Validity and reproducibility of an adolescent web-based food frequency questionnaire

To assess the validity and reproducibility of a newly developed, cost-effective, and easy to administer, Web-based food frequency questionnaire (FFQ) for the dietary assessment of adolescents.

Cross-sectional validation of a Web-based FFQ, which contained 15 food groups (water; soft drinks, including fruit juice and diet soft drinks; alcoholic beverages; soup; milk and milk products; fruit; sweet and savory snacks/fillings; sauces and fat spreads; breakfast cereals; bread; cheese, fish/eggs/meat; pasta/rice; vegetables; and potatoes). Reference data for validation were 3-day estimated food records. Analyses were done for all participants and for consumers only (consumer in both Web-based FFQ and food record).

A selected group of adolescents (12 to 18 years of age, n=104) from participating secondary schools in Ghent, Belgium.

For all participants, the measured intakes of water, fruit, breakfast cereals, fish/eggs/meat, pasta/rice, and potatoes were not significantly different between the two methods. The Spearman correlation for all foods was on average 0.38 (ranging from 0.20 for pasta/rice to 0.64 for breakfast cereals). When analyzed for consumers only, the Web-based FFQ showed significantly lower estimates for soft drinks, sweet and savory snacks/fillings, sauces and fat spreads, cheese, pasta/rice, and vegetables. The average Spearman correlation for all foods collectively was 0.30. When reproducibility of the Web-based FFQ was assessed, the average Spearman correlation coefficient for all foods collectively was 0.62.

Most questions on the 15 food groups had acceptable reproducibility, whereas validation only showed reliable intakes for water, fruit, bread, and fish/eggs/meat. This Web-based FFQ could be a start for development of dietary assessment methods in public health nutrition contexts.