小剂量叶酸预防出生缺陷的效果分析

目的：探讨孕前3月（至少1月）至孕早期3月服用小剂量叶酸预防出生缺陷的效果。方法回顾性分析1181例产妇（包括＜20周因出生缺陷而终止妊娠者）临床资料,其中服用过叶酸的625例为观察组,未服用过叶酸的556例为对照组,对出生缺陷情况进行统计。结果两组共发生出生缺陷31例,其中观察组5例（0．80％）,对照组26例（4．68％）,两组比较差异显著（χ2＝17．30,P＜0．05）;两组共发生神经管畸形6例,均发生在对照组,发生率为1．08％,显著高于观察组（χ2＝4．81,P＜0．05）。结论孕前3月（至少1月）至孕早期3月服用小剂量叶酸能有效预防出生缺陷尤其是神经管畸形的发生。     

叶酸与出生缺陷的预防

叶酸属于B族维生素,是DNA和RNA合成过程中不可缺少的重要物质,在细胞生长、分化、修复和宿主防御等方面扮演重要角色.近年来,各国学者对其在生殖领域的作用进行了大量的研究,母体叶酸的缺乏与神经管畸形、先天性心脏病、唇腭裂等出生缺陷的发生均有关联,研究证实.围妊娠期增补叶酸可有效降低胎儿发生神经管畸形等出生缺陷的危险性.     

叶酸与出生缺陷的预防

叶酸属于B族维生素,是DNA和RNA合成过程中不可缺少的重要物质,在细胞生长、分化、修复和宿主防御等方面扮演重要角色。近年来,各国学者对其在生殖领域的作用进行了大量的研究,母体叶酸的缺乏与神经管畸形、先天性心脏病、唇腭裂等出生缺陷的发生均有关联,研究证实,围妊娠期增补叶酸可有效降低胎儿发生神经管畸形等出生缺陷的危险性。     

叶酸预防神经管畸形在相关人群中的知晓率及行为

目的 了解妇幼卫生人员、婚检妇女和孕妇对孕前和孕早期服用叶酸预防神经管畸形的知识掌握程度及相关行为。 方法 根据不同的对象自行设计知识和行为调查问卷,由妇幼卫生人员、婚检妇女和孕妇自己填写,将结果进行x2检验和方差分析。 结果 76.7%(155/202)的妇幼卫生人员知道服用叶酸可以减少神经管畸形的发生,26.7%(54/202)的知道叶酸应当从孕前开始服用,仅有5.9%(12/202)的人知道叶酸每天摄入的适当量是0.4 mg-1 mg,34.7%(70/202)的妇幼卫生人员推荐的剂量大于1 mg;194名婚检妇女仅4人(2.1%)知道叶酸可以预防胎儿畸形,4人在服用叶酸增补剂,2人知道要从孕前服用;31.9%(67/210)的孕妇知道叶酸与神经管畸形的关系,16.2%(34/210)知道应从孕前服用,14.3%(30/210)孕妇在服用叶酸增补剂,仅4人(1.9%)真正从孕前开始服用。 结论 妇女增补叶酸预防神经管畸形的知识还没有得到很好的普及,叶酸的服用率低。建议培训妇幼人员(特别是县乡级人员)正确指导妇女应用叶酸的知识和能力,加大婚前教育宣传力度,增加服用叶酸预防神经管畸形知识的知晓率。     

叶酸预防神经管畸形在相关人群中的知晓率及行为

目的：了解妇幼卫生人员、婚检妇女和孕妇对孕前和孕早期服用叶酸预防神经管畸形的知识掌握程度及相关行为。方法：根据不同的对象自行设计知识和行为调查问卷，由妇幼卫生人员、婚检妇女和孕妇自己填写，将结果进行χ^2检验和方差分析。结果：76．7％（155／202）的妇幼卫生人员知道服用叶酸可以减少神经管畸形的发生，26．7％（54／202）的知道叶酸应当从孕前开始服用，仅有5．9％（12／202）的人知道叶酸每天摄入的适当量是0．4mg-1mg，34.7%(70/202)的妇幼卫生人员推荐的剂量大于1mg；194名婚检妇女仅4人（2．1％）知道叶酸可以预防胎儿畸形，4人在服用叶酸增补剂，2人知道要从孕前服用；31．9％（67／210）的孕妇知道叶酸与神经管畸形的关系，16．2％（34／210）知道应从孕前服用，14．3％（30／210）孕妇在服用叶酸增补剂，仅4人（1．9％）真正从孕前开始服用。结论：妇女增补叶酸预防神经管畸形的知识还没有得到很好的普及，叶酸的服用率低。建议培训妇幼人员（特别是县乡级人员）正确指导妇女应用叶酸的知识和能力，加大婚前教育宣传力度，增加服用叶酸预防神经管畸形知识的知晓率。     

