IGF-1 LR3, also called Long R3 IGF-1, is a modified insulin-like growth factor 1 analogue studied mostly in animal, cell, and laboratory research. The supplied evidence set identified no registered clinical trials, so human benefits, safety, and dosing cannot be established from this literature. Chia does not offer IGF-1 LR3.
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See if you qualify →What it is
IGF-1 LR3 means Long R3 insulin-like growth factor 1, a modified insulin-like growth factor 1 analogue. It is discussed in research as a growth-factor analogue, but the located evidence does not support claims of proven human muscle gain, fat loss, longevity, or metabolic benefit.
The name “Long R3” points to a modified form of IGF-1 used in experiments. One laboratory paper studied recombinant expression of IGF-1 and LR3 IGF-1 fused with xylanase in Pichia pastoris, which supports a research-manufacturing statement, not a patient-treatment claim 1.
People often search for IGF-1 LR3 in the same breath as bodybuilding peptides, human growth hormone, and GH-axis compounds. That is why we compare it later with peptides for muscle growth and sermorelin, but the evidence base is not the same for each compound.
Names, class, and why it is called Long R3 IGF-1
- Common name: IGF-1 LR3.
- Long name: Long R3 insulin-like growth factor 1.
- Class: insulin-like growth factor 1 analogue.
- Related pathway: insulin-like growth factor 1 signaling through growth and metabolism pathways studied in animal and cell models 9.
- Common search context: bodybuilding, recovery, growth hormone comparisons, and peptide access questions.
Mechanism of action
Long R3 IGF-1 is proposed to act through IGF-1 signaling pathways, including pathways tied to cell growth and metabolism. In humans, the clinical mechanism for patient outcomes is unestablished because the located evidence does not include randomized human trials.
IGF-1 signaling, IGF-1 receptors, and growth pathways
IGF-1 biology overlaps with growth and metabolic signaling. In fetal sheep cardiomyocytes, IGF-1-induced proliferation was mediated through extracellular signal-regulated kinase, or ERK, and phosphoinositol-3 kinase, or PI3K, pathways 12.
That does not mean IGF-1 LR3 has proven growth effects in people. A fetal sheep study found coronary vascular growth matched IGF-1-stimulated cardiac growth, while another fetal sheep study found IGF-1 infusion increased organ growth without stimulating nutrient transfer to the fetus 5 8. These are animal findings, not patient outcomes.
What animal and cell studies can and cannot tell us
Animal and cell studies help explain biology. They cannot prove that a peptide improves body composition, recovery, cognition, or lifespan in humans. For IGF-1 LR3, that distinction matters because several studies are in fetal sheep, mice, rats, beef heifers, or cell systems 2 6 7 9.
For example, intranasal long R3 IGF-1 promoted amyloid plaque remodeling in a male 5XFAD mouse Alzheimer’s disease model, but failed to preserve cognitive function 6. A rat sciatic nerve model studied controlled IGF-1 LR3 release in a nerve conduit, but that is preclinical nerve-regeneration research, not human treatment evidence 7.
Evidence
IGF-1 LR3 evidence is thin for patient decisions. The assigned evidence grade is C, meaning human research exists, none of it randomised; no registered clinical trials were identified in the supplied trial data.
Evidence grade rubric
A — two or more human randomised controlled trials. B — one human randomised trial, or two or more human clinical trials. C — human research exists, none of it randomised. D — animal or in-vitro research only; no human studies indexed. E — no trial evidence indexed in PubMed. The grade describes the quantity and design of published evidence, not whether the substance works, and not whether it is safe.
What the grade means for a patient
A C grade does not prove benefit, and it does not prove harm. It means the available research design is not strong enough to support confident patient claims about muscle gain, fat loss, longevity, recovery, or safety.
