Validation of a web-based dietary questionnaire designed for the DASH (dietary approaches to stop hypertension) diet: the DASH online questionnaire.

OBJECTIVE With the upsurge in online dietary modification programmes, online dietary assessment tools are needed to capture food intake. Although the DASH (Dietary Approaches to Stop Hypertension) diet is recommended by the US Department of Agriculture, there are no online instruments that capture DASH food servings. Our objective was to assess the validity of a new, short, online dietary questionnaire developed to capture intake of DASH food servings. The DASH Online Questionnaire (OLQ) was validated against the well-known Block Food Frequency Questionnaire (FFQ). DESIGN This was a cross-sectional validation of the DASH OLQ, which contained eleven food groups (breakfast cereals; dairy; drinks; fats and oils; fruits; grains and snacks; meat, fish and poultry; mixed dishes; sweets; vegetables; and nuts, seeds and legumes). Each subject completed a DASH OLQ once weekly for four weeks and one 98.2 Block FFQ (110 questions) between weeks 2 and 4. DASH OLQ were averaged and then compared with the Block FFQ for nutrient intakes as well as intakes of DASH food groups. SETTING Boston University Medical Center, Boston, Massachusetts. SUBJECTS One hundred and ninety-one faculty and staff at Boston University Medical Center aged 20-70 years. RESULTS There were significant positive correlations between the Block FFQ and the DASH OLQ for all food groups ranging from r = 0.8 for the nuts/seeds/legumes category to r = 0.3 for vegetables and mixed dishes. A comparison of nutrient intakes found strong positive correlations in all nutrient categories. Of particular interest in the DASH diet and the web-based nutrition and physical activity programme were total fat (r = 0.62), total carbohydrate (r = 0.67), total K (r = 0.68), total Ca (r = 0.69), total vitamin C (r = 0.60) and total energy intake (r = 0.68). CONCLUSIONS The DASH OLQ captures food and nutrient intake well in relation to the more established Block FFQ.