Relative validity of adolescent dietary patterns: a comparison of a FFQ and 3 d food record.

Interest in empirically derived dietary patterns has increased over the past decade. However, relatively few studies have evaluated dietary patterns using different dietary methods, or in young populations. We quantitatively compared dietary patterns from a FFQ with those from a 3 d food record (FR) in a cohort of adolescents. Subjects from the Western Australian Pregnancy Cohort (Raine) Study completed a semi-quantitative FFQ and a 3 d FR at 14 years of age (n 783). Major dietary patterns were identified using exploratory factor analysis on thirty-eight food groups. Dietary pattern z-scores were compared using 95 % limits of agreement (LOA) and Spearman's r. Two major dietary patterns were identified in the FFQ and FR: a 'Healthy' pattern, which was high in fresh fruit, vegetables, whole grains and grilled or canned fish, and a 'Western' pattern, which was high in take-away foods, confectionery, soft drinks, crisps and fried potato. The nutrient profiles of these dietary patterns were similar when estimated by the FFQ and FR. The LOA between dietary pattern scores from the FFQ and FR were - 1·69 to 1·75 ('Healthy') and - 1·89 to 1·82 ('Western'). Minor differences in agreement were observed when boys and girls were analysed separately. Spearman's correlation coefficients between the FFQ and the FR were r 0·45 ('Healthy') and r 0·36 ('Western'). Comparable dietary patterns may be obtained from the FFQ and FR using exploratory factor analysis. This supports the use of major dietary patterns identified using the FFQ in this adolescent cohort.