Multivitamin Use Among Hispanic Women of Reproductive Age in the United States, 2013-2022.

Background: The U.S. Public Health Service and the Institute of Medicine recommend that all women capable of becoming pregnant consume 400 µg of folic acid daily to help prevent neural tube defects (NTDs). Hispanic women are at higher risk of having babies with NTDs than non-Hispanic White women. This study assessed multivitamin (MV) use, a main source of folic acid, among Hispanic women of reproductive age using a survey of solely U.S. Hispanic adults. Materials and Methods: MV use was assessed as part of Porter Novelli's Estilos survey, fielded annually through the largest online U.S. Hispanic panel, Offerwise's QueOpinas. During the study period of 2013-2022, 9,999 surveys were completed; selection was weighted to match the U.S. Census American Community Survey proportions. Log-binomial regression models were applied to estimate MV use trends by age groups, acculturation levels, and pregnancy intention. Results: Among 3,700 Hispanic women of reproductive age, overall no MV use increased from 39.3% in 2013 to 54.7% in 2022 (p for trend <0.0001), especially among Hispanic women aged 18-34 years and those classified as acculturated. Among women planning to get pregnant, daily MV use was 31.1% in 2013 compared with 18.7% in 2020-2022 (p = 0.04). Conclusions: Given the increase in no MV use among Hispanic women of reproductive age, targeted interventions may help reach at-risk groups for NTDs prevention.

Update on the impact of voluntary folic acid fortification of corn masa flour on red blood cell folate concentrations-National Health and Nutrition Examination Survey, 2011-March 2020.

BACKGROUND: Folic acid is a micronutrient that is effective at preventing neural tube defects (NTDs). In 2016, the FDA authorized the voluntary fortification of corn masa flour (CMF) with folic acid to reduce disparities in NTDs among infants of women who do not regularly consume other fortified cereal grains, in particular Hispanic women of reproductive age (WRA). METHODS: We analyzed data from the National Health and Nutrition Examination Survey (NHANES) from 2011 to March 2020 assessing the impact of voluntary fortification of CMF on the folate status of Hispanic WRA. We analyzed folic acid usual intake and red blood cell (RBC) folate concentrations among non-pregnant, non-lactating Hispanic WRA, comparing pre-fortification (2011-2016) to post-fortification (2017-March 2020) data. RBC folate concentrations were used to create model-based estimation of NTD rates. RESULTS: The proportion of Hispanic WRA with folic acid usual intakes <400 µg/d did not change (2011-2016: 86.1% [95% Confidence Interval, CI: 83.7-88.5]; 2017-March 2020: 87.8% [95% CI: 84.8-90.7]; p = .38) nor did the proportion of Hispanic WRA with RBC folate below optimal concentrations (<748 nmol/L, 2011-2016: 16.0% [95% CI: 13.7-18.2]; 2017-March 2020: 18.1% [95% CI: 12.1-24.0]; p = 0.49). Model-based estimates of NTD rates suggest further improvements in the folate status of Hispanic WRA might prevent an additional 157 (95% Uncertainty Interval: 0, 288) NTDs/year. CONCLUSIONS: Voluntary fortification of CMF with folic acid has yet to have a significant impact on the folate status of WRA. Continued monitoring and further research into factors such as fortified product availability, community knowledge, and awareness of folic acid benefits would inform and improve future public health interventions.

Folate and vitamin B12 usual intake and biomarker status by intake source in United States adults aged ≥19 y: NHANES 2007-2018.

