Post-folic Acid Fortification Era Research Articles

Ancestry-Specific Interactions Between Circulatory Folate and One-Carbon Metabolism Genes’ Haplotypes for Higher-Grade Cervical Intraepithelial Neoplasia

Abstract Objectives Determine ancestry-specific interactions between circulatory folate concentrations, haplotypes of the one-carbon (1C) pathway genes and risk of higher-grade cervical intraepithelial neoplasia (CIN2+) in the US post-folic acid fortification era. Methods Study included self-reported African American and Caucasian American women positive for high-risk human papillomavirus (HPV) genotypes and diagnosed with ≤ CIN1 (non-cases, n = 340) or CIN2+ (cases, n = 337). Plasma and red blood cell (RBC) folate, vitamins B12 (B12) and C, and total carotene levels were measured. 660 single nucleotide polymorphisms of the 1C pathway genes and 104 ancestry informative markers (AIMs) were analyzed using buffy coat DNA and customizable Illumina GoldenGate arrays. Global African ancestry (GA) was estimated using the AIMs. Ancestry-based African American (AFR) had GA ≥ 0.8 and European Americans (EA) otherwise. Common haplotype blocks (n = 50) were tested for interactions with circulatory folate using logistic regression adjusting for age, education, body mass index (BMI), body fat %, smoking, parity, hormonal contraception use, plasma total carotene, B12 and C. False discovery rate < 0.1 was considered significant. Results Some of the main findings were, increasing plasma folate (1 SD) decreases the risk of CIN2 + when homozygous for haplotype CG at (rs575425, rs586199) of BHMT gene in EA (odds ratio/OR = 0.13, CI = 0.04,0.44), and for haplotype TA at (rs559062, rs515064) of CTH in AFR (OR = 0.23, CI = 0.1,0.52); increasing RBC folate (1 SD) decreases risk of CIN2 + when homozygous for haplotypes TA at (rs559062, rs515064) of CTH (OR = 0.27, CI = 0.12,0.61), AC at (rs7706298, rs10512934) of MTRR (OR = 0.21, CI = 0.08,0.57), and AGA at (rs11672909, rs759920, rs7253062) of DNMT1 (OR = 0.4, CI = 0.18,0.90) in AFR; and increasing RBC folate (1 SD) increases the risk of CIN2 + when homozygous for haplotypes GG at (rs3856027, rs4650051) of CTH gene (OR = 3.52, CI = 1.27,9.71), and CGG at (rs11672909, rs759920, rs7253062) of DNMT1 (OR = 5.70, CI = 1.86,17.49) in AFR. Conclusions Circulatory folate differentially modulates the risk for CIN2 + by interacting with haplotypes of the 1C pathway genes according to ancestry in reproductive-aged women exposed to US folic acid fortification program. Funding Sources National Cancer Institute

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

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. 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. Participants were recruited in Ottawa and Kingston, Canada, from 2002 to 2009. Women were recruited when presenting for prenatal care in the early second trimester. 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. 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.

Maternal postpartum plasma folate status and preterm birth in a high-risk US population.

While maternal folate deficiency has been linked to poor pregnancy outcomes such as neural tube defects, anaemia and low birth weight, the relationship between folate and preterm birth (PTB) in the context of the US post-folic acid fortification era is inconclusive. We sought to explore the relationship between maternal folate status and PTB and its subtypes, i.e. spontaneous and medically indicated PTB. Observational study. Boston Birth Cohort, a predominantly urban, low-income, race/ethnic minority population at a high risk for PTB.ParticipantsMother-infant dyads (n 7675) enrolled in the Boston Birth Cohort. A sub-sample (n 2313) of these dyads had maternal plasma folate samples collected 24-72 h after delivery. Unadjusted and adjusted logistic regressions revealed an inverse relationship between the frequency of multivitamin supplement intake and PTB. Compared with less frequent use, multivitamin supplement intake 3-5 times/week (adjusted OR (aOR) = 0·78; 95 % CI 0·64, 0·96) or >5 times/week (aOR = 0·77; 95 % CI 0·64, 0·93) throughout pregnancy was associated with reduced risk of PTB. Consistently, higher plasma folate levels (highest v. lowest quartile) were associated with lower risk of PTB (aOR = 0·74; 95 % CI 0·56, 0·97). The above associations were similar among spontaneous and medically indicated PTB. If confirmed by future studies, our findings raise the possibility that optimizing maternal folate levels across pregnancy may help to reduce the risk of PTB among the most vulnerable US population in the post-folic acid fortification era.

