The Emerging Role of Unmetabolized Folic Acid in Human Diseases: Myth or Reality?
An increase in folate intake before and during pregnancy can prevent many neural tube defects. This prompted over 50 countries worldwide to mandate fortification of breakfast cereals or staple foods with folic acid (FA), which is the synthetic oxidised form of the vitamin used in supplements and fortified foods. After ingestion, FA is reduced by dihydrofolate reductase (DHFR) and then converted to the biologically active forms. The presence of detectable amounts of unmetabolised FA in blood of individuals who have consumed supplements or fortified foods has attracted attention in recent years. A direct correlation exists between FA intake and unmetabolised FA in serum and suggests that a saturable level of DHFR exists. Factors affecting FA reduction, such as age, intestinal pH, alcohol, FA dose and duration of supplement usage, and possibly polymorphisms of folate-metabolising enzymes, can affect the presence of FA in blood. However, minor amounts of FA might also be produced during sample preparation. In pregnant women taking supplements, FA does not seem to accumulate in the newborns. Concentrations of unmetabolized FA are correlated to and predicted by those of total folate or 5-MTHF. Evidence of a negative health effect of free FA in blood is not consistent and suggests rather artificial factors. FA has no known cofactor function that would increase the likelihood of a causal role for free FA in disease development.
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Document Type: Research Article
Publication date: October 1, 2012
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- Current Drug Metabolism aims to cover all the latest and outstanding developments in drug metabolism and disposition. The journal serves as an international forum for the publication of timely reviews in drug metabolism. Current Drug Metabolism is an essential journal for academic, clinical, government and pharmaceutical scientists who wish to be kept informed and up-to-date with the latest and most important developments. The journal covers the following areas:
In vitro systems including CYP-450; enzyme induction and inhibition; drug-drug interactions and enzyme kinetics; pharmacokinetics, toxicokinetics, species scaling and extrapolations; P-glycoprotein and transport carriers; target organ toxicity and interindividual variability; drug metabolism and disposition studies; extrahepatic metabolism; phase I and phase II metabolism; recent developments for the identification of drug metabolites and adducts.
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