Dietary intake methodology I. USDA surveys and supporting research.

Nationwide food consumption and dietary surveys have been conducted about every 10 yr by the U.S. Department of Agriculture (USDA) since the mid-1930s to fulfill responsibilities for monitoring dietary patterns among the nation's population. Survey findings have implications for policies and programs related to food production and marketing, food safety, food assistance, and nutrition education. Until 1965, these surveys measured household food consumption only, but subsequent surveys were expanded to include food intakes by individuals in the sample households. Since 1985, small-scale continuing surveys of food intakes by individuals have been conducted during the years between the large decennial surveys. The 1-d recall was used in the first dietary intake survey. Then, to capture day-to-day variation in diets, 3 d of intake data, 1-d recall and 2-d records, were collected in 1977-1978, 1987-1988, and 1989. Prior to the 1977-1978 dietary intake survey, USDA embarked upon an intensive program of extramural research that was designed to improve methodologies for surveying individuals' dietary intakes. Since 1975, many major investigations have been completed and results have been incorporated in current survey procedures. Studies included testing of varied recall and diary methods, approaches for validating survey data, debriefings of survey respondents and interviewers, intersurvey comparisons, and testing of panel approaches with in-person, telephone, and mail contacts.