Homocysteinemia is Associated with a Lower Degree of PBMC LINE-1 Methylation and a Higher Risk of CIN 2C in the U.S. Post-Folic Acid Fortification Era

ABSTRACTThe primary aim of the study was to determine whether plasma concentrations of homocysteine (Hcy), a functional indicator of methyl donor nutrients, are associated with altered risk of higher grades of cervical intraepithelial neoplasia (CIN 2+) and the degree of methylation in long interspersed nucleotide elements (LINE-1s) of peripheral blood mononuclear cells, a potential biomarker of CIN 2+ in a population of women exposed to the United States folic acid fortification program. The secondary aim was to assess the determinants of plasma Hcy in the same population. The study included 457 women diagnosed with either CIN 2+ (cases, n = 132) or ≤ CIN 1 (non-cases, n = 325). Unconditional logistic regression models were used to test the associations after adjusting for relevant risk factors of cervical cancer. Women with higher Hcy concentrations were at a greater risk of being diagnosed with CIN 2+ [odds ratio (OR) = 1.86, P = 0.005]. Higher plasma folate concentrations were a significant determinant of lower Hcy (OR = 0.40, P = 0.0002). Women with higher Hcy concentrations were more likely to have a lower degree of LINE-1 methylation (OR = 2.30, P = 0.0007). These results suggested that further improvement in folate status in this population may be beneficial for lowering Hcy and improving the degree of LINE-1 methylation.

Folate, vitamin B12 and Homocysteine status in the post-folic acid fortification era in different subgroups of the Brazilian population attended to at a public health care center.

BackgroundFolate and vitamin B12 are essential nutrients, whose deficiencies are considerable public health problems worldwide, affecting all age groups. Low levels of these vitamins have been associated with high concentrations of homocysteine (Hcy) and can lead to health complications. Several genetic polymorphisms affect the metabolism of these vitamins. The aims of this study were to assess folate, vitamin B12 and homocysteine status in distinct Brazilian individuals after the initiation of folic acid fortification by Brazilian authorities and to investigate the effects of RFC1 A80G, GCPII C1561T and MTHFR C677T polymorphisms on folate, vitamin B12 and Hcy levels in these populations.MethodsA total of 719 individuals including the elderly, children, as well as pregnant and lactating women were recruited from our health care center. Folate, vitamin B12 and Hcy levels were measured by conventional methods. Genotype analyses of RFC1 A80G, GCPII C1561T and MTHFR C677T polymorphisms were performed by PCR-RFLP.ResultsThe overall prevalence of folate and vitamin B12 deficiencies were 0.3% and 4.9%, respectively. Folate deficiency was observed only in the elderly (0.4%) and pregnant women (0.3%), whereas vitamin B12 deficiency was observed mainly in pregnant women (7.9%) and the elderly (4.2%). Plasma Hcy concentrations were significantly higher in the elderly (33.6%). Pregnant women carrying the MTHFR 677TT genotype showed lower serum folate levels (p = 0.042) and higher Hcy levels (p = 0.003). RFC1 A80G and GCPII C1561T polymorphisms did not affect folate and Hcy levels in the study group. After a multivariate analysis, Hcy levels were predicted by variables such as folate, vitamin B12, gender, age and RFC1 A80G polymorphism, according to the groups studied.ConclusionOur results suggest that folate deficiency is practically nonexistent in the post-folic acid fortification era in the subgroups evaluated. However, screening for vitamin B12 deficiency may be particularly relevant in our population, especially in the elderly.

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.

A comparison of folate status in women of child-bearing age in Korea and in the United States

