Food, Nutrition, and Health Program, Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia, Canada.
British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada.
J Nutr. 2019 Aug 1;149(8):1354-1362. doi: 10.1093/jn/nxz082.
Vitamin B-6 (B-6), in the form of pyridoxal 5'phosphate (PLP), is critical for one-carbon metabolism reactions and cellular function. Plasma PLP concentration decreases throughout pregnancy, but the functional consequences of this have not been studied. Plasma cystathionine is a sensitive indicator of suboptimal B-6 status in healthy adults.
The aim of this study was to determine the relation between plasma PLP and cystathionine concentrations, and to assess longitudinal changes in plasma concentrations of metabolites of one-carbon metabolism, including total homocysteine (tHcy), cysteine, methionine, glycine, serine, and glutathione, over the course of pregnancy.
This was a prospective cohort study of 186 healthy Brazilian pregnant women (20-40 y). Plasma PLP and metabolite concentrations were quantified in fasting maternal blood samples collected between 5-13, 20-26, and 30-36 weeks of gestation. Linear mixed regression models were used to determine the association of 1) first-trimester PLP tertiles, and 2) the variation of PLP concentration throughout pregnancy, with related metabolite concentrations across weeks of gestation.
Median (IQR) PLP concentration decreased from 36.2 (29.2-44.5) to 21.0 (15.9-26.0) to 16.8 (12.9-21.4) nmol/L in the first, second, and third trimester, respectively, whereas cystathionine concentration increased from 63.2 (49.7-78.9) to 122 (98.0-167) to 143 (114-193) nmol/L, respectively (both P < 0.001). The variation of PLP throughout pregnancy was inversely associated with cystathionine concentration across weeks of gestation, after adjusting for confounding factors; β (95% CI) = -0.387 (-0.752, -0.219), P = 0.04. This association significantly differed by trimester and was strongest in the third trimester. Plasma concentrations of glycine, serine, methionine, cysteine, and tHcy decreased, and that of glutathione increased, between the first and second trimesters (all P < 0.05).
The variation of PLP concentration predicted cystathionine concentration throughout pregnancy. Increases in plasma cystathionine across trimesters may reflect maternal intracellular B-6 deficiency.
维生素 B-6（B-6）以磷酸吡哆醛 5'-磷酸盐（PLP）的形式存在，对一碳代谢反应和细胞功能至关重要。孕妇的血浆 PLP 浓度在整个孕期逐渐降低，但尚未研究其对功能的影响。血浆胱硫醚是健康成年人中 B-6 状态不佳的敏感指标。
本研究旨在确定血浆 PLP 和胱硫醚浓度之间的关系，并评估一碳代谢代谢物（包括总同型半胱氨酸（tHcy）、半胱氨酸、蛋氨酸、甘氨酸、丝氨酸和谷胱甘肽）的血浆浓度在整个孕期的纵向变化。
这是一项对 186 名健康巴西孕妇（20-40 岁）的前瞻性队列研究。在妊娠 5-13、20-26 和 30-36 周时采集空腹孕妇血样，检测血浆 PLP 和代谢物浓度。线性混合回归模型用于确定 1）第一孕期 PLP 三分位数和 2）整个孕期 PLP 浓度的变化与妊娠周数相关代谢物浓度之间的关联。
PLP 浓度中位数（IQR）分别从第 1、2 和 3 孕期的 36.2（29.2-44.5）降至 21.0（15.9-26.0）和 16.8（12.9-21.4）nmol/L，而胱硫醚浓度分别从 63.2（49.7-78.9）增至 122（98.0-167）和 143（114-193）nmol/L（均 P<0.001）。调整混杂因素后，整个孕期 PLP 变化与妊娠周数的胱硫醚浓度呈负相关；β（95%CI）=-0.387（-0.752，-0.219），P=0.04。这种关联在孕晚期差异显著，且最强。在第 1 和第 2 孕期之间，甘氨酸、丝氨酸、蛋氨酸、半胱氨酸和 tHcy 的血浆浓度降低，谷胱甘肽的浓度升高（均 P<0.05）。
PLP 浓度的变化可以预测整个孕期的胱硫醚浓度。妊娠期间血浆胱硫醚浓度的增加可能反映了母体细胞内的 B-6 缺乏。
