DangerousContraindicated
Berberine
Berberine can lower glucose and IGF-1 LR3 may cause insulin-like glucose lowering, increasing hypoglycemia risk.
Recommendation: Do not combine; avoid human IGF-1 LR3 use altogether.
IGF-1 LR3 (Long R3 IGF-1)
Peptide ·Insufficient evidence ·Reviewed May 2026
IGF-1 LR3 is a modified recombinant IGF-1 analog with an N-terminal extension and an arginine substitution that greatly reduces binding to IGF-binding proteins. It is not FDA-approved for any human indication, has essentially no published human efficacy or long-term safety data, and is mainly a laboratory research reagent or black-market performance-enhancing substance. Serious concerns include hypoglycemia, soft-tissue or organ growth signaling, edema, neuropathy, tumor-growth risk, contamination or mislabeling, and WADA-prohibited status.
What it's good for
- Used as a cell culture and animal research reagent1
- Activates IGF-1 receptor signaling
- No approved human supplement or therapeutic benefit
- Performance claims are not clinically established
What to watch for
- Hypoglycemia
- Sweating or shakiness
- Dizziness
- Any unsupervised human use
- Active cancer or history of cancer without oncology clearance
The bottom line
Evidence rating insufficient. Most-documented uses: used as a cell culture and animal research reagent, activates igf-1 receptor signaling, no approved human supplement or therapeutic benefit. 3 sources indexed (1998–2025), with 3 interaction records on file.
The science
How it works, mechanistically.
Core mechanism
IGF-1 LR3 activates the IGF-1 receptor and downstream PI3K/Akt/mTOR and MAPK signaling pathways, promoting glucose uptake, protein synthesis, cell survival, and cell proliferation. Reduced IGF-binding protein affinity makes more peptide bioavailable than native IGF-1 in experimental systems, which may increase potency and risk. Unlike FDA-approved mecasermin, IGF-1 LR3 lacks approved indications, dosing, pharmacovigilance, and long-term human safety data.
Class
Unapproved long-acting IGF-1 analog research reagent
Found in food
None
Low-status signs
No IGF-1 LR3 deficiency exists; true IGF-1 deficiency is a medical condition managed with approved therapies when indicated
Dosing
Dosing & protocol.
Common range
No FDA-approved human dose; no evidence-based supplement dose exists
Recommended form
Not recommended for human use; laboratory research reagent only
Any human injection of research-grade IGF-1 LR3 carries major sterility, identity, dosing, and safety risks.
Forms
Forms & what to buy.
Ranked by evidence and value.
Laboratory Research Reagent Recommended
Intended for controlled laboratory experiments, not human administration. Not for human use.
Black-Market or Research Chemical Vial
Identity, purity, sterility, and dose cannot be trusted. Injection can cause serious harm.
Cost
What it actually costs.
Real-world pricing across three quality tiers. Assumes Research reagent vial.
BudgetBest value
$120 /mo
$4.00 per dose
Mid
$360 /mo
$12.00 per dose
Premium
$900 /mo
$30.00 per dose
Research-market pricing is not a dosing recommendation; human use is not approved. Updated 2026-06-04.
Goals
Goal-based dosing.
Cell Culture Research
Dose: Protocol-specific laboratory concentration1
Timing: Laboratory protocol only
Not a human supplementation goal.
Muscle Growth or Performance
Timing: Not applicable
Human efficacy and safety are not established and use is WADA-prohibited.
IGF-1 Deficiency
Dose: No approved dose
Timing: Not applicable
Approved medical alternatives and endocrine diagnosis are required for true IGF-1 disorders.
Lab work
Markers to track.
What to test, the optimal window inside the conventional range, and how long a response takes.
Fasting Glucose Glucose
IGF-1 receptor activation can lower glucose and may cause hypoglycemia.
Optimal
75–90 mg/dL
Conventional
70–99 mg/dL
Responds in
Immediate to hours after exposure
70optimal99
CGM or fingerstick monitoring cannot make unapproved use safe; severe hypoglycemia is urgent.
