Cork Center for Vitamin D and Nutrition Research, School of Food and Nutritional Sciences.
Irish Center for Fetal and Neonatal Translational Research (INFANT).
Am J Clin Nutr. 2018 Jul 1;108(1):77-91. doi: 10.1093/ajcn/nqy064.
In the absence of dose-response data, Dietary Reference Values for vitamin D in nonpregnant adults are extended to pregnancy.
The aim was to estimate vitamin D intake needed to maintain maternal 25-hydroxyvitamin D [25(OH)D] in late gestation at a concentration sufficient to prevent newborn 25(OH)D <25-30 nmol/L, a threshold indicative of increased risk of nutritional rickets.
We conducted a 3-arm, dose-response, double-blind, randomized placebo-controlled trial in Cork, Ireland (51.9oN). A total of 144 white-skinned pregnant women were assigned to receive 0, 10 (400 IU), or 20 (800 IU) µg vitamin D3/d from ≤18 wk of gestation. Vitamin D metabolites at 14, 24, and 36 wk of gestation and in cord sera, including 25(OH)D3, 3-epi-25(OH)D3, 24,25(OH)2D3, and 25(OH)D2 were quantified by liquid chromatography-tandem mass spectrometry. A curvilinear regression model predicted the total vitamin D intake (from diet and antenatal supplements plus treatment dose) that maintained maternal 25(OH)D in late gestation at a concentration sufficient to maintain cord 25(OH)D at ≥25-30 nmol/L.
Mean ± SD baseline 25(OH)D was 54.9 ± 10.7 nmol/L. Total vitamin D intakes at the study endpoint (36 wk of gestation) were 12.1 ± 8.0, 21.9 ± 5.3, and 33.7 ± 5.1 µg/d in the placebo and 10-µg and 20-µg vitamin D3 groups, respectively; and 25(OH)D was 24.3 ± 5.8 and 29.2 ± 5.6 nmol/L higher in the 10- and 20-µg groups, respectively, compared with placebo (P < 0.001). For maternal 25(OH)D concentrations ≥50 nmol/L, 95% of cord sera were ≥30 nmol/L and 99% were >25 nmol/L. The estimated vitamin D intake required to maintain serum 25(OH)D at ≥50 nmol/L in 97.5% of women was 28.9 µg/d.
Thirty micrograms of vitamin D per day safely maintained serum 25(OH)D concentrations at ≥50 nmol/L in almost all white-skinned women during pregnancy at a northern latitude, which kept 25(OH)D at >25 nmol/L in 99% and ≥30 nmol/L in 95% of umbilical cord sera. This trial was registered at www.clinicaltrials.gov as NCT02506439.
在缺乏剂量-反应数据的情况下，将非妊娠成年人的维生素 D 膳食参考值扩展到妊娠期间。
旨在估计维生素 D 摄入量，以维持妊娠晚期母体 25-羟维生素 D [25(OH)D]浓度，使其足以预防新生儿 25(OH)D <25-30 nmol/L，这一阈值表明营养性佝偻病的风险增加。
我们在爱尔兰科克（51.9oN）进行了一项 3 臂、剂量反应、双盲、随机安慰剂对照试验。共有 144 名白种肤色的孕妇被分配接受 0、10（400 IU）或 20（800 IU）µg 维生素 D3/d，从妊娠≤18 周开始。妊娠 14、24 和 36 周以及脐带血清中的维生素 D 代谢物，包括 25(OH)D3、3-epi-25(OH)D3、24,25(OH)2D3 和 25(OH)D2，通过液相色谱-串联质谱法进行定量。曲线回归模型预测了总维生素 D 摄入量（来自饮食和产前补充剂加上治疗剂量），以维持妊娠晚期母体 25(OH)D 浓度，足以维持脐带 25(OH)D 浓度≥25-30 nmol/L。
平均 ± SD 基线 25(OH)D 为 54.9 ± 10.7 nmol/L。研究终点（妊娠 36 周）的总维生素 D 摄入量分别为安慰剂组和 10-µg 和 20-µg 维生素 D3 组的 12.1 ± 8.0、21.9 ± 5.3 和 33.7 ± 5.1 µg/d；与安慰剂组相比，10-µg 和 20-µg 维生素 D3 组的 25(OH)D 分别高 24.3 ± 5.8 和 29.2 ± 5.6 nmol/L（P < 0.001）。对于母体 25(OH)D 浓度≥50 nmol/L，95%的脐带血清≥30 nmol/L，99%的脐带血清>25 nmol/L。维持 97.5%白人孕妇血清 25(OH)D 浓度≥50 nmol/L所需的维生素 D 摄入量估计为 28.9 µg/d。
每天摄入 30 µg 维生素 D 可安全地维持妊娠期间几乎所有白种肤色女性的血清 25(OH)D 浓度≥50 nmol/L，使 99%的孕妇脐带血清 25(OH)D 浓度>25 nmol/L，95%的孕妇脐带血清 25(OH)D 浓度≥30 nmol/L。该试验在 www.clinicaltrials.gov 上注册为 NCT02506439。
