Comparison of Two Dietary Folate Intake Instruments and Their Validation by RBC Folate

• Published in: Journal of agricultural and food chemistry 2007-05, Vol.55 (9), p.3737-3740
• Main Authors: Owens, Janel E, Holstege, Dirk M, Clifford, Andrew J
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Diet; Diet Records; dietary intake; Dietary Supplements; erythrocytes; Erythrocytes - chemistry; Female; folate-targeted semiquantitative Block dietary folate equivalents screener; folic acid; Folic Acid - administration & dosage; Folic Acid - blood; food frequency questionnaires; Food industries; food intake; Fundamental and applied biological sciences. Psychology; high-throughput liquid chromatography tandem mass spectrometry; human nutrition; Humans; liquid chromatography; Male; mass spectrometry; Nutritional Status; ROC Curve; Surveys and Questionnaires
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf063649h

An optimal folate nutritional status is important in minimizing developmental and degenerative disease. Therefore, constant monitoring of folate intake and of biomarkers of folate nutritional status is essential. The objective of this research was to compare two folate intake instruments and validate each one against RBC folate measured by a high-throughput liquid chromatography tandem mass spectrometry (HT LC-MS/MS) method described in the companion paper (Owens, J. E.; Holstege, D. M.; Clifford, A. J. J. Agric. Food Chem. 2007, 55, 3292−3297). A food frequency questionnaire (FFQ) and a folate-targeted semiquantitative Block dietary folate equivalents (DFE) screener were compared and individually validated against an HT LC-MS/MS method. RBC folate was 1178 ± 259 nmol/L (mean ± SD) in a population of 337 normal adult subjects. Folate intakes were 556 ± 265 μg/day by the FFQ and 524 ± 276 μg/day by the DFE screener. Folate intakes by the DFE screener were approximately 34 μg less than by the FFQ (paired t test, p < 0.01), but the intake instruments were highly correlated for total folate intake (r = 0.608, p < 0.01). Correlations between instruments and RBC folate were low (r < 0.35) but strong (p < 0.01). ROC curve analysis indicates that the measurement of RBC folate by the HT LC-MS/MS method is a better predictive tool than are intake instruments for the evaluation of marginal folate status. Keywords: RBC folate; LC-MS/MS; analytical method; folate intake; FFQ; DFE screener