Baseline - Dietary
There are a variety of ways to select a dietary exposure: questionnaire variables, nutrients, and food groups.
Food Frequency
The baseline questionnaire includes questions about the consumption frequency and serving size of over 300 foods and dietary supplements. The variables associated with these questions are primarily categorized as:
* Frequency
* Serving Size
* Food Name / Brand Name - for write-in foods
These variables can be used directly, or converted into daily nutrient consumption values when combined with the NDSR recipe/nutrient database.
A list of all the dietary subject response variables is available here
.
Nutrient Consumption
We estimate a subjects' daily nutrient consumption, by combining questionnaire food-consumption data with nutrient information from the Nutrition Data System for Research (NDSR or NDS).
Three main classes of nutrient consumption data are available: basic nutrients, custom nutrients and food group nutrients.
Basic Nutrients
The basic nutrients are those provided natively by the NDSR system, such as grams, kilocalories, carbohydrates, fat, vitamin a, etc. Over 170 of these are available and are listed in the NDSR nutrient variable list
.
Custom Nutrients
It is possible to obtain consumption data for nutrients not provided by the NDSR system (e.g. Phenol Explorer, USDA NDB) or from literature searches. While the list of these ingredients is quite large, the task remains feasible and has been accomplished on more than one occasion by a number of researchers.
Food Groups
Food group nutrients consist of basic (or custom) nutrients only taken from certain food groups.
In addition to the typical nutrient (like calcium), grams and kilocalories are considered nutrients for bookkeeping purposes.
Examples of such variables include grams of vegetables (VEGETABLES_GRAM), and calcium from dairy (DAIRY_CA).
Food Group Nutrients
Food groups
are used to differentiate nutrient sources (e.g. animal protein).