Four instruments collect dietary data.
The Diet History Questionnaire (DHQ II) is an online food frequency questionnaire (FFQ) that asks about a list of foods eaten in the past 12 months. The usual frequency and portion size of these foods were self-reported by participants. Participants were asked to complete the DHQ2 twice, one year apart.
The food frequency files contain one record per food, with the two administrations split into different datasets. The nutrient file contains one record per person with an array of the two administrations.
You may view data dictionaries and formats for the DHQ files. Datasets can be obtained by submitting a request.