NHANES (National Health and Nutrition Examination Survey) is a large-scale program studying the health and nutrition of the US population. It is run by the National Center for Health Statistics (NCHS) at the CDC. What makes NHANES unique is that it combines an interview, a full medical examination and laboratory tests.
NHANES data have become the foundation for many reference ranges and models of biological age, including PhenoAge.
How the survey works
NHANES has been conducted since 1971 and became continuous in 1999: each year about 5,000 people are examined, selected to be representative of the entire US population. Every participant undergoes an interview at home, then an examination in a mobile medical center with measurements and blood draws. This makes the sample nationally representative.
What NHANES has given medicine
NHANES data underpin pediatric growth charts, reference ranges for blood pressure, lipids and many lab tests, and estimates of the prevalence of obesity, diabetes and vitamin deficiencies. Thanks to standardized measurements, the results are comparable across decades and countries.
NHANES and biological age
NHANES is especially important for the science of aging. The PhenoAge model (Levine, 2018) was calibrated on NHANES III data with long-term mortality follow-up: from 9 routine blood biomarkers it estimates "phenotypic age" and the risk of death. That is why many biological-age calculators rely specifically on NHANES references.
Calculate using this marker
Calculators where NHANES is used directly:
Frequently asked questions
How does NHANES differ from an ordinary survey?
Most surveys rely on what participants say. In NHANES people are not only interviewed but also physically examined: blood pressure, height and weight are measured, and blood and urine are collected for laboratory tests. This yields objective data, not just self-rated health.
Why do biological-age models use NHANES specifically?
NHANES combines standardized blood tests with many years of mortality follow-up of participants. That is an ideal basis for linking biomarkers to real mortality risk — as done in PhenoAge. So the norms and coefficients of such models are often taken from NHANES.