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1.
Cochrane Database Syst Rev ; 1: CD013823, 2024 01 08.
Artículo en Inglés | MEDLINE | ID: mdl-38189492

RESUMEN

BACKGROUND: Vitamin B12 deficiency is a major public health problem worldwide, with the highest burden in elderly people, pregnant women, and young children. Due to its role in DNA synthesis and methylation, folate metabolism, and erythropoiesis, vitamin B12 supplementation during pregnancy may confer longer-term benefits to maternal and child health outcomes. OBJECTIVES: To evaluate the benefits and harms of oral vitamin B12 supplementation during pregnancy on maternal and child health outcomes. SEARCH METHODS: We searched the Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP) on 2 June 2023, and reference lists of retrieved studies. SELECTION CRITERIA: Randomised controlled trials (RCTs), quasi-RCTs, or cluster-RCTs evaluating the effects of oral vitamin B12 supplementation compared to placebo or no vitamin B12 supplementation during pregnancy. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Four review authors independently assessed trial eligibility. Two review authors independently extracted data from included studies and conducted checks for accuracy. Three review authors independently assessed the risk of bias of the included studies using the Cochrane RoB 1 tool. We used GRADE to evaluate the certainty of evidence for primary outcomes. MAIN RESULTS: The review included five trials with 984 pregnant women. All trials were conducted in low- and middle-income countries, including India, Bangladesh, South Africa, and Croatia. At enrolment, 26% to 51% of pregnant women had vitamin B12 deficiency (less than 150 pmol/L), and the prevalence of anaemia (haemoglobin less than 11.0 g/dL) ranged from 30% to 46%. The dosage of vitamin B12 supplementation varied from 5 µg/day to 250 µg/day, with administration beginning at 8 to 28 weeks' gestation through to delivery or three months' postpartum, and the duration of supplementation ranged from 8 to 16 weeks to 32 to 38 weeks. Three trials, involving 609 pregnant women, contributed data for meta-analyses of the effects of vitamin B12 supplementation compared to placebo or no vitamin B12 supplementation. Maternal anaemia: there may be little to no difference for maternal anaemia by intervention group, but the evidence is very uncertain (70.9% versus 65.0%; risk ratio (RR) 1.08, 95% confidence interval (CI) 0.93 to 1.26; 2 trials, 284 women; very low-certainty evidence). Maternal vitamin B12 status: vitamin B12 supplementation during pregnancy may reduce the risk of maternal vitamin B12 deficiency compared to placebo or no vitamin B12 supplementation, but the evidence is very uncertain (25.9% versus 67.9%; RR 0.38, 95% CI 0.28 to 0.51; 2 trials, 272 women; very low-certainty evidence). Women who received vitamin B12 supplements during pregnancy may have higher total vitamin B12 concentrations compared to placebo or no vitamin B12 supplementation (mean difference (MD) 60.89 pmol/L, 95% CI 40.86 to 80.92; 3 trials, 412 women). However, there was substantial heterogeneity (I2 = 85%). Adverse pregnancy outcomes: the evidence is uncertain about the effect on adverse pregnancy outcomes, including preterm birth (RR 0.97, 95% CI 0.55 to 1.74; 2 trials, 340 women; low-certainty evidence), and low birthweight (RR 1.50, 95% CI 0.93 to 2.43; 2 trials, 344 women; low-certainty evidence). Two trials reported data on spontaneous abortion (or miscarriage); however, the trials did not report quantitative data for meta-analysis and there was no clear definition of spontaneous abortion in the study reports. No trials evaluated the effects of vitamin B12 supplementation during pregnancy on neural tube defects. Infant vitamin B12 status: children born to women who received vitamin B12 supplementation had higher total vitamin B12 concentrations compared to placebo or no vitamin B12 supplementation (MD 71.89 pmol/L, 95% CI 20.23 to 123.54; 2 trials, 144 children). Child cognitive outcomes: three ancillary analyses of one trial reported child cognitive outcomes; however, data were not reported in a format that could be included in quantitative meta-analyses. In one study, maternal vitamin B12 supplementation did not improve neurodevelopment status (e.g. cognitive, language (receptive and expressive), motor (fine and gross), social-emotional, or adaptive (conceptual, social, practical) domains) in children compared to placebo (9 months, Bayley Scales of Infant and Toddler Development Third Edition (BSID-III); 1 trial; low-certainty evidence) or neurophysiological outcomes (72 months, event-related potential measures; 1 trial; low-certainty evidence), though children born to women who received vitamin B12 supplementation had improved expressive language domain compared to placebo (30 months, BSID-III; 1 trial; low-certainty evidence). AUTHORS' CONCLUSIONS: Oral vitamin B12 supplementation during pregnancy may reduce the risk of maternal vitamin B12 deficiency and may improve maternal vitamin B12 concentrations during pregnancy or postpartum compared to placebo or no vitamin B12 supplementation, but the evidence is very uncertain. The effects of vitamin B12 supplementation on other primary outcomes assessed in this review were not reported, or were not reported in a format for inclusion in quantitative analyses. Vitamin B12 supplementation during pregnancy may improve maternal and infant vitamin B12 status, but the potential impact on longer-term clinical and functional maternal and child health outcomes has not yet been established.