HbA1cInsulinIGF-1
Insulin-Like Growth Factor 1 IGF-1
Standard IGF-1 may not reflect IGF-1 LR3 exposure; endogenous axis may be suppressed in animal studies.1,2
Optimal
80–250 ng/mL
Conventional
50–300 ng/mL
Responds in
Not reliable for exposure monitoring
50optimal300
Do not rely on routine IGF-1 assays to manage LR3 safety.
IGFBP-3Fasting glucoseHbA1c
Why people use it
Symptoms it's matched to.
Where this appears in the symptom-to-supplement map, ranked by relevance.
Poor muscle recovery
3% relevance
Anabolic claims are extrapolated from receptor biology and preclinical work, not approved human outcomes.
AthleticInsufficient evidenceAvoid
High risk and WADA-prohibited.
Low IGF-1 on labs
2% relevance
It is an unapproved analog, not an appropriate treatment for low IGF-1.2
HormoneInsufficient evidenceAvoid
Use specialist endocrine evaluation and approved therapies when indicated.
Hypoglycemia risk
1% relevance
IGF-1 receptor activation can increase glucose uptake and lower blood glucose.
MetabolicInsufficient evidenceAvoid
Hypoglycemia is a safety risk, not a benefit.
Safety
Full safety detail.
Side effects
- Hypoglycemia
- Sweating or shakiness
- Dizziness
- Edema
- Headache
- Jaw or soft-tissue discomfort
- Neuropathy symptoms
- Injection-site reaction
- Theoretical tumor-growth acceleration
Contraindications
- Any unsupervised human use
- Active cancer or history of cancer without oncology clearance
- Diabetes or recurrent hypoglycemia
- Pregnancy and breastfeeding
- Children and adolescents outside specialist endocrine care
- Competitive athletes subject to anti-doping rules2
- Use of research-grade or black-market injectable products3,1
Interactions
Interaction records.
DangerousContraindicated
Alpha-Lipoic Acid
Alpha-lipoic acid may lower glucose and could add to IGF-1 LR3-related hypoglycemia risk.
Recommendation: Do not combine; seek medical care for hypoglycemia symptoms after any exposure.
ModerateCaution
Potassium
Insulin-like signaling can shift potassium into cells during hypoglycemia treatment contexts, making electrolyte self-management unsafe.
Recommendation: Do not self-correct symptoms with potassium; seek urgent care for severe weakness, palpitations, or hypoglycemia.
Search all 3 interaction records for IGF-1 LR3 (Long R3 IGF-1) →
Sources
Sources, by evidence tier.
Numbered references. Citations throughout the page link here.
Mechanistic & preclinical
1- 1Long [R3] insulin-like growth factor-I reduces growth, plasma growth hormone, IGF binding protein-3 and endogenous IGF-I concentrations in pigsNeeds sourceNo linkOwens PC et al. · Journal of Endocrinology · 1998
Continuous Long R3 IGF-I infusion altered growth and suppressed endogenous GH/IGF-axis markers in pigs.
Reference material
2- 2The 2026 Prohibited List: International StandardNeeds sourceNo linkWorld Anti-Doping Agency · World Anti-Doping Agency · 2025
IGF-1 and analogues are prohibited growth factors for athletes.
- 3Detection of His-tagged Long-R3-IGF-I in a black market productNeeds sourceNo linkThevis M et al. · Drug Testing and Analysis · 2010
Analytical testing identified modified Long-R3-IGF-I in a black-market product, underscoring doping and quality concerns.
Keep exploring
Deep dives & adjacent profiles.
This page is educational. Do not start, stop, or change a supplement or medication based on it without checking with a qualified healthcare professional.
Use this with your stack
IGF-1 LR3 (Long R3 IGF-1) in NutriStack.
Add it to your stack, see how it interacts with everything else you take, and get a Stack Score that updates the moment it does.