IGF-1 LR3 Research Peptides

Compare IGF-1 LR3 research products by labelled quantity, price per mg, testing evidence and product transparency. See what’s available from suppliers and use our comparison tools to make more informed decisions.

Research-use products only. Not presented as supplements, medicines, or products for human or veterinary consumption.

3products compared

1labelled quantities

£38.99 – £75.00per mg

2with verified testing evidence

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Quantity: 1 mg / vial

£38.99per mg

£38.99per pack

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Product & testing details

Supplier: Ascend Peptides UK
Vials per pack: 1
Price per vial: £38.99
Listing last checked: 2026-09-22 11:39:13

Evidence status: Verified independent evidence
Manufacturer statement: "≥98% purity. Janoshik tested."; site also says "Independently verified by Janoshik Laboratories" and "HPLC Purity & LC-MS Identity Verified" and "Batch-Specific Certificates of Analysis (COAs) are available before every purchase."
Laboratory: Janoshik Analytical
Certification body: Not recorded
Batch: 20260114
Batch-specific report: Recorded
Report date: 2026-04-07
Evidence checked: 2026-09-22

Certificate of analysis ↗

IGF-1 LR3 1mg

Ascend Peptides UK

£38.99per mg

£38.99per pack

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Best Tested

Quantity: 1 mg / vial

£44.99per mg

£44.99per pack

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Product & testing details

Supplier: UK Peptides (ukpeptides.org)
Vials per pack: 1
Price per vial: £44.99
Listing last checked: 2026-09-22 11:25:55

Evidence status: Verified independent evidence
Manufacturer statement: Independently Tested · Accredited External Lab; Third-party HPLC-UV testing; Lot-matched CoAs published; every lot is tested by an external analytical laboratory before it ships — HPLC-UV for purity, mass spectrometry for identity.
Laboratory: MZ Biolabs
Certification body: Not recorded
Batch: 2026-07-15
Batch-specific report: Recorded
Report date: 2026-07-31
Evidence checked: 2026-09-22

Certificate of analysis ↗

IGF-1 LR3 1mg

UK Peptides (ukpeptides.org)

£44.99per mg

£44.99per pack

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Lowest Price per mg

Quantity: 1 mg / vial

£38.99per mg

£38.99per pack

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Product & testing details

Supplier: Ascend Peptides UK
Vials per pack: 1
Price per vial: £38.99
Listing last checked: 2026-09-22 11:39:13

Evidence status: Verified independent evidence
Manufacturer statement: "≥98% purity. Janoshik tested."; site also says "Independently verified by Janoshik Laboratories" and "HPLC Purity & LC-MS Identity Verified" and "Batch-Specific Certificates of Analysis (COAs) are available before every purchase."
Laboratory: Janoshik Analytical
Certification body: Not recorded
Batch: 20260114
Batch-specific report: Recorded
Report date: 2026-04-07
Evidence checked: 2026-09-22

Certificate of analysis ↗

IGF-1 LR3 1mg

Ascend Peptides UK

£38.99per mg

£38.99per pack

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Vial size

Research peptide product comparison
#	Product	Quantity	Price / vial	Price / mg	Testing	Score
1	IGF-1 LR3 1mgAscend Peptides UK	1 mg / vial	£38.99per vial	£38.99per mg	Testing evidence Evidence status Verified independent evidence Manufacturer statement "≥98% purity. Janoshik tested."; site also says "Independently verified by Janoshik Laboratories" and "HPLC Purity & LC-MS Identity Verified" and "Batch-Specific Certificates of Analysis (COAs) are available before every purchase." Laboratory Janoshik Analytical Certification body Not recorded Batch 20260114 Batch-specific report Recorded Report date 2026-04-07 Evidence checked 2026-09-22 Certificate of analysis ↗	Why this score? Testing & analytical evidence 35/45 Value 20/25 Product identity 12/15 Supplier transparency 10/10 Label & listing transparency 5/5 Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.	Buy Now
2	IGF-1 LR3 1mgUK Peptides (ukpeptides.org)	1 mg / vial	£44.99per vial	£44.99per mg	Testing evidence Evidence status Verified independent evidence Manufacturer statement Independently Tested · Accredited External Lab; Third-party HPLC-UV testing; Lot-matched CoAs published; every lot is tested by an external analytical laboratory before it ships — HPLC-UV for purity, mass spectrometry for identity. Laboratory MZ Biolabs Certification body Not recorded Batch 2026-07-15 Batch-specific report Recorded Report date 2026-07-31 Evidence checked 2026-09-22 Certificate of analysis ↗	Why this score? Testing & analytical evidence 36/45 Value 18/25 Product identity 12/15 Supplier transparency 10/10 Label & listing transparency 5/5 Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.	Buy Now
3	IGF-LR3 1mgReta Research	1 mg / vial	£75.00per vial	£75.00per mg	Testing evidence Evidence status Testing claimed Manufacturer statement Lyophilised powder, 1mg vial, ≥99% purity by HPLC, Certificate of Analysis on request. Research-grade peptides, independently HPLC-tested and dispatched fast across the UK. Independent Certificates of Analysis, published for every lot we ship. Every batch is verified by HPLC purity assay, mass-spec identity, and COA published. Laboratory Not recorded Certification body Not recorded Batch Not recorded Batch-specific report Not established in this record Report date Not recorded Evidence checked 2026-09-22	Why this score? Testing & analytical evidence 10/45 Value 11/25 Product identity 12/15 Supplier transparency 10/10 Label & listing transparency 5/5 Displayed points and weights are rounded; the total uses unrounded weights. Pending dimensions are excluded. Provisional scores may change after review.	Buy Now

Quantity: 1 mg / vial

£38.99per mg

£38.99per pack

View Analysis Buy Now

Product & testing details

Supplier: Ascend Peptides UK
Vials per pack: 1
Price per vial: £38.99
Listing last checked: 2026-09-22 11:39:13

Evidence status: Verified independent evidence
Manufacturer statement: "≥98% purity. Janoshik tested."; site also says "Independently verified by Janoshik Laboratories" and "HPLC Purity & LC-MS Identity Verified" and "Batch-Specific Certificates of Analysis (COAs) are available before every purchase."
Laboratory: Janoshik Analytical
Certification body: Not recorded
Batch: 20260114
Batch-specific report: Recorded
Report date: 2026-04-07
Evidence checked: 2026-09-22

Certificate of analysis ↗

Quantity: 1 mg / vial

£44.99per mg

£44.99per pack

View Analysis Buy Now

Product & testing details

Supplier: UK Peptides (ukpeptides.org)
Vials per pack: 1
Price per vial: £44.99
Listing last checked: 2026-09-22 11:25:55

Evidence status: Verified independent evidence
Manufacturer statement: Independently Tested · Accredited External Lab; Third-party HPLC-UV testing; Lot-matched CoAs published; every lot is tested by an external analytical laboratory before it ships — HPLC-UV for purity, mass spectrometry for identity.
Laboratory: MZ Biolabs
Certification body: Not recorded
Batch: 2026-07-15
Batch-specific report: Recorded
Report date: 2026-07-31
Evidence checked: 2026-09-22

Certificate of analysis ↗

Quantity: 1 mg / vial

£75.00per mg

£75.00per pack

View Analysis Buy Now

Product & testing details

Supplier: Reta Research
Vials per pack: 1
Price per vial: £75.00
Listing last checked: 2026-09-22 11:04:33

Evidence status: Testing claimed
Manufacturer statement: Lyophilised powder, 1mg vial, ≥99% purity by HPLC, Certificate of Analysis on request. Research-grade peptides, independently HPLC-tested and dispatched fast across the UK. Independent Certificates of Analysis, published for every lot we ship. Every batch is verified by HPLC purity assay, mass-spec identity, and COA published.
Laboratory: Not recorded
Certification body: Not recorded
Batch: Not recorded
Batch-specific report: Not established in this record
Report date: Not recorded
Evidence checked: 2026-09-22

What is IGF-1 LR3?

