The National Health and Nutrition Examination Survey (NHANES) is a program of studies designed to assess the health and nutritional status of adults and children in the United States. The survey is unique in that it combines interviews and physical examinations. The NHANES interview includes demographic, socioeconomic, dietary, and health-related questions. The examination component consists of medical, dental, and physiological measurements, as well as laboratory tests administered by highly trained medical personnel. Findings from this survey are used to determine the prevalence of major diseases and risk factors for diseases, as well as to assess nutritional status and its association with health promotion and disease prevention. NHANES findings are also the basis for national standards for such measurements as height, weight, and blood pressure.
Risk factors, those aspects of a person's lifestyle, constitution, heredity, or environment that may increase the chances of developing a certain disease or condition, are examined by the NHANES. In particular, smoking, alcohol consumption, sexual practices, drug use, physical fitness and activity, weight, and dietary intake are studied. Data on certain aspects of reproductive health, such as use of oral contraceptives and breastfeeding practices, are also collected. The diseases, medical conditions, and health indicators studied include: anemia, cardovascular disease, diabetes, environmental exposures, eye diseases, hearing loss, infectious diseases, kidney disease, nutrition, obesity, oral health, osteoporosis, physical fitness and functioning, reproductive history and sexual behavior, respiratory disease (asthma, chronic bronchitis, emphysema), sexually transmitted diseases, and vision. Health interviews are conducted in respondents' homes by a study team consisting of a physician, medical and health technicians, as well as dietary and health interviewers.
The study uses a complex, multistage probability sampling design. The four stages are: U.S. counties (PSU) -> segments (e.g., city blocks) -> households -> individuals. African American, Mexican American, low SES European American, Adolescents, and older (60+) individuals were oversampled.