The Diet History Questionnaire (DHQ) and the DHQ nutrient database were modified for use in Canada through the collaborative efforts of Dr. Amy Subar and staff at the Risk Factor Assessment Branch, and Dr. Ilona Csizmadi and colleagues in the Division of Population Health and Information at the Alberta Cancer Board 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.
Modifications to the Standard U.S. DHQ
Two line items were removed from the standard DHQ as they referred to products currently not available in Canada; highly fortified cereals (Total, Product 19, and Right Start) and potato chips made with Olean or Olestra fat substitutes. In addition, a number of items not on the original version of the DHQ were added. The question that queried intake of orange and grapefruit juice was modified by adding an embedded question to determine the proportion of orange and grapefruit juice intake that was fortified with calcium. To better capture vitamin D intake, a separate question was added to ascertain the intake of supplemental vitamin D not included in multivitamin preparations. Finally, Splenda (sucralose), a modified sugar that is not fully absorbed or metabolized and is 600 times sweeter than sucrose, was added as a third possible choice in the category of artificial sweeteners.
The Questionnaire Data Dictionary used with Diet*Calc software was modified with respect to column location and variable coding in order to be consistent with the Canadian-modified DHQ data file. The Canadian DHQ has been programmed in TELEform for scanning data entry and creation of the data file.
Modifications to the Nutrient Database
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.
Briefly, 2,411 foods in the original nutrient database were identified as those most likely to differ in food composition as a result of differences in food fortification practices between the US and Canada. These foods were examined for differences in 12 nutrients: vitamins A, C, B6, B12, and D, thiamin, riboflavin, niacin, folate, calcium, iron, and zinc. These nutrients were selected as those most relevant to the study of associations between diet and chronic disease.
Food composition data for Canada were obtained from the Canadian Nutrient File (CNF, Version 2001b) . This large relational database compiled by the Nutrition Research Division at Health Canada, is the most comprehensive and valid source of Canadian food composition information. The database contains average values for the content of 112 nutrients in 4,943 foods available in Canada. Although much of the CNF data are derived from the United States Department of Agriculture Nutrient Database for Standard Reference (SR13), the nutrient composition does vary with respect to fortification and regulatory standards specific to Canada and includes foods and brand names available only in Canada.
Twenty-five percent of the 2,411 foods originally identified for examination required modification to reflect Canadian levels of food fortification. All of the 25 percent were modified for folate, and approximately 7 percent to 10 percent were modified for riboflavin, calcium, iron, zinc, niacin, thiamin, and vitamins A, B6, B12 and C. In addition, 262 foods or 11 percent of the foods were modified for vitamin D.
The most frequently affected foods with respect to nutrient modifications were ready-to-eat cereals and commercially prepared baked products. In addition, milk replacements (rice and soy) are fortified with vitamins D, A, B12, riboflavin, zinc and calcium in Canada but not in the 1994-96 CSFII nutrient database. The fortification of margarine with vitamin D in Canada and not in the US is also noteworthy due to its widespread presence in the daily diet.
Questions pertaining to the Canadian versions of the DHQ and nutrient database may be sent to email@example.com.
Current Studies Using the Modified Canadian DHQ
The Alberta Cohort Study (The Tomorrow Project®: PI Dr. Heather Bryant) - The Tomorrow Project, a research initiative of the Alberta Cancer Board with funding from the Alberta Cancer Foundation, is a prospective cohort study that aims to determine how lifestyle, diet, physical activity, and other behaviours are likely to influence cancer risk in the population of Alberta, Canada. As of September 2005, approximately 18,500 Albertans aged 35-69 years, without a cancer diagnosis at enrolment, have been enrolled into the cohort. Participants have been asked to complete the Canadian version of the DHQ, as well as questionnaires designed to assess health, lifestyle and past year physical activity. Recruitment to the cohort is ongoing.
Case-control study of endometrial cancer – PI Dr. Christine Friedenreich of the Alberta Cancer Board is conducting a population-based case-control study of lifestyle risk factors for endometrial cancer risk in Alberta, Canada. A sample of 500 incident cases and 1000 population controls are completing interviewer-administered questionnaires, providing blood samples and completing the Canadian version of the DHQ. Data collection will be completed in early 2006.
Alberta Physical Activity and Breast Cancer Prevention Trial (ALPHA Trial) – Co-PIs Dr. Christine Friedenreich and Dr. Kerry Courneya (Alberta Cancer Board and University of Calgary) are conducting a two-armed, two-site randomized controlled intervention trial of aerobic exercise among 320 postmenopausal, previously sedentary women aged 50-74 years of age. The exercise intervention involves five days per week of aerobic exercise while the control group is maintaining their regular lifestyle. At baseline and at the end of the 12 month long intervention, the participants complete several questionnaires and tests including the Canadian version of the DHQ.
DHQ & Diet*Calc Files for the Canadian Version
Canadian DHQ & Diet*Calc Files
dhq.canadian.zip [ZIP - 1.07 MB] - all files
The contents of the zip file are: