Dietary Assessment

The Purdue Diet Assessment Center (PDAC) is available to support nutrition assessment protocols both within and outside the Indiana Clinical and Translational Sciences Institute (CTSI). The PDAC has over 700 square feet of dedicated space within the Purdue CRC equipped with two individual offices for consultation, four workstations with computers, phone headsets, and sound barriers. The gold standard University of Minnesota Nutrition Data System for Research (NDSR) state of the art software is utilized for data entry and analysis. The PDAC staff work with investigators providing guidance and support for research proposals by:

• assisting with proposal writing
• selecting appropriate methodologies
• choosing the most suitable diet outcomes and other variables for analysis
• calculation of nutrient and food related variables
• guidance on statistical analysis
• interpretation of diet and related data
• assisting with manuscript preparation

Specifically, PDAC provides comprehensive support to investigators who include dietary assessment in their research protocols.  Multiple established methods are used to collect and process dietary intake data from participants enrolled in research studies including:

Dietary Recalls

The dietary 24 hr recall is an in-depth interview that collects detailed information on all foods and beverages consumed by a participant during the previous 24 hrs.  These recalls are best administered “unannounced” (not scheduled on a specific day) so that participants cannot change their eating habits based on anticipation of interview.  Trained PDAC staff conduct recalls over the telephone or in person. NDSR interactive software prompts the interviewer to probe for detailed information about specific quantities, brand names, and cooking methods for each food.  The accuracy of the recall is highly dependent upon participant memory and the communication skills of both the participant and interviewer.  For this reason, PDAC interviewers are specially trained to effectively probe for information using neutral and non-leading questions.  It is suggested that all participants receive a Food Amounts Booklet prior to the call.

Diet Record Analysis

Subjects record all food and beverages consumed over three consecutive days (two weekdays and one weekend day). The consumed foods can be measured using a scale or other household items, such as measuring cups or spoons, or estimated using a portion size guide.  Trained staff must provide detailed instructions on how to record intake and the completed records are entered into the Nutrition Data System for Research (NDSR) for analysis.