Validity of the Food Frequency Questionnaire Assessing the Folate Intake in Women of Reproductive Age Living in a Country without Food Fortification: Application of the Method of Triads

• Published in: Nutrients Vol. 9; no. 2; p. 128
• Main Authors: Zekovic, Milica, Djekic-Ivankovic, Marija, Nikolic, Marina, Gurinovic, Mirjana, Krajnovic, Dusanka, Glibetic, Marija
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 13.02.2017; MDPI
• Subjects: Adolescent; Adult; Anthropometry; Biomarkers; Biomarkers - blood; Correlation analysis; Correlation coefficients; Cross-Sectional Studies; Diet; Dietary intake; Erythrocytes; Fasting; Female; FFQ; folate; Folic acid; Folic Acid - administration & dosage; Folic Acid - blood; Food; Food fortification; Food, Fortified; Humans; Mental Recall; method of triads; Middle Aged; Nutrition Assessment; Reproducibility of Results; Reproduction; Serbia; Surveys and Questionnaires; validation; Validity; Vitamin B; women; Young Adult; Serbia; FFQ; method of triads; folate; validation; women
• ISSN: 2072-6643; 2072-6643
• DOI: 10.3390/nu9020128

The study aimed to examine the external validity of the Folate Food Frequency Questionnaire (F-FFQ) designed for assessing the folate intake in Serbian women of reproductive age. The F-FFQ was tested against repeated 24 h dietary recalls and correspondent nutritional biomarkers (red blood cells (RBC) and serum folate concentrations) using the method of triads. In a cross sectional study, 503 women aged 18-49 years completed dietary questionnaires and representative validation subsample ( = 50) provided fasting blood samples for biomarker analyses. Correlation coefficients were calculated between each of the dietary methods and three pair-wise correlations were applied for the calculation of validity coefficients. Correlation coefficients observed between F-FFQ and three 24 h recalls were = 0.56 ( < 0.001) and = 0.57 ( < 0.001) for total sample and validation group, respectively. Bland-Altman plot and cross-classification analyses indicated good agreement between methods. High validity coefficients were determined between the true intake (I) and dietary assessment methods, F-FFQ (Q) and 24 h dietary recalls (R) (ρQI = 0.871 and ρQI = 0.814; ρRI = 0.652 and ρRI = 0.698), and moderate ones for biomarkers (B) (ρBI = 0.428 and ρBI = 0.421). The F-FFQ is valid instrument for the assessment of dietary folate intake in women living in Serbia, a country without mandatory folic acid food fortification.