A web-based dietary assessment method for exploring zinc bioavailability: Developing a food list and pre-testing

Background: Zinc is an essential trace element that contributes to many different biological functions. Inadequate dietary zinc intakes play an important role in zinc deficiency in premenopausal women, so a dietary assessment tool has been developed to assess usual zinc intake. The Web Meal-Based Intake Assessment Tool (Web-MBIAT) described in this study is an internet-based dietary assessment tool that assesses individuals’ usual intake of zinc and its absorption modifiers by meal, over the past month. Aims: The aim of the research project was to compile a food list designed to measure intakes of zinc and its absorption modifiers for the Web-MBIAT, and pilot and pre-test the Web-MBIAT in a sample of premenopausal, adult women to assess ease of use. Design: Food items were included in the main food list if they contained ≥0.5mg zinc/100g or ≥50mg phytate/100g. Food items were also included if they were part of a food group which contributed ≥3% zinc or ≥6% phytate to the diet of the target audience. The food list was incorporated into the Web-MBIAT which was then pilot and pre-tested with 10 premenopausal adult women in Dunedin, New Zealand. Results: A total of 467 of the 2710 foods in FOODfiles 2010 Version 02, were included in the main food list. Participants found the Web-MBIAT relatively easy to use giving it a mean score of 8.2 (on a scale of 1 to 10, with 10 being the easiest) when asked to score how easy the Web-MBIAT was to complete. Participants found quantifying portion sizes the most difficult part of completing the Web-MBIAT. Participant suggestions to improve ease of use included adding more measure descriptors, recording what was consumed the week before completing the Web-MBIAT, having physical or visual examples of portion sizes, and providing the participants with a list of all the food items in the Web-MBIAT during the interview. Conclusion: Piloting and pre-testing of the Web-MBIAT revealed that participants found it relatively easy to complete, but several improvements need to be made, particularly concerning quantifying portion sizes, to improve performance and ease of use before validation in the future