面粉强化叶酸对出生缺陷的影响

大量数据显示面粉中强化叶酸能有效预防出生缺陷的发生并降低其危害性。影响叶酸强化面粉对出生缺陷作用的因素可能包括:种族差异、孕妇年龄及受教育程度、围产期的医疗质量水平、叶酸强化的剂量等。面粉中强化叶酸是预防出生缺陷安全有效的措施,能够最大程度地保障妇女在孕期摄入足够的叶酸以预防和控制新生儿出生缺陷的发生。     

038 面粉强化叶酸对出生缺陷的影响

大量数据显示面粉中强化叶酸能有效预防出生缺陷的发生并降低其危害性.影响叶酸强化面粉对出生缺陷作用的因素可能包括:种族差异、孕妇年龄及受教育程度、围产期的医疗质量水平、叶酸强化的剂量等.面粉中强化叶酸是预防出生缺陷安全有效的措施,能够最大程度地保障妇女在孕期摄入足够的叶酸以预防和控制新生儿出生缺陷的发生.     

推广使用叶酸增补剂预防神经管畸形

“妇女增补叶酸预防神经管畸形”是卫生部“十年百项”计划推广项目之一 ,也是国家“九五”攻关项目。我所 1997年 8月开始在本区推广应用叶酸增补剂斯利安片 (含叶酸 0 .4mg/片 ) ,现将用药效果报告如下。1　对象与方法1.1　对象　婚前医学检查女青年为用药对象。其年龄最大者30岁 ,最小 2 2岁。 1998年 1月至 2 0 0 0年 12月已分娩 3 341人(均住院分娩 )。其中孕前、孕期持续服药者 1418人为干预组 ,未服药及间歇服药者 192 3人为对照组。1.2　方法斯利安用法 :孕前期、孕期全程用药 ,哺乳期继续用药。孕前期 3个月 ,孕期全程用药用量为每…     

美国公布叶酸预防神经管缺陷效果

1998年美国政府要求所有制造商在其生产的各类谷物中添加叶酸以来 ,先天性神经管缺陷 (包括脊柱裂和无脑畸形 )的总发病率下降了 2 7%。美国疾病控制中心日前公布了这个结果。自 1992年起 ,美国卫生部建议育龄妇女每日应摄入叶酸 4 0 0μg。但目前仅有 30 %～ 35 %的育龄妇女增     

计划生育技术人员有关增补叶酸预防胎儿神经管缺陷的KAP调查分析

目的:调查四川省基层计划生育技术人员对育龄妇女增补叶酸预防神经管缺陷的知晓率, 对增补叶酸的态度、是否愿意向育龄妇女推荐的行为等情况, 为实施叶酸预防神经管缺陷的干预措施提供科学依据。方法: 调查指标包括叶酸的知识、增补叶酸的方法、时间和剂量以及相应的态度和行为, 设计调查问卷, 对507名计划生育专业技术人员进行现场调查, 收集有效答卷485份, 数据录入计算机, 进行统计学分析。结果: 53. 8%的被调查人员知道叶酸来源, 不同职称组没有统计学差异。增补叶酸最佳时间的知晓率为45 .8%, 正确补充剂量的知晓率约30 .0%, 且不同技术职称、不同工作单位的人员均显示出显著性差异(P<0. 01)。89. 7%的人认为有必要增补叶酸, 75 .1%的人愿意向育龄妇女推荐。结论: 对于育龄妇女实施增补叶酸的措施, 计划生育技术人员有积极的态度和行为, 但正确补充叶酸的知晓率较低, 影响干预措施的落实。需要进一步有针对性地加强计划生育技术人员有关增补叶酸知识的培训。     

