健康孕妇妊娠早、晚期的膳食芳香族氨基酸需要量。

Dietary Aromatic Amino Acid Requirements During Early and Late Gestation in Healthy Pregnant Women.

机构信息

British Columbia Children's Hospital Research Institute, British Columbia Children's Hospital, Vancouver, Canada.

Department of Pediatrics, University of British Columbia, Vancouver, Canada.

出版信息

J Nutr. 2020 Dec 10;150(12):3224-3230. doi: 10.1093/jn/nxaa317.

DOI:10.1093/jn/nxaa317

PMID:33188409

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC7726121/

Abstract

BACKGROUND

Phenylalanine and tyrosine (referred to as total aromatic amino acids; TAAs) are essential for protein synthesis, and are precursors for important catecholamines. Current estimated average requirement (EAR) recommendations for TAA during pregnancy are 36 mg·kg-1·d-1, and has not been experimentally determined.

OBJECTIVES

The aim was to determine TAA requirements (dietary phenylalanine in the absence of tyrosine) during early and late gestation using the indicator amino acid oxidation (IAAO, with L-[1-13C]leucine) technique.

METHODS

Nineteen healthy pregnant women (age 22-38 y) were studied at a range of phenylalanine intakes (5 to 100 mg·kg-1·d-1) in early (13-19 wk) and/or late (33-39 wk) pregnancy for a total of 51 study days. Graded test intakes were provided as 8 hourly isonitrogenous and isocaloric meals. Breath samples were collected for 13C enrichment analysis on an isotope ratio mass spectrometer. A plasma sample was collected and analyzed for phenylalanine and tyrosine concentrations on an amino acid analyzer. The TAA requirement in early and late pregnancy was calculated using 2-phase linear regression crossover analysis that identified breakpoints in 13CO2 production (the requirement) in response to phenylalanine intakes.

RESULTS

TAA requirement during early pregnancy was 44 mg·kg-1·d-1 (95% CI: 28.3, 58.8) and during late pregnancy was 50 mg·kg-1·d-1 (95% CI: 36.1, 63.1). In early and late pregnancy, plasma phenylalanine and tyrosine concentrations rose linearly in response to graded phenylalanine intakes.

CONCLUSIONS

Our results suggest that the current EAR of 36 mg·kg-1·d-1 for TAAs is underestimated. When compared with results previously determined in nonpregnant adults, early pregnancy requirements were similar (43 compared with 44 mg·kg-1·d-1, respectively). During late pregnancy, a 14% higher TAA requirement was observed when compared with early pregnancy. The results from this study have potential implications for creating gestation stage-specific TAA recommendations.

摘要

背景

苯丙氨酸和酪氨酸（总称为芳香族氨基酸；TAA）是蛋白质合成所必需的，也是重要儿茶酚胺的前体。目前，妊娠期间 TAA 的估计平均需求量（EAR）推荐值为 36mg·kg-1·d-1，但尚未经过实验确定。

目的

本研究旨在使用指示剂氨基酸氧化（IAAO，用 L-[1-13C]亮氨酸）技术确定妊娠早期和晚期 TAA 的需求量（无酪氨酸时的膳食苯丙氨酸）。

方法

19 名健康孕妇（年龄 22-38 岁）在妊娠早期（13-19 周）和/或妊娠晚期（33-39 周）接受了 51 天的研究，苯丙氨酸摄入量范围为 5 至 100mg·kg-1·d-1，共进行了 51 天的研究。分级测试摄入量作为 8 小时等氮和等热量的膳食提供。收集呼吸样本，用同位素质谱仪进行 13C 丰度分析。采集血浆样本，用氨基酸分析仪分析苯丙氨酸和酪氨酸浓度。使用 2 相线性回归交叉分析来计算妊娠早期和晚期 TAA 的需求量，该分析确定了 13CO2 产量（需求量）对苯丙氨酸摄入量反应的转折点。

结果

妊娠早期 TAA 的需求量为 44mg·kg-1·d-1（95%CI：28.3，58.8），妊娠晚期 TAA 的需求量为 50mg·kg-1·d-1（95%CI：36.1，63.1）。在妊娠早期和晚期，血浆苯丙氨酸和酪氨酸浓度随苯丙氨酸摄入量的分级增加而呈线性增加。

结论

我们的结果表明，目前 36mg·kg-1·d-1 的 TAA EAR 值被低估了。与非妊娠成年人之前确定的结果相比，妊娠早期的需求量相似（分别为 43mg·kg-1·d-1 和 44mg·kg-1·d-1）。在妊娠晚期，TAA 的需求量比妊娠早期高 14%。本研究的结果可能对制定特定妊娠阶段的 TAA 推荐值具有重要意义。