What will be the public health impact?

To date, no national surveys have been able to provide estimates of usual dietary intake or objective assessments of physical activity. These estimates will contribute to public health aims in several arenas:

• Surveillance. The ability to estimate the population's distribution of usual intake of food and nutrients, within a survey that also assesses health and other risk-related behaviors (such as physical activity), will allow researchers the unique opportunity to study relationships among all these factors.
• Health Promotion/Disease Prevention. Several of the Healthy People 2010 objectives relate to food and nutrient intake (e.g., those on fruits, vegetables, and grains). These objectives are stated in terms of affecting the prevalences of intakes above or below a recommended level (rather than the mean intakes). However, until estimates of distribution of usual intakes can be made with better precision, tracking these objectives will be suspect.
• Health Policy. The Dietary Guidelines for Americans represent a statement of federal nutrition policy, and they guide all federal nutrition education and food assistance efforts. The recent addition of a guideline on physical activity highlights the increased focus on this behavioral risk factor. Usual intake estimates and objective estimates of physical activity will help in assessing how well the public is following these 10 guidelines.
• Program Evaluation. Programs such as "5 a Day for Better Health" depend on nationally representative data on usual food intakes to track progress in meeting program objectives.
• Health Disparities. Because the NHANES sample is nationally representative and includes persons from a range of income, education, and sociocultural backgrounds, the resulting estimates of food intake and physical activity will be able to be examined by many variables to determine whether there are differences in these behaviors that may result in health disparities.