IGF-1 LR3.
It is a modified copy of insulin-like growth factor 1 that slips past the binding proteins which normally park the natural version, so it stays active far longer at the IGF-1 receptor.
Reviewed March 2026
- Category
- Peptide
What IGF-1 LR3 is, and what it does.
- Does it work
- It suits laboratory work, where its long-acting behaviour is the whole point. Swallowed, it is digested like any other protein, which is the fact to understand before anything else.
- How much to take
- 20 to 50 micrograms a day is the maintenance band on record. Because it is a protein, an oral serving is broken down in the gut, so a stated amount and a delivered amount differ.
- Time to feel it
- No human onset timeline is established across the 37 records at Europe PMC. Swallowed, it is digested like any protein, so an oral serving has no timeline of its own.
- The first dose
- Nothing about day one has been published in people. The one well-documented physiological signal of IGF-1 exposure is a fall in blood glucose, which is a measurement rather than a feeling.
- With regular use
- Nobody has run a long-term human study of this analogue. Its receptor pathway is a general growth signal present in most tissues, which is the standing pharmacological caution.
- How well tolerated
- Human tolerability has not been established for this analogue. It drives a general growth signalling pathway present in most tissues, so a doctor belongs in any decision about it.
- How it feels
- Nobody has measured the subjective experience in a published human study. The one well-documented physiological effect of IGF-1 exposure is a fall in blood glucose.
- The overlooked benefit
- The arginine swap and the added N-terminal tail stop binding proteins parking it, which is exactly why cell-culture labs keep it as a standard tool for IGF-1 receptor work.
20 to 50mcg a day is where IGF-1 LR3 works.
Source: Growth factor research; bodybuilding/research peptide literature
The proof, claim by claim.
These words describe the research, not the molecule's worth. Research strength is how much work stands behind one claim, and it is never a product score.
IGF-1 LR3 has emerging evidence. Based on 37+ studies.
- IGF-1 receptor activation and downstream Akt and MAPK signallingIn vitro study
- reduced binding to IGF binding proteins and longer circulating half-lifeNarrative review
- muscle protein synthesis signallingAnimal study
- glucose lowering through insulin receptor cross-activationNarrative review
- oral bioavailability in humansNarrative review
Questions people ask about IGF-1 LR3.
- When should I take it?
- Timing matters less than consistency. Pick a time that works for you and take it daily.
- Can I take it with other supplements?
- Usually fine. The main thing to watch is not doubling up on the same ingredient from different products. If you're on prescription meds, check with your pharmacist first.
- Any side effects to watch for?
- Most people tolerate it well at recommended doses. GI upset is the most common complaint with any supplement. Start with a lower dose and work up. If something feels off, stop and reassess.
- Who benefits most from this?
- Honestly, most people would benefit more from the basics. But if you've got a specific reason to try it, the risk is generally low.
Why these belong in the same formula. Each row says what the basis is, from settled biochemistry through to a trial that measured the pair.
IGF-1 receptor activation runs through PI3K and Akt to mTORC1, and leucine activates the same complex through a separate sensing route involving Rag GTPases. The convergence point is the same kinase complex, which is why the two are discussed together. This is pathway biochemistry; no human study has tested the analogue with leucine.
Signalling that raises protein synthesis rates does nothing without amino acids arriving to be incorporated, and whey is a rapidly absorbed complete protein source. That makes protein intake an enabling condition rather than a second active. The requirement is settled physiology; the pairing has not been trialled.
HMB is studied for its effects on protein breakdown signalling, a different arm from the synthesis arm that IGF-1 receptor activation drives. The two are stacked on that reasoning in training contexts. No combination data exists and HMB's own effect sizes are modest.
Creatine acts on phosphocreatine availability for short high-intensity efforts and has no bearing on IGF-1 receptor signalling. It appears in the same stacks because the training goal overlaps, not the mechanism. No combination evidence.
IGF-1 increased collagen deposition by human dermal fibroblasts in a 2026 cell-culture study, and the post-translational hydroxylation that stabilises that collagen requires ascorbate as a cofactor. Signalling that raises collagen output therefore raises demand on an ascorbate-dependent step. The cofactor relationship is established and the collagen finding is in vitro, not a human outcome.
