Myths vs facts: TSH and longevity

TSH (thyroid-stimulating hormone) is a key regulator of metabolism and is often discussed in the context of longevity. A common myth is that slightly elevated TSH (subclinical hypothyroidism) promotes longevity by slowing metabolism and reducing oxidative stress. While some observational studies in centenarians show mildly higher TSH levels, this is likely an age-related adaptation rather than a causal protective factor. The scientific consensus is that both very high and very low TSH are associated with increased mortality, mainly from cardiovascular disease. A TSH within the normal reference range (approximately 0.4–4.0 mU/L) is considered optimal for general health. Evidence is based on human observational studies, not interventional longevity trials. Home TSH tests can provide a snapshot but are not diagnostic. Acting on a home test without medical guidance can lead to inappropriate supplementation and health risks. In summary, TSH is a useful biomarker but not a simple longevity switch. Individual interpretation requires clinical context.