IGF-1 LR3 is a recombinant analogue of insulin-like growth factor 1. FDA's substance registry lists the preferred name LONG-(ARG3)INSULIN-LIKE GROWTH FACTOR-I and aliases including IGF-1 LR3 and Long R3 insulin-like growth factor-I. The original recombinant design uses the complete human IGF-1 sequence, changes the third IGF-1 residue from glutamate to arginine, and adds a 13-residue N-terminal extension derived from methionyl porcine growth hormone plus Val-Asn. The resulting protein contains 83 residues rather than the 70 residues of mature human IGF-1. [S1] [S2] [S3]

Evidence snapshot

The defining 1992 analogue work showed that Long-[Arg3]-IGF-I had greater biological potency than native IGF-1 in several IGFBP-producing cell systems, while being less potent than IGF-1 in a cell line without detectable IGFBP secretion. That pattern supports reduced binding-protein sequestration rather than a simple claim of universally stronger receptor action. [S3]
Animal findings are not a simple muscle-growth story. Long R3 IGF-I increased some organ weights in guinea pigs but did not increase overall body growth, while a pig study reported reduced feed intake and average daily gain during infusion. [S10] [S11]
Metabolic effects have been observed in animals: subcutaneous Long R3 IGF-I lowered plasma glucose and insulin in neonatal calves, whereas oral exposure in the same study did not produce those effects. [S12]
Common online claims of a 20–30, 30–40 or 56–72 hour human half-life were not traced to a validated human pharmacokinetic study. This handoff therefore does not publish a human half-life figure. [S8]

View sources and methodology →

Quick facts

Chemical class: Recombinant protein / growth-factor analogue derived from human IGF-1; 83 amino acids. [S1] [S2] [S3]
What “LR3” means: “Long” refers to a 13-residue N-terminal extension; “R3” refers to arginine replacing glutamate at position 3 of the mature IGF-1 sequence. [S2] [S3] [S4]
Binding-protein behaviour: Designed to bind IGF-binding proteins far less strongly than native IGF-1 while retaining activity at the IGF-1 receptor. [S3] [S9]
Human evidence: No peer-reviewed human administration study of IGF-1 LR3 was identified in the targeted literature/registry search; published evidence is laboratory and animal research. [S8]
UK medicine distinction: Mecasermin (Increlex) is authorised recombinant human IGF-1 in the UK; it is the unmodified 70-residue human IGF-1 sequence, not IGF-1 LR3. [S6] [S17]
Sport status: WADA's 2026 list prohibits IGF-1 and its analogues under S2.3 Growth Factors and Growth Factor Modulators. [S16]

The verified 83-residue sequence exists in research-reagent documentation, but the category page should not imply that a supplier vial has that identity unless its own analytical evidence supports it.

IGF-1 LR3 is not native IGF-1, mecasermin or IGF-1 DES

IGF terminology is easy to blur. Endogenous mature human IGF-1 is a 70-residue growth factor. Mecasermin is recombinant human IGF-1 with the same amino-acid sequence as endogenous human IGF-1 and is the active ingredient in the authorised medicine Increlex. IGF-1 DES, or des(1-3) IGF-I, instead removes the first three residues of IGF-1. IGF-1 LR3 keeps the 70-residue IGF-1 domain, changes Glu3 to Arg and adds a 13-residue N-terminal extension. IGF-2 and growth hormone are different hormones altogether. [S3] [S5] [S6]

Compound	Identity	Evidence rule
Endogenous human IGF-1	Native 70-residue human growth factor.	Physiology studies are context, not LR3 intervention evidence. [S6]
Recombinant human IGF-1 / mecasermin	Recombinant protein with sequence identical to endogenous human IGF-1.	Clinical efficacy and safety data do not automatically transfer to LR3. [S6]
IGF-1 LR3	83-residue analogue: 13-residue N-terminal extension plus Glu3→Arg in the IGF-1 domain.	Use only studies that explicitly identify Long R3 / Long-[Arg3]-IGF-I. [S1] [S2] [S3]
IGF-1 DES	Des(1-3) IGF-I; residues 1–3 removed from the native IGF-1 sequence.	Separate analogue with separate binding and activity data. [S5]
IGF-2	Separate insulin-like growth factor encoded by a different gene.	Do not treat IGF-2 studies as IGF-1 LR3 evidence. [S6]
Growth hormone	Upstream pituitary hormone that stimulates IGF-1 production among other actions.	GH outcomes are not direct IGF-1 LR3 outcomes. [S6]

The UK authorisation of Increlex applies to mecasermin, not IGF-1 LR3.