Asunto(s)
Aborto Espontáneo , Anemia , Niño , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Embarazo , Suplementos Dietéticos , Evaluación de Resultado en la Atención de Salud , Vitamina B 12 , Vitaminas
2.
Annu Rev Nutr ; 42: 423-452, 2022 08 22.
Artículo en Inglés | MEDLINE | ID: mdl-35995050

RESUMEN

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.


Asunto(s)
Ácido Fólico , Defectos del Tubo Neural , Suplementos Dietéticos , Femenino , Alimentos Fortificados , Humanos , Defectos del Tubo Neural/prevención & control , Embarazo , Vitamina B 12
3.
BMC Med Educ ; 23(1): 766, 2023 Oct 13.
Artículo en Inglés | MEDLINE | ID: mdl-37833686

RESUMEN

BACKGROUND: Limited diagnostic capabilities, resources and health worker skills have deterred the advancement of birth defects surveillance systems in most low- and middle-income countries (LMICs). Empowering health workers to identify and diagnose major external birth defects (BDs) is crucial to establishing effective hospital-based BD surveillance. Makerere University-Johns Hopkins University (MU-JHU) Research Collaboration BD Surveillance System consists of three diagnostic levels: (1) surveillance midwives, (2) MU-JHU clinical team, and (3) U.S. Centers for Disease Control and Prevention (CDC) birth defects subject matter experts (SMEs) who provide confirmatory diagnosis. The diagnostic concordance of major external BDs by surveillance midwives or MU-JHU clinical team with CDC birth defects SMEs were estimated. METHODS: Study staff went through a series of trainings, including birth defects identification and confirmation, before surveillance activities were implemented. To assess the diagnostic concordance, we analyzed surveillance data from 2015 to 2021 for major external BDs: anencephaly, iniencephaly, encephalocele, spina bifida, craniorachischisis, microcephaly, anophthalmia/microphthalmia, anotia/microtia, cleft palate alone, cleft lip alone, cleft lip with cleft palate, imperforate anus, hypospadias, talipes equinovarus, limb reduction, gastroschisis, and omphalocele. Positive predictive value (PPV) as the proportion of BDs diagnosed by surveillance midwives or MU-JHU clinical team that were confirmed by CDC birth defects SMEs was computed. PPVs between 2015 and 2018 and 2019-2021 were compared to assess the accuracy of case diagnosis over time. RESULTS: Of the 204,332 infants examined during 2015-2021, 870 infants had a BD. Among the 1,245 BDs identified, 1,232 (99.0%) were confirmed by CDC birth defects SMEs. For surveillance midwives, PPV for 7 of 17 BDs was > 80%. For the MU-JHU clinical team, PPV for 13 of 17 BDs was > 80%. Among surveillance midwives, PPV improved significantly from 2015 to 2018 to 2019-2021, for microcephaly (+ 50.0%), cleft lip with cleft palate (+ 17.0%), imperforate anus (+ 30.0%), and talipes equinovarus (+ 10.8%). Improvements in PPV were also observed among MU-JHU clinical team; however, none were significant. CONCLUSION: The diagnostic accuracy of the midwives and clinical team increased, highlighting that BD surveillance, by front-line health care workers (midwives) in LMICs is possible when midwives receive comprehensive training, technical support, funding and continuous professional development.


Asunto(s)
Ano Imperforado , Labio Leporino , Fisura del Paladar , Pie Equinovaro , Microcefalia , Masculino , Humanos , Uganda/epidemiología , Hospitales
4.
Cochrane Database Syst Rev ; 2(2022)2022 02 01.
Artículo en Inglés | MEDLINE | ID: mdl-36321557

RESUMEN

BACKGROUND: Description of the condition Malaria, an infectious disease transmitted by the bite of female mosquitoes from several Anopheles species, occurs in 87 countries with ongoing transmission (WHO 2020). The World Health Organization (WHO) estimated that, in 2019, approximately 229 million cases of malaria occurred worldwide, with 94% occurring in the WHO's African region (WHO 2020). Of these malaria cases, an estimated 409,000 deaths occurred globally, with 67% occurring in children under five years of age (WHO 2020). Malaria also negatively impacts the health of women during pregnancy, childbirth, and the postnatal period (WHO 2020). Sulfadoxine/pyrimethamine (SP), an antifolate antimalarial, has been widely used across sub-Saharan Africa as the first-line treatment for uncomplicated malaria sTo examine the effects of folic acid supplementation, at various doses, on malaria susceptibility (risk of infection) and severity among people living in areas with various degrees of malaria endemicity. We will examine the interaction between folic acid supplements and antifolate antimalarial drugs. Specifically, we will aim to answer the following. Among uninfected people living in malaria endemic areas, who are taking or not taking antifolate antimalarials for malaria prophylaxis, does taking a folic acid-containing supplement increase susceptibility to or severity of malaria infection? Among people with malaria infection who are being treated with antifolate antimalarials, does folic acid supplementation increase the risk of treatment failure?Criteria for considering studies for this review Types of studies Inclusion criteria Randomized controlled trials (RCTs) Quasi-RCTs with randomization at the individual or cluster level conducted in malaria-endemic areas (areas with ongoing, local malaria transmission, including areas approaching elimination, as listed in the World Malaria Report 2020) (WHO 2020) Exclusion criteria Ecological studies Observational studies In vivo/in vitro studies Economic studies Systematic literature reviews and meta-analyses (relevant systematic literature reviews and meta-analyses will be excluded but flagged for grey literature screening) Types of participants Inclusion criteria Individuals of any age or gender, living in a malaria endemic area, who are taking antifolate antimalarial medications (inclu


