Myths vs facts: Cortisol and longevity

Cortisol, the primary stress hormone, is often linked to longevity in popular media. Fact: Chronically elevated cortisol can accelerate aging by promoting inflammation, insulin resistance, and cardiovascular damage. However, the myth is that a single cortisol measurement (saliva, hair, or blood) can predict your lifespan. Evidence for a direct causal role of cortisol in human longevity is mixed and confounded by lifestyle factors. While some studies show associations between high cortisol and increased mortality, effect sizes are modest and not actionable for individuals. Cortisol levels fluctuate with sleep, diet, and stress, making single-point tests unreliable. The context provided (microbiome, ferritin, pharmacogenetics) does not contain direct evidence on cortisol and longevity. Therefore, we rate the evidence as 'mixed' – plausible mechanisms exist, but robust human data linking test results to longevity are lacking. Practical advice: focus on stress management rather than testing. MyBody-X cortisol tests can indicate stress patterns but are not validated for longevity prediction. Caveat: Not diagnostic for lifespan.