EVIDENCE DESK / COMPARISON
Four Compounds, Four Endpoint Levels
A side-by-side reading of what changes, who was studied, and how close each record comes to direct clinical or lifespan evidence.
The short version
These four compounds should not be compared as if they were rival versions of the same treatment. They act through different systems, were studied in different populations, and answer different questions. NAD+ precursor trials most clearly show that a blood biomarker can move. MOTS-c studies add molecular detail and animal performance, while human data remain observational. Tesamorelin has controlled human trials for visceral and liver-fat measures in adults with HIV-associated lipodystrophy. Semaglutide has large trials that count major cardiovascular and kidney events in defined high-risk groups [1][9][13][19][20].
The evidence therefore forms a ladder, not a leaderboard. Higher rungs do not make a compound universally better; they show that a research program has tested outcomes closer to lived health. None of the four corpora contains a trial proving longer lifespan in healthy humans. The most reliable comparison asks which endpoint was measured, in which species and population, and what claim that design can reasonably support.
The endpoint matrix
| File | Biological entry point | Strongest endpoint represented here | Evidence maturity | What it does not establish |
|---|---|---|---|---|
| NAD+ | Redox and enzyme-substrate biology | Blood NAD+ plus selected metabolic and walking measures | Human precursor trials; tissue translation remains sparse [1][2][3] | Human lifespan extension |
| MOTS-c | Mitochondrial stress signaling, AMPK, CK2 | Mouse muscle and physical performance; human risk association | Mechanistic and animal-heavy; observational human cohort [8][9][11] | Human efficacy of administered MOTS-c |
| Tesamorelin | Pituitary GHRH receptor and GH/IGF-1 axis | Visceral, trunk, and liver-fat measures | Human randomized trials in HIV-associated lipodystrophy [13][15][17] | General anti-aging benefit outside the studied indication |
| Semaglutide | GLP-1 receptor signaling | Weight change and major cardiovascular and kidney events | Large human randomized outcome trials [19][20][21] | Universal longevity or benefit in healthy populations |
Mechanism is the beginning
NAD+ participates in energy transfer and supplies enzymes involved in repair and signaling [4]. MOTS-c links mitochondrial stress to AMPK, nuclear gene responses, and CK2-related muscle effects [8][10][12]. Tesamorelin stimulates the body’s own pulsatile growth-hormone pathway. Semaglutide activates GLP-1 receptors across metabolic and appetite-control systems. Each mechanism is coherent enough to motivate research. None is a substitute for an outcome.
Mechanistic evidence is strongest when it identifies a target, confirms target engagement, and predicts an effect that later appears in controlled studies. It is weakest when the pathway name itself becomes the conclusion. “Mitochondrial,” “growth hormone,” and “cellular energy” may sound adjacent to longevity, but scientific proximity in language is not proof of longer life.
Biomarkers and functional measures
NAD+ precursor trials show why biomarkers are valuable: they can confirm that an intervention changes the intended biological pool [2][5]. The harder question is whether that change improves function or health. Selected studies add walking and insulin-sensitivity measures, but findings differ by endpoint [2][3].
MOTS-c illustrates the next step and its own limitation. Mouse treadmill capacity, grip strength, and gait are functional outcomes rather than mere pathway signals [11]. Yet species remains decisive. A functional result in an old mouse does not become a human healthspan result through analogy. Human circulating MOTS-c may contribute to risk prediction in a specific hemodialysis cohort, but prediction is not proof that administered peptide changes the outcome [9].
Surrogates and clinical events
Tesamorelin trials measured visceral adipose tissue, liver fat, trunk fat, and lean mass [13][15]. These are closer to clinical concerns than a molecular marker and can be appropriate endpoints for a body-composition indication. They remain surrogates for downstream questions such as disability, cardiovascular events, or survival. The evidence is also population-specific.
Semaglutide trials move into major event counting. Kidney failure and large losses of kidney function were part of one composite; cardiovascular death, heart attack, and stroke were part of another [19][20]. Composite endpoints require careful reading because several events are grouped, but they address outcomes of direct importance. This is the closest record here to longevity-relevant clinical evidence, while still not being a lifespan trial.
Safety evidence matures too
Evidence maturity applies to harms as well as benefits. MOTS-c lacks a mature human safety record. NAD+ products span precursor supplements, compounded settings, and aggressively marketed wellness uses that are not interchangeable. Tesamorelin’s known clinical context is tied to GH/IGF-1 signaling and a specific approved population. Semaglutide has a broader adverse-event record, with gastrointestinal effects, biliary disease, and unresolved low-incidence signals summarized in a dedicated review [22].
The absence of a detected harm in a small or short study is not the same as evidence of long-term safety. Conversely, a warning or monitored signal is not proof that every user will experience an event. The appropriate conclusion follows the design, population, and amount of accumulated exposure.
The lifespan gap
No entry on this desk closes the lifespan gap. NAD+ and MOTS-c are closest to foundational aging biology. Tesamorelin changes indication-specific body composition. Semaglutide reduces important clinical events in defined populations. Those statements can all be supported without converting any compound into a proven longevity intervention.
A lifespan claim would need a trial or exceptionally strong converging evidence designed around survival, with suitable comparators, long follow-up, and transparent handling of competing risks. Until then, the honest endpoint language is also the most informative: biomarker, function, surrogate, or clinical event.