Collagen's obligate Gly-X-Y repeat means roughly a third of its residues are glycine, so any signal that raises collagen synthesis raises glycine demand. This is amino acid composition, not an interaction study. It pairs with the in vitro collagen deposition finding as substrate to signal.
Proline residues are hydroxylated after translation to stabilise the collagen helix, making proline supply part of the same substrate requirement as glycine. Established composition biochemistry. No combination measurement.
Lysine residues in collagen are hydroxylated by an ascorbate-dependent enzyme and later cross-linked by copper-dependent lysyl oxidase, so lysine sits in the maturation path of new collagen. Established biochemistry, relevant as substrate rather than as a second signal.
Hydrolysed collagen delivers glycine, proline and hydroxyproline in the ratio collagen synthesis draws on. Whether the peptides do more than supply those amino acids is still debated. Early, and the pairing has not been tested with the analogue.
Zinc repletion has been associated with higher circulating IGF-1 in nutrition literature, an association and a marker rather than a demonstrated outcome. It bears on the endogenous axis, not on an exogenous analogue's receptor binding. Recorded so the axis link is visible without implying an effect.
Every phosphorylation step in the PI3K, Akt and mTOR cascade uses magnesium-ATP as the substrate, so magnesium is an obligate cofactor of the signalling itself. This is textbook enzymology and is not a claim that supplementing magnesium changes any measure. Enabling rather than additive.
Vitamin D status and IGF-1 concentrations are correlated in observational endocrine work, and each influences the other's regulatory machinery. That is association, not causation, and it concerns the endogenous axis. Early, and included for context only.
Intravenous arginine provokes growth hormone release in standard endocrine testing, and growth hormone drives hepatic IGF-1 production. Oral arginine's effect on the axis is far less consistent. The link is upstream of an exogenous analogue and does not add to it.
IGF-1 shares enough structural homology with insulin to activate the insulin receptor at higher concentrations, which is why glucose falls during IGF-1 infusion. Berberine lowers glucose by AMPK-linked mechanisms of its own. Combining two glucose-lowering agents makes the drop additive, which is a caution worth recording rather than a benefit.
Chromium supplementation is studied for insulin sensitivity markers, with modest and inconsistent results. Any glucose-lowering it contributes points the same way as IGF-1 receptor and insulin receptor cross-activation. Recorded as a directional caution, not an efficacy pairing.
Gymnema is used for blood sugar support and shares the downward direction on glucose. Stacked with a peptide that activates the insulin receptor, the effects add rather than cancel. Included as a direction-of-effect flag.
Bitter melon constituents have been reported to lower blood glucose in small studies of varying quality. The point of the row is that the direction of effect adds to insulin receptor cross-activation. Not an efficacy claim for either.
Cinnamon extracts have small and inconsistent effects on fasting glucose markers in trials. Where they act, they act in the same direction as insulin receptor activation. Recorded for additivity awareness.
1-deoxynojirimycin from white mulberry inhibits intestinal alpha-glucosidase, blunting the post-meal glucose rise. That reduces the incoming glucose at the same time insulin receptor cross-activation is increasing uptake. The two mechanisms are separate and their glucose effects add.
Alpha-lipoic acid has been studied against insulin sensitivity markers with mixed findings. Any glucose-lowering contribution points the same way as an insulin-receptor cross-reactive peptide. A directional flag, not a benefit pairing.
IGF-1 LR3 is a 83-residue class protein, and proteins are cleaved by pepsin, trypsin and chymotrypsin before absorption. Protease-containing products accelerate that same degradation. The practical point is that this molecule has no meaningful oral route, with or without added enzymes, which is settled protein pharmacology.
Nothing specific on file for IGF-1 LR3. Match the label to the daily amount above, and tell your doctor what you take.
Not medical advice. Show the label to your pharmacist.What IGF-1 LR3 actually does.
IGF-1 LR3 is a modified recombinant analogue of insulin-like growth factor 1 carrying an arginine substitution at position 3 and a 13-residue N-terminal extension derived from a viral peptide sequence, which is what the LR3 name records.