Reduced IGF-binding-protein affinity is the defining research property

The original Long R3 design was intended to reduce sequestration by insulin-like growth factor-binding proteins (IGFBPs). In the 1992 study, Long-[Arg3]-IGF-I showed enhanced potency relative to native IGF-1 in cell systems that produced IGFBPs, whereas in chicken embryo fibroblasts without detectable IGFBP secretion it was less potent than native IGF-1. Human fibroblast work likewise found Long R3 IGF-I to be much more potent than IGF-1 in an IGFBP-rich assay and relatively unaffected by added IGFBP-3. These experiments support altered binding-protein interaction; they do not establish a human therapeutic advantage. [S3] [S9]

IGFBP interaction

Long R3 IGF-I was engineered to interact much less strongly with IGF-binding proteins than native IGF-1. [S3] [S9]

Established laboratory property

IGF-1 receptor activity

The analogue retains activity through the type-1 IGF receptor, but potency varies with the experimental system. [S3]

Context-dependent

Why potency changes

Greater apparent potency in some assays can reflect reduced capture by IGFBPs rather than intrinsically stronger receptor binding. [S3] [S9]

Mechanistic interpretation

Do not turn 'reduced IGFBP affinity' into an unsupported statement that the analogue has a specific prolonged human half-life.

What direct IGF-1 LR3 research actually shows

Direct research spans recombinant-protein development, receptor/binding-protein biology, cell culture and multiple animal models. The evidence shows that IGF-1 LR3 is biologically active, but outcomes are highly dependent on species, tissue, route and endpoint. It has increased proliferation or protein-synthesis signals in some cell systems and altered organ, gut or metabolic measurements in animals. Those findings do not amount to human evidence for muscle gain, recovery or body-composition benefit. [S3] [S9] [S10] [S11] [S12] [S13] [S14]

Cell culture

Used as a growth-factor reagent because low IGFBP affinity can produce strong IGF-signalling effects in serum-free or low-serum culture systems. [S2] [S3] [S9]

Laboratory evidence

Animal growth

Organ or tissue effects have been reported, but whole-body growth responses are inconsistent across species. [S10] [S11] [S13]

Animal evidence

Metabolic effects

Animal studies report changes in glucose, insulin, GH and IGFBP-related measures depending on species and route. [S11] [S12]

Animal evidence

Human outcomes

No peer-reviewed human administration study of IGF-1 LR3 was identified in the evidence review and targeted searches. [S8]

Direct human evidence not located

Research context	What was observed	Limitation
IGFBP-producing cell systems	Greater apparent biological potency than native IGF-1 in several assays.	In-vitro potency; not a human outcome. [S3] [S9]
Guinea pigs	Higher fractional weights of several organs without increased overall body growth.	Species-specific seven-day infusion. [S10]
Finisher pigs	Reduced average daily gain, feed intake, IGFBP-3, endogenous IGF-I and insulin during infusion.	Opposes a simple 'more IGF means more growth' narrative. [S11]
Neonatal calves	Subcutaneous exposure lowered plasma glucose and insulin; oral exposure did not show the same effect.	Animal route-specific metabolic result. [S12]
Sheep skin	Local infusion altered blood flow, oxygen/amino-acid utilisation and protein-synthesis-related measures without increasing wool-follicle cell replication.	Local tissue physiology, not whole-body muscle gain. [S13]

Commercial claims about muscle growth or recovery go beyond the direct human evidence because no peer-reviewed human administration study was located.