同型半胱氨酸诱发鸡胚神经管畸形及叶酸的保护作用

为了揭示同型半胱氨酸（ｈｏｍｏｃｙｓｔｅｉｎｅ，ＨＣＹ）是否能导致胚胎发生神经管畸形（ＮＴＤｓ）和可能的致畸机制及验证叶酸和ＶＢ１２的干预效果，本研究应用鸡胚致畸试验、扫描电镜观察、尼罗兰盐活体染色、原位ＤＮＡ片段末端标记、甲基绿—派若宁染色显示核酸法、叶酸和Ｂ１２干预实验等方法检测了用ＨＣＹ（０～１６μｍｏｌ／胚胎）的不同胚龄胚胎１２７４只。结果显示ＨＣＹ对神经胚形成期和器官形成期的胚胎均有显著的致畸性并呈剂量－反应关系（Ｐ＜０．０００１），鸡胚发生ＮＴＤｓ的主要表现是露脑，裂脑和脊柱裂。首次发现ＨＣＹ能诱发神经系统细胞凋亡过度，其部位与ＮＴＤｓ发生部位相吻合。ＨＣＹ能抑制卵黄囊血管分化；损伤羊膜组织及细胞超微结构，如微绒毛变短，胞膜上出现空洞样变等。注射５μｇ叶酸明显拮抗ＨＣＹ（８μｍｏｌ／胚胎）的致畸性，ＮＴＤｓ发生率由４３．５％降至０（Ｐ＜０．０５）；注射１μｇＶＢ１２不能明显保护胚胎（Ｐ＞０．０５）。本研究结果说明ＨＣＹ能诱导胚胎发生ＮＴＤｓ；细胞凋亡在ＮＴＤｓ发生过程中起重要作用；叶酸能有效地预防ＮＴＤｓ；ＨＣＹ自身所诱发的ＮＴＤｓ可能是多种机制相互作用或联合作用的结果     

Folic Acid Food Fortification in Canada

By January 1998, most Canadian cereal grains (e.g., white flour) were being fortified with folic acid, with a large percentage being fortified by mid-1997. This was in compliance with both American and Canadian mandatory fortification deadlines of January and November 1998, respectively. It was estimated that between 0.1 to 0.2 mg of additional synthetic folic acid per day would be provided through this initiative, the goal of which was to lower the rate of neural tube defects (NTD). The current report outlines some of the changes to the health status of Canadians in relation to its folic acid food fortification initiative.     

Folate Deficiency and Folic Acid Supplementation: The Prevention of Neural-Tube Defects and Congenital Heart Defects

Diet, particularly vitamin deficiency, is associated with the risk of birth defects. The aim of this review paper is to show the characteristics of common and severe neural-tube defects together with congenital heart defects (CHD) as vitamin deficiencies play a role in their origin. The findings of the Hungarian intervention (randomized double-blind and cohort controlled) trials indicated that periconceptional folic acid (FA)-containing multivitamin supplementation prevented the major proportion (about 90%) of neural-tube defects (NTD) as well as a certain proportion (about 40%) of congenital heart defects. Finally the benefits and drawbacks of three main practical applications of folic acid/multivitamin treatment such as (i) dietary intake; (ii) periconceptional supplementation; and (iii) flour fortification are discussed. The conclusion arrived at is indeed confirmation of Benjamin Franklin’s statement: “An ounce of prevention is better than a pound of care”.     

Association between Serum Unmetabolized Folic Acid Concentrations and Folic Acid from Fortified Foods

Objective: To investigate the association between serum unmetabolized folic acid (UMFA) concentrations and folic acid from fortified foods and nutrients known as dietary methyl-group donors (folate, methionine, choline, betaine and vitamins B2, B6 and B12) in participants exposed to mandatory fortification of wheat and maize flours with folic acid.

Methods: Cross-sectional study carried out with 144 healthy Brazilian participants, both sexes, supplement nonusers. Serum folate, UMFA, vitamin B12 and total plasma homocysteine (tHcy) were biochemically measured. Dietary intake was assessed by 2 non-consecutive 24-hour dietary recalls (24-HRs) and deattenuated energy-adjusted nutrient data were used for statistical analysis.

