Secular trends in dietary intake in the United States.

This review focuses on dietary intake and dietary supplement use among the U.S. population age 1-74 based on four National Health and Nutrition Examination Surveys conducted in 1971-74, 1976-80, 1988-94, and 1999-2000. Secular trends in intake of energy, macronutrients, cholesterol, sodium, calcium, iron, folate, zinc, vitamins A and C, fruits, vegetables, and grain products are summarized. During the 30-year period, mean energy intake increased among adults, and changed little among children age 1-19, except for an increase among adolescent females. Factors contributing to increases in energy intake include increases in the percentage of the population eating away from home (particularly at fast-food restaurants), larger portion sizes of foods and beverages, increased consumption of sweetened beverages, changes in snacking habits, and improved dietary methodology. Dietary supplement use increased among adult men and women, decreased among children age 1-5, and was stable for children age 6-11 and adolescents.