Vanderbilt Center for Human Nutrition

VCHN Diet and Nutrition Assessment Center is a resource available to researchers to provide expertise in the design, data collection, processing, assessment and/or analysis of all forms of dietary and nutrient intake: foods, beverages, dietary supplements, liquid nutrition supplements, tube feedings, parenteral support, and medications.

Dietary and nutrient intakes can be assessed for cross-sectional studies, observational/epidemiological studies, experiments, clinical trials and interventions. Six methods of assessing intakes are available:

Assessment method will depend on the goals of the study. In research, the goal is usually to capture information on usual diet, nutritional status, dietary behaviors, the adequacy of macronutrient and micronutrient intakes, or the effects of an intervention on dietary intakes and/or nutritional status. In addition to individual or group intakes, we are also able to assess family or household intakes.

The Diet and Nutrition Assessment Center can provide expert consultation on study design, reliable and valid assessment strategies and tools, assistance with study implementation, performance of data collection, and conduct of statistical analysis of dietary and nutrient data. Please call or email for further information: 936-1299 or heidi.j.silver@vanderbilt.edu 

Methods

Food Frequency Questionnaires are mostly used for observational or epidemiological studies. We can modify instruments to include specific foods or nutrients, or be population-specific. The objective of a FFQ is to get an estimate of usual or habitual intake.

USDA Multi-Pass Interview Method

For 24-hour dietary recall, we use the USDA multi-pass interview method in conjunction with the University of Minnesota Nutrition Data System software (NDS-R 2005). NDS-R is the most comprehensive nutrient database available for research, containing data for over 18,000 foods with millions of variations depending upon food preparation method and food ingredients. The database contains over 8,000 brand name foods, as well as dietary supplements and nutrient-containing medications. Calculations are available for 120 nutrients and nutrient ratios. There are a variety of output data sets that can be generated including food data, nutrient data, meal data and recipe data.

Daily Diet Records

Daily Diet Records or Food Diaries are provided with training to subjects so they can measure or estimate and record concurrently all the foods and drinks consumed over a specific period of time. Foods can be weighed, measured or estimated. The method requires adequate instruction, training via demonstration with food models, and observation of performance. Household measuring utensils or food portion visuals are often provided.

Diet History

Diet History requires an in-depth interview with each subject in a private setting. Information on the past intakes and behaviors as well as current intakes and behaviors is gathered in a systematic manner. Diet history attempts to gather information over a long period of time, which may be 3, 6, or 12 months, or even years. Precision may be somewhat sacrificed over greater periods of time, but the objective is to understand changes in intakes or behaviors that have occurred – often in relation to weight or other nutrition-related variables.

Weighed Intakes

Weighed Intakes offer the most accurate method of assessing dietary intake as all food and fluid items are precisely weighed before and after intake. The amount of detail is greater, but the method requires using food scales and providing in-depth instruction - which can be performed in or outpatient. The method has been used successfully in motivated populations such as retirees or in populations who are receiving pre-made meals.    

Observed intakes can be performed in or outpatient. In addition to direct observation and recording of intakes by the diet assessment professional, trained observation, photography and/or videography may be used.