype, independently or together, was associated with homocysteine or blood folate concentrations when ethnic groups were combined. In Mexican women, however, a linear trend (P

APPLICATIONS/CONCLUSIONS

These data demonstrate ethnic differences in genetic polymorphisms that are diet responsive and may be useful when investigating ethnic variations in chronic disease, developmental anomalies, and folate requirements.

Collapse

Key Words Collapse

MESH Headings

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Asian/genetics
• Asian People/genetics
• Black People/genetics
• Ethnicity/genetics
• Ethnicity/statistics & numerical data
• Female
• Folic Acid/administration & dosage
• Folic Acid/blood
• Gene Frequency
• Genetic Heterogeneity
• Genotype
• Homocysteine/blood
• Humans
• Methylenetetrahydrofolate Reductase (NADPH2)
• Mexican Americans/genetics
• Middle Aged
• Mutation
• Nutritional Requirements
• Oxidoreductases Acting on CH-NH Group Donors/genetics
• Polymorphism, Genetic
• Prevalence
• Racial Groups/genetics
• White People/genetics
• Black or African American

Collapse

Grants

• S06GM53933 NIGMS NIH HHS

Collapse

Affiliation(s)

Setareh Torabian Esfahani Agricultural Sciences in the Human Nutrition and Food Science Department, Cal Poly Pomona University, Pomona, CA 91768, USA
Edward A Cogger
Marie A Caudill

Collapse

Does prenatal screening for 5,10-methylenetetrahydrofolate reductase (MTHFR) mutations in high-risk neural tube defect pregnancies make sense?

Despite the fact that neural tube defects (NTDs) are the most common congenital malformations of the central nervous system, investigators have yet to identify responsible gene(s). Research efforts have been productive in the identification of environmental factors, such as periconceptional folic acid supplementation, that modulate risk for the development of NTDs. Studies of the folic acid biosynthetic pathway led to the discovery of an association between elevated levels of homocysteine and NTD risk. Researchers subsequently identified single nucleotide polymorphisms in the gene coding for the enzyme 5,10-methylenetetrahydrofolate reductase (MTHFR). Association studies suggested it was a potential risk factor for NTDs, because the thermolabile form of the enzyme led to elevated homocysteine concentrations when folic acid intake is low. Numerous studies analyzing MTHFR variants have resulted in positive associations with increased NTD risk only in certain populations, suggesting that these variants are not large contributors to the etiology of NTDs. With our limited understanding of the genes involved in regulating NTD susceptibility, the paucity of data on how folic acid protects the developing embryo, as well as the observed decrease in birth prevalence of NTDs following folic acid supplementation and food fortification, it makes little sense for prospective parents to be tested for MTHFR variants, or for variants of other known folate pathway genes.

Relationship of folate to colorectal and cervical cancer: review and recommendations for practitioners

Evidence suggests that folate may play a role in cancer prevention. A plausible mechanism for prevention lies in the integral role that folate plays in deoxyribonucleic acid (DNA) synthesis and methylation. DNA methylation most likely regulates gene expression. Abnormal methylation, specifically hypomethylation, has been associated with tumorigenesis. The availability of methyl groups needed for adequate DNA methylation may be negatively influenced by low folate status, alcohol intake, or genetic polymorphisms that affect folate metabolism. Observational studies evaluating the association between folate and risk for colorectal and cervical cancers or precancerous conditions have produced conflicting results, and clinical trial data are needed to confirm a cause-and-effect relationship. However, several studies show interesting associations between cancer risk and factors that influence methyl group availability. Although data relating folate to cancer risk remain equivocal, when coupled with the other potential health benefits associated with folate, evidence supports recommending that people consume folate-rich foods such as fruits and vegetables. People consuming alcohol on a daily basis may especially benefit from additional folate in their diets.

Folic acid fortification, folate status and plasma homocysteine

Folic acid fortification of enriched cereal-grain products (which became mandatory in the U.S. on January 1, 1998) was intended to increase folate intake among childbearing-aged women to reduce their risk of neural tube birth defect (NTD)-affected pregnancies. Interest now focuses on assessing the effects of fortification on risk of NTDs and on folate intake relative to homocysteine (Hcy) concentrations and risk of vascular disease, although a causal relationship between the latter two has not been demonstrated. Increased serum folate levels were first reported in 1999. Data from the Framingham Offspring Study cohort showed increased mean serum folate in middle-aged and older adults; additionally, the prevalence of high Hcy concentrations had decreased by approximately 50% in subjects examined before (1995-1996) and after (1997-1998) fortification. Another analyses of samples collected between 1994 and 1999 identified a trend of increasing serum folate values from 1996 onward with values in 1998 160% of those measured in 1996. Comparisons between 1988-1994 National Health and Nutrition Examination Survey (NHANES) III data and 1999 NHANES showed increased serum and erythrocyte folate concentrations among childbearing-aged women. While recent data show improved folate status in a short period of time, much about long-term effects of the fortification program remains unknown. Interest in the effects of increased folate intakes on risk of NTDs or vascular disease needs to be balanced against concerns about masking the anemia of vitamin B-12 deficiency and the general lack of data about safety of continuous high intakes. Careful monitoring over time is necessary to determine that the program functions as intended.