Human administration evidence was not located

The 2026 Frontiers review of performance-enhancing peptides placed IGF-1 LR3 in its lowest evidence tier and states that no peer-reviewed human studies exist. Targeted searches for IGF-1 LR3, Long R3 IGF-I and Long-[Arg3]-IGF-I did not locate a ClinicalTrials.gov interventional programme for the exact analogue. Papers indexed with human-related terms can still be cell-culture studies using human cells rather than administration to people. [S8] [S9]

Mecasermin trials and authorised-product data are excluded from the direct LR3 evidence count because mecasermin is unmodified recombinant human IGF-1, not Long R3 IGF-I. [S6]

Registered-trial searches: molecule identity matters

No verified ClinicalTrials.gov record for the exact IGF-1 LR3 analogue was located in the targeted searches. Searching the broader IGF-1 field returns studies of recombinant human IGF-1, mecasermin and other IGF-related interventions, but those are different molecules. Because the exact analogue was not matched to a registry record, the structured trial array is left empty rather than borrowing trials from mecasermin or native IGF-1. [S6] [S8]

A study that says 'IGF-1' is not automatically an IGF-1 LR3 study. The intervention must explicitly match the modified 83-residue analogue.

Human half-life claims are not verified

The best-supported pharmacological distinction is reduced IGFBP binding, not a validated human half-life. Animal studies show biological effects during controlled infusion and route-dependent metabolic responses, but they do not establish a human elimination half-life. Reagent datasheets sometimes describe greater stability or prolonged activity, while commercial pages commonly quote long half-life figures. No primary human pharmacokinetic study measuring an IGF-1 LR3 half-life was located in the targeted search, and the 2026 review reports no peer-reviewed human studies. [S2] [S8] [S10] [S11] [S12]

Binding-protein interaction

Strongly reduced IGFBP affinity is directly supported by laboratory research. [S3] [S9]

Verified

Laboratory stability

Reagent stability and resistance to sequestration are not the same measurement as plasma elimination half-life. [S2] [S3]

Different concept

Human circulating half-life

No validated primary human PK measurement was located. [S8]

Unknown

Duration of biological effect

A prolonged signalling response in a model does not by itself define pharmacokinetic half-life. [S3] [S9]

Do not conflate

Do not publish commonly repeated '20–30 h', '30–40 h' or '56–72 h' human half-life figures unless a primary human PK study is located.

Safety concerns are partly direct and partly contextual

Direct human safety data for IGF-1 LR3 were not located. Animal studies demonstrate that the analogue can alter glucose/insulin physiology and organ or endocrine measures, which shows biological activity but cannot quantify human adverse-event risk. Mecasermin provides useful IGF-signalling context: the authorised UK medicine can cause hypoglycaemia and carries warnings about benign and malignant neoplasia, but those incidence data belong to mecasermin, not LR3. Separately, epidemiological studies associate higher circulating endogenous IGF-1 with modestly higher risk of some cancers. None of that proves that IGF-1 LR3 causes cancer in humans, but it also prevents a credible claim that mitogenic risk is absent. [S6] [S7] [S10] [S11] [S12] [S19]

Glucose regulation

Direct LR3 animal evidence includes lowered plasma glucose and insulin after subcutaneous exposure in neonatal calves. [S12]

Direct animal finding

Organ / endocrine effects

Guinea-pig and pig studies reported altered organ weights, GH, endogenous IGF-I, IGFBP-3 or insulin measures. [S10] [S11]

Direct animal findings

Hypoglycaemia context

Mecasermin can reduce blood glucose and is managed as a hypoglycaemia risk in authorised clinical use; this is contextual evidence, not an LR3 incidence estimate. [S6]

Different IGF-1 medicine

Cancer-related uncertainty

IGF signalling is mitogenic and higher circulating IGF-1 has epidemiological associations with some cancers, but direct human cancer-risk data for IGF-1 LR3 are absent. [S7] [S19]

Plausible concern, unquantified for LR3

Do not copy mecasermin adverse-event rates onto IGF-1 LR3. The correct conclusion is that LR3 human safety is inadequately characterised.

