Cardiovascular & General
Irisin
Irisin is the closest thing there is to exercise in molecular form: when muscle works, it cuts this fragment loose from a larger membrane protein and releases it into the blood. In mice the fragment turns ordinary white fat into the heat-burning brown kind and rescues memory in Alzheimer's models, which is why it was seized on as a possible chemical link between training and metabolic health, and why the literature around it ran to thousands of papers within a decade of its discovery. The human record is entirely observational — blood levels compared against body composition, bone density, training programmes and disease states. No irisin-based product has ever entered a human clinical trial, so nothing on file says what taking it would do.
Last updated
Mechanism
Muscle PGC-1alpha drives FNDC5 expression and irisin release, raising UCP1 in white adipocytes via MAPK signalling.
Reported effects
What sources associate with this compound. Reported categories, not outcomes we have graded — each would need its own citation and rung.
- Adipose browning research
- Exercise metabolism marker
- Bone metabolism context
Dosing on file unverified
No irisin-based therapeutic has entered human clinical trials as of 2026; in vitro: 5-100 ng/mL
Carried from a source that labels it unverified, and reproduced with that label attached. A record of what is reported, not a recommendation. No citation on this page establishes it.
Half-life, storage & sport
- Elimination half-life
- 0.39 h, 0.3 h and 0.32 h at 100, 500 and 1000 ug/kg (mice) — study. Communications biology 2025; mice.
The half-life on file is 21 min, measured in mice. No dosing schedule could be read from this record, so the curve below is one dose drawn from the moment it is given. Nothing here says how often it is repeated.
The measurement is not human. It was made in mice, and small mammals clear peptides faster than people do — so this is the fastest plausible shape rather than the expected one.
The rise is not modelled and the axis is not a blood level. No absorption rate constant and no volume of distribution are on file, so each dose appears at full height the instant it is given, and the axis is percent of this compound's own peak.
Literature on file 11
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human observational
FNDC5 and irisin in humans: I. Predictors of circulating concentrations in serum and plasma and II. mRNA expression and circulating concentrations in response to weight loss and exercise (Metabolism 2012, cited 881x) graded on: an observational human design — read from the indexed abstract — “Cross-sectional”
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animal in vivo
Exercise-linked FNDC5/irisin rescues synaptic plasticity and memory defects in Alzheimer's models (Nature Medicine 2019, cited 817x) graded on: an animal model — read from the indexed abstract — “mice”
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review or editorial
Irisin in the aging immune landscape: A new player at the crossroads of immunosenescence and sepsis. graded on: indexed as "Review" - secondary literature, not a study — “Review”
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human observational
Serum Bone-, Muscle- and Fat- Derived Factors Sclerostin, Irisin and Leptin Show Different Correlations With Body Composition and Bone Mineral Density in Chinese Men With Obesity: A Cross-Sectional Study. graded on: an observational human design — “Cross-Sectional”
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human observational
The Effect of Progressive Resistance Training on Irisin and Cognition in Healthy Older Adults. graded on: 12-week single-arm resistance-training trial, 24 completers plus a 6-person reference group — read from the abstract — “abstract review”
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human observational
Predictive Factors for Changes in Serum Irisin Concentrations after Different Exercise Interventions. graded on: 16-week exercise protocols vs control in 289 adults; allocation method not stated — read from the abstract — “abstract review”
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animal in vivo
Irisin-treated microbiota restore blood-testis barrier integrity and spermatogenesis in chronically stressed rats. graded on: an animal model — “rats”
Not graded
4 citations whose study design could not be read from the title. Left ungraded rather than guessed at.
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not graded
NCT02204670: Exercise and Irisin Trial (EXIT): Prospective Cohort Study of the Determinants of the Metabolic Response to Exercise in Obese Adolescents graded on: NCT02204670 is completed and has posted no results - a registration, not a reported outcome — “NCT02204670”
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not graded
NCT04133896: Circulating IL-6, Clusterin and Irisin in Obese Subjects With Different Grades of Obesity: Association With Insulin Resistance and Sexual Dimorphism graded on: NCT04133896 is completed and has posted no results - a registration, not a reported outcome — “NCT04133896”
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not graded
NCT06416033: Serum Irisin Level In Leprosy Patients graded on: NCT06416033 is completed and has posted no results - a registration, not a reported outcome — “NCT06416033”
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not graded
NCT06696599: Serum and Corporal Irisin Level and Its Correlation With Erectile Function in Diabetic Obese Patients graded on: NCT06696599 is not yet recruiting and has posted no results - a registration, not a reported outcome — “NCT06696599”
Notes unverified prose
Endogenous myokine; no therapeutic dosing; no FDA approval; No human clinical trials; preclinical
Not on file 9
8 of the 8 fields we track hold nothing on this record, and each says why. 1 further absence is named below. A blank field is a bug; a named absence is a finding.
- molecular weightnothing we hold supplies it
- molecular formulanothing we hold supplies it
- CAS registry numbernothing we hold supplies it
- PubChem identifiernothing we hold supplies it
- amino-acid sequencenothing we hold supplies it
- SMILES stringnothing we hold supplies it
- InChInothing we hold supplies it
- InChI keynothing we hold supplies it
- route of administrationnot applicable to this compound
Each field links to every other record missing the same thing. The full ledger holds 765 gaps across 163 records.