Biological age refers to how old your body appears to be based on measurable biomarkers rather than your birth year. Two people born in the same year can have biological ages that differ by a decade or more depending on genetics, lifestyle, environment, and health history. The key insight driving consumer biological age testing is that this gap is measurable, and that interventions — ranging from exercise and sleep to certain supplements and dietary protocols — can close it over time. The clinical relevance is significant: biological age has been shown to be a stronger predictor of healthspan, disease risk, and mortality than chronological age alone.

The most widely cited biological age tests use epigenetic clocks — statistical models built on DNA methylation patterns. Methylation is a chemical modification to DNA that regulates gene expression without changing the underlying genetic code. As we age, methylation patterns change in predictable ways. Researchers like Steve Horvath built early clocks by identifying sites across the genome where methylation correlates tightly with age. Modern clocks, including TruAge (used by TruDiagnostic), GrimAge, and PhenoAge, have refined these models to capture not just calendar aging but pace of aging and risk of age-related disease. TruDiagnostic is the most well-known consumer provider using methylation-based biological age testing.

GlycanAge uses a completely different methodology — it measures IgG glycan patterns in the blood rather than DNA methylation. Glycans are sugar chains attached to proteins, and their profile on immune system antibodies changes with age and inflammation. GlycanAge positions its score as more reflective of immune system aging and inflammatory status than methylation clocks, which it argues captures a broader picture of systemic health. The two approaches are measuring different things and often produce different biological age estimates for the same individual. Neither is definitively superior — they are answering different questions about the aging process.

A biological age score lower than your chronological age is generally considered favorable but should not be overinterpreted from a single measurement. The most actionable use of biological age testing is longitudinal — testing at a consistent interval (typically every six to twelve months) to track whether the interventions you are making are moving the number. A single score provides a baseline; the trend over time is where the insight lives. Scores can also vary between methodologies, so comparing a TruDiagnostic result to a GlycanAge result is not straightforward.

The most consistent research-backed interventions for improving biological age scores include sustained aerobic exercise, high-quality sleep, stress reduction, and avoiding smoking. Dietary interventions such as time-restricted eating and the fasting mimicking diet (ProLon) have shown measurable methylation improvements in some trials. Supplements like NMN, NR, and rapamycin are under active investigation, with early results suggesting modest improvements in some biomarkers, though long-term human data remains limited. Elysium Health's Basis (NR) has published some of the only supplement-specific biological age data. Any supplement claiming dramatic biological age reversal should be viewed skeptically until larger trials confirm the findings.