Vitamin B-12 status is inversely associated with plasma homocysteine in young women with C677T and/or A1298C methylenetetrahydrofolate reductase polymorphisms

Methylenetetrahydrofolate reductase (MTHFR) polymorphisms may negatively influence one-carbon metabolism and increase health risks in women of reproductive age. The effect of MTHFR single nucleotide polymorphisms at bp 677 and/or 1298 and differences in folate and vitamin B-12 status on plasma homocysteine concentration in women of reproductive age (20-30 y; n = 186) were investigated. From the multivariate regression model, homozygotes (n = 23) for the C677T MTHFR variant had plasma homocysteine concentrations that were higher (P < 0.05) than those observed in the other 5 genotype groups, including those who were heterozygous for both variants (677CT/1298AC; n = 32). Plasma homocysteine was negatively associated with plasma vitamin B-12 concentration (P = 0.015) and serum folate (P = 0.049), with the degree of correlation between plasma vitamin B-12 and homocysteine concentrations dependent on MTHFR genotype. The C677T and A1298C MTHFR polymorphisms were significant predictors (P < 0.05) of plasma homocysteine when regression analysis was used to model plasma homocysteine concentration as a function of genotype, supplement use, serum folate and plasma vitamin B-12 concentration. Plasma homocysteine decreased as vitamin B-12 concentration increased (P = 0.0005) in individuals who were heterozygous for both the C677T and A1298C variants with nonsignificant trends (P = 0.114-0.128) in individuals homozygous for either the C677T or A1298C variants. In contrast, within the group of individuals with the wild-type genotype for both the C677T and A1298C MTHFR variants, homocysteine was not associated with changes in plasma vitamin B-12 concentrations. These data suggest that enhancing vitamin B-12 status may significantly decrease homocysteine in young women with C677T and/or A1298C MTHFR polymorphisms, even when vitamin B-12 concentrations are within the normal range.

Fortification strategies to meet micronutrient needs: successes and failures

Food fortification is likely to have played an important role in the current nutritional health and well-being of populations in industrialized countries. Starting in the early part of the 20th century, fortification was used to target specific health conditions: goitre with iodized salt; rickets with vitamin D-fortified milk; beriberi, pellagra and anaemia with B-vitamins and Fe-enriched cereals; more recently, in the USA, risk of pregnancy affected by neural-tube defects with folic acid-fortified cereals. A relative lack of appropriate centrally-processed food vehicles, less-developed commercial markets and relatively low consumer awareness and demand, means it has taken about another 50 years for fortification to be seen as a viable option for the less-developed countries. The present paper reviews selected fortification initiatives in developing countries to identify different factors that contributed to their successful implementation, as well as the challenges that continually threaten the future of these programmes. Ultimately, the long-term sustainability of fortification programmes is ensured when consumers are willing and able to bear the additional cost of fortified foods. There has been an enormous increase in fortification programmes over the last couple of decades in developing countries. Considerable progress has been made in reducing vitamin A and I deficiencies, although less so with Fe, even as Zn and folic acid deficiencies are emerging as important public health problems. Food fortification based on sound principles and supported by clear policies and regulations can play an increasingly large role in this progress towards prevention and control of micronutrient malnutrition.

Prevalence of aneuploidies in South Carolina in the 1990s

PURPOSE

Folate insufficiency due to nutritional deficiency or folate processing gene mutations has been proposed as a trisomy 21 risk factor. This study examined the possibility that increased folic acid intake among women of childbearing age may decrease the prevalence of trisomy 21 and other aneuploidies.

METHODS

The prevalence of aneuploidies from 1990 through 1999 was compared with folic acid use in women of childbearing age in South Carolina.

RESULTS

Folic acid use and the prevalence of all aneuploidies significantly increased during this period.

CONCLUSION

Increased folic acid utilization in South Carolina was not associated with decreased prevalence of trisomy 21 or other aneuploidies.