BACKGROUND: Folate and vitamin B12 are important biomarkers of nutritional status of populations. OBJECTIVES: This study aims to estimate folate and vitamin B12 usual intakes among United States adults and examine folate and vitamin B12 biomarker status by intake source. METHODS: We analyzed data for United States adults aged ≥19 y from National Health and Nutrition Examination Survey 2007-2018 (n = 31,128), during which time voluntary corn masa flour (CMF) fortification was started. Usual intake was estimated using the National Cancer Institute method. Folate intake included folate from natural foods and folic acid from 4 sources: enriched cereal grain products (ECGPs), CMF, ready-to-eat cereals (RTEs), and folic acid-containing supplements (SUP). Vitamin B12 intake was mainly from food and supplements. RESULTS: The median natural food folate intake (222 µg dietary folate equivalents (DFE)/d) was below the estimated average requirement (EAR) of 320 µg DFE/d. The proportions of those who consumed folic acid from ECGP/CMF only, ECGP/CMF + RTE, ECGP/CMF + SUP, and ECGP/CMF + RTE + SUP were 50%, 18%, 22%, and 10%, respectively. Median usual folic acid intakes (µg/d) were 236 (IQR: 152, 439) overall and 134, 313, 496, and 695 in the ECGP/CMF only, ECGP/CMF + RTE, ECGP/CMF + SUP, and ECGP/CMF + RTE + SUP folic acid consumption groups, respectively. Overall, 2.0% (95% CI: 1.7%, 2.3%) of adults, all of whom used folic acid supplements, consumed greater than the tolerable upper intake level (UL) of 1000 µg/d folic acid. The median usual vitamin B12 intake (µg/d) was 5.2 for vitamin B12 supplement nonusers and 21.8 for users. Consumption of RTE and/or supplements with folic acid was associated with higher serum and red blood cell folate concentrations. Vitamin B12 supplement users had significantly higher serum vitamin B12 concentrations. CONCLUSIONS: Folic acid fortification plays a critical role in helping United States adults meet the folate EAR. At current fortification levels, United States adults who do not consume supplements do not have the usual folic acid intake exceeding the UL.

Folic Acid and the Prevention of Birth Defects: 30 Years of Opportunity and Controversies.

For three decades, the US Public Health Service has recommended that all persons capable of becoming pregnant consume 400 µg/day of folic acid (FA) to prevent neural tube defects (NTDs). The neural tube forms by 28 days after conception. Fortification can be an effective NTD prevention strategy in populations with limited access to folic acid foods and/or supplements. This review describes the status of mandatory FA fortification among countries that fortify (n = 71) and the research describing the impact of those programs on NTD rates (up to 78% reduction), blood folate concentrations [red blood cell folate concentrations increased ∼1.47-fold (95% CI, 1.27, 1.70) following fortification], and other health outcomes. Across settings, high-quality studies such as those with randomized exposures (e.g., randomized controlled trials, Mendelian randomization studies) are needed to elucidate interactions of FA with vitamin B12 as well as expanded biomarker testing.

Vitamin B-12 malabsorption and renal function are critical considerations in studies of folate and vitamin B-12 interactions in cognitive performance: NHANES 2011-2014.

BACKGROUND: Cognitive health is a public health concern among older adults. Dietary supplement (SUP) use is common and concerns have been raised about high folic acid intake among those with vitamin B-12 deficiency and exacerbation of poor cognitive performance (PCP). OBJECTIVES: We evaluated SUP use, usual folic acid intake, and blood folate and vitamin B-12 concentrations in relation to cognitive performance. METHODS: We used NHANES 2011-2014 data on adults aged ≥60 y (n = 2867) and estimated total usual folic acid intake from diet and supplements, vitamin B-12 intake from SUPs, blood folates, vitamin B-12 concentrations, vitamin B-12 insufficiency (≤258 pmol/L), high folate (serum folate ≥59 nmol/L or RBC folate ≥1609 nmol/L), and PCP (<34 on the Digit Symbol Substitution Test). We assessed folate distributions adjusted for multiple variables, including renal function. RESULTS: Compared with persons without PCP, adults with PCP were less likely to use supplements containing folic acid (mean ± SEE: 34.4% ± 2.4%) or vitamin B-12 (mean ± SEE: 47.5% ± 1.6%). Among vitamin B-12-insufficient adults, 18.0% ± 1.6% (mean ± SEE) reported taking a vitamin B-12 supplement. Among participants with high folate and insufficient vitamin B-12 concentrations, 34.3% ± 11.5% (mean ± SEE) reported taking vitamin B-12-containing supplements. Persons with high folate and normal vitamin B-12 concentrations had lower odds of PCP [aOR (adjusted odds ratio): 0.61; 95% CI: 0.45, 0.83] than persons with normal folate and vitamin B-12. Persons with high folate and normal methylmalonic acid (MMA) had lower odds of PCP (OR: 0.56; 95% CI: 0.40, 0.78) than those with normal folate and MMA concentrations. After adjustment for renal function, elevated risk of PCP was attenuated among persons with high folate and MMA. Concurrent high folate and insufficient vitamin B-12 concentrations were not associated with PCP. CONCLUSIONS: Differential associations between vitamin B-12 and MMA highlight the need to consider renal function in studies of high folate and low vitamin B-12 status. Consumption of vitamin B-12 supplements concurrent with low vitamin B-12 status may indicate vitamin B-12 malabsorption.