Results: Ninety eight (68.1%) participants were women. Median (interquartile range) age was 35.5 (28.0–52.0) years. Elevated serum folate concentrations (>45 nmol/L) were found in 17 (11.8%), while folate deficiency (<7 nmol/L) in 10 (6.9%) participants. No one had vitamin B12 deficiency (<148 pmol/L). An elevated serum UMFA concentration was defined as > 1 nmol/L (90th percentile). UMFA concentrations were positively correlated with folic acid intake and negatively correlated to choline, methionine and vitamin B6 intakes. Participants in the lowest quartile of UMFA concentrations had lower dietary intake of total folate (DFEs) and folic acid, and higher dietary intake of methionine, choline and vitamin B6 than participants in the highest quartile of UMFA. Folic acid intake (OR [95% CI] = 1.02 [1.01–1.04)] and being a male (OR [95% CI] = 0.40 [0.19–0.87) were associated with increased and reduced odds for UMFA concentrations > 0.55 nmol/L (median values), respectively.

Conclusion: UMFA concentrations were directly influenced by folic acid intake from fortified foods in a healthy convenience sample of adult Brazilians exposed to mandatory flour fortification with folic acid.     

Women Taking a Folic Acid Supplement in Countries with Mandatory Food Fortification Programs May Be Exceeding the Upper Tolerable Limit of Folic Acid: A Systematic Review

Background: In preconception and pregnancy, women are encouraged to take folic acid-based supplements over and above food intake. The upper tolerable limit of folic acid is 1000 mcg per day; however, this level was determined to avoid masking a vitamin B12 deficiency and not based on folic acid bioavailability and metabolism. This review’s aim is to assess the total all-source intake of folate in women of childbearing age and in pregnancy in high-income countries with folate food fortification programs. Methods: A systematic search was conducted in five databases to find studies published since 1998 that reported folate and folic acid intake in countries with a mandatory fortification policy. Results: Women of childbearing age do not receive sufficient folate intake from food sources alone even when consuming fortified food products; however, almost all women taking a folic acid-based supplement exceed the upper tolerable limit of folic acid intake. Conclusions: Folic acid supplement recommendations and the upper tolerable limit of 1000 mcg set by policy makers warrant careful review in light of potential adverse effects of exceeding the upper tolerable limit on folic acid absorption and metabolism, and subsequent impacts on women’s health during their childbearing years.     

Folic Acid Fortification of Wheat Flour: Chile

Neural tube defects (open spina bifida, anencephaly, and encephalocele) represent the first congenital malformations to be preventable through public health measures such as supplementation and/or food fortification with folic acid. In Chile, starting in January 2000, the Chilean Ministry of Health legislated to add folic acid to wheat flour (2.2 mg/kg) to reduce the risk of NTDs. This policy resulted in an estimated mean additional supply of 427 μg/d in significant increases in serum folate and red cell folate of 3.8 and 2.4-fold, respectively, in women of fertile age, one year after fortification. The impact on the rate of NTDs is presently being studied in all births, both live births and still births, with birth weight >500 g in the city of Santiago. Preliminary results show a reduction of 40% in the rates on NTDs from the pre-fortification period (1999–2000) to post-fortification period (2001-June 2002). Fortification of wheat flour with folic acid in Chile is effective in preventing NTDs in Chile.     

Effectiveness of Folic Acid Fortified Flour for Prevention of Neural Tube Defects in a High Risk Region

Despite efforts to tackle folate deficiency and Neural Tube Defects (NTDs) through folic acid fortification, its implementation is still lacking where it is needed most, highlighting the need for studies that evaluate the effectiveness of folic acid fortified wheat flour in a poor, rural, high-risk, NTD region of China. One of the most affected regions, Shanxi Province, was selected as a case study. A community intervention was carried out in which 16,648 women of child-bearing age received fortified flour (eight villages) and a control group received ordinary flour (three villages). NTD birth prevalence and biological indicators were measured two years after program initiation at endline only. The effect on the NTD burden was calculated using the disability-adjusted life years (DALYs) method. In the intervention group, serum folate level was higher than in the control group. NTDs in the intervention group were 68.2% lower than in the control group (OR = 0.313, 95% CI = 0.207–0473, p < 0.001). In terms of DALYs, burden in intervention group was approximately 58.5% lower than in the control group. Flour fortification was associated with lower birth prevalence and burden of NTDs in economically developing regions with a high risk of NTDs. The positive findings confirm the potential of fortification when selecting an appropriate food vehicle and target region. As such, this study provides support for decision makers aiming for the implementation of (mandatory) folic acid fortification in China.