The located research includes animal work where IGF-1 LR3 did not promote growth in late-gestation growth-restricted fetal sheep 2. It also includes animal work on protein metabolism in beef heifers 4, cell work on IGF-1 signaling 9, and preclinical models involving brain plaque remodeling and nerve regeneration 6 7.
| Evidence type | What it can show | What it cannot show |
|---|---|---|
| Animal studies | Signals about growth pathways, organs, glucose-stimulated insulin secretion, or tissue models | Human muscle gain, fat loss, longevity, safety, or dosing |
| Cell and lab studies | Mechanisms such as IGF-1 signaling or recombinant expression | Clinical benefit in people |
| Human randomized trials | Patient-level efficacy and adverse-event rates when designed well | None were identified in the supplied trial data |
What studies exist
| Year | Design | Study | Journal | Record |
|---|---|---|---|---|
| 2023 | Primary study | Recombinant expression of IGF-1 and LR3 IGF-1 fused with xylanase in Pichia pastoris | Applied microbiology and biotechnology | PMID 37261455 |
| 2025 | Primary study | IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep | American journal of physiology. Endocrinology and metabolism | PMID 39679943 |
| 2023 | Primary study | Attenuated glucose-stimulated insulin secretion during an acute IGF-1 LR3 infusion into fetal sheep does not persist in isolated islets | Journal of developmental origins of health and disease | PMID 37114757 |
| 1999 | Primary study | Action of long(R3)-insulin-like growth factor-1 on protein metabolism in beef heifers | Domestic animal endocrinology | PMID 10370861 |
| 2020 | Primary study | Coronary vascular growth matches IGF-1-stimulated cardiac growth in fetal sheep | FASEB journal : official publication of the Federation of American Societies for Experimental Biology | PMID 32573852 |
| 2025 | Primary study | Intranasal long R3 insulin-like growth factor-1 treatment promotes amyloid plaque remodeling in cerebral cortex but fails to preserve cognitive function in male 5XFAD mice | Journal of Alzheimer's disease : JAD | PMID 39610283 |
| 2025 | Primary study | Revolutionary decellularized Alstroemeria stem-based nerve conduit integrated with GelMA and controlled IGF-1 LR3 release for enhanced rat sciatic nerve regeneration | International journal of biological macromolecules | PMID 41015370 |
| 2021 | Primary study | IGF-1 infusion to fetal sheep increases organ growth but not by stimulating nutrient transfer to the fetus | American journal of physiology. Endocrinology and metabolism | PMID 33427051 |
| 2022 | Primary study | N-Linked Glycosylation in Chinese Hamster Ovary Cells Is Critical for Insulin-like Growth Factor 1 Signaling | International journal of molecular sciences | PMID 36499281 |
| 2026 | Review / secondary | The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration | Frontiers in endocrinology | PMID 42395176 |
| 2021 | Primary study | Reduced glucose-stimulated insulin secretion following a 1-wk IGF-1 infusion in late gestation fetal sheep is due to an intrinsic islet defect | American journal of physiology. Endocrinology and metabolism | PMID 33938236 |
| 2011 | Primary study | IGF-1 has plaque-stabilizing effects in atherosclerosis by altering vascular smooth muscle cell phenotype | The American journal of pathology | PMID 21281823 |
This table is retrieved from PubMed and ClinicalTrials.gov rather than assembled by hand, so it shows what is indexed — including the absences. Last retrieved 2026-09-09.
Reported dosing ranges
No human dosing range for IGF-1 LR3 can be established from the located evidence. The available sources do not provide a patient dosing framework, and this page does not give cycle guidance, titration advice, or body-weight dosing instructions.