Periconceptional folic acid use prevents both rare and common neural tube defects in China.

BACKGROUND: Neural tube defects (NTDs) encompass a variety of distinct types. We assessed if the preventive effect of folic acid (FA) varied by NTD type and infant sex. METHODS: We examined all pregnancies with NTD status confirmation from a pregnancy-monitoring system in selected locations in northern and southern regions of China between 1993 and 1996. Women who took 400 µg of FA daily during 42 days after last menstrual period were considered FA users. We analyzed NTD prevalence by FA use status, NTD type, geographic region, and infant sex. RESULTS: Among 626,042 pregnancies, 700 were affected by an NTD. Among FA nonusers, 65 pregnancies (8.8 per 10,000) in the north and 51 pregnancies (1.2 per 10,000) in the south were affected by one of the two rare NTDs, that is, craniorachischisis, iniencephaly. FA use prevented occurrence of these two rare NTDs and reduced the prevalence of spina bifida (SB) by 78% (from 17.9 to 3.9 per 10,000) in the north and 51% (from 2.4 to 1.2 per 10,000) in the south. Among FA users, SB prevalence, including SB with high lesion level, was significantly reduced in both geographic regions. FA use reduced prevalence of anencephaly and encephalocele by 85% and 50%, respectively in the north, while it did not reduce the prevalence of these two NTDs in the south. There was a greater reduction in NTD prevalence in female than in male infants and fetuses. CONCLUSIONS: This is the first study to show that FA prevents the entire spectrum of NTD types.

Systematic Process Framework for Conducting Implementation Science Research in Food Fortification Programs.

Food fortification has proven to be an effective approach for preventing micronutrient deficiencies in many settings. Factors that lead to successful fortification programs are well established. However, due to the multisectoral nature of fortification and the added complexities present in many settings, the barriers to success are not always evident and the strategies to address them are not always obvious. We developed a systematic process for identifying and addressing gaps in the implementation of a food fortification program. The framework is composed of 4 phases: (1) connect program theory of change to program implementation; (2) develop an implementation research agenda; (3) conduct implementation research; and (4) analyze findings and develop/disseminate recommendations for next steps. We detail steps in each phase to help guide teams through the process. To our knowledge, this is the first attempt to outline a systematic process for applying implementation science research to food fortification. The development of this framework is intended to promote implementation research in the field of food fortification, thus improving access to and effectiveness of this key public health intervention.

Defining the plasma folate concentration associated with the red blood cell folate concentration threshold for optimal neural tube defects prevention: a population-based, randomized trial of folic acid supplementation.

