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How the grades work

Same method as the guide

Human evidence beats animal evidence. Replicated results beat single studies. Real outcomes beat surrogate ones. Each intervention below is graded by that rule — the same rule we apply to our own research.

The tiers
TIER 1Decades of human evidence
TIER 2Strong but conditional
TIER 3Promising, under study
TIER 4Currently unproven
Tier
Category
InterventionEvidenceCategoryWhat the evidence actually says
Physical activityTIER 1Lifestyle150 minutes of moderate exercise weekly is associated with reduced all-cause mortality across decades of cohort data; strength training preserves muscle and function into old age.
SleepTIER 1LifestyleConsistent, sufficient sleep is tied to metabolic, cardiovascular, cognitive, and immune outcomes across the literature — one of the few inputs with near-universal effect.
Diet qualityTIER 1NutritionWhole-food patterns with adequate protein and limited ultra-processed food are consistently associated with better healthspan. The "best diet" debate matters less than the direction.
Not smoking, moderating alcoholTIER 1LifestyleThe baseline every other intervention builds on.
Time-restricted eatingTIER 2NutritionHuman trials show modest metabolic benefits — real, but smaller than popular claims, and partly because it reduces total intake. Skipping it costs you little if it does not suit you.
Vitamin DTIER 2NutritionCorrecting a genuine deficiency is clearly beneficial; raising already-normal levels is not. Test first, supplement if low, re-test.
Protein intakeTIER 2NutritionOlder adults and athletes often under-eat protein relative to muscle needs; meeting roughly 1.2–1.6 g/kg supports muscle maintenance.
Omega-3sTIER 2NutritionSolid evidence for cardiovascular risk reduction in people with elevated triglycerides; the "everyone should take them" case is weaker than the marketing.
MetforminTIER 3CompoundCompelling biology and animal evidence, now in human trials. Not approved for longevity, and should not be taken for it outside a clinical trial.
RapamycinTIER 3CompoundExtends lifespan in animal models and is being studied in humans. The safety profile for off-label longevity use is far from established.
NAD+ precursors (NMN, NR)TIER 3CompoundLevels decline with age and supplementation restores them — but restoring a molecule is not the same as restoring health. Human outcome data remains thin.
SenolyticsTIER 3CompoundClearing senescent cells works in animal models; human trials are early, and which cells to clear (and when) is far from answered.
"Anti-aging" supplement stacksTIER 4CompoundIf the label lists a dozen compounds with vague "pathway" claims, you are paying for a story, not data.
"Biological age" consumer testsTIER 4TestResearch tools, not personal health verdicts. The consumer versions are not validated for the claims made about them.
Red-light panelsTIER 4DeviceThe object feels scientific; the evidence for general longevity benefit does not match the price tag.
PEMF and similar devicesTIER 4DeviceNo general longevity evidence that matches the marketing. Treat any claim to the contrary as a hypothesis without support.

Evidence grades reflect the field consensus as of mid-2026 and will be updated as the science moves. This explorer describes science — it is not a recommendation to take, stop, or change any treatment.

The interventions with the most evidence are the least glamorous. That is not a marketing failure — it is a signal about where the science actually stands.

The Intervention Hierarchy · Souverain Labs