Asunto(s)
Anemia , Antimaláricos , Antagonistas del Ácido Fólico , Defectos del Tubo Neural , Niño , Lactante , Embarazo , Recién Nacido , Femenino , Humanos , Preescolar , Antimaláricos/uso terapéutico , Sulfadoxina/uso terapéutico , Pirimetamina/uso terapéutico , Antagonistas del Ácido Fólico/uso terapéutico , Peso al Nacer , Parasitemia/tratamiento farmacológico , Vitaminas , Ácido Fólico/uso terapéutico , Anemia/tratamiento farmacológico , Suplementos Dietéticos , Hierro/uso terapéutico , Recurrencia
5.
J Nutr ; 150(4): 851-860, 2020 04 01.
Artículo en Inglés | MEDLINE | ID: mdl-31875475

RESUMEN

BACKGROUND: Serum folate forms were measured in the US population during recent NHANES to assess folate status. OBJECTIVE: We describe post-folic acid-fortification concentrations of serum folate forms in the fasting US population ≥1 y from the NHANES 2011-2016. METHODS: We measured 5 biologically active folates and 1 oxidation product (MeFox) of 5-methyltetrahydrofolate (5-methyl-THF). We calculated geometric means of 5-methyl-THF, unmetabolized folic acid (UMFA), nonmethyl folate (sum of tetrahydrofolate, 5-formyltetrahydrofolate, and 5,10-methenyltetrahydrofolate), total folate (sum of above biomarkers), and MeFox by demographic, physiologic, and lifestyle variables; estimated the magnitude of variables on biomarker concentrations after covariate adjustment; and determined the prevalence of UMFA >2 nmol/L. RESULTS: After demographic adjustment, age, sex, and race-Hispanic origin were significantly associated with most folate forms. MeFox increased with age, while 5-methyl-THF, UMFA, and nonmethyl folate displayed U-shaped age patterns. Compared with non-Hispanic whites, non-Hispanic blacks had 23% lower predicted 5-methyl-THF but comparable UMFA; non-Hispanic Asians had comparable 5-methyl-THF but 28% lower UMFA; Hispanics, non-Hispanic Asians, and non-Hispanic blacks had ∼20% lower MeFox. After additional physiologic and lifestyle adjustment, predicted UMFA and MeFox concentrations were 43% and 112% higher, respectively, in adults with chronic kidney disease and 17% and 15% lower, respectively, in adults consuming daily 1-<2 alcoholic beverages; 5-methyl-THF concentrations were 20% lower in adult smokers. The prevalence of UMFA >2 nmol/L was highest in persons aged ≥70 y (9.01%) and lowest in those aged 12-19 y (1.14%). During 2011-2014, the prevalence was 10.6% in users and 2.22% in nonusers of folic acid-containing supplements. CONCLUSIONS: In fasting persons ≥1 y, the demographic, physiologic, and lifestyle characteristics observed with serum total folate differed among folate forms, suggesting biological and/or genetic influences on folate metabolism. High UMFA was mostly observed in supplement users and older persons.


Asunto(s)
Ácido Fólico/sangre , Estilo de Vida , Encuestas Nutricionales , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Biomarcadores/sangre , Niño , Preescolar , Estudios Transversales , Femenino , Humanos , Lactante , Masculino , Persona de Mediana Edad , Prevalencia , Tetrahidrofolatos/metabolismo , Adulto Joven
6.
Birth Defects Res A Clin Mol Teratol ; 103(6): 517-26, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25884850

RESUMEN

BACKGROUND: Red blood cell (RBC) folate concentrations are a potential biomarker of folate-sensitive neural tube defect (NTD) risk in the population. The purpose of this analysis was to describe women in the U.S. population with RBC folate concentrations below those associated with optimal NTD prevention. METHODS: We used data from the 2007 to 2012 National Health and Nutrition Examination Survey (NHANES) to assess the RBC folate status of U.S. women of childbearing age relative to risk categories for NTD risk based on RBC folate concentrations. We defined suboptimal RBC folate concentrations as those associated with a prevalence of ≥9 NTDs per 10,000 live births. RESULTS: Among nonpregnant women age 12 to 49 years, 22.8% (95% Confidence Interval: 21.1, 24.6) had suboptimal RBC folate concentrations. Women had greater odds of having a suboptimal RBC folate concentration if they did not use dietary supplements containing folic acid; had mandatorily fortified enriched cereal grain products as their only source of folic acid; were non-Hispanic black or Hispanic; or were current smokers. CONCLUSION: Based on RBC folate concentrations, we would predict that the majority of U.S. women of reproductive age are not at increased risk for folate sensitive NTDs in the presence of mandatory folic acid fortification. Prevention policies and programs can be aimed at population subgroups identified as having higher predicted risk for folate-sensitive NTDs based on RBC folate concentrations.


