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Calculation of red blood cell folate steady state conditions after supplementation with different folate forms and dosages
Author(s) -
Pietrzik Klaus F.,
Lamers Yvonne,
Brämswig Susanne,
PrinzLangenohl Reinhild,
Pietrzik Claus U.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a860
Subject(s) - folic acid , dose , medicine , pregnancy , red blood cell , placebo , pharmacokinetics , pill , red cell , anemia , physiology , pharmacology , biology , pathology , genetics , alternative medicine
Maternal red blood cell (RBC) folate levels > 906 nmol/L have been related to the lowest risk of NTD affected pregnancy. While the appearance of folate in RBC has been followed after folic acid supplementation, data on disappearance kinetics are not yet available. The aim of our investigation was to calculate the disappearance kinetics of folate in RBC. Two randomized, placebo‐controlled, double blind intervention trials were performed to investigate the appearance of folate in RBC in healthy pregnancy‐aged women following different supplementation strategies (I: n=144; 400μg/d folic acid, 416μg/d and 208μg/d (6S)‐5‐methyltetrahydrofolate for 24 wks; II: n=46; 800μg/d of folic acid for 16 wks). In RBC folate concentrations, no steady state was reached after 24 and 16 wks of intervention, respectively. However, data allow calculating biological half‐life (t½) for RBC folate to be about 8 wks. Therefore, taken into account pharmacokinetic principles, steady state conditions for RBC folate should be reached after 5 t½ (40 wks). We propose that the disappearance kinetics of RBC folate can be calculated on the basis of this t½ value. This might be of special interest in case of adding folate or folic acid to oral contraceptives. After pill cessation (to get pregnant), the period of time of RBC folate > 906 nmol/L was estimated to be more than 1 t½ and thus showed protective levels with respect to neural tube defects.