The importance of using folate intake expressed as dietary folate equivalents in predicting folate status

Abstract

In order to achieve valid assessments of folate status, folate food composition data needs to be expressed in the same chemical form and units as the recommendations for folate intakes. Dietary folate (e.g. both naturally occurring and synthetic folic acid) and supplemental folic acid intakes were assessed twice in a cross-sectional study, using a validated dietary assessment method, the Food Choice Map, and two databases: the Canadian Nutrient File (CNF 2001), where folate was expressed as μg, and an updated version of the CNF 2001, where folate was expressed as dietary folate equivalents (DFEs). A fasting blood sample was used to measure serum folate. Statistically significant mean differences ( p < 0.05) were observed in the energy adjusted mean daily folate intakes from the original CNF (471 ± 216 μg/d; mean ± S.D.) versus those obtained from the updated database (648 ± 358 μg DFE/d; mean ± S.D.). No significant correlation was observed between the folate intakes assessed by the two versions of the database ( r = 0.1). Folate intakes estimated from either database were significantly correlated irrespective of folate supplement usage. Using the Estimated Average Requirement (EAR) as the nutritional cut-off point and serum folate as a biological cut-off point, folate intakes estimated as μg DFEs/d predict folate status better than the μg/d estimation. Assessment of folate nutritional status is incomplete if content values in the food composition database do not account for (1) the differences in bioavailability between naturally occurring folate and synthetic folic acid found as a food fortificant, and (2) folate supplement usage.