BACKGROUND: Although the associations of dietary glycemic index (GI) and dietary glycemic load (GL) with many chronic diseases have been examined in epidemiologic studies, information regarding the reproducibility and validity of these measures assessed with the use of food-frequency questionnaires (FFQs) is lacking. OBJECTIVE: We examined the reproducibility and validity of dietary GI and dietary GL and of carbohydrate intake as assessed by using an FFQ. DESIGN: Swedish men (n = 141) aged 40-74 y completed 2 FFQs 1 y apart and two 1-wk weighed diet records 6 mo apart. Dietary GI, dietary GL, and carbohydrate intake (starches and sugars) were calculated from both FFQs and diet records. We used intraclass correlations between the 2 FFQs to measure reproducibility and Pearson correlations between the diet records and the FFQs to assess the relative validity. RESULTS: Reproducibility of the FFQs was 0.66 (95% CI: 0.56, 0.75) for dietary GI, 0.61 (95% CI: 0.50, 0.71) for dietary GL, and 0.61 (95% CI: 0.50, 0.71) for carbohydrate. The correlations between the FFQs and diet records were 0.62 (95% CI: 0.45, 0.74) for dietary GI, 0.77 (95% CI: 0.56, 0.88) for dietary GL, and 0.76 (95% CI: 0.55, 0.88) for carbohydrate after adjustment for within-person variation in the FFQs and diet records. CONCLUSION: In this sample of men, an FFQ measured dietary GI, dietary GL, and carbohydrate with reproducibility and validity similar to other commonly studied nutritional factors.
BACKGROUND: Although the associations of dietary glycemic index (GI) and dietary glycemic load (GL) with many chronic diseases have been examined in epidemiologic studies, information regarding the reproducibility and validity of these measures assessed with the use of food-frequency questionnaires (FFQs) is lacking. OBJECTIVE: We examined the reproducibility and validity of dietary GI and dietary GL and of carbohydrate intake as assessed by using an FFQ. DESIGN: Swedish men (n = 141) aged 40-74 y completed 2 FFQs 1 y apart and two 1-wk weighed diet records 6 mo apart. Dietary GI, dietary GL, and carbohydrate intake (starches and sugars) were calculated from both FFQs and diet records. We used intraclass correlations between the 2 FFQs to measure reproducibility and Pearson correlations between the diet records and the FFQs to assess the relative validity. RESULTS: Reproducibility of the FFQs was 0.66 (95% CI: 0.56, 0.75) for dietary GI, 0.61 (95% CI: 0.50, 0.71) for dietary GL, and 0.61 (95% CI: 0.50, 0.71) for carbohydrate. The correlations between the FFQs and diet records were 0.62 (95% CI: 0.45, 0.74) for dietary GI, 0.77 (95% CI: 0.56, 0.88) for dietary GL, and 0.76 (95% CI: 0.55, 0.88) for carbohydrate after adjustment for within-person variation in the FFQs and diet records. CONCLUSION: In this sample of men, an FFQ measured dietary GI, dietary GL, and carbohydrate with reproducibility and validity similar to other commonly studied nutritional factors.
Authors: Marit M E van Bakel; Nadia Slimani; Edith J M Feskens; Huaidong Du; Joline W J Beulens; Yvonne T van der Schouw; Furio Brighenti; Jytte Halkjaer; Anne E Cust; Pietro Ferrari; Jennie Brand-Miller; H Bas Bueno-de-Mesquita; Petra Peeters; Eva Ardanaz; Miren Dorronsoro; Francesca L Crowe; Sheila Bingham; Sabine Rohrmann; Heiner Boeing; Ingegerd Johansson; Jonas Manjer; Anne Tjonneland; Kim Overvad; Eiliv Lund; Guri Skeie; Amalia Mattiello; Simonetta Salvini; Françoise Clavel-Chapelon; Rudolf Kaaks Journal: J Nutr Date: 2009-01-21 Impact factor: 4.798
Authors: Nancy C Howarth; Suzanne P Murphy; Lynne R Wilkens; Brian E Henderson; Laurence N Kolonel Journal: Am J Clin Nutr Date: 2008-10 Impact factor: 7.045