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. NHANES is a major program of the National Center for Health Statistics (NCHS). The NHANES program began in the early 1960s and has been conducted as a series of surveys focusing on different population groups or health topics. In 1999, the survey became a continuous program that has a changing focus on a variety of health and nutrition measurements to meet emerging needs.

Data Collection
The survey examines a nationally representative sample of about 5,000 persons each year. These persons are located in counties across the country, 15 of which are visited each year. 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. For a complete description of the survey content for NHANES 1999-2020, go to:

Biological specimens collected in the laboratory component of NHANES include whole blood, plasma, serum, urine, hair, DNA, saliva, and nasal and vaginal swabs. Laboratory tests done on almost all survey cycles include complete blood count, lipids, a chemistry panel (kidney, hepatic function), folate/RBC folate, iron status, STDs (HIV, herpes, hepatitis), cotinine, heavy metals (lead mercury, cadmium), C-reactive protein, urinary creatinine and albumin, and diabetes (glucose, insulin, HbA1c). Laboratory tests done on a periodic basis include vitamins B6, B12, C and D, homocysteine/MMA, FSH/LH, PTH, thyroid function, bone alkaline phosphatase, cryptosporidium, helicobactor pylori, HLA-B27, environmental chemicals, latex, measles, varicella, MRSA, PSA, and selenium. The 24-Hour dietary recall supplement (1999-2006) was followed up in 2017-2018.