JMIR Publications

ABSTRACT

Background:

A web-based dietary assessment tool, RiksmatenFlex, was developed for the national dietary survey of adolescents in Sweden.

Objective:

To describe the development of RiksmatenFlex and to test the validity of reported dietary intake by RiksmatenFlexDiet.

Methods:

Adolescents aged 11-12, 14-15 and 17-18 years were recruited through schools. In total, 78 students had complete dietary information and were included in the study. Diet was reported at two school visits a few weeks apart with either RiksmatenFlexDiet (the day before, a random day later) or 24-hour dietary recall interviews (face-to-face, random day later by phone) in a cross-over, randomized design. Weight and height were measured and blood samples drawn at the first school visit. Students wore an accelerometer for 7 days. Dietary intake captured by both dietary methods was compared and energy intake by both methods was compared with accelerometer estimated energy expenditure. Intake of whole grain wheat and rye and fruit and vegetables by both methods was compared with carotenoids and alkylresorcinols (AR) in plasma, respectively.

Results:

Mean (SD) of reported energy intake was 8.92 (2.77) by RiksmatenFlexDiet and 8.04 (2.67) MJ by the dietary recall interviews (P=.01). Intake of fruit and vegetables was 224 (169) and 227 (150) grams, and whole grain wheat and rye 12.4 (13.2) and 12.0 (13.1), respectively, and intake did not differ between the methods. Intraclass correlations ranged from 0.57 for protein and carbohydrates to 0.23 for vegetables. Compared with accelerometer estimated energy expenditure energy intake by RiksmatenFlexDiet was over reported by 8% (P=.03) but not by the dietary recall interviews (P=.53). The spearman correlations between reported energy intake and estimated energy expenditure was 0.34 (P=.008) for RiksmatenFlexDiet and 0.16 (P=.21) for the dietary recall interviews. Spearman correlations between whole grain wheat and rye and plasma total AR homologues was 0.36 (P=.002) for RiksmatenFlexDiet and 0.29 (P=.02) for the dietary recall interviews. Spearman correlations between intake of fruit and vegetables and plasma carotenoids were weak for both dietary tools. The strongest correlations were observed between fruit- and vegetable intake and lutein/zeaxanthin, for RiksmatenFlexDiet 0.46 (P<.001) and for recall interviews 0.28 (P=.02).

Conclusions:

RiksmatenFlexDiet provides information on energy, fruit, vegetables and whole grain wheat and rye that is at least as valid as that from 24-hour dietary recall interviews in Swedish adolescents. The tool is user friendly and can easily be adapted to other age groups and has a great potential for cost-effective collections of dietary intake in national surveys and other studies in Sweden.