HN — Mitochondrial-Derived Peptide
A 21-amino acid peptide encoded within the mitochondrial genome — making it, along with MOTS-c, one of only two known mitochondrially-encoded peptides with systemic signalling activity. Humanin circulates in the bloodstream, declines significantly with age, and correlates inversely with Alzheimer's disease risk. It protects neurons from amyloid beta toxicity, improves insulin sensitivity, and modulates the IGF-1 axis. Circulating levels in centenarians are significantly higher than in the general population — positioning it as a compelling longevity biomarker and intervention target.
01 — Research Summary
Humanin has a substantial basic science and observational research base — over 200 publications — that establishes it as a meaningful longevity biomarker and neuroprotective agent. Human intervention trials are limited but growing.
Higher circulating Humanin levels in centenarians and their offspring. A landmark observational study found centenarians have significantly higher circulating Humanin levels than age-matched controls, and their offspring also have elevated levels — suggesting Humanin is both a longevity biomarker and potentially heritable longevity factor.
Lower Humanin levels correlate with higher Alzheimer's disease risk. Research established a significant inverse relationship between circulating Humanin levels and Alzheimer's disease risk — with lower levels observed in MCI and Alzheimer's patients, making it one of the most compelling neuroprotective biomarker relationships in the field.
Humanin administration improved insulin sensitivity in clinical study. A small human study demonstrated Humanin administration improved insulin sensitivity and reduced inflammatory markers — providing the first human intervention evidence and extending its profile beyond neuroprotection into metabolic health.
Direct protection of neurons from amyloid beta toxicity confirmed. Multiple mechanistic studies confirmed Humanin directly protects neurons from amyloid beta-induced apoptosis through STAT3 and IGFBP3 pathways — providing molecular grounding for the Alzheimer's inverse correlation.
02 — Mechanism of Action
Humanin operates through multiple converging neuroprotective and metabolic pathways — consistent with its role as a systemic mitochondrial stress signal.
Like MOTS-c, Humanin is encoded within mitochondrial DNA — specifically the 16S rRNA gene — and is released into circulation in response to cellular stress. It functions as a mitokine: a hormone-like signal from mitochondria that coordinates responses across distant tissues.
Humanin activates STAT3 (signal transducer and activator of transcription 3), a key survival signalling pathway in neurons. STAT3 activation promotes expression of anti-apoptotic genes and suppresses pro-death signalling — directly mediating Humanin's neuroprotective effects.
Humanin directly binds amyloid beta oligomers — the toxic aggregates central to Alzheimer's pathology — preventing them from engaging neuronal membrane receptors and triggering apoptotic cascades. This direct neutralisation mechanism is distinct from most neuroprotective approaches.
Humanin interacts with IGF-binding protein 3 (IGFBP3), modulating the IGF-1 signalling axis. This interaction affects both metabolic function (insulin sensitivity, fat metabolism) and cellular survival — explaining Humanin's dual neuroprotective and metabolic effects.
Humanin suppresses multiple pro-inflammatory pathways — including NF-κB and NLRP3 inflammasome activation — reducing chronic neuroinflammation that drives neurodegenerative disease progression and metabolic aging.
Humanin and MOTS-c are the two known mitochondrially-encoded peptides with systemic activity. They have complementary but distinct roles: MOTS-c primarily targets metabolic regulation through AMPK, while Humanin primarily targets neuroprotection and the IGF-1 axis. Both decline with age, and both are increasingly included in comprehensive longevity protocols. The combination is sometimes called the 'mitochondrial longevity duo.'
03 — Dosing Protocols
Human dosing protocols are adapted from the small human study and animal research. No established therapeutic protocol exists.
| Protocol | Dose | Frequency | Duration | Notes |
|---|---|---|---|---|
| Community protocol | 50–100 mcg | 3x per week | 8–12 week cycles | Adapted from animal and preliminary human data. Subcutaneous injection. |
| Conservative start | 25–50 mcg | 2x per week | 4 weeks, then reassess | Lower frequency to assess response. Minimal side effects anticipated. |
| Longevity maintenance | 50 mcg | 1–2x per week | Ongoing with breaks | Lower frequency maintenance between active cycles. |
| Stack with MOTS-c | 50 mcg Humanin + 5–10 mg MOTS-c | Separate injection days | 8–12 weeks | Mitochondrial peptide dual protocol — complementary mechanisms. |
Humanin has a very favourable safety profile in all published research with no significant adverse effects documented at research doses. The primary practical concern is sourcing quality — the 21-amino acid sequence must be synthesised correctly and verified by mass spectrometry. Human intervention data is limited; protocols are extrapolated from basic science rather than validated clinical trials.
04 — Community Experiences
Humanin is primarily discussed in serious longevity research communities — r/longevity and specialist forums — where it is most often framed as the neurological complement to MOTS-c in the mitochondrial peptide category. The centenarian correlation data and Alzheimer's inverse relationship generate consistent interest, but the limited human intervention data keeps it in the 'compelling but unproven' category for most community members.
These are user-reported experiences from public forums. Not endorsed by Whats That Peptide and should not be interpreted as clinical evidence. Individual results vary. Always consult a healthcare professional.
"Centenarians have higher levels. Their offspring have higher levels. The Alzheimer's inverse correlation is strong. The direct neuroprotective mechanism is well-characterised. The gap is human intervention trials but the observational evidence is more compelling than most compounds in this space..."
"These two are genuinely complementary — MOTS-c for metabolic regulation and AMPK, Humanin for neuroprotection and IGF-1. I think of them as the mitochondrial signalling pair. Both decline with age, both have compelling mechanism data..."
"The one human study used 50 mcg doses. Most community protocols cluster around this. The animal-to-human dose scaling also suggests this range. Start here rather than trying to extrapolate higher without data..."
"If you're already running MOTS-c and NAD+, Humanin adds the neuroprotective dimension they don't cover. If you're not running those, start there — the evidence is stronger. Humanin is a compelling addition to an already-comprehensive stack, not a standalone first choice..."