Those modifications sharply reduce binding to the insulin-like growth factor binding proteins that normally sequester circulating IGF-1, so a larger fraction stays unbound and the circulating half-life is considerably longer than that of native IGF-1.
The molecule acts at the IGF-1 receptor, a receptor tyrosine kinase, whose autophosphorylation recruits IRS proteins and activates the PI3K to Akt to mTORC1 arm and the Ras to MAPK arm.
IGF-1 shares substantial sequence homology with insulin and cross-activates the insulin receptor at sufficient concentrations, which is the established explanation for the fall in blood glucose seen during IGF-1 infusion.
Where IGF-1 LR3 comes from.
This is grown, not mixed. Bacteria are given the gene for the modified peptide, they make it inside their cells, and the peptide is then extracted, refolded into the right shape, and cleaned up through several chromatography stages before being freeze-dried into a vial. Getting the folding right is the difficult part, because a wrongly folded version has the same mass and a different behaviour.
Produced by a cultured organism rather than harvested. The strain is selected and the conditions are controlled, so batches sit closer together than a field crop.
A synthetic gene encoding the modified IGF-1 sequence, with the position-3 arginine substitution and the N-terminal extension, is inserted into an expression plasmid and carried by a bacterial host, most commonly Escherichia coli. The starting material is a cell bank, not a chemical.
The host is grown in a controlled fermenter and expression is induced. Recombinant IGF-1 class peptides typically accumulate as insoluble inclusion bodies in bacterial cytoplasm, which is a normal feature of the route rather than a fault.
Cells are lysed mechanically or chemically and inclusion bodies are separated by centrifugation and washing, removing the bulk of host cell protein before the peptide is ever in solution.
The peptide is solubilised under denaturing conditions and refolded under controlled redox conditions so the three disulfide bonds form in the correct pairing. Refolding yield and disulfide isomer purity are the hardest parts of this route and the main source of batch variation.
Successive ion exchange and reversed-phase chromatography steps separate correctly folded monomer from misfolded isomers, aggregates, truncated species and residual host protein and endotoxin.
Grade is defined by mass spectrometry identity, chromatographic purity, aggregate content, residual host cell protein and DNA, and bacterial endotoxin. Peptide content by mass is not the same figure as net peptide, and the two are often conflated on a certificate.
Purified peptide is buffer-exchanged, filled with a bulking agent, freeze-dried and sealed. The dry solid is what is shipped and stored.
Research-grade suppliers commonly report gross peptide mass rather than net peptide content, and often do not report aggregate content, disulfide isomer purity or endotoxin at all, so the specification a buyer sees is usually less complete than the analysis the process actually requires.
Getting IGF-1 LR3 from food.
The whole-food sources on file. A supplement closes the gap, it does not replace dinner.
A gram-for-gram figure (how much of each you would eat to match a dose) will appear here once it is sourced and reviewed. This page will not print a number it cannot cite.
The forms it comes in.
The essence, in one line each.
- IGF-1 increased collagen deposition by human dermal fibroblasts in culture, which the authors frame as useful for tissue engineering; the readout is deposited matrix in a dish, not a measured outcome in a person.In vitro study. Brownell D et al., 2026 (Cells). PMID 42274614 ↗
- An IGF-1 LR3 infusion did not produce a detectable increase in growth in late-gestation growth-restricted fetal sheep; this is a failure to detect an effect in that model, not a demonstration that no effect exists.Animal study. White A et al., 2025 (American Journal of Physiology: Endocrinology and Metabolism). PMID 39679943 ↗
- Glucose-stimulated insulin secretion was attenuated during an acute IGF-1 LR3 infusion into fetal sheep and the authors report that the attenuation did not persist afterwards.Animal study. White A et al., 2023 (Journal of Developmental Origins of Health and Disease). PMID 37114757 ↗
- The review names IGF-1 among the shared signalling pathways it maps between bone and prostate tissue; the material is mechanistic pathway discussion, not supplementation data.Narrative review. Jiang Z et al., 2026 (International Journal of Surgery). PMID 41532438 ↗
These are the studies our verdict leans on, chosen from the 4 we read for IGF-1 LR3. The full linked list is below.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This information is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Consult your healthcare provider before starting any supplement regimen.