Vitamin B12-folate interrelationships

The studies discussed in this review support the view that biochemical and clinical symptoms common to both folate and vitamin B12 deficiency are due to the induction of a functional folate deficiency, which in turn is induced by cobalamin deprivation. The interrelationship between these two vitamin...

Full description

Saved in:
Bibliographic Details
Published in:Annual review of nutrition 1985, Vol.5, p.115-141
Main Authors: Shane, B, Stokstad, E.L.R
Format: Article
Language:English
Subjects:
5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase - metabolism
Amino Acids - metabolism
Animals
Biological and medical sciences
Bone Marrow - metabolism
Enzymes. Coenzymes. Vitamins. Pigments
folates
Folic Acid - blood
Folic Acid - metabolism
Folic Acid - pharmacology
Folic Acid Deficiency - pathology
Formates - metabolism
Formiminoglutamic Acid - metabolism
Fundamental and applied biological sciences. Psychology
Histidine - metabolism
Homeostasis
Humans
interactions
Liver - metabolism
Megaloblasts - pathology
metabolism
Metabolisms and neurohumoral controls
Methionine - biosynthesis
Methionine - pharmacology
Methylation
Nitrous Oxide - pharmacology
Peptide Synthases - metabolism
Pteroylpolyglutamic Acids - metabolism
Purines - biosynthesis
relationships
Serine - metabolism
Thymidine Monophosphate - biosynthesis
Thymidylate Synthase - metabolism
Thyroid Gland - physiology
Vertebrates: anatomy and physiology, studies on body, several organs or systems
Vitamin B 12 - metabolism
Vitamin B 12 - pharmacology
Vitamin B 12 Deficiency - pathology
vitamin B12
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The studies discussed in this review support the view that biochemical and clinical symptoms common to both folate and vitamin B12 deficiency are due to the induction of a functional folate deficiency, which in turn is induced by cobalamin deprivation. The interrelationship between these two vitamins is best explained by the methyl trap hypothesis stating that vitamin B12 deficiency can lead to lowered levels of methionine synthetase, which results in a functional folate deficiency by trapping an increased proportion of folate as the 5-methyl derivative. In addition, as 5-methyl-H4PteGlu is a poor substrate for folylpolyglutamate synthetase, there is a decreased synthesis of folylpolyglutamates and consequently a decreased retention of folates by tissues. The real folate deficiency that ensues because of decreased tissue folate levels is probably as important physiologically as the functional deficiency caused by the methyl trap. The sparing effect of methionine can be explained by adenosylmethionine inhibition of methylenetetrahydrofolate reductase, which would prevent the buildup of 5-methyl-H4PteGlun. A deficiency in vitamin B12 would not, in itself, be sufficient to cause a disturbance in folate metabolism. The deficiency would have to result in lowered methyltransferase levels before any such disturbance would be manifest.
ISSN:0199-9885
1545-4312
DOI:10.1146/annurev.nu.05.070185.000555