Asunto(s)
Biomarcadores/sangre , Eritrocitos/química , Ácido Fólico/sangre , Defectos del Tubo Neural/epidemiología , Encuestas Nutricionales/estadística & datos numéricos , Medición de Riesgo/estadística & datos numéricos , Adolescente , Adulto , Femenino , Ácido Fólico/análisis , Humanos , Embarazo , Medición de Riesgo/métodos , Estados Unidos/epidemiología
7.
J Nutr ; 144(2): 170-6, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24306216

RESUMEN

Whether folic acid fortification and supplementation at the population level have led to a higher prevalence of vitamin B-12 deficiency in the absence of anemia remains to be examined among a nationally representative sample of older U.S. adults. We assessed the prevalence of low vitamin B-12 status in the absence of anemia or macrocytosis before and after fortification among adults aged >50 y using cross-sectional data from the NHANES 1991-1994 (prefortification) and 2001-2006 (postfortification). We compared the prefortification and postfortification prevalence of multiple outcomes, including serum vitamin B-12 deficiency (<148 pmol/L) and marginal deficiency (148-258 pmol/L) with and without anemia (hemoglobin <130 g/L for men, <120 g/L for women) and with and without macrocytosis (mean cell volume >100 fL) using multinomial logistic regression, adjusting for age, sex, ethnicity, body mass index, C-reactive protein, and vitamin B-12 supplement use. Prefortification and postfortification serum vitamin B-12 deficiency without anemia [4.0 vs. 3.9%; adjusted prevalence ratio (aPR) (95% CI): 0.98 (0.67, 1.44)] or without macrocytosis [4.2 vs. 4.1%; aPR (95% CI): 0.96 (0.65, 1.43)] remained unchanged. Marginal deficiency without anemia [25.1 vs. 20.7%; aPR (95% CI): 0.82 (0.72, 0.95)] or without macrocytosis [25.9 vs. 21.3%; aPR (95% CI): 0.82 (0.72, 0.94)] were both significantly lower after fortification. After fortification, higher folic acid intake was associated with a lower prevalence of low serum B-12 status in the absence of anemia or macrocytosis. Results suggest that the prevalence of low serum B-12 status in the absence of anemia or macrocytosis among older U.S. adults did not increase after fortification. Thus, at the population level, we found no evidence to support concerns that folic acid adversely affected the clinical presentation of vitamin B-12 deficiency among older adults.


Asunto(s)
Suplementos Dietéticos , Ácido Fólico/farmacología , Alimentos Fortificados , Hemoglobinas/metabolismo , Deficiencia de Vitamina B 12/epidemiología , Vitamina B 12/sangre , Complejo Vitamínico B , Anciano , Anemia Macrocítica/sangre , Estudios Transversales , Dieta , Femenino , Ácido Fólico/efectos adversos , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Encuestas Nutricionales , Prevalencia , Estados Unidos/epidemiología , Deficiencia de Vitamina B 12/sangre , Deficiencia de Vitamina B 12/etiología , Complejo Vitamínico B/efectos adversos , Complejo Vitamínico B/sangre , Complejo Vitamínico B/farmacología
8.
Birth Defects Res ; 116(3): e2329, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38526193

RESUMEN

BACKGROUND: Maternal folate and vitamin B12 deficiency can lead to serious adverse pregnancy outcomes. There are no nationally representative estimates on folate and vitamin B12 status among women of reproductive age (WRA) in Malawi. OBJECTIVE: We assessed folate and vitamin B12 status among nonpregnant WRA in Malawi and predicted the risk of folate-sensitive neural tube defects (NTDs) were they to become pregnant. METHODS: Using data from the cross-sectional, nationally representative 2015-2016 Malawi Micronutrient Survey, we calculated the proportion of folate and vitamin B12 deficiency and insufficiency by demographic characteristics among 778 nonpregnant WRA (15-49 years). We predicted NTD prevalence using red blood cell (RBC) folate distributions and a published Bayesian model of the association between RBC folate and NTD risk. Analyses accounted for complex survey design. RESULTS: Among WRA, 8.5% (95% CI: 6.2, 11.6) and 13.3% (10.0, 17.4) had serum (<7 nmol/L) and RBC folate (<305 nmol/L) deficiency, respectively. The proportion of vitamin B12 deficiency (<148 pmol/L) and insufficiency (≤221 pmol/L) was 11.8% (8.6, 16.0) and 40.6% (34.1, 47.4), respectively. RBC folate insufficiency (<748 nmol/L, defined as the concentration associated with the threshold for elevated NTD risk: >8 cases per 10,000 births) was widespread: 81.4% (75.0, 86.4). The predicted NTD risk nationally was 24.7 cases per 10,000 live births. RBC folate insufficiency and higher predicted NTD risk were more common among WRA living in urban areas or with higher education. CONCLUSIONS: These findings highlight the importance of nutritional and NTD surveillance in Malawi and the opportunity for improving folate and vitamin B12 nutrition among Malawian WRA.


Asunto(s)
Defectos del Tubo Neural , Oligoelementos , Embarazo , Femenino , Humanos , Micronutrientes , Ácido Fólico , Vitamina B 12 , Teorema de Bayes , Estudios Transversales , Malaui/epidemiología , Defectos del Tubo Neural/epidemiología , Defectos del Tubo Neural/etiología , Nacimiento Vivo , Vitaminas
9.
Am J Clin Nutr ; 118(1): 241-254, 2023 07.
Artículo en Inglés | MEDLINE | ID: mdl-37172826

RESUMEN

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.