Correspondence: Chandrika J Piyathilake Department of Nutrition Sciences, University of Alabama at Birmingham, 1675 University Blvd, Webb 326, Birmingham, AL 35294, USA Tel +1 205 975 5398 Email piyathic@uab.edu Background: Even though several studies have demonstrated that periconceptional supplementation with folic acid (FA) reduces the occurrence of neural tube defects, FA fortification has been a topic of intense debate due to the possible adverse effects of higher folate status on several health conditions. Several countries, including Korea, have been indecisive as to whether fortification is warranted or not. It is therefore helpful for these countries to compare folate concentrations in their populations with populations exposed to mandatory FA fortification. Purpose: To evaluate the differences in the distribution of circulating concentrations of folate in Korea and the United States (US) at different time points. Methods: The Korean study populations consisted of women of child-bearing age recruited in 1999 and in 2009. The US study populations consisted of women of child-bearing age recruited in the post FA fortification era (2005 and 2009). Plasma and red blood cell (RBC) folate concentrations were measured using the Lactobacillus casei microbiological assay. Results: The percentage of US women with neural tube defect-protective levels of RBC folate was significantly higher compared to Korean women in 1999 and 2009. However, in 2009, when FA supplements became readily available for Koreans, 50% of Korean women in the study achieved the neural tube defect-protective level of RBC folate; 11% of them demonstrating supraphysiologic concentrations of plasma folate. Even though FA fortification in the US resulted in more than 80% of women achieving .400 ng/mL of RBC folate by 2009, nearly 50% also demonstrated having supraphysiologic concentrations of plasma folate, which prompted some researchers to raise concerns about possible adverse effects of higher folate status on several health conditions. Conclusion: Encouraging Korean women of reproductive age to take FA supplements and evaluating the outcome of such efforts would be worthwhile prior to implementing a populationwide mandatory FA fortification in Korea.

Lower Risk of Cervical Intraepithelial Neoplasia in Women with High Plasma Folate and Sufficient Vitamin B12 in the Post-Folic Acid Fortification Era

The purpose of this study was to determine the influence of plasma folate and vitamin B12 concentrations on cervical cancer risk in the U.S. after the folic acid fortification era. The study included 376 premenopausal women of childbearing age who tested positive for infections with high-risk (HR) human papillomaviruses (HPVs) and were diagnosed with cervical intraepithelial neoplasia (CIN) grade 2 or higher (CIN 2+, cases) or <or=CIN 1 (noncases). CIN 2+ (yes/no) was the dependent variable in logistic regression models that specified plasma folate concentrations combined with plasma B12 concentrations as the independent predictors of primary interest, adjusting for age, race, education, smoking, parity, number of life-time male sexual partners, use of contraceptives, waist circumference, physical activity, healthy eating index, and circulating concentrations of vitamins A, C, tocopherol, and total carotene. Women with supraphysiologic concentrations of plasma folate (>19.8 ng/mL) who also had sufficient plasma vitamin B12 (>or=200.6 pg/mL) had 70% lower odds of being diagnosed with CIN 2+ (P = 0.04) when compared with women with plasma folate of <or=19.8 ng/mL and plasma vitamin B12 of <200.6 pg/mL. Our results do not corroborate the concern that supraphysiologic plasma folate concentrations seen in the post-U.S. folic acid fortification era increase the risk of CIN in premenopausal women of childbearing age. In fact, higher folate is associated with significantly lower risk of CIN, especially when vitamin B12 is sufficient, demonstrating the importance of vitamin B12 in the high-folate environment created by the folic acid fortification program.

Polygenic association with total homocysteine in the post-folic acid fortification era: The CARDIA study

Elevated plasma concentration of total homocysteine (tHcy) has been linked with many diseases. tHcy is associated with a variety of factors, including polymorphisms in genes involved in homocysteine metabolism. It is not clear whether US-mandated fortification of grain products with folic acid has affected the association of genetic variants with tHcy levels. We determined tHcy concentrations in sera from 997 Caucasians and 692 African Americans participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study before and after folic acid fortification. DNA was genotyped for variants present in four genes involved in homocysteine metabolism: cystathionine β-synthase (CBS) 844ins68, methionine synthase (MS) 2756A>G; methionine synthase reductase (MTRR) 66A>G and methylenetetrahydrofolate reductase (MTHFR) 677C>T and 1298A>C. A greater number of African Americans were homozygous for the MS 2756GG, MTRR 66GG and CBS 844ins68 genotypes compared to Caucasians, while prevalence of MTHFR 677TT and 1298CC genotypes was substantially lower in African Americans compared to Caucasians. The overall variance in tHcy levels at y 0, 7 and 15 that can be explained by the combined presence of all five variants increased slightly over time in Caucasians (17%, y 0; 21%, y 7; and 26%, y 15) and in African Americans (13%, y 0; 17% y 7; and 18% y 15) largely due to decrease in tHcy variance.

