哺乳期加拿大妇女每天摄入 1000μg 叶酸，其血清叶酸水平高于血清总叶酸的阈值浓度。

Lactating Canadian Women Consuming 1000 µg Folic Acid Daily Have High Circulating Serum Folic Acid Above a Threshold Concentration of Serum Total Folate.

机构信息

Department of Life Sciences, Institute of Technology Sligo, Sligo, Ireland.

Department of Food, Nutrition, and Health, University of British Columbia, and the British Columbia Children's Hospital Research Institute, Vancouver, Canada.

出版信息

J Nutr. 2018 Jul 1;148(7):1103-1108. doi: 10.1093/jn/nxy070.

DOI:10.1093/jn/nxy070

PMID:29901753

Abstract

BACKGROUND

Consumption of high-dose folic acid supplements is common throughout pregnancy and lactation in several countries, including Canada, Brazil, and the United States, and may lead to high levels of circulating unmetabolized folic acid.

OBJECTIVE

The objective of the study was to characterize serum and whole-blood folate forms in Canadian lactating women regularly consuming a daily high-dose folic acid supplement.

METHODS

One-hundred and seventeen Canadian lactating women aged between 18 and 42 y, with a geometric mean ± SD prepregnancy body mass index (kg/m2) of 23.1 ± 1.2, were enrolled in a vitamin D supplementation trial between 13 and 22 wk of gestation. As part of the trial, the women received a daily multivitamin containing 1000 µg folic acid throughout pregnancy and lactation until 8 wk postpartum. At 8 wk postpartum, serum folate forms, including folic acid and RBC total folate, were determined from nonfasted blood samples. Differences in median folate vitamer concentrations among quintiles of serum total folate status were assessed by the Wald test and quantile regression methods. A breakpoint in the relation between serum folic acid and serum total folate was modeled with the use of the segmented package in R.

RESULTS

Median serum total folate concentration among participants was 79.3 nmol/L (5th-95th percentile 30.7-186 nmol/L) and median RBC folate concentration was 2790 nmol/L (5th-95th percentile 1330-4850 nmol/L). There was a breakpoint in the relation between serum total folate and serum folic acid at 78.5 nmol/L (95% CI: 67.9, 89.1 nmol/L), below which serum folic acid was not associated with serum total folate, and above which serum folic acid increased 0.78 nmol/L (95% CI: 0.70, 0.86 nmol/L; P < 0.001) for each 1 nmol/L increase in serum total folate.

CONCLUSIONS

These data demonstrate the potential for high serum folic acid concentrations proportional to overall folate concentrations in lactating women with serum total folate >80 nmol/L taking high-dose supplemental folic acid. This study was registered at clinicaltrials.gov as NCT01112891.

摘要

背景

在加拿大、巴西和美国等几个国家，孕妇和哺乳期妇女普遍会服用大剂量叶酸补充剂，这可能导致循环中未代谢的叶酸水平升高。

目的

本研究旨在描述经常服用高剂量叶酸补充剂的加拿大哺乳期妇女的血清和全血叶酸形式。

方法

本研究共纳入 117 名年龄在 18 至 42 岁之间的加拿大哺乳期妇女，她们在妊娠 13 至 22 周时参加了维生素 D 补充试验，这些妇女的妊娠前体重指数（kg/m2）几何均数±标准差为 23.1±1.2。作为试验的一部分，这些妇女在妊娠和哺乳期每天接受含有 1000μg叶酸的多种维生素补充剂，直至产后 8 周。在产后 8 周时，从非禁食的血样中测定血清叶酸形式，包括叶酸和 RBC 总叶酸。采用 Wald 检验和分位数回归方法评估血清总叶酸状态五分位数组间叶酸维生素浓度中位数的差异。使用 R 中的分段包来模拟血清叶酸与血清总叶酸之间的关系中的断点。

结果

参与者的血清总叶酸浓度中位数为 79.3 nmol/L（5 分位至 95 分位为 30.7-186 nmol/L），RBC 叶酸浓度中位数为 2790 nmol/L（5 分位至 95 分位为 1330-4850 nmol/L）。血清总叶酸与血清叶酸之间存在 78.5 nmol/L（95%CI：67.9，89.1 nmol/L）的关系断点，在此点以下，血清叶酸与血清总叶酸无关，在此点以上，血清叶酸浓度每增加 1 nmol/L，血清总叶酸浓度增加 0.78 nmol/L（95%CI：0.70，0.86 nmol/L；P<0.001）。