Some animal and laboratory studies describe exposure methods in specific models. Those details are not clinical dosing instructions because fetal sheep, beef heifers, rats, mice, and cell systems do not predict safe or effective dosing in people 2 4 6 7.
| Source | Model | Reported exposure context | Can this guide patient dosing? |
|---|---|---|---|
| White et al., 2025 2 | Late-gestation growth-restricted fetal sheep | IGF-1 LR3 was studied in a fetal sheep growth model | No |
| White et al., 2023 3 | Fetal sheep and isolated islets | Acute IGF-1 LR3 infusion was studied for glucose-stimulated insulin secretion questions | No |
| Hill et al., 1999 4 | Beef heifers | Long(R3)-IGF-1 was studied in protein metabolism research | No |
| Engel et al., 2025 6 | Male 5XFAD mice | Intranasal long R3 IGF-1 was studied in an Alzheimer’s disease mouse model | No |
| Yavuz et al., 2025 7 | Rat sciatic nerve model | Controlled IGF-1 LR3 release was studied in a nerve conduit model | No |
| Human clinical dosing | Humans | No evidence-based patient dosing range was identified in the supplied literature | No |
Legal status
Our regulatory log holds no confirmed federal action for IGF-1 LR3. That means we have not found one with a primary source — not that none exists.
This section is generated from a dated log of federal actions rather than written by hand, and it is re-checked daily against the Federal Register and FDA sources. Last checked 2026-09-09. See the full legal-status tracker for every compound we follow.
Safety
IGF-1 LR3 safety is not established for patient use from the located research. The main safety concern is not just side effects; it is the lack of human clinical trial data that would define adverse-event rates, contraindications, drug interactions, and monitoring needs.
Glucose and insulin-signaling questions
Several animal studies raise glucose and insulin-signaling questions. In fetal sheep, an acute IGF-1 LR3 infusion was linked with attenuated glucose-stimulated insulin secretion, and a separate one-week IGF-1 infusion study found reduced glucose-stimulated insulin secretion due to an intrinsic islet defect 3 10.
These animal findings do not prove the same effect in adults. They do mean a person with diabetes, hypoglycemia risk, insulin use, or glucose-lowering medication should not treat IGF-1 LR3 as a simple fitness supplement.
Growth-factor biology and theoretical risks
Growth-factor pathways can affect tissues in complex ways. Animal studies have linked IGF-1 signaling with fetal cardiac growth, coronary vascular growth, and organ growth 5 8. Cell and animal research also links IGF-1 biology with ERK and PI3K growth pathways 12.
That biology is one reason we avoid simple claims like “builds muscle” or “supports longevity.” A study in a mouse Alzheimer’s model changed amyloid plaque measures but did not preserve cognitive function, which shows how a biomarker change may not become a meaningful clinical benefit 6.
Why research-chemical purity and identity are separate safety issues
A separate risk is product identity and quality. Research-use material is not the same process as clinician evaluation, prescription decision-making, and dispensing by a state-licensed pharmacy. Without those safeguards, a person may not know the substance identity, sterility, impurity profile, or handling standards.
This is why our general peptide-safety advice focuses on the route of care, not hype. If you are comparing online claims, our guide on whether you can buy IGF-1 LR3 explains why research-chemical shortcuts are different from medical care.
Interactions
Interaction studies for IGF-1 LR3 in patients were not identified in the supplied evidence set. That is not reassurance; it means interaction risk has not been mapped in the way clinicians would want before routine patient use.
Diabetes medications, insulin, and glucose-lowering therapies
Because animal studies raise glucose-stimulated insulin secretion questions, people using insulin or glucose-lowering therapies would need clinician review before considering any growth-factor-related peptide 3 10. The located research does not define how IGF-1 LR3 would interact with diabetes medications in people.
Growth hormone, peptides, and anabolic agents
The supplied research does not establish safe combinations of IGF-1 LR3 with human growth hormone, GH secretagogues, anabolic agents, or other peptides. Because IGF-1 signaling can intersect with growth pathways in animal and cell models, stacking compounds without medical oversight adds uncertainty rather than clarity 8 12.