Asunto(s)
Ácido Fólico , Estado Nutricional , Adulto , Humanos , Estados Unidos , Encuestas Nutricionales , Suplementos Dietéticos , Vitamina B 12 , Grano Comestible , Biomarcadores , Alimentos Fortificados
10.
Am J Clin Nutr ; 117(5): 985-997, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-37137617

RESUMEN

BACKGROUND: RBC folate concentrations are monitored at the population level, with a recommended threshold for optimal neural tube defect (NTD) prevention. A corresponding threshold for serum folate has not been established. OBJECTIVES: This study aimed to estimate the serum folate insufficiency threshold corresponding to the RBC folate threshold for NTD prevention and examine how this threshold is modified by vitamin B12 status. METHODS: Participants were women (15-40 y; not pregnant or lactating; n = 977) from a population-based biomarker survey in Southern India. RBC folate and serum folate were measured via microbiologic assay. RBC folate deficiency (<305 nmol/L) and insufficiency (<748 nmol/L), serum vitamin B12 deficiency (<148 pmol/L) and vitamin B12 insufficiency (<221 pmol/L), elevated plasma MMA (>0.26 µmol/L), elevated plasma homocysteine (>10.0 µmol/L), and elevated HbA1c (≥6.5%) were evaluated. Bayesian linear models were used to estimate unadjusted and adjusted thresholds. RESULTS: Compared with adequate vitamin B12 status, the estimated serum folate threshold was higher in participants with serum vitamin B12 deficiency (72.5 vs. 28.1 nmol/L) or vitamin B12 insufficiency (48.7 vs. 24.3 nmol/L) and elevated MMA (55.6 vs. 25.9 nmol/L). The threshold was lower in participants with elevated HbA1c (HbA1c ≥6.5% vs. <6.5%; 21.0 vs. 40.5 nmol/L). CONCLUSIONS: The estimated serum folate threshold for optimal NTD prevention was similar to previous reports (24.3 vs. 25.6 nmol/L) among participants with sufficient vitamin B12 status. However, this threshold was more than 2-fold higher in participants with vitamin B12 deficiency and substantially higher across all indicators of insufficient vitamin B12 status (<221 pmol/L, elevated MMA, combined B12, impaired vitamin B12 status), and lower in participants with elevated HbA1c. Findings suggest a serum folate threshold for NTD prevention may be possible in some settings; however, it may not be appropriate in populations with high prevalence of vitamin B12 insufficiency. Am J Clin Nutr 2023;xx:xx-xx. This trial was registered at https://clinicaltrials.gov as NCT04048330.


Asunto(s)
Defectos del Tubo Neural , Deficiencia de Vitamina B 12 , Humanos , Femenino , Embarazo , Masculino , Ácido Fólico , Teorema de Bayes , Hemoglobina Glucada , Lactancia , Defectos del Tubo Neural/epidemiología , Defectos del Tubo Neural/prevención & control , Vitamina B 12 , Deficiencia de Vitamina B 12/epidemiología , Biomarcadores , Eritrocitos , Vitaminas , Homocisteína
11.
Curr Dev Nutr ; 7(3): 100052, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-37181934

RESUMEN

Background: Women of reproductive age are at an increased risk of anemia and micronutrient deficiencies. Evidence supports the role of periconceptional nutrition in the development of neural tube defects (NTDs) and other pregnancy complications. Vitamin B12 deficiency is a risk factor for NTDs and may modify folate biomarkers that predict NTD risk at the population level. There is an interest in mandatory fortification with vitamin B12 and folic acid for anemia and birth defect prevention. However, there are limited population-representative data needed to inform policy and guidelines. Objectives: This randomized trial will be conducted to evaluate the efficacy of quadruple-fortified salt (QFS; iron, iodine, folic acid, vitamin B12) in 1,000 households in Southern India. Methods: Women 18 to 49 y who are not pregnant or lactating and reside within the catchment area of our community-based research site in Southern India will be screened and invited to participate in the trial. After informed consent, women and their households will be randomized to receive one of the following 4 interventions: 1) double-fortified salt (DFS; iron, iodine), 2) DFS + folic acid (iron, iodine, folic acid), 3) DFS + vitamin B12 (iron, iodine, vitamin B12), or 4) DFS + folic acid and vitamin B12 (QFS; iron, iodine, folic acid, vitamin B12) for 12 mo. Structured interviews will be conducted by trained nurse enumerators to collect sociodemographic, anthropometric, dietary, health, and reproductive history data. Biological samples will be collected at baseline, midpoint, and endpoint. Whole blood will be analyzed for hemoglobin using Coulter Counter. Total vitamin B12 will be measured by chemiluminescence; red blood cell folate and serum folate will be evaluated using the World Health Organization-recommended microbiologic assay. Conclusions: The results of this randomized trial will help to evaluate the efficacy of QFS to prevent anemia and micronutrient deficiencies. Clinical trial registration numbers: NCT03853304 and Clinical Trial Registry of India REF/2019/03/024479. Registration number: NCT03853304 and REF/2019/03/024479.