Clinical Utility of Genotyping the 677C>T Variant of Methylenetetrahydrofolate Reductase in Humans Is Decreased in the Post-Folic Acid Fortification Era

Moderate hyperhomocysteinemia is associated with many diseases. Major factors affecting plasma total homocysteine (tHcy) concentrations include folate concentrations and polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene. Because U.S.-mandated fortification of grain products with folic acid has improved folate and tHcy status in Americans, we investigated the effect of the MTHFR 677C>T variant before and after fortification. We determined tHcy and folate concentrations in sera from 844 Caucasian and 587 African American participants in the Coronary Artery Risk Development in Young Adults study before and after fortification and we genotyped the MTHFR 677C>T variant. MTHFR 677TT homozygotes had higher (P < 0.01) tHcy concentrations both before and after fortification compared with MTHFR 677CC homozygotes. However, the difference between these 2 genotypes decreased from 2.5 μmol/L before fortification to <0.7 μmol/L postfortification (P < 0.01). In addition, the prevalence of moderate hyperhomocysteinemia (tHcy > 13 μmol/L) in 677TT homozygotes decreased from 33% before fortification to 12% postfortification (P < 0.01). Using a cutoff value of 13 μmol/L to define moderate hyperhomocysteinemia, the sensitivity of the MTHFR 677TT genotype to predict elevations in homocysteine was low (∼30%) both before and after folic acid fortification. Increasing the cutoff from 13 to 19 μmol/L increased the sensitivity of the assay before fortification to 62% but decreased the sensitivity to 17% postfortification. We conclude that after folic acid fortification in the US, measurement of tHcy rather than genotyping of MTHFR 677TT should be used as the primary assay for the diagnosis and monitoring of moderate hyperhomocysteinemia.

Folate Status of Young Canadian Women after Folic Acid Fortification of Grain Products

Women of childbearing age are advised to consume folic acid–containing supplements. Whether this remains necessary after folic acid fortification of the food supply in North America has yet to be determined. The objectives of this study were to assess folate intakes and the contribution of folic acid to the diets of women of childbearing age in the post–folic acid fortification era. Using a cross-sectional study design, fasting blood samples were obtained from 95 women (aged 18 to 25 years), and the samples were analyzed for serum and red blood cell folate, as well for total homocysteine. Dietary and supplemental folate intakes were assessed. The biochemical evidence showed that no women were folate deficient, but only 14% reached red blood cell folate concentrations associated with significant reductions in neural tube defect risk. Mean dietary intake of food folic acid was 96±64 μg/day, supplemental folic acid was 94±189 μg/day, natural folate was 314±134 μg/day, and the total intake, as dietary folate equivalents, was 646±368 μg dietary folate equivalents/day. Therefore, intakes of folic acid from fortified foods are within the level originally predicted for the fortification efforts; however, only 17% of participants met the special recommendation for women capable of becoming pregnant (400 μg folic acid daily from supplements, fortified foods, or both in addition to consuming food folate from a varied diet). These data suggest that women of childbearing age are achieving positive folate status in the postfortification era, but it may not be sufficient to achieve red blood cell folate concentrations associated with a significant reduction in neural tube defect risk. Even with food fortification, women of childbearing age should be advised to take a folic acid–containing supplement on a daily basis.

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.

Vitamin B12 deficiency is the dominant nutritional cause of hyperhomocysteinemia in a folic acid-fortified population

Prevalence rates for folate deficiency and hyperhomocysteinemia have been markedly reduced following the introduction of folic acid fortification in the United States. We report the prevalence of hyperhomocysteinemia in a population of community-dwelling elderly Latinos in the post-folic acid fortification era. We measured homocysteine, total vitamin B12, holotranscobalamin, red blood cell folate, and serum creatinine in 1096 subjects aged > or =60 years. Hyperhomocysteinemia (>13 micromol/L) was observed in 16.5% of the subjects. The population attributable risk percentages for hyperhomocysteinemia were 29.7% for total B12 <148 pmol/L, 36.4% for holotranscobalamin <35 pmol/L, and 41.4% for creatinine >115 micromol/L. In contrast, the population attributable risk percentage for hyperhomocysteinemia was only 0.3% for red blood cell folate <365 nmol/L. We conclude that in the post-folic acid fortification era, low vitamin B12 status has become the dominant nutritional determinant of hyperhomocysteinemia. Steps to either reduce the prevalence of vitamin B12 deficiency or to identify and treat individuals with vitamin B12 deficiency could further reduce the prevalence of hyperhomocysteinemia.