How to obtain it legally
A legitimate medical process starts with a clinician evaluation, not a cart page. A clinician reviews your goals, diagnoses, medications, lab context when needed, and risks before deciding whether any treatment is appropriate; a prescription is never guaranteed.
Clinician evaluation, prescription decisions, and pharmacy standards
For treatments Chia offers, care is 100% online: a short health questionnaire is reviewed by a licensed US provider, and medications are compounded by state-licensed US 503A pharmacies and shipped to the patient’s door when prescribed. Dosing is provider-guided and adjusted over time through the patient portal. Compounded medications are not FDA-approved.
What research-chemical vendors are not
A research-chemical vendor is not a medical evaluation. It does not replace clinician review, a prescription decision, pharmacy standards, adverse-effect monitoring, or follow-up when symptoms or lab questions come up.
Where Chia fits: education on IGF-1 LR3 and clinician-reviewed alternatives Chia actually offers
Chia does not offer IGF-1 LR3. We do offer clinician-reviewed access to treatments in our live catalog, including sermorelin in injection, nasal spray, and tablet forms, with injection plans currently starting at $179/month.
Sermorelin is a growth-hormone-releasing hormone analogue, which makes it a different category from IGF-1 LR3. If your real goal is muscle, body composition, or recovery, our guide to peptides for muscle growth and fat loss and our article on how to get a sermorelin prescription may be more useful next reads.
How does IGF-1 LR3 compare with HGH and other growth-related peptides?
IGF-1 LR3, HGH, and sermorelin are often discussed together, but they are not interchangeable. They sit at different points in the growth hormone and IGF-1 axis, and the evidence and safety questions differ by compound.
| Compound | What it is | Where it acts conceptually | Evidence caution |
|---|---|---|---|
| IGF-1 LR3 | Modified insulin-like growth factor 1 analogue | IGF-1 signaling pathways studied in animal, cell, and lab models | No evidence-based patient dosing range was identified from the supplied literature |
| Human growth hormone | Hormone in the GH-IGF-1 axis | Upstream hormone that can affect IGF-1 biology | Not established by IGF-1 LR3 studies |
| Sermorelin | Growth-hormone-releasing hormone analogue | Stimulates the GH axis upstream | Different compound and evidence base; Chia offers sermorelin in listed forms |
IGF-1 LR3 versus human growth hormone
IGF-1 LR3 is not human growth hormone. The located studies focus on IGF-1 or Long R3 IGF-1 biology in models such as fetal sheep, mice, rats, beef heifers, and cells; they do not establish that IGF-1 LR3 is better than HGH for any patient goal 2 4 6 7.
IGF-1 LR3 versus sermorelin
Sermorelin works upstream in the growth hormone axis, while IGF-1 LR3 is an IGF-1 analogue. If you are comparing sermorelin with other GH-axis peptides, our overview of best peptide stacks for muscle growth explains why mechanism, evidence, and oversight matter more than online stack claims.
IGF-1 LR3 is mainly discussed in research and performance-enhancement contexts. The supplied evidence does not establish a proven human use for muscle gain, fat loss, longevity, cognition, or recovery.
There is not enough clinical evidence in the supplied literature to say IGF-1 LR3 is better than human growth hormone. They are different compounds in related growth pathways.
Safety for bodybuilding is not established from the located evidence. The main concerns are unknown human adverse-event rates, glucose and insulin-signaling questions, growth-factor biology, and product-quality risks from nonmedical sources.
The supplied evidence does not show that IGF-1 LR3 increases testosterone in humans. It should not be used as a testosterone or hormone-optimization shortcut.
No evidence-based patient dosing range can be established from the located literature. Animal and lab exposure details are not dosing instructions for people.
The supplied evidence does not establish IGF-1 LR3 as a fat-loss treatment in humans. For weight management, a clinician should review evidence-based options that fit your health history.
No. Chia does not offer IGF-1 LR3. We do offer clinician-reviewed telehealth care for treatments in our live catalog, including sermorelin and GLP-1 weight-management options when clinically appropriate.
