FOLATE REQUIREMENTS OF PREGNANT HUMAN SUBJECTS

一种用氚标记叶酸的慢性体内补充方案 受控代谢条件下的酸将被用来估计叶酸 对孕妇的要求。主要的研究目标是提供 孕妇用于饮食的叶酸需要量估计 摄入量建议和产前叶酸补充政策 确保胎儿正常发育和产妇健康。具体的 目标是通过以下方式估计叶酸需求量：(1)应用 动力学方法学；以及(2)尿叶酸排泄量的测定 产品。标记的和未标记的叶酸(D5或D0)将是 两组孕妇从14周开始在整个妊娠期间服用 妇女摄入受控的叶酸(400或800微克/天)。 所需费用估计数将与2中确定的估计数进行比较。 非孕对照组。人类社会的出现和消失 标记叶酸和分解代谢物的同位素富集法测定 尿液和血液将是动力学要求的基础- 决心。数据将适合特定型号和要求 基于总体库和部分分解代谢率的估计。 第二种方法是对(1)尿的总和进行量化 叶酸分解代谢物[D5或D0对氨基苯谷氨酸(PABG)和 衍生物(apABG，PABA)；和(2)代谢完整叶酸(CH3THFA)。 饮食中分解代谢产物对尿液排泄的影响 产品将根据回收的D4pABG添加到饮食中。 叶酸代谢动力学参数的变化及定量研究 排泄物产品因应两个摄入量水平将作为 产前叶酸需要量估计的基础。这些数据将 提供膳食叶酸和补充叶酸的理由 针对孕妇的推荐政策。这些新技术的应用 需求数据将确保足够的叶酸摄入量，以预防 与健康相关的后果(如神经管缺陷、胎儿受损 生长、巨幼细胞性贫血)的妇女叶酸缺乏 生育年龄。

A chronic in vivo supplementation protocol with deuterium-labeled folic acid under controlled metabolic conditions will be used to estimate folate requirements of pregnant women. The primary research goal is to provide folate requirement estimates for pregnant women to be used for dietary intake recommendations and prenatal folic acid supplementation polices to ensure normal fetal development and maternal health. The specific objectives are to estimate folate requirements by (1) the application of kinetic methodology; and (2) quantitation of urinary folate excretory products. Deuterium labeled and unlabeled folic acid (D5, or D0) will be given throughout gestation beginning at 14 wks to 2 groups of pregnant women consuming controlled intakes of folate (400 or 800 micrograms/d). Requirement estimates will be compared to estimates determined in 2 nonpregnant control groups. The appearance and disappearance of the labeled folates and catabolites as determined by isotope enrichment of urine and blood will be the basis of the kinetic requirement- determination. The data will be fit to specific models and the requirement based on the estimation of total body pool and fractional catabolic rate. A second approach will be the quantitation of the sum of (1) urinary folate catabolites [D5, or D0 p-aminobenzyolglutamate (pABG) and derivatives (apABG, pABA); and (2) metabolized intact folate (CH3THFA). The contribution of catabolites present in the diet to urinary excretory products will be based on the recovery of D4 pABG added to the diet. Changes in kinetic parameters and quantitation of metabolized folate excretory products in response to the two levels of intake will serve as the basis for prenatal folate requirement estimates. These data will provide a justification for dietary folate and supplemental folic acid recommendation polices for pregnant women. Application of these new requirement data will ensure adequate intake of folate for prevention of health related consequences (i.e. neural tube defects, impaired fetal growth, megaloblastic anemia) of folate inadequacy in women of reproductive age.