A validation of the original, longer food frequency questionnaire (84 foods) was performed among 196 participants with repeated 24-hour food recall interviews and plasma β-carotene measurements (Johansson et al., 2002). The participants also answered the same food questionnaire twice within a 1-year period. There was a good agreement of the reported energy and nutrient intake between the two questionnaire occasions. A somewhat higher food intake was estimated with the food frequency questionnaire compared to the 24-hour food recall interviews. Despite a high proportion of under-reporters the validity of the FFQ is considered equal to that of other FFQs used in prospective cohort studies (Johansson et al., 2001). Recently, intake of a number of essential fatty acids, fatty acid profile in erythrocyte membranes (Wennberg et al., 2009), vitamin B intake (Johansson et al., 2010), and plant sterols (Klingberg et al., 2013) have been validated against 24-hour food recall interviews
References
Johansson I, Hallmans G, Ericsson S, Hagman U, Bruce Å, Wikman Å, Kaaks R, Riboli R. Evaluation of the accuracy of a dietary questionnaire aimed for the Västerbotten study. Scand J Nutr1994;38:50-55