12.
Birth Defects Res A Clin Mol Teratol ; 94(11): 864-74, 2012 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-22933447

RESUMEN

BACKGROUND: Maternal nutritional status has been evaluated to clarify its role in development of neural tube defects (NTDs). Maternal folate intake during pregnancy has been closely evaluated for its association with NTDs. The study objective was to examine associations between NTDs and other dietary periconceptional micronutrient intake, particularly nutrients involved in one-carbon metabolism or antioxidant activity. METHODS: Using data from the National Birth Defects Prevention Study, 1997-2005, logistic regression models were used to estimate the relative risk of NTDs based on maternal micronutrient intake. RESULTS: Results were stratified according to folic acid supplement use, race/ethnicity, and maternal body mass index. Analyses included 954 cases (300 with anencephaly, 654 with spina bifida) and 6268 controls. Higher intakes of folate, thiamin, betaine, iron, and vitamin A were associated with decreased risk of anencephaly among some ethnic and clinical groups. In some groups, higher intakes of thiamin, riboflavin, vitamin B(6) , vitamin C, vitamin E, niacin, and retinol were associated with decreased risk of spina bifida. CONCLUSION: In addition to folic acid, other micronutrients, including thiamin, betaine, riboflavin, vitamin B(6) , vitamin C, vitamin E, niacin, iron, retinol, and vitamin A, may decrease the risk of NTD occurrence. Birth Defects Research (Part A) 2012. © 2012 Wiley Periodicals, Inc.


Asunto(s)
Antioxidantes/administración & dosificación , Carbono/metabolismo , Ácido Fólico/administración & dosificación , Micronutrientes/administración & dosificación , Defectos del Tubo Neural/epidemiología , Defectos del Tubo Neural/metabolismo , Vitaminas/administración & dosificación , Adulto , Antioxidantes/metabolismo , Población Negra , Índice de Masa Corporal , Estudios de Casos y Controles , Suplementos Dietéticos , Femenino , Ácido Fólico/metabolismo , Encuestas Epidemiológicas , Hispánicos o Latinos , Humanos , Modelos Logísticos , Masculino , Fenómenos Fisiologicos Nutricionales Maternos , Micronutrientes/metabolismo , Defectos del Tubo Neural/diagnóstico , Defectos del Tubo Neural/etnología , Embarazo , Factores de Riesgo , Estados Unidos/epidemiología , Vitaminas/metabolismo , Población Blanca
13.
Am J Clin Nutr ; 116(1): 74-85, 2022 07 06.
Artículo en Inglés | MEDLINE | ID: mdl-35584808

RESUMEN

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.


Asunto(s)
Deficiencia de Vitamina B 12 , Vitamina B 12 , Anciano , Cognición , Suplementos Dietéticos , Ácido Fólico , Homocisteína , Humanos , Riñón/fisiología , Ácido Metilmalónico , Encuestas Nutricionales , Vitaminas
14.
Clin Nutr ESPEN ; 49: 483-494, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-35623855

RESUMEN

BACKGROUND: Women of reproductive age (WRA) are at increased risk for anemia and iron deficiency. However, there is limited population-level data in India, which could help inform evidence-based recommendations and policy. AIMS: To conduct a population-based biomarker survey of anemia, iron deficiency, and inflammation in WRA in Southern India. METHODS: Participants were WRA (15-40 y) who were not pregnant or lactating. Blood samples (n = 979) were collected and analyzed for hemoglobin (Hb), serum ferritin (SF), soluble transferrin receptor (sTfR), C-reactive protein (CRP), and alpha-1 acid glycoprotein (AGP). Anemia and severe anemia were defined as Hb < 12.0 and < 8.0 g/dL. Serum ferritin was adjusted for inflammation using BRINDA methods. Iron deficiency was defined as SF <15.0 µg/L, iron insufficiency was defined as SF < 20.0 and < 25.0 µg/L, and iron deficiency anemia was defined as Hb < 12.0 g/dL and SF < 15.0 µg/L. Inflammation was defined as CRP > 5.0 mg/L or AGP > 1.0 g/L. Restricted cubic spline regression models were also used to determine if alternative SF thresholds should be used t to classify iron deficiency. RESULTS: A total of 41.5% of WRA had anemia, and 3.0% had severe anemia. Findings from spline analyses suggested a SF cut-off of < 15.0 µg/L, consistent with conventional cut-offs for iron deficiency. 46.3% of WRA had SF < 15.0 µg/L (BRINDA-adjusted: 61.5%), 55.0% had SF < 20.0 µg/L (72.7%), 61.8% had SF < 25.0 µg/L (81.0%), and 30.0% had IDA (34.5%). 17.3% of WRA had CRP > 5.0 mg/L and 22.2% had AGP > 1.0 g/L. The prevalence of ID (rural vs. urban: 49.1% vs. 34.9%; p = 0.0004), iron insufficiency (57.8% vs. 43.8%; p = 0.0005), and IDA (31.8% vs. 22.4%; p = 0.01) were significantly higher in rural areas, although CRP levels were lower and there were no differences in elevated CRP or AGP. CONCLUSIONS: The burden of anemia and iron deficiency in this population was substantial, and increased after adjusting for inflammation, suggesting potential to benefit from screening and interventions. REGISTRATION NUMBER: NCT04048330.


