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Am J Clin Nutr. 2006 Apr;83(4):842-50.

[6S]-5-Methyltetrahydrofolate is at least as effective as folic acid in preventing a decline in blood folate concentrations during lactation.

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Department of Nutritional Sciences, University of Toronto, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada.



Studies in nonpregnant, nonlactating women suggest that folate supplementation in the form of 5-methyltetrahydrofolate ([6S]-5-methylTHF) is at least as effective as folic acid in increasing blood folate indexes. No data, however, are available on the effect of supplemental [6S]-5-methylTHF on blood folate concentrations during lactation.


We assessed the relative effectiveness of [6S]-5-methylTHF, a placebo, and folic acid in maintaining blood folate indexes during lactation in a sample of healthy Canadian women consuming folic acid-fortified foods.


This study was designed as a 16-wk, randomized, placebo-controlled intervention. Pregnant women (n = 72) advised to consume a folic acid-containing prenatal supplement (1000 microg/d) during pregnancy were enrolled at 36 wk gestation. After delivery, the women were randomly assigned to receive [6S]-5-methylTHF (416 microg/d, 906 nmol/d) or a placebo or were assigned to a folic acid (400 microg/d, 906 nmol/d) reference group.


At 16 wk of lactation, the mean red blood cell (RBC) folate concentration in women in the [6S]-5-methylTHF group (2178; 95% CI: 1854, 2559 nmol/L) was greater than that in the folic acid (1967; 1628, 2377 nmol/L; P < 0.05) and placebo (1390; 1198, 1613 nmol/L; P < 0.002) groups after adjustment for baseline concentrations (36 wk gestation). The distribution of folate forms in RBCs did not differ significantly between the [6S]-5-methylTHF and placebo groups. However, the folic acid group had greater amounts of 5-formylTHF (P < 0.03).


[6S]-5-MethylTHF appeared to be as effective as, and perhaps more effective than, folic acid in preserving RBC folate concentrations during lactation.

[Indexed for MEDLINE]

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