Validity and reproducibility of an interviewer-administered food frequency questionnaire for the assessment of riboflavin intake in Malaysian women in Selangor

Introduction: The aim of this study was to assess the validity and reproducibility of a food frequency questionnaire (FFQ) specifically developed for the assessment of riboflavin intake among Malaysian women in Selangor. Methods: The study was carried out in Universiti Putra Malaysia (UPM), which consisted of 204 healthy women (102 Chinese and 102 Malay) aged between 19 and 45 years. The FFQs were interviewer-administered, which were completed twice; at the beginning of the study (FFQ-1) and two weeks thereafter (FFQ-2). A two-day 24-hour dietary recall (24DR) was interviewer-administered as the standard criteria method. Data were analyzed using Wilcoxon signed ranks test, Spearman correlation coefficient (SCC), intra-class correlation coefficient (ICC) and Bland-Altman plots to determine the validity and reproducibility. Results: Median riboflavin intake derived from 24DRs was significantly higher than FFQ-2 (p<0.01). Both FFQ-1 and FFQ-2 correlated significantly (p<0.01) with 24DRs with r-value of 0.264 and 0.227, respectively. As for reproducibility between FFQs, SCC value was statistically significant (p<0.01) at 0.545 whereby ICC value was 0.752, which considered as good. Most data points fell between the limits of agreements and were found closer to the horizontal line in the middle. However, the plots showed no linear trend existed between FFQ and 24DR over the range of mean riboflavin intake. Conclusion: The newly developed FFQ were found to be valid and relatively reproducible in the assessment of riboflavin intake among Malaysian women in Selangor

Suboptimal biochemical riboflavin status is associated with lower hemoglobin and higher rates of anemia in a sample of Canadian and Malaysian women of reproductive age

Background: Riboflavin is required for several redox reactions. Clinical riboflavin deficiency occurs mainly in low-income countries, where it is associated with anemia. The functional significance of suboptimal riboflavin status in different populations and its role in anemia is not well understood. Objectives: We assessed the biomarker status of riboflavin and its association with hemoglobin concentration and anemia in women living in Vancouver, Canada, and Kuala Lumpur, Malaysia. Methods: Healthy nonpregnant, nonbreastfeeding women (19-45 y) were recruited from Canada ( n = 206) and Malaysia (n = 210) via convenience sampling. Fasting blood was collected to assess riboflavin status [erythrocyte glutathione reductase activity coefficient (EGRac)], hematological indicators, soluble transferrin receptor (sTfR), ferritin, vitamin A, folate, and vitamin B-12 concentrations. Linear and logistic regression models were used to assess the association of riboflavin status with hemoglobin concentration and anemia. Results: EGRac (mean ± SD) values were higher, indicating poorer riboflavin status, in Malaysian compared with Canadian women (1.49 ± 0.17 compared with 1.38 ± 0.11). Likewise, riboflavin biomarker deficiency (EGRac ≥1.40) was significantly more prevalent among Malaysians than Canadians (71% compared with 40%). More Malaysian than Canadian women were anemic (hemoglobin <120 g/L; 18% compared with 7%). With use of linear regression (pooled sample; n = 416), EGRac values were negatively associated with hemoglobin concentration (r = -0.18; P < 0.001). This relation remained significant (P = 0.029) after adjusting for age, parity, ethnicity, vitamin B-12, folate, sTfR, ferritin, and vitamin A. Women with riboflavin deficiency (EGRac ≥1.40) were twice as likely to present with anemia (adjusted OR: 2.38; 95% CI: 1.08, 5.27) compared with women with EGRac <1.40. Conclusions: Biochemical riboflavin deficiency was observed in Canadian and Malaysian women, with higher rates of deficiency among Malaysian women. Deficient biomarker status of riboflavin was a weak but significant predictor of hemoglobin and anemia, suggesting that the correction of riboflavin deficiency may potentially play a small protective role in anemia, but this requires further investigation

Validity and Reproducibility of an Interviewer-administered Food Frequency Questionnaire for the Assessment of Riboflavin Intake in Malaysian Women in Selangor DUPLICATE

Introduction: The aim of this study was to assess the validity and reproducibility of a food frequency questionnaire (FFQ) specifically developed for the assessment of riboflavin intake among Malaysian women in Selangor. Methods: The study was carried out in Universiti Putra Malaysia (UPM), which consisted of 204 healthy women (102 Chinese and 102 Malay) aged between 19 and 45 years. The FFQs were interviewer-administered, which were completed twice; at the beginning of the study (FFQ-1) and two weeks thereafter (FFQ-2). A two-day 24-hour dietary recall (24DR) was interviewer-administered as the standard criteria method. Data were analyzed using Wilcoxon signed ranks test, Spearman correlation coefficient (SCC), intra-class correlation coefficient (ICC) and Bland-Altman plots to determine the validity and reproducibility. Results: Median riboflavin intake derived from 24DRs was significantly higher than FFQ-2 (p<0.01). Both FFQ-1 and FFQ-2 correlated significantly (p<0.01) with 24DRs with r-value of 0.264 and 0.227, respectively. As for reproducibility between FFQs, SCC value was statistically significant (p<0.01) at 0.545 whereby ICC value was 0.752, which considered as good. Most data points fell between the limits of agreements and were found closer to the horizontal line in the middle. However, the plots showed no linear trend existed between FFQ and 24DR over the range of mean riboflavin intake. Conclusion: The newly developed FFQ were found to be valid and relatively reproducible in the assessment of riboflavin intake among Malaysian women in Selangor