Asunto(s)
Anemia , Deficiencias de Hierro , Adolescente , Adulto , Anemia/epidemiología , Biomarcadores , Proteína C-Reactiva/metabolismo , Femenino , Ferritinas , Hemoglobinas/metabolismo , Humanos , Inflamación/epidemiología , Hierro , Lactancia , Embarazo , Adulto Joven
15.
Nutrients ; 13(4)2021 Apr 16.
Artículo en Inglés | MEDLINE | ID: mdl-33923768

RESUMEN

Surveillance data have highlighted continued disparities in neural tube defects (NTDs) by race-ethnicity in the United States. Starting in 2016, the Food and Drug Administration (FDA) authorized voluntary folic acid fortification of corn masa flour to reduce the risk of neural tube defects (NTDs) among infants of Hispanic women of reproductive age. To assess the impact of voluntary corn masa fortification, cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) 2011-2018 for Hispanic women of reproductive age with available red blood cell (RBC) folate concentrations were analyzed, with additional analyses conducted among Hispanic women whose sole source of folic acid intake was fortified foods (enriched cereal grain products (ECGP) only), excluding ready-to-eat cereals and supplements. RBC folate concentration (adjusted geometric mean) among Hispanic women of reproductive age did not differ between 2011-2016 and 2017-2018, though RBC folate concentration increased significantly among lesser acculturated Hispanic women consuming ECGP only. Concentrations of RBC folate for those born outside the U.S and residing in the U.S <15 years increased from 894 nmol/L (95% CI: 844-946) in 2011-2016 to 1018 nmol/L (95% CI: 982-1162; p < 0.001) in 2017-2018. Primarily Spanish-speaking Hispanic women of reproductive age who only consumed ECGP saw an increase from 941 nmol/L (95% CI: 895-990) in 2011-2016 to 1034 nmol/L (95% CI: 966-1107; p = 0.03) in 2017-2018. By subpopulation, we observed no significant changes in the proportion at risk of NTDs (<748 nmol/L) and no changes in the model-based estimated NTD rates following voluntary corn masa fortification. This analysis suggests that there is a remaining risk among Hispanics for folate sensitive NTDs, though continued monitoring of folate status in future NHANES data cycles will help inform the long-term efficacy of voluntary fortification of corn masa flour.


Asunto(s)
Harina/análisis , Ácido Fólico/administración & dosificación , Alimentos Fortificados/análisis , Hispánicos o Latinos/estadística & datos numéricos , Zea mays/química , Aculturación , Adulto , Anencefalia/epidemiología , Anencefalia/etnología , Anencefalia/prevención & control , Estudios Transversales , Eritrocitos/química , Femenino , Ácido Fólico/sangre , Humanos , Recién Nacido , Masculino , Fenómenos Fisiologicos Nutricionales Maternos/efectos de los fármacos , Fenómenos Fisiologicos Nutricionales Maternos/etnología , Encuestas Nutricionales , Estado Nutricional , Estados Unidos/epidemiología , Adulto Joven
16.
Curr Dev Nutr ; 5(5): nzab069, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-34027296

RESUMEN

BACKGROUND: Women of reproductive age (WRA) are a high-risk population for anemia and micronutrient deficiencies. However, there are few representative population-level data from India, which could help inform evidence-based recommendations and policy. OBJECTIVE: To conduct a population-based biomarker survey of anemia and vitamin B-12 and folate status in WRA as part of a periconceptional surveillance program in southern India. METHODS: Participants were WRA (15-40 y) who were not pregnant or lactating. Whole blood (n = 979) was analyzed for hemoglobin via a Coulter counter (Coulter HMX). Plasma, serum, and RBCs were processed and stored at -80°C or less until batch analysis. Vitamin B-12 concentrations were measured via chemiluminescence; RBC and serum folate concentrations were evaluated via microbiological assay. Anemia and severe anemia were defined as hemoglobin <12.0 g/dL and <8.0 g/dL, respectively. Vitamin B-12 deficiency and insufficiency were defined as total vitamin B-12 <148 pmol/L and <221 pmol/L, respectively. Folate deficiency and insufficiency were defined as RBC folate <305 nmol/L and <748 nmol/L. A previously developed Bayesian model was used to predict neural tube defect (NTD) prevalence per 10,000 births. RESULTS: A total of 41.5% of WRA had anemia and 3.0% had severe anemia. A total of 48.3% of WRA had vitamin B-12 deficiency and 74.3% had vitamin B-12 insufficiency. The prevalence of RBC folate deficiency was 7.6%, and 79.3% of WRA had RBC folate <748 nmol/L, the threshold for optimal NTD prevention. Predicted NTD prevalence per 10,000 births based on RBC folate concentrations was 20.6 (95% uncertainty interval: 16.5-25.5). CONCLUSIONS: The substantial burden of anemia, vitamin B-12 deficiency, and RBC folate insufficiency in WRA in this setting suggests an opportunity for anemia and birth defects prevention. Findings will directly inform the development of a randomized trial for anemia and birth defects prevention in southern India.This study was registered at clinicaltrials.gov as NCT04048330.