UK regulatory and anti-doping context

The UK has an authorised IGF-1 medicine, Increlex, whose active ingredient is mecasermin: recombinant human IGF-1 with a sequence identical to endogenous human IGF-1. That authorisation does not apply to IGF-1 LR3. Targeted MHRA/emc searches for IGF-1 LR3 and Long R3 IGF-I did not locate a UK-authorised LR3 medicinal product as of 2026-09-22. MHRA separately regulates certain unlicensed medicines, which is not equivalent to a research-use vial holding a marketing authorisation. For sport, WADA's 2026 S2.3 category prohibits IGF-1 and its analogues; IGF-1 LR3 falls within that analogue wording even if the exact commercial shorthand is not individually listed. [S6] [S16] [S17] [S18]

Mecasermin

Authorised UK recombinant human IGF-1 medicine for severe primary IGF-1 deficiency in children and adolescents. [S6]

Authorised medicine

IGF-1 LR3

No UK marketing-authorisation record for the exact LR3 analogue was located in the targeted product-information search. [S17] [S18]

Search finding

WADA

IGF-1 and its analogues are prohibited under S2.3 Growth Factors and Growth Factor Modulators. [S16]

Prohibited at all times

A 'research use only' label is a supplier presentation statement; it does not establish medicine authorisation, legal status for every circumstance or suitability for human use.

How to interpret IGF-1 LR3 research-product listings

IGF-1 LR3 listings require careful attention to units. UK listings reviewed use both milligrams and micrograms: 1 mg and 1,000 mcg are the same labelled mass, while 100 mcg is 0.1 mg. Check the original unit before comparing quantities. Product quality also needs more than a headline HPLC purity value. Identity, expected molecular mass, sequence/form, biological activity, batch match and analytical method answer different questions. [S2] [S20] [S21]

Units

1 mg = 1000 mcg. Preserve original label units and normalise computationally without changing what the supplier actually states. [S20] [S21]

Critical

Amount per vial

Keep vial content separate from solution concentration and pack total. [S20] [S21]

Separate fields

Identity

Mass spectrometry or other appropriate identity evidence should be matched to the expected 83-residue analogue, not merely a generic IGF-1 label. [S1] [S2] [S15]

Identity-critical

Purity / activity

HPLC purity, molecular identity and cell-based biological activity are different measurements; none alone establishes suitability for human use. [S2] [S15]

Do not collapse

Listing field	What it means	What it does not prove
1000 mcg / 1 mg	Equivalent labelled mass.	Concentration or biological activity. [S20] [S21]
Amount per vial	Supplier-declared total mass in one vial.	Concentration after preparation or pack-total amount. [S20] [S21]
HPLC purity	Chromatographic purity under the stated method.	Correct 83-residue identity, potency, sterility or suitability for human use. [S2] [S21]
Mass spectrometry	Can support molecular identity/mass when method and expected analyte are appropriate.	Biological activity or clinical safety by itself. [S2] [S15]
Cell-based activity	Functional response in a defined assay.	Human efficacy, human half-life or medicine authorisation. [S2] [S3]

A 1 mg vial is 1,000 mcg, not 1,000 mg. Small quantities must be compared without confusing micrograms and milligrams.

Frequently asked questions

What does IGF-1 LR3 stand for?

It refers to Long R3 IGF-I. 'Long' denotes a 13-residue N-terminal extension, while 'R3' denotes replacement of glutamate with arginine at position 3 of the IGF-1 portion. [S1] [S2] [S3]

How many amino acids are in IGF-1 LR3?

The verified analogue contains 83 amino acids: a 13-residue N-terminal extension followed by the 70-residue human IGF-1 domain with the Glu3→Arg substitution. [S2] [S3] [S4]

Is IGF-1 LR3 the same as mecasermin?

No. Mecasermin is recombinant human IGF-1 with the same 70-amino-acid sequence as endogenous human IGF-1. IGF-1 LR3 is an 83-residue modified analogue. [S3] [S6]

Is IGF-1 LR3 the same as IGF-1 DES?

No. IGF-1 DES removes residues 1–3 from IGF-1, while LR3 adds a 13-residue extension and substitutes arginine for glutamate at position 3. [S3] [S5]

Why is IGF-1 LR3 used in cell culture?

It was engineered as a potent IGF growth-factor reagent with greatly reduced IGF-binding-protein interaction, which can make IGF signalling more available in serum-free or low-serum culture systems. [S2] [S3] [S9]

Has IGF-1 LR3 been tested in humans?

