Evidence check: Cortisol in the context of longevity

The provided context does not contain direct evidence on cortisol in relation to longevity. Cortisol is a key stress hormone regulated by the HPA axis; chronically elevated levels are associated with accelerated aging, immune dysfunction, and metabolic syndrome. However, the evidence is primarily epidemiological and mechanistic, not from interventional longevity trials. Consumer DNA or microbiome tests (as mentioned in the context) are not validated for assessing cortisol status or genetic risk for cortisol dysregulation. The effect size of common genetic variants on cortisol levels is small, and lifestyle factors (sleep, stress management, exercise) have a much larger impact. Evidence grade: unclear/mixed due to lack of direct context and absence of robust RCTs linking cortisol modulation to extended lifespan. Clinical assessment via validated biomarkers (salivary cortisol, dexamethasone suppression test) is recommended. Safety note: Do not attempt to manipulate cortisol without medical supervision; chronic elevation or suppression can have serious health consequences.