A comparison of a high‐throughput LC‐MS/MS method and two dietary intake survey instruments for erythrocyte folate status

The primary goal of the mandatory national folate fortification policy was to optimize folate nutritional status for the prevention of neural tube defects. While red blood cell (RBC) folate is considered the best indicator of folate status, concerns about the quality of the measurement and its relation to folate intake remain. The results of two folate intake instruments, a food frequency questionnaire (FFQ) and a folate‐targeted semi‐quantitative Block Dietary Folate Equivalents (DFE) Screener were compared to a newly developed high‐throughput LC‐MS/MS method for 370 normal adults. RBC folate was 1178 ± 259 nmol/L (mean ± SD). Folate intakes were 556 ± 265 μg/day by the FFQ and 520 ± 272 μg/d by the DFE. Intakes by both instruments were highly correlated (r = 0.607, p < 0.01) and folate intakes by the DFE were approximately 36 μg less than by the FFQ (p < 0.01). The RBC folate values determined by the LC‐MS/MS method were compared with the DFE (r = 0.335) and FFQ (r = 0.283). In conclusion, the RBC folate concentrations by LC‐MS/MS validated the folate intake assessment instruments. This study demonstrates that the DFE Screener produces estimates that are similar to an established FFQ.