No peer-reviewed human administration study was identified in the targeted search. A 2026 review explicitly categorised IGF-1 LR3 as having no peer-reviewed human studies. [S8]

Does IGF-1 LR3 build muscle in humans?

That has not been demonstrated in controlled human research. Cell and animal studies show IGF-related growth and metabolic effects, but those cannot establish human muscle-gain or recovery outcomes. [S8] [S10] [S11] [S13]

What is the human half-life of IGF-1 LR3?

A validated human half-life was not located. Commonly repeated online figures are not used here because no primary human pharmacokinetic study supporting them was identified. [S8]

Can IGF-1 LR3 affect blood glucose?

Direct human data were not located. In neonatal calves, subcutaneous Long R3 IGF-I lowered plasma glucose and insulin, showing that metabolic effects are biologically plausible but species- and route-specific. [S12]

Does IGF-1 LR3 cause cancer?

There is no direct human study establishing cancer risk for IGF-1 LR3. IGF signalling is mitogenic, mecasermin carries neoplasia warnings, and higher endogenous circulating IGF-1 has epidemiological associations with some cancers; these are contextual concerns rather than proof that LR3 causes cancer. [S6] [S7] [S19]

Is IGF-1 LR3 approved in the UK?

No UK marketing-authorisation record for the exact LR3 analogue was located in the targeted MHRA/emc search. The authorised IGF-1 medicine Increlex contains mecasermin, which is a different molecule. [S6] [S17] [S18]

Is IGF-1 LR3 banned in sport?

Yes for athletes subject to WADA rules. The 2026 Prohibited List places IGF-1 and its analogues in S2.3 Growth Factors and Growth Factor Modulators. [S16]

Is 1000 mcg the same as 1 mg?

Yes. 1000 micrograms equals 1 milligram. Product comparison should still preserve the supplier's original unit so that quantity transcription errors are visible. [S20] [S21]

Does a 99% purity claim prove an IGF-1 LR3 vial is genuine?

No. Purity, molecular identity, quantity and biological activity are separate questions. A useful record should show what method was used, the expected analyte, the batch and whether identity as the 83-residue LR3 analogue was actually demonstrated. [S2] [S15] [S21]

