I<scp>N</scp> V<scp>IVO</scp> K<scp>INETICS OF</scp> F<scp>OLATE</scp> M<scp>ETABOLISM</scp>

Gregory, Jesse F.; Quinlivan, Eoin P.

doi:10.1146/annurev.nutr.22.120701.083554

Cited by 58 publications

(34 citation statements)

References 79 publications

(144 reference statements)

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“…The elimination constant in our study is higher than reported in radioactive folic acid studies conducted in two healthy adults (Krumdieck et al, 1978;Clifford et al, 1998). Exchange with hydrogen of the deuterium in the folic acid tracer may result in underestimation of the 5-methylTHF enrichment (Gregory & Quinlivan, 2002). The extent of this isotope effect under the study conditions is very limited.…”

Section: Discussioncontrasting

confidence: 75%

[6S]5-methyltetrahydrofolate or folic acid supplementation and absorption and initial elimination of folate in young and middle-aged adults

et al. 2005

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Objectives: To assess the effects of supplementation with the diastereoisomer of 5-methyltetrahydrofolate ([6S]5-methylTHF), as an alternative supplement for folic acid, on folate absorption and elimination, in two age groups. Design: A randomized, double-blind intervention study. Subjects: A total of 12 young (o30 y) and 12 middle-aged (Z50 y) healthy volunteers were recruited. Methods: Volunteers were randomized to receive daily supplementation with 400 mg folic acid or equimolar amounts of [6S]5-methylTHF during 5 weeks. Before and after supplementation, absorption and initial elimination were calculated following oral [ 2 H 2 ]folic acid test doses using isotope kinetics in plasma. Results: Folic acid absorption was lower in the middle-aged as compared to the young adults, both before (P ¼ 0.03) and after (P ¼ 0.05) supplementation. In the young adults, absorption decreased by 22% after [6S]5-methylTHF and increased by 21% after folic acid (P ¼ 0.02). In the other age group, no such changes were found. The folate rate constant of elimination increased after folic acid supplementation in the young ( þ 50%; P ¼ 0.05) but not in the middle-aged ( þ 18%; P ¼ 0.5) adults. Conclusions: Young adults show increased folate turnover after folic acid supplementation relative to the effect of [6S]5-methylTHF supplementation. Similar differences are not observed in middle-aged adults, in whom folic acid absorption was found to be lower as compared to the young adults.

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Section: Discussioncontrasting

confidence: 75%

[6S]5-methyltetrahydrofolate or folic acid supplementation and absorption and initial elimination of folate in young and middle-aged adults

et al. 2005

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“…Of note, tissues with low levels of cytosolic FDH mRNA also displayed low levels of mRNA for the mitochondrial enzyme. However, mtFDH mRNA levels were notably lower than those of cytosolic FDH in liver and kidney, the two major organs of the folate metabolism (44). In contrast to the cytosolic enzyme, which is typically not detectable in cancer tissues and cell lines, mtFDH mRNA and protein are clearly present in cancer cell lines (Fig.…”

Section: Identification Of the Mitochondrial Fdh Gene And Comparison mentioning

confidence: 93%

ALDH1L2 Is the Mitochondrial Homolog of 10-Formyltetrahydrofolate Dehydrogenase

Krupenko

Dubard

Strickland

et al. 2010

Journal of Biological Chemistry

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Real-time PCR performed on an array of human tissues hasshown that although cytosolic FDH mRNA is highest in liver, kidney, and pancreas, mtFDH mRNA is most highly expressed in pancreas, heart, and brain. In contrast to the cytosolic enzyme, which is not detectable in cancer cells, the presence of mtFDH was demonstrated in several human cancer cell lines by conventional and real-time PCR and by Western blot. Analysis of genomes of different species indicates that the mitochondrial enzyme is a later evolutionary product when compared with the cytosolic enzyme. We propose that this novel mitochondrial enzyme is a likely source of CO 2 production from 10-formyltetrahydrofolate in mitochondria and plays an essential role in the distribution of one-carbon groups between the cytosolic and mitochondrial compartments of the cell.

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“…More generally, the damage reactions undergone by all B vitamins account for their dietary requirements; if vitamins were not continuously damaged, they would last forever and not need to be constantly resupplied. In this context, it is noteworthy that the whole-body half-life of thiamin (and its phosphates) in humans is one to two orders of magnitude shorter than those of other B vitamins for which estimates are available, as follows: thiamin, 9.5 to 18.5 d (Ariaey-Nejad et al, 1970); folates, 60 to 150 d (Gregory and Quinlivan, 2002); vitamin B 6 , ;500 d (Coburn, 1990); vitamin B 12 (absent from plants), 480 to 1284 d (Hall, 1964). …”

Section: Chemical and Metabolic Lability: Why Bad Things Happen To Gomentioning

confidence: 99%

Does Abiotic Stress Cause Functional B Vitamin Deficiency in Plants?

et al. 2016

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B vitamins are the precursors of essential metabolic cofactors but are prone to destruction under stress conditions. It is therefore a priori reasonable that stressed plants suffer B vitamin deficiencies and that certain stress symptoms are metabolic knock-on effects of these deficiencies. Given the logic of these arguments, and the existence of data to support them, it is a shock to realize that the roles of B vitamins in plant abiotic stress have had minimal attention in the literature (100-fold less than hormones) and continue to be overlooked. In this article, we therefore aim to explain the connections among B vitamins, enzyme cofactors, and stress conditions in plants. We first outline the chemistry and biochemistry of B vitamins and explore the concept of vitamin deficiency with the help of information from mammals. We then summarize classical and recent evidence for stress-induced vitamin deficiencies and for plant responses that counter these deficiencies. Lastly, we consider potential implications for agriculture.

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IN VIVO KINETICS OF FOLATE METABOLISM

Cited by 58 publications

References 79 publications

[6S]5-methyltetrahydrofolate or folic acid supplementation and absorption and initial elimination of folate in young and middle-aged adults

[6S]5-methyltetrahydrofolate or folic acid supplementation and absorption and initial elimination of folate in young and middle-aged adults

ALDH1L2 Is the Mitochondrial Homolog of 10-Formyltetrahydrofolate Dehydrogenase

Does Abiotic Stress Cause Functional B Vitamin Deficiency in Plants?

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