Direct and Functional Biomarkers of Vitamin B6 Status

卷:35

Ueland, Per Magne ; Ulvik, Arve ; Rios-Avila, Luisa ; Midttun, Oivind ; Gregory, Jesse F.

Univ Bergen

关键词: direct biomarkers;    functional biomarkers;    B6 vitamers;    transaminase tests;    kynurenines;    amino acids;    transsulfuration metabolites;    one-carbon metabolites;    targeted metabolic profiling;    metabolomics;   

DOI  :  10.1146/annurev-nutr-071714-034330

学科分类：食品科学和技术

【 摘 要 】

Measures of B6 status are categorized as direct biomarkers and as functional biomarkers. Direct biomarkers measure B6 vitamers in plasma/serum, urine and erythrocytes, and among these plasma pyridoxal 5' -phosphate (PLP) is most commonly used. Functional biomarkers include erythrocyte transaminase activities and, more recently, plasma levels of metabolites involved in PLP-dependent reactions, such as the kynurenine pathway, one-carbon metabolism, transsulfuration (cystathionine), and glycine decarboxylation (serine and glycine). Vitamin B6 status is best assessed by using a combination of biomarkers because of the influence of potential confounders, such as inflammation, alkaline phosphatase activity, low serum albumin, renal function, and inorganic phosphate. Ratios between substrate-products pairs have recently been investigated as a strategy to attenuate such influence. These efforts have provided promising new markers such as the PAr index, the 3-hydroxykynurenine: xanthurenic acid ratio, and the oxoglutarate: glutamate ratio. Targeted metabolic profiling or untargeted metabolomics based on mass spectrometry allow the simultaneous quantification of a large number of metabolites, which are currently evaluated as functional biomarkers, using data reduction statistics.