Sources & methodology

[S1] LONG-(ARG3)INSULIN-LIKE GROWTH FACTOR-I ↗U.S. Food and Drug Administration Substance Registration System / Chemical Database / Authority Page Read
[S2] LONG R3 IGF-1, human (I1271) - Product Information ↗Sigma-Aldrich / Merck / Research Reagent Datasheet / Full Text Read
[S3] Novel recombinant fusion protein analogues of insulin-like growth factor (IGF)-I indicate the relative importance of IGF-binding protein and receptor binding for enhanced biological potency ↗Journal of Molecular Endocrinology / PubMed / Primary Laboratory Study / Abstract Only
[S4] Secondary structure determination of 15N-labelled human Long-[Arg-3]-insulin-like growth factor 1 by multidimensional NMR spectroscopy ↗Journal of Biomolecular NMR / PubMed / Structural Primary Study / Abstract Only
[S5] Insulin-like growth factor 1, des-(1-3)- ↗PubChem, National Library of Medicine / Chemical Database / Authority Page Read
[S6] Increlex 10 mg/ml solution for injection - Summary of Product Characteristics ↗electronic Medicines Compendium / Uk Medicine Product Information / Authority Page Read
[S7] Mecasermin (Increlex): risk of benign and malignant neoplasia ↗Medicines and Healthcare products Regulatory Agency / Uk Regulatory Safety Source / Authority Page Read
[S8] The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration ↗Frontiers in Endocrinology / Narrative Review / Full Text Read
[S9] Cytokines modulate the sensitivity of human fibroblasts to stimulation with insulin-like growth factor-I (IGF-I) by altering endogenous IGF-binding protein production ↗Journal of Endocrinology / PubMed / Cell Culture Primary Study / Abstract Only
[S10] Long R3 insulin-like growth factor-I (IGF-I) infusion stimulates organ growth but reduces plasma IGF-I, IGF-II and IGF binding protein concentrations in the guinea pig ↗Journal of Endocrinology / PubMed / Animal Primary Study / Abstract Only
[S11] Long [R3] insulin-like growth factor-I reduces growth, plasma growth hormone, IGF binding protein-3 and endogenous IGF-I concentrations in pigs ↗Journal of Endocrinology / PubMed / Animal Primary Study / Abstract Only
[S12] Endocrine and metabolic changes in neonatal calves in response to growth hormone and long-R3-insulin-like growth factor-I administration ↗Journal of Endocrinology / PubMed / Animal Primary Study / Abstract Only
[S13] Direct infusion of a variant of insulin-like growth factor-I into the skin of sheep and effects on local blood flow, amino acid utilization and cell replication ↗Journal of Endocrinology / PubMed / Animal Primary Study / Abstract Only
[S14] Effects of insulin-like growth factor-I and its analogue, long-R3-IGF-I, on intestinal absorption of 3-O-methyl-D-glucose are less pronounced than gut mucosal growth responses ↗Growth Factors / PubMed / Animal Primary Study / Abstract Only
[S15] Detection of His-tagged Long-R3-IGF-I in a black market product ↗Drug Testing and Analysis / PubMed / Analytical Case Report / Abstract Only
[S16] 2026 Prohibited List ↗World Anti-Doping Agency / Sport Authority / Authority Page Read
[S17] Find product information about medicines ↗Medicines and Healthcare products Regulatory Agency / Uk Regulatory Guidance / Authority Page Read
[S18] Supply unlicensed medicinal products (specials) ↗Medicines and Healthcare products Regulatory Agency / Uk Regulatory Guidance / Authority Page Read
[S19] Insulin-like growth factor (IGF)-I, IGF binding protein-3, and cancer risk: systematic review and meta-regression analysis ↗The Lancet / PubMed / Systematic Review / Abstract Only
[S20] IGF-1 LR3 1000mcg ↗Patriot Peptides / Supplier Page / Full Text Read
[S21] IGF-1 LR3 1 mg ↗Solent Biopeptides / Supplier Page / Full Text Read

We separate animal models, observational human studies and ongoing trials. Scientific evidence is assessed independently of future supplier documentation. How we verify testing →

Page updated: 22 September 2026Sources checked: 22 September 2026

Testing evidence in this comparison

Verified independent evidence: 2
Testing claimed: 1

What does IGF-1 LR3 cost?

Lowest: £38.99 / mg · Median: £44.99 / mg · Highest: £75.00 / mg

IGF-1 LR3 Research Peptides

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IGF-1 LR3 1mgAscend Peptides UK

IGF-1 LR3 1mg

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IGF-1 LR3 1mgUK Peptides (ukpeptides.org)

IGF-1 LR3 1mg

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IGF-1 LR3 1mgAscend Peptides UK

IGF-1 LR3 1mg

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IGF-1 LR3 1mgAscend Peptides UK

IGF-1 LR3 1mgUK Peptides (ukpeptides.org)

IGF-LR3 1mgReta Research

What is IGF-1 LR3?

IGF-1 LR3 is not native IGF-1, mecasermin or IGF-1 DES

Reduced IGF-binding-protein affinity is the defining research property

IGFBP interaction

IGF-1 receptor activity

Why potency changes

What direct IGF-1 LR3 research actually shows

Cell culture

Animal growth

Metabolic effects

Human outcomes

Human administration evidence was not located

Registered-trial searches: molecule identity matters

Human half-life claims are not verified

Binding-protein interaction

Laboratory stability

Human circulating half-life

Duration of biological effect

Safety concerns are partly direct and partly contextual

Glucose regulation

Organ / endocrine effects

Hypoglycaemia context

Cancer-related uncertainty

UK regulatory and anti-doping context

Mecasermin

IGF-1 LR3

WADA

How to interpret IGF-1 LR3 research-product listings

Units

Amount per vial

Identity

Purity / activity

Frequently asked questions

Sources & methodology

Testing evidence in this comparison

What does IGF-1 LR3 cost?