Collection of food and dietary supplement intake data: What We Eat in America-NHANES.

This paper describes the collection process for the integrated dietary component of the National Health and Nutrition Examination Survey(NHANES) 2002 (entitled What We Eat in America-NHANES), referred to here as the integrated survey. The dietary components of previous NHANES cycles and the Continuing Survey of Food Intake in Individuals (CSFII) are also described. The collection process for foods in the integrated survey consists of an in-person 24-h recall using a computerized 5-step method and a second nonconsecutive 24-h recall via telephone. A food frequency questionnaire is being pilot-tested to provide information on the propensity to consume certain foods. Dietary supplement intakes over the past 30 d are assessed for all persons during the household interview. Other diet-related data are also obtained. Strengths of the integrated survey include information on food and supplement intakes in a representative sample of the civilian noninstitutionalized population of the United States that can be linked to anthropometric, biochemical, clinical and disease history information in NHANES. After reviewing the current state of the art on dietary and dietary supplement data collection, discussion groups consisting of members of key stakeholder community concluded that, although the most advanced methods for dietary data collection available are being used, the differences between how information on food and dietary supplement intakes is collected make it challenging to combine data describing nutrients from both sources to obtain estimates of total nutrient intakes. The discussion groups concluded that more research is needed on these issues and provided key recommendations for future efforts in this important area of public health surveillance.