Diet History Questionnaire II: Background

The Diet History Questionnaire (DHQ) is a freely available food frequency questionnaire (FFQ) developed by staff at the Risk Factor Monitoring and Methods Branch (RFMMB). It can be used by researchers, clinicians, or teachers without permission. The original DHQ I was designed based on cognitive research findings, to be easy to use. It had 124 food items and included both portion size and dietary supplement questions. The DHQ II has a food list that has been updated based on more recent dietary data and consists of 134 food items and 8 dietary supplement questions (list of changes between DHQ I and DHQ II). Early testing showed that the paper-and-pencil version of DHQ I took about 1 hour to complete. No testing has been done on the DHQ II but we assume completion times are similar. Our web based versions, however, are likely to take less time to complete. Unlike, DHQ I, there are four different versions of DHQ II, in both paper and electronic formats (DHQ*Web). These four versions differ by time frame and portion size questions:

1. Past year, with portion size (our standard FFQ format): asks about intake in the past year and includes questions about portion size.
2. Past year, without portion size: asks about usual intake in the past year and excludes questions about portion size.
3. Past month, with portion size: asks about intake in the past month and includes questions about portion size.
4. Past month, without portion size: asks about usual intake in the past month and excludes questions about portion size.

Data from two relatively old studies conducted to assess validity showed that the DHQ I (past year time frame, with portion size questions) provided reasonable nutrient estimates. The first, using a checklist approach, showed that many of the cognitive improvements introduced in the DHQ I provided a better measure of frequency than the 1992 Block FFQ. The second validation, which compared the DHQ I to two FFQs that were widely used at the time the study was conducted (the 1995 Block FFQ and the "purple version" of the Willett FFQ), showed the DHQ I to be as good as or superior to those instruments for most nutrients (see Eating at America's Table Study). There are no plans to validate the updated DHQ II, however, there are few major changes to the overall food list. The affects of excluding portion size or asking about the past month versus the past year have not been evaluated. We recommend you ask portion size questions in cases when the FFQ is your primary dietary assessment instrument. However, data from any version of the DHQ could be used as a covariate in models that use the NCI Method to assess usual intakes when 24-hour dietary recalls or food records are the primary dietary assessment instrument tools.

The food list and nutrient/food group database used with the DHQ are based on national dietary data (the National Health and Nutrition Examination Surveys (NHANES) data collection in 2001-2002, 2003-2004, 2005-2006).

DHQ II is the current version of the questionnaire distributed by the NCI. You may analyze DHQ II data from either the paper or electronic forms with the Diet*Calc software developed by the NCI. Diet*Calc may be used to analyze data files from both the paper and electronic DHQ II modes of administration. You may modify the DHQ to suit your research needs, but this option will only be available for the paper and pencil versions and certain guidelines (described in the program's help system) must be followed when making modifications to the forms and the Diet*Calc software. The ability to offer modified electronic versions is also available on a case-by-case basis.

To use Diet*Calc, an ASCII text file containing data from completed DHQs must be created from paper-based forms or obtained from DHQ*Web. Diet*Calc will interpret the DHQ data to provide nutrient and food group intake estimates.