O'Callaghan Karen M, Qamar Huma, Gernand Alison D, Onoyovwi A K, Zlotkin Stanley, Mahmud Abdullah A, Ahmed Tahmeed, Keya Farhana K, Roth Daniel E
Department of Nutritional Sciences, King's College London, London, UK.
Centre for Global Child Health and SickKids Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada.
BMJ Nutr Prev Health. 2023 Dec;6(2):282-292. doi: 10.1136/bmjnph-2023-000758. Epub 2023 Nov 14.
Vitamin D may modify iron status through regulation of hepcidin and inflammatory pathways. This study aimed to investigate effects of maternal vitamin D supplementation on iron status in pregnancy and early infancy.
In a trial in Dhaka, Bangladesh, women (n=1300) were randomised to one of five vitamin D regimens from 17 to 24 weeks' gestation until 26 weeks postpartum (prenatal; postpartum doses): 0;0, 4200;0, 16 800;0, 28 000;0 or 28 000;28 000 IU/week. All participants received standard iron-folic acid supplementation. In this secondary analysis (n=998), we examined effects of prenatal;postpartum vitamin D on serum ferritin and other biomarkers of maternal iron status (transferrin saturation, total iron binding capacity, soluble transferrin receptor and hepcidin) at delivery, and infant ferritin and haemoglobin at 6 months of age. Using linear regression, we estimated per cent mean differences between each intervention group and placebo with 95% CIs, with and without adjustment for baseline ferritin or inflammatory biomarkers (C reactive protein and α-1-acid glycoprotein (AGP)).
At delivery, ferritin concentrations were similar between each intervention group and placebo in unadjusted (n=998) and baseline ferritin-adjusted analyses (n=992; p>0.05). Compared with placebo, AGP was lower in each intervention group (per cent difference (95% CI) = -11% (-21 to -1.0), -14% (-23 to -3.5) and -11% (-19 to -2.0) in the 4200 IU/week, 16 800 IU/week and 28 000 IU/week groups, respectively; n=779). In the subgroup of women with baseline 25-hydroxyvitamin D < 30 nmol/L, ferritin was lower in each intervention group versus placebo (-23% (-37 to -5.0), -20% (-35 to -1.9) and -20% (-33 to -4.1) in the 4200 IU/week, 16 800 IU/week and 28 000 IU/week groups, respectively; n=645); effects were slightly attenuated after adjustment for inflammation (n=510). There were no effects of vitamin D on other iron biomarkers among women at delivery or infants aged 6 months.
These findings do not support improvement of iron status by vitamin D. The effect of prenatal vitamin D supplementation on ferritin may reflect an anti-inflammatory mechanism.
维生素D可能通过调节铁调素和炎症途径来改变铁状态。本研究旨在探讨孕期补充维生素D对妊娠及婴儿早期铁状态的影响。
在孟加拉国达卡进行的一项试验中，1300名女性从妊娠17至24周随机分为五种维生素D方案之一，直至产后26周（产前；产后剂量）：0；0、4200；0、16800；0、28000；0或28000；28000国际单位/周。所有参与者均接受标准的铁叶酸补充剂。在这项二次分析（n = 998）中，我们研究了产前；产后维生素D对分娩时血清铁蛋白及其他母体铁状态生物标志物（转铁蛋白饱和度、总铁结合力、可溶性转铁蛋白受体和铁调素）以及6月龄婴儿铁蛋白和血红蛋白的影响。使用线性回归，我们估计了每个干预组与安慰剂组之间的平均差异百分比及其95%置信区间，同时对基线铁蛋白或炎症生物标志物（C反应蛋白和α-1-酸性糖蛋白（AGP））进行了调整或未调整。
在分娩时，未调整分析（n = 998）和基线铁蛋白调整分析（n = 992；p>0.05）中，各干预组与安慰剂组的铁蛋白浓度相似。与安慰剂相比，各干预组的AGP较低（4200国际单位/周、16800国际单位/周和28000国际单位/周组的差异百分比（95%置信区间）分别为-11%（-21至-1.0）、-14%（-23至-3.5）和-11%（-19至-2.0）；n = 779）。在基线25-羟基维生素D<30 nmol/L的女性亚组中，各干预组的铁蛋白低于安慰剂组（4200国际单位/周、16800国际单位/周和28000国际单位/周组分别为-23%（-37至-5.0）、-20%（-35至-1.9）和-20%（-33至-4.1）；n = 645）；在调整炎症因素后影响略有减弱（n = 510）。维生素D对分娩时女性或6月龄婴儿的其他铁生物标志物没有影响。
这些发现不支持维生素D改善铁状态。产前补充维生素D对铁蛋白的影响可能反映了一种抗炎机制。
