Diet History Questionnaire: Development of the DHQ Nutrient Database
The nutrient and food
group database, created for analyzing
the DHQ, is based on national dietary intake data from the 1994-96 US Department
of Agriculture's Continuing Survey
of Food Intake by Individuals (CSFII). These 24-hour dietary recall data were used
to decide which foods to include
on the DHQ and what the portion sizes should be.
The CSFII foods were placed into food groups consistent with line items on the
DHQ. For example, there are many
different individual foods that are subsumed by the line item, "lasagna, stuffed
shells, stuffed manicotti, ravioli,
or tortellini." The CSFII data were analyzed to provide a mean nutrient or food
group value, by gender and portion
size, based on all reported intakes of the various lasagna, stuffed shells, etc.,
reported on 24-hour recalls in CSFII.
This produced a single nutrient or food group value by portion size and gender for
each food on the DHQ.
Nutrient values were not computed separately by age group because our research
(cited below) showed that separate
nutrient values by age group did not improve estimates. However, for investigators
interested in adding age-specific
values in the database, the Diet*Calc software has the flexibility to allow you to
do so. For a more detailed description
of the method used to create the values for the DHQ database, please see:
Subar AF, Midthune D, Kulldorff M, Brown CC, Thompson FE, Kipnis V,
Schatzkin A. An evaluation of alternative
approaches to assigning nutrient values to food groups in food frequency
questionnaires. Am J Epidemiol 2000;152;279-86.
Nutrients from Nutrition Data System for Research
The methods used to add nutrients such as carotenoids and tocopherols to the DHQ
database are the result of the efforts
of Dr. Lori Beth Dixon at New York University and Thea Zimmerman at Westat. In the
DHQ database such nutrients are
clearly marked in the variable labels as "(NDS-R based)". The methods used to add
NDS-R nutrients to the DHQ database
are described in:
Dixon LB, Zimmerman TP, Kahle LL, Subar AF. Adding carotenoids to the
NCI Diet History Questionnaire Database.
J Food Comp Anal 2003;16:269-280.
To summarize, however, these values are the result of matching 1994-96 CSFII food
codes to similar foods in the nutrient
database of the Nutrition Data Systems for Research (NDS-R) from the University of
Minnesota, which has nutrient values
not available from the USDA Survey Nutrient Database. The values for the DHQ were
then computed using the databased
approach described in:
Subar AF, Midthune D, Kulldorff M, Brown CC, Thompson FE, Kipnis V,
Schatzkin A. An evaluation of alternative
approaches to assigning nutrient values to food groups in food frequency
questionnaires. Am J Epidemiol 2000;152;279-286.
Addition of Glycemic Load
The Glycemic Index (GI) is a measure of the glycemic effect of carbohydrate in a
particular food compared to an equivalent amount of carbohydrate in a standard amount of
glucose or white bread. The GI is the ratio of the area under the curve for the glycemic
response to the test food to the area under the curve for the glycemic response to
glucose. The Glycemic Load (GL) of a serving of a specific food is simply the product of
its GI (divided by 100) and the grams of carbohydrate from a single serving of that food.
It is important to note that a food with a high GI may not always have a high GL. This
can happen if the food has very little carbohydrate (for example, meat) or if the food is
consumed in small quantities.
The methods to add GL to the DHQ are the result of the efforts of Andrew Flood at the University of Minnesota in conjunction
with Amy Subar at NCI and Steve Hull and Thea Zimmerman of Westat. We assigned published GI values1
to each of the individual CSFII foods consistent with line items on the DHQ. In cases where CSFII foods did not correspond
tightly to foods with published GI values, we used decision criteria to assign GI values. We then calculated gender
and serving size-specific GL for each of the 225 food groups using a weighted mean method published by Subar et al2.
(The Diet*Calc software incorporates these GL values in the latest nutrient database. As a reference, we also provide
users with the overall GI values by DHQ food group to provide a sense of the values
upon which the GL values are based.) Quality assessments were made to help evaluate the success of this method for
assigning GL values. A publication on this method is in press at the Journal of the American Dietetic Association.
In addition, we provide two files. The first is
a listing of GI values for individual CSFII food codes
that provides GI values for those foods consumed by adults and queried on
the DHQ or other FFQs used at NCI. It is organized by CSFII food code. The second, a
DHQ-only version,
is organized by DHQ food groups consistent with line items on the
questionnaire. It includes links to GI values published by Foster-Powell et al1. We also
provide both files together as an
MS Excel file.
In all these files, the foods listed as
having a null value are those to which we did not assign a GI value because they were not
important contributors to a food group for which we were calculating a GL value.
1. Foster-Powell K, Holt SH, Brand-Miller JC. International table of glycemic
index and glycemic load values: 2002. Am J Clin Nutr 2002;76(1):5-56.
2. Subar AF, Midthune D, Kulldorff M, Brown CC, Thompson FE, Kipnis V,
Schatzkin A. An evaluation of alternative approaches to assigning nutrient values to food
groups in food frequency questionnaires. Am J Epidemiol 2000;152(3):279-86.
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