BACKGROUND: For women of reproductive age, a population-level red blood cell (RBC) folate concentration below the threshold 906 nmol/L or 400 ng/mL indicates folate insufficiency and suboptimal neural tube defect (NTD) prevention. A corresponding population plasma/serum folate concentration threshold for optimal NTD prevention has not been established. OBJECTIVE: The aim of this study was to examine the association between plasma and RBC folate concentrations and estimated a population plasma folate insufficiency threshold (pf-IT) corresponding to the RBC folate insufficiency threshold (RBCf-IT) of 906 nmol/L. METHODS: We analyzed data on women of reproductive age (n = 1673) who participated in a population-based, randomized folic acid supplementation trial in northern China. Of these women, 565 women with anemia and/or vitamin B-12 deficiency were ineligible for folic acid intervention (nonintervention group); the other 1108 received folic acid supplementation for 6 mo (intervention group). We developed a Bayesian linear model to estimate the pf-IT corresponding to RBCf-IT by time from supplementation initiation, folic acid dosage, methyltetrahydrofolate reductase (MTHFR) genotype, body mass index (BMI), vitamin B-12 status, or anemia status. RESULTS: Using plasma and RBC folate concentrations of the intervention group, the estimated median pf-IT was 25.5 nmol/L (95% credible interval: 24.6, 26.4). The median pf-ITs were similar between the baseline and postsupplementation samples (25.7 compared with 25.2 nmol/L) but differed moderately (±3-4 nmol/L) by MTHFR genotype and BMI. Using the full population-based baseline sample (intervention and nonintervention), the median pf-IT was higher for women with vitamin B-12 deficiency (34.6 nmol/L) and marginal deficiency (29.8 nmol/L) compared with the sufficient group (25.6 nmol/L). CONCLUSIONS: The relation between RBC and plasma folate concentrations was modified by BMI and genotype and substantially by low plasma vitamin B-12. This suggests that the threshold of 25.5 nmol/L for optimal NTD prevention may be appropriate in populations with similar characteristics, but it should not be used in vitamin B-12 insufficient populations. This trial was registered at clinicaltrials.gov as NCT00207558.

Systematic Review and Bayesian Meta-analysis of the Dose-response Relationship between Folic Acid Intake and Changes in Blood Folate Concentrations.

The threshold for population-level optimal red blood cell (RBC) folate concentration among women of reproductive age for the prevention of neural tube defects has been estimated at 906 nmol/L; however, the dose-response relationship between folic acid intake and blood folate concentrations is uncharacterized. To estimate the magnitude of blood folate concentration increase in response to specific dosages of folic acid under steady-state conditions (as could be achieved with food fortification), a systematic review of the literature and meta-analysis was conducted. Of the 14,002 records we identified, 533 were selected for full-text review, and data were extracted from 108 articles. The steady-state concentrations (homeostasis) of both serum/plasma and RBC folate concentrations were estimated using a Bayesian meta-analytic approach and one-compartment physiologically-based pharmacokinetic models. RBC folate concentrations increased 1.78 fold (95% credible interval (CI): 1.66, 1.93) from baseline to steady-state at 375⁻570 µg folic acid/day, and it took a median of 36 weeks of folic acid intake (95% CI: 27, 52) to achieve steady-state RBC folate concentrations. Based on regression analysis, we estimate that serum/plasma folate concentrations increased 11.6% (95% CI: 8.4, 14.9) for every 100 µg/day folic acid intake. These results will help programs plan and monitor folic acid fortification programs.

Trends in Multivitamin Use Among Women of Reproductive Age: United States, 2006-2016.

BACKGROUND: Women of reproductive age can consume 0.4 milligrams of folic acid daily to reduce the risk of a neural tube defect (NTD)-affected pregnancy. Multivitamins (MVs) are one source of folic acid. MATERIALS AND METHODS: Using HealthStyles survey data (n = 9268), we assessed change in prevalence of MV use during 2006-2016 among women by age (18-24, 25-34, and 35-44 years), race/ethnicity (non-Hispanic [NH] white, NH black, Hispanic), and pregnancy status (trying to get pregnant, not pregnant nor trying to get pregnant, and pregnant) using log-binomial regression. RESULTS: Daily MV consumption decreased overall from 32.7% to 23.6% during 2006-2016 for women aged 18-44 years (p for trend <0.001). Age-specific decreases were seen in women aged 25-34 years (2006: 34.1%; 2016: 23.7%; p < 0.001) and 35-44 years (2006: 37.3%; 2016: 27.1%; p < 0.001). Decreases in daily MV intake were found among NH whites (2006: 35.4%; 2016: 24.9%; p < 0.001) and Hispanics (2006: 30.6%; 2016: 22.1%; p < 0.001), but remained unchanged among NH blacks (2006: 23.7%; 2016: 21.8%; p = 0.87). Daily MV intake remained unchanged for women trying to get pregnant (2006: 40.2%; 2012: 38.3%; p = 0.19), decreased for women not pregnant nor trying to get pregnant (2006: 31.3%; 2012: 21.3%; p < 0.001), and fluctuated for pregnant women (2006: 53.8%; 2012: 71.0%; p = 0.21). Prevalence of no MV consumption increased significantly across all age and race/ethnicity groups. CONCLUSIONS: Overall MV intake decreased for the past decade and varied by age, race/ethnicity, and pregnancy status. Innovative messaging and targeted interventions for increasing folic acid intake are needed to reduce NTDs.

Characteristics of U.S. Adults with Usual Daily Folic Acid Intake above the Tolerable Upper Intake Level: National Health and Nutrition Examination Survey, 2003-2010.

The Food and Drug Administration mandated that by 1998, all enriched cereal grain products (ECGP) be fortified with folic acid in order to prevent the occurrence of neural tube defects. The Institute of Medicine established the tolerable upper intake level (UL) for folic acid (1000 µg/day for adults) in 1998. We characterized U.S. adults with usual daily folic acid intake exceeding the UL. Using NHANES 2003-2010 data, we estimated the percentage of 18,321 non-pregnant adults with usual daily folic acid intake exceeding the UL, and among them, we calculated the weighted percentage by sex, age, race/ethnicity, sources of folic acid intake, supplement use and median usual daily folic acid intakes. Overall, 2.7% (standard error 0.6%) of participants had usual daily intake exceeding the UL for folic acid; 62.2% were women; 86.3% were non-Hispanic whites; and 98.5% took supplements containing folic acid. When stratified by sex and age groups among those with usual daily folic acid intake exceeding the UL, 20.8% were women aged 19-39 years. Those with usual daily intake exceeding the folic acid UL were more likely to be female, non-Hispanic white, supplement users or to have at least one chronic medical condition compared to those not exceeding the folic acid UL. Among those with usual daily folic acid intake exceeding the UL who also took supplements, 86.6% took on average >400 µg of folic acid/day from supplements. Everyone with usual daily folic acid intake exceeding the UL consumed folic acid from multiple sources. No one in our study population had usual daily folic acid intake exceeding the UL through consumption of mandatorily-fortified enriched cereal grain products alone. Voluntary consumption of supplements containing folic acid is the main factor associated with usual daily intake exceeding the folic acid UL.

Contributions of enriched cereal-grain products, ready-to-eat cereals, and supplements to folic acid and vitamin B-12 usual intake and folate and vitamin B-12 status in US children: National Health and Nutrition Examination Survey (NHANES), 2003-2006.

BACKGROUND: US children consume folic acid from multiple sources. These sources may contribute differently to usual intakes above the age-specific tolerable upper intake level (UL) for folic acid and to folate and vitamin B-12 status. OBJECTIVE: We estimated usual daily folic acid intakes above the UL and adjusted serum and red blood cell folate, serum vitamin B-12, homocysteine, and methylmalonic acid (MMA) concentrations in US children by age group and by the following 3 major folic acid intake sources: enriched cereal-grain products (ECGP), ready-to-eat cereals (RTE), and supplements containing folic acid (SUP). DESIGN: We analyzed data in 4 groups of children aged 1-3, 4-8, 9-13, and 14-18 y from the National Health and Nutrition Examination Survey (NHANES), 2003-2006 (n = 7161). RESULTS: A total of 19-48% of children consumed folic acid from ECGP only. Intakes above the UL varied from 0-0.1% of children who consumed ECGP only to 15-78% of children who consumed ECGP+RTE+SUP. In children aged 1-8 y, 99-100% of those who consumed ≥ 200 µg folic acid/d from supplements exceeded their UL. Although < 0.5% of children had folate deficiency or low vitamin B-12 status, the consumption of RTE or SUP with folic acid was associated with higher mean folate and vitamin B-12 concentrations and, in some older children, with lower homocysteine and MMA concentrations. CONCLUSIONS: Our data suggest that the majority of US children consume more than one source of folic acid. Postfortification, the consumption of RTE or SUP increases usual daily intakes and blood concentrations of folate and vitamin B-12.