Impact of voluntary fortification and supplement use on dietary intakes and biomarker status of folate and vitamin B-12 in Irish adults

Background: Ireland has traditionally operated a liberal policy of voluntary fortification, but little is known about how this practice, along with supplement use, affects population intakes and status of folate and vitamin B-12. Objective: The aim was to examine the relative impact of voluntary fortification and supplement use on dietary intakes and biomarker status of folate and vitamin B-12 in Irish adults. Design: Folic acid and vitamin B-12 from fortified foods and supplements were estimated by using brand information for participants from the cross-sectional National Adult Nutrition Survey 2008–2010. Dietary and biomarker values were compared between 6 mutually exclusive consumption groups formed on the basis of folic acid intake. Results: The consumption of folic acid through fortified foods at low, medium, and high levels of exposure [median (IQR) intakes of 22 (13, 32), 69 (56, 84), and 180 (137, 248) μg/d, respectively]; from supplements [203 (150, 400) μg/d]; or from both sources [287 (220, 438) μg/d] was associated with significantly higher folate intakes and status compared with nonconsumption of folic acid (18% of the population). Median (IQR) red blood cell (RBC) folate increased significantly from 699 (538, 934) nmol/L in nonconsumers to 1040 (83, 1390) nmol/L in consumers with a high intake of fortified foods (P < 0.001), with further nonsignificant increases in supplement users. Supplement use but not fortification was associated with significantly higher serum vitamin B-12 concentrations relative to nonconsumers (P < 0.001). Two-thirds of young women had suboptimal RBC folate for protection against neural tube defects (NTDs); among nonconsumers of folic acid, only 16% attained optimal RBC folate. Conclusions: The consumption of voluntarily fortified foods and/or supplement use was associated with significantly higher dietary intakes and biomarker status of folate in Irish adults. Of concern, the majority of young women remain suboptimally protected against NTDs.