17.
Nature ; 425(6960): 851-6, 2003 Oct 23.
Artículo en Inglés | MEDLINE | ID: mdl-14520413

RESUMEN

Hedgehog signalling--an essential pathway during embryonic pancreatic development, the misregulation of which has been implicated in several forms of cancer--may also be an important mediator in human pancreatic carcinoma. Here we report that sonic hedgehog, a secreted hedgehog ligand, is abnormally expressed in pancreatic adenocarcinoma and its precursor lesions: pancreatic intraepithelial neoplasia (PanIN). Pancreata of Pdx-Shh mice (in which Shh is misexpressed in the pancreatic endoderm) develop abnormal tubular structures, a phenocopy of human PanIN-1 and -2. Moreover, these PanIN-like lesions also contain mutations in K-ras and overexpress HER-2/neu, which are genetic mutations found early in the progression of human pancreatic cancer. Furthermore, hedgehog signalling remains active in cell lines established from primary and metastatic pancreatic adenocarcinomas. Notably, inhibition of hedgehog signalling by cyclopamine induced apoptosis and blocked proliferation in a subset of the pancreatic cancer cell lines both in vitro and in vivo. These data suggest that this pathway may have an early and critical role in the genesis of this cancer, and that maintenance of hedgehog signalling is important for aberrant proliferation and tumorigenesis.


Asunto(s)
Transformación Celular Neoplásica , Regulación Neoplásica de la Expresión Génica , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patología , Transducción de Señal , Transactivadores/genética , Transactivadores/metabolismo , Adenocarcinoma/tratamiento farmacológico , Adenocarcinoma/genética , Adenocarcinoma/metabolismo , Adenocarcinoma/patología , Animales , Apoptosis/efectos de los fármacos , División Celular/efectos de los fármacos , Línea Celular Tumoral , Genes erbB-2/genética , Genes ras/genética , Proteínas Hedgehog , Humanos , Ratones , Ratones Desnudos , Mutación , Trasplante de Neoplasias , Neoplasias Pancreáticas/tratamiento farmacológico , Neoplasias Pancreáticas/genética , Transducción de Señal/efectos de los fármacos , Factores de Tiempo , Trasplante Heterólogo , Alcaloides de Veratrum/farmacología , Alcaloides de Veratrum/uso terapéutico
18.
BMJ Open ; 10(10): e038305, 2020 10 29.
Artículo en Inglés | MEDLINE | ID: mdl-33122315

RESUMEN

INTRODUCTION: Women of reproductive age (WRA) are a high-risk population for anaemia and micronutrient deficiencies. Evidence supports the role of periconceptional nutrition in the development of adverse pregnancy complications. However, in India, there are limited population-based data to guide evidence-based recommendations and priority setting. The objective of this study is to conduct a population-based biomarker survey of anaemia and vitamin B12 and folate status in WRA as part of a periconceptional surveillance programme in Southern India. METHODS: WRA (15-40 years) who are not pregnant or lactating and reside within 50 km2 of our community research site in Southern India will be screened and invited to participate in the biomarker survey at our research facility at Arogyavaram Medical Centre. After informed consent/assent, structured interviews will be conducted by trained nurse enumerators to collect sociodemographic, dietary, anthropometry, health and reproductive history data. Venous blood samples will be collected at enrolment; whole blood will be analysed for haemoglobin. Plasma, serum and red blood cells (RBCs) will be processed and stored <-80°C until batch analysis. Vitamin B12 concentrations will be measured via chemiluminescence, and RBC and serum folate concentrations will be evaluated using the World Health Organisation (WHO)-recommended microbiological assay at our laboratory in Bangalore. A WHO surveillance system will also be established to determine the baseline prevalence of birth defects in this setting. ETHICS AND DISSEMINATION: This study has obtained clearance from the Health Ministry Screening Committee of the Indian Council of Medical Research. The study protocol was reviewed and approved by the Institutional Review Board at Cornell University and the Institutional Ethics Committees at Arogyavaram Medical Centre and St. John's Research Institute. Findings from this biomarker survey will establish the burden of anaemia and micronutrient deficiencies in WRA and directly inform a randomised trial for anaemia and birth defects prevention in Southern India. The results of this study will be disseminated at international research conferences and as published articles in peer-reviewed journals. TRIAL REGISTRATION NUMBERS: Clinical trials registration number NCT04048330, NCT03853304 and Clinical Trials Registry of India (CTRI) registration number REF/2019/03/024479.


Asunto(s)
Anemia , Lactancia , Anemia/epidemiología , Anemia/prevención & control , Biomarcadores , Femenino , Humanos , India/epidemiología , Embarazo , Vitamina B 12
19.
Am J Clin Nutr ; 109(5): 1452-1461, 2019 05 01.
Artículo en Inglés | MEDLINE | ID: mdl-31005964

RESUMEN

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.


Asunto(s)
Suplementos Dietéticos , Eritrocitos/metabolismo , Deficiencia de Ácido Fólico/diagnóstico , Ácido Fólico/uso terapéutico , Defectos del Tubo Neural/prevención & control , Atención Preconceptiva/métodos , Vitamina B 12/sangre , Adulto , Teorema de Bayes , Índice de Masa Corporal , China , Femenino , Ácido Fólico/sangre , Deficiencia de Ácido Fólico/sangre , Deficiencia de Ácido Fólico/tratamiento farmacológico , Genotipo , Humanos , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Terapia Nutricional , Salud Poblacional , Atención Preconceptiva/normas , Embarazo , Valores de Referencia , Deficiencia de Vitamina B 12/sangre , Adulto Joven
20.
Nutrients ; 11(1)2019 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-30609688

RESUMEN

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.


Asunto(s)
Ácido Fólico/administración & dosificación , Ácido Fólico/sangre , Teorema de Bayes , Relación Dosis-Respuesta a Droga , Alimentos Fortificados , Humanos , Estado Nutricional
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