Ask what human evidence supports the goal, what side effects and interactions are known, what monitoring is needed, where the medication is prepared, and whether a prescription is appropriate for your health history.
References
- 1.PMID 37261455 [primary study] Lu Z, Liu N, Huang H, et al. Recombinant expression of IGF-1 and LR3 IGF-1 fused with xylanase in Pichia pastoris. Applied microbiology and biotechnology. 2023.
- 2.PMID 39679943 [primary study] White A, Stremming J, Wesolowski SR, et al. IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep. American journal of physiology. Endocrinology and metabolism. 2025.
- 3.PMID 37114757 [primary study] White A, Stremming J, Brown LD, et al. Attenuated glucose-stimulated insulin secretion during an acute IGF-1 LR3 infusion into fetal sheep does not persist in isolated islets. Journal of developmental origins of health and disease. 2023.
- 4.PMID 10370861 [primary study] Hill RA, Hunter RA, Lindsay DB, et al. Action of long(R3)-insulin-like growth factor-1 on protein metabolism in beef heifers. Domestic animal endocrinology. 1999.
- 5.PMID 32573852 [primary study] Jonker SS, Giraud GD, Chang EI, et al. Coronary vascular growth matches IGF-1-stimulated cardiac growth in fetal sheep. FASEB journal : official publication of the Federation of American Societies for Experimental Biology. 2020.
- 6.PMID 39610283 [primary study] Engel MG, Narayan S, Cui MH, et al. Intranasal long R3 insulin-like growth factor-1 treatment promotes amyloid plaque remodeling in cerebral cortex but fails to preserve cognitive function in male 5XFAD mice. Journal of Alzheimer's disease : JAD. 2025.
- 7.PMID 41015370 [primary study] Yavuz E, Sağır MS, Ercan A, et al. Revolutionary decellularized Alstroemeria stem-based nerve conduit integrated with GelMA and controlled IGF-1 LR3 release for enhanced rat sciatic nerve regeneration. International journal of biological macromolecules. 2025.
- 8.PMID 33427051 [primary study] Stremming J, Heard S, White A, et al. IGF-1 infusion to fetal sheep increases organ growth but not by stimulating nutrient transfer to the fetus. American journal of physiology. Endocrinology and metabolism. 2021.
- 9.PMID 36499281 [primary study] Salvi R, Kumar C, Brahmbhatt K, et al. N-Linked Glycosylation in Chinese Hamster Ovary Cells Is Critical for Insulin-like Growth Factor 1 Signaling. International journal of molecular sciences. 2022.
- 10.PMID 33938236 [primary study] White A, Stremming J, Boehmer BH, et al. Reduced glucose-stimulated insulin secretion following a 1-wk IGF-1 infusion in late gestation fetal sheep is due to an intrinsic islet defect. American journal of physiology. Endocrinology and metabolism. 2021.
- 11.PMID 21281823 [primary study] von der Thüsen JH, Borensztajn KS, Moimas S, et al. IGF-1 has plaque-stabilizing effects in atherosclerosis by altering vascular smooth muscle cell phenotype. The American journal of pathology. 2011.
- 12.PMID 12947030 [primary study] Sundgren NC, Giraud GD, Schultz JM, et al. Extracellular signal-regulated kinase and phosphoinositol-3 kinase mediate IGF-1 induced proliferation of fetal sheep cardiomyocytes. American journal of physiology. Regulatory, integrative and comparative physiology. 2003.
About this article
Chia Health Editorial Team — Evidence-reviewed health education
This article is for educational purposes only and is not a substitute for individualized medical advice. Talk to a licensed clinician before starting, stopping, or changing any prescription.
AI tools may assist with research and drafting. Chia's editorial team reviews source use, clarity, treatment information, and safety framing before publication. A clinician is named only after explicit sign-off. Read our editorial standards.
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