Almost every longevity headline traces back to a single lab, a short-lived or genetically uniform strain of mouse, and a result nobody else has reproduced. The National Institute on Aging's Interventions Testing Program (ITP) was built to be the antidote to exactly that. It is the most rigorous lifespan-testing platform in the field, and when a compound passes it, that means something specific and hard-won. This is an explainer of how the ITP works, what it has actually found, and why it deserves to be the benchmark every longevity claim is measured against.
Why the ITP is different
Most published mouse lifespan studies use a single inbred strain at a single site. That is fragile: an effect can be an artifact of one genetic background, one facility's diet or pathogens, or one lab's unblinded optimism. The ITP was designed to remove those failure modes. It runs every candidate in genetically heterogeneous UM-HET3 mice — a four-way cross that gives each animal a different genome, mimicking the diversity of an outbred population — and it runs the same protocol simultaneously at three independent laboratories (the Jackson Laboratory, the University of Michigan, and UT Health San Antonio). Studies are pre-specified, dosing is standardized, and survival is analyzed with the treatment groups blinded. A result only counts if it holds up across all three sites in this diverse population. That is a far higher bar than the typical single-lab paper, which is precisely why an ITP positive carries weight the rest of the literature cannot claim.
What the ITP has found to extend lifespan
Rapamycin is the standout. Fed to UM-HET3 mice even when started late in life, it extended lifespan in both sexes across the program — the result that made it the reference compound for the entire field.[1] That a drug given to already-old animals could still add lifespan is genuinely remarkable, and it is why we treat it separately in our full rapamycin write-up. It has been replicated within the ITP's own follow-up work.[2]
Beyond rapamycin, the ITP has flagged a handful of compounds. Acarbose, a carbohydrate-blocking diabetes drug, extended lifespan — preferentially in males — alongside 17-α-estradiol (a non-feminizing estrogen, males) and nordihydroguaiaretic acid (NDGA), a plant antioxidant, also males-favored.[3]A later dose-response study confirmed the male-biased pattern for this group.[4] A separate experiment showed 17-α-estradiol still extended male lifespan even when started late in life.[5] Canagliflozin, an SGLT2-inhibitor diabetes drug, extended lifespan in males but not females.[6] And glycine, a simple amino acid, produced a modest lifespan extension in both sexes.[7] The through-line is that most of these are metabolic interventions, and most are sex-specific.
What failed despite the hype
The ITP is just as valuable for what it has killed. Resveratrol — the red-wine molecule that launched a thousand supplements — did not extend lifespan in the program, and neither did simvastatin.[2] A separate ITP cohort found that nicotinamide riboside (a widely marketed NAD+ booster) and three other candidates produced no lifespan benefit in either sex.[5] These null results rarely make headlines, but they are the most useful thing the ITP produces: a clean, replicated verdict that deflates compounds the market has already decided are winners. It is the same translation gap that has dogged metformin, whose human longevity case still rests on a trial that has not reported.
The honest caveats
None of this should be over-read. First, these are mice — a proven lifespan effect in UM-HET3 animals is a strong signal of biological plausibility, not evidence that the compound does anything for human aging. Second, the sex-specificity is striking: acarbose, 17-α-estradiol, NDGA and canagliflozin all favored or were limited to males, which is a warning against assuming any result generalizes. Third, dose and timing matter enormously; several compounds only worked at particular doses or when started at particular ages, and lifespan extension is not the same as compressed morbidity or better healthspan. Fourth, lifespan is not healthspan — living longer is not automatically living better, and the ITP measures survival, not quality of life. A compound with no ITP data at all — for example the senolytic fisetin, whose lifespan case rests on smaller studies — has simply not been held to this standard yet.
Why it is the benchmark
When you hear that a molecule “extends lifespan,” the first question worth asking is whether it has been through the ITP — and if so, whether it passed, failed, or was never tested. The program's combination of genetic diversity, multi-site replication, blinding and pre-registration makes its positives credible and its negatives decisive in a field awash with fragile single-lab claims. It cannot tell you what will work in people; nothing can yet. But it is the cleanest filter we have for separating compounds with real, reproducible biology from compounds with a good story. That is why the ITP is the standard every longevity candidate should be measured against, and why “did it pass the ITP?” is one of the most honest questions in the field.