The Diet History Questionnaire (DHQ) and the DHQ nutrient database were modified for use in Canada. While the modifications were primarily carried out in order to develop a nutrient database that reflected Canadian nutrient fortification practices, a few questionnaire changes were also made to the DHQ.
The methods used to modify the nutrient database to reflect Canadian food fortification practices are described in detail in the manuscript:
Csizmadi I, Kahle L, Ullman R, Dawe U, Zimmerman TP, Friedenreich CM, Bryant H, Subar AF. Adaptation and evaluation of the National Cancer Institute’s Diet History Questionnaire and nutrient database for Canadian populations. Public Health Nutr 2007 Jan;10(1):88-96.
A copy of the Canadian DHQ II food frequency questionnaire, along with the data dictionary and nutrient database modified for certain Canadian-specific dietary differences, are available for download from the National Cancer Institute, Division of Cancer Control & Population Sciences.