Effect of Vitamin B6 Depletion in Adult Man on the Plasma Concentration and the Urinary Excretion of Free Amino Acids

Park, Youngmee Kang; Linkswiler, Hellen

doi:10.1093/jn/101.2.185

Cited by 38 publications

(21 citation statements)

References 21 publications

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“…Studies in animals and humans and mathematical modeling have shown effects of vitamin B-6 deficiency on several aspects of metabolism that are consistent with the multiple metabolic functions of PLP (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). Our previous studies showed that low vitamin B-6 status with a plasma PLP concentration ,30 nmol/L, which is consistent with marginal deficiency (26), also induces metabolic effects including alterations in concentrations of certain constituents of one-carbon and tryptophan pathways (17,18,20,27).…”

Section: Introductionsupporting

confidence: 57%

“…An elevation in glycine can be explained primarily by the reduced activity of glycine decarboxylase activity during vitamin B-6 deficiency (24). Shortterm vitamin B-6 restriction has little effect on plasma leucine (16,20). However, the chronic low vitamin B-6 status in this study likely reduced branched-chain aminotransferase activity that was restored by supplementation.…”

Section: Discussionmentioning

confidence: 60%

“…Increased glycine has been reported in liver (49,50), muscle, and plasma of vitamin B-6-deficient rats (50,51), in the plasma of vitamin B-6-deficient humans (16,18,20,23), and in vitamin B-6restricted cultured cells (52), concurrent with modeling predictions (24). Major processes for the metabolism of glycine include PLP-dependent reactions catalyzed by serine hydroxymethyltransferase isoforms and by glycine decarboxylase in the glycine cleavage system (53).…”

Section: Discussionmentioning

confidence: 92%

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Pyridoxine supplementation does not alter in vivo kinetics of one-carbon metabolism but modifies patterns of one-carbon and tryptophan metabolites in vitamin B-6–insufficient oral contraceptive users

Rios‐Avila¹,

Coats²,

Ralat³

et al. 2015

The American Journal of Clinical Nutrition

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Section: Introductionsupporting

confidence: 57%

Section: Discussionmentioning

confidence: 60%

Section: Discussionmentioning

confidence: 92%

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Pyridoxine supplementation does not alter in vivo kinetics of one-carbon metabolism but modifies patterns of one-carbon and tryptophan metabolites in vitamin B-6–insufficient oral contraceptive users

Rios‐Avila¹,

Coats²,

Ralat³

et al. 2015

The American Journal of Clinical Nutrition

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“…The low medium and intracellular serine concentrations are in contrast with reports on the effect of vitamin B6 deprivation on human plasma, in which the concentrations of glycine showed an increase of 28% after 2 weeks of vitamin B6 depletion and serine showed an increase of 47% after 1 week of depletion (Park and Linkswiler 1971). This behaviour was also observed in a 28-day vitamin B6 restriction diet study, where the plasma levels of healthy men and women for glycine and serine showed an increase of 15% and 12%, respectively (da Silva et al 2013).…”

Section: Discussioncontrasting

confidence: 99%

Vitamin B6 is essential for serine de novo biosynthesis

Ramos

Pras‐Raves

Gerrits

et al. 2017

J of Inher Metab Disea

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Pyridoxal 5′-phosphate (PLP), the metabolically active form of vitamin B6, plays an essential role in brain metabolism as a cofactor in numerous enzyme reactions. PLP deficiency in brain, either genetic or acquired, results in severe drug-resistant seizures that respond to vitamin B6 supplementation. The pathogenesis of vitamin B6 deficiency is largely unknown. To shed more light on the metabolic consequences of vitamin B6 deficiency in brain, we performed untargeted metabolomics in vitamin B6-deprived Neuro-2a cells. Significant alterations were observed in a range of metabolites. The most surprising observation was a decrease of serine and glycine, two amino acids that are known to be elevated in the plasma of vitamin B6 deficient patients. To investigate the cause of the low concentrations of serine and glycine, a metabolic flux analysis on serine biosynthesis was performed. The metabolic flux results showed that the de novo synthesis of serine was significantly reduced in vitamin B6-deprived cells. In addition, formation of glycine and 5-methyltetrahydrofolate was decreased. Thus, vitamin B6 is essential for serine de novo biosynthesis in neuronal cells, and serine de novo synthesis is critical to maintain intracellular serine and glycine. These findings suggest that serine and glycine concentrations in brain may be deficient in patients with vitamin B6 responsive epilepsy. The low intracellular 5-mTHF concentrations observed in vitro may explain the favourable but so far unexplained response of some patients with pyridoxine-dependent epilepsy to folinic acid supplementation.

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“…An alternative explanation that would account for both the observed increases in glycine and serine as well as the observed decreases in alanine, isoleucine, leucine, and valine in early lactation might be a deficiency of pyridoxal 5′-phosphate, the metabolically active form of vitamin B 6 . 35 Pyridoxal Figure 2. Plasma glycine-to-alanine ratios as a measure for the nutritional status throughout lactation for two breeds.…”

Section: Changes In Plasma Metabolites Throughout Lactationmentioning

confidence: 99%

Correlations between Milk and Plasma Levels of Amino and Carboxylic Acids in Dairy Cows

et al. 2013

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The objective of this study was to investigate the relationship between the concentrations of 19 amino acids, glucose, and seven carboxylic acids in the blood and milk of dairy cows and their correlations with established markers of ketosis. To that end, blood plasma and milk specimens were collected throughout lactation in two breeds of dairy cows of different milk yield. Plasma concentrations of glucose, pyruvate, lactate, α-aminobutyrate, β-hydroxybutyrate (BHBA), and most amino acids, except for glutamate and aspartate, were on average 9.9-fold higher than their respective milk levels. In contrast, glutamate, aspartate, and the Krebs cycle intermediates succinate, fumarate, malate, and citrate were on average 9.1-fold higher in milk than in plasma. For most metabolites, with the exception of BHBA and threonine, no significant correlations were observed between their levels in plasma and milk. Additionally, milk levels of acetone showed significant direct relationships with the glycine-toalanine ratio and the BHBA concentration in plasma. The marked decline in plasma concentrations of glucose, pyruvate, lactate, and alanine in cows with plasma BHBA levels above the diagnostic cutoff point for subclinical ketosis suggests that these animals fail to meet their glucose demand and, as a consequence, rely increasingly on ketone bodies as a source of energy. The concomitant increase in plasma glycine may reflect not only the excessive depletion of protein reserves but also a potential deficiency of vitamin B 6 .

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Effect of Vitamin B6 Depletion in Adult Man on the Plasma Concentration and the Urinary Excretion of Free Amino Acids

Cited by 38 publications

References 21 publications

Pyridoxine supplementation does not alter in vivo kinetics of one-carbon metabolism but modifies patterns of one-carbon and tryptophan metabolites in vitamin B-6–insufficient oral contraceptive users

Pyridoxine supplementation does not alter in vivo kinetics of one-carbon metabolism but modifies patterns of one-carbon and tryptophan metabolites in vitamin B-6–insufficient oral contraceptive users

Vitamin B6 is essential for serine de novo biosynthesis

Correlations between Milk and Plasma Levels of Amino and Carboxylic Acids in Dairy Cows

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