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document
How well do blood folate concentrations predict dietary folate intakes in a sample of Canadian lactating women exposed to high levels of folate ? An observational study . BACKGROUND In 1998 , mandatory folic acid fortification of white flour and select cereal grain products was implemented in Canada with the intention to increase dietary folate intakes of reproducing women . Folic acid fortification has produced a dramatic increase in blood folate concentrations among reproductive age women , and a reduction in neural tube defect ( NTD ) -affected pregnancies . In response to improved blood folate concentrations , many health care professionals are asking whether a folic acid supplement is necessary for NTD prevention among women with high blood folate values , and how reliably high RBC folate concentrations predict folate intakes shown in randomized controlled trials to be protective against NTDs . The objective of this study was to determine how predictive blood folate concentrations and folate intakes are of each other in a sample of well-educated lactating Canadian women exposed to high levels of synthetic folate . METHODS The relationship between blood folate concentrations and dietary folate intakes , determined by weighed food records , were assessed in a sample of predominantly university-educated lactating women ( 32 +/- 4 yr ) at 4- ( n = 53 ) and 16-wk postpartum ( n = 55 ) . RESULTS Median blood folate concentrations of all participants were well above plasma and RBC folate cut-off levels indicative of deficiency ( 6.7 and 317 nmol/L , respectively ) and all , except for 2 subjects , were above the cut-off for NTD-risk reduction ( > 906 nmol/L ) . Only modest associations existed between total folate intakes and plasma ( r = 0.46 , P < 0.001 ) and RBC ( r = 0.36 , P < 0.01 ) folate concentrations at 16-wk postpartum . Plasma and RBC folate values at 16-wk postpartum correctly identified the quartile of folate intake of only 26 of 55 ( 47 % ) and 18 of 55 ( 33 % ) of subjects , respectively . The mean RBC folate concentration of women consuming 151-410 microg/d of synthetic folate ( 2nd quartile of intake ) did not differ from that of women consuming > 410 microg/d ( 3rd and 4th quartile ) . CONCLUSION Folate intakes , estimated by food composition tables , and blood folate concentrations are not predictive of each other in Canadian lactating women exposed to high levels of folate . Synthetic intakes > 151-410 microg/d in these women produced little additional benefit in terms of maximizing RBC content . More studies are needed to examine the relationship between blood folate concentration and NTD risk . Until data from such studies are available , women planning a pregnancy should continue to consume a daily folic acid supplement of 400 microg .
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Intervention_Physical
blood folate
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Intervention_Other
dietary folate intakes
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Intervention_Pharmacological
folic acid supplement
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Intervention_Physical
blood folate
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Intervention_Physical
blood folate
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Intervention_Physical
blood folate
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Intervention_Physical
total folate intakes
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Intervention_Pharmacological
Folate intakes
33267
Intervention_Physical
blood folate
33268
Intervention_Pharmacological
folic acid supplement
33269
Outcome_Physical
blood folate concentrations
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Outcome_Physical
blood folate concentrations
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Outcome_Physical
folate intakes
33272
Outcome_Physical
blood folate concentrations
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Outcome_Physical
dietary folate intakes
33274
Outcome_Physical
blood folate concentrations
33275
Outcome_Physical
total folate intakes
33276
Outcome_Physical
plasma
33277
Outcome_Physical
folate concentrations
33278
Outcome_Physical
Plasma and RBC folate values
33279
Outcome_Physical
RBC folate concentration
33280
Outcome_Physical
Folate intakes
33281
Outcome_Physical
blood folate concentrations
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Outcome_Physical
folate
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Outcome_Physical
blood folate concentration
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Participant_Sex
women
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Participant_Condition
folate
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Participant_Condition
reproducing
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Participant_Sex
women
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Participant_Sex
women
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Participant_Condition
high blood folate values
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Participant_Sex
women
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Participant_Condition
synthetic folate
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Participant_Sex
women
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Participant_Age
( 32 +/- 4 yr )
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Participant_Sample-size
53
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Participant_Sample-size
55