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Our sources

Every study this site cites, in one place. 103 distinct sources across 63 publications, 41 of them carrying a PubMed ID and 75 linking directly to the source so you can check the claim yourself.

We do not have a physician on staff, and we say so plainly on our about page. What we have instead is this: every claim traced to something you can open and read. If a source below does not say what we claim it says, that is a correction we want to make, and here is how to tell us.

What kind of evidence this actually is

The mix matters more than the count. A bibliography can look impressive while resting almost entirely on mouse studies, which is the normal state of affairs in the peptide world. Here is ours, honestly broken down.

Cited sources by study type
Study typeCount
Randomized Controlled Trial40
Animal Study15
In-Vitro11
Systematic Review4
Observational Study3
Mechanism2
Case Series1

48 of our typed sources are human studies and 26 are animal or laboratory work. That second number is not a flaw in our research, it is the actual state of the peptide literature, and it is why so many claims on this site are graded preclinical rather than proven.

What we cite, and what we refuse to

What counts as a source

  • Peer-reviewed journal articles, identified by PubMed ID or DOI so you can check them
  • Systematic reviews and meta-analyses, which we weight above individual trials
  • Regulatory primary sources: FDA approvals, Federal Register notices, advisory committee proceedings
  • Trial registries and full trial publications, in preference to press releases
  • Company press releases, but only when clearly labelled as such and only when no publication exists yet

What does not

  • Vendor and clinic websites, which have a commercial interest in the answer
  • Wikipedia, which is a starting point for research, not a citation
  • Podcast episodes and social media threads as evidence for a factual claim
  • Secondary write-ups of a study when the study itself is available
  • Any source we cannot link to, so you can never be asked to take our word for it

The bibliography

Grouped by publication, most-relied-upon first. Each entry links to the source and lists the pages that cite it.

A minority of entries below describe a body of work rather than a single paper, for example the Russian-language clinical literature on Selank, or the in-vitro antimicrobial work on LL-37. Those have no single identifier to link because no single paper is being cited, and we would rather say that than dress a summary up as a specific study. Replacing them with named, individually citable papers is ongoing, and our build currently reports 28 of 103 entries in that category.

New England Journal of Medicine · 14 sources

  1. Phase 3 Trial of Semaglutide in Metabolic Dysfunction-Associated Steatohepatitis (ESSENCE)

    2025 · Randomized Controlled Trial · n=800 · PMID 40305708

    Cited on Semaglutide

  2. Cardiovascular Outcomes with Tirzepatide versus Dulaglutide in Type 2 Diabetes (SURPASS-CVOT)

    2025 · Randomized Controlled Trial · n=13,165 · PMID 41406444

    Cited on Tirzepatide

  3. Orforglipron, an Oral Small-Molecule GLP-1 Receptor Agonist for Obesity Treatment (ATTAIN-1)

    2025 · Randomized Controlled Trial · PMID 40960239

    Cited on Orforglipron

  4. Effects of Semaglutide on Chronic Kidney Disease in Patients with Type 2 Diabetes (FLOW)

    2024 · Randomized Controlled Trial · n=3,533 · PMID 38785209

    Cited on Semaglutide

  5. Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity (SURMOUNT-OSA)

    2024 · Randomized Controlled Trial · PMID 38912654

    Cited on Tirzepatide

  6. Testosterone Treatment and Fractures in Men with Hypogonadism

    2024 · Randomized Controlled Trial · n=5,204 · PMID 38231621

    Cited on Testosterone (TRT)

  7. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes (SELECT)

    2023 · Randomized Controlled Trial · n=17,604 · PMID 37952131

    Cited on Semaglutide

  8. Cardiovascular Safety of Testosterone-Replacement Therapy (TRAVERSE)

    2023 · Randomized Controlled Trial · PMID 37326322

    Cited on Testosterone (TRT)

  9. Triple-Hormone-Receptor Agonist Retatrutide for Obesity: A Phase 2 Trial

    2023 · Randomized Controlled Trial · n=338 · PMID 37366315

    Cited on Retatrutide

  10. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1)

    2022 · Randomized Controlled Trial · n=2,539 · PMID 35658024

    Cited on Tirzepatide

  11. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1)

    2021 · Randomized Controlled Trial · n=1,961 · PMID 33567185

    Cited on Semaglutide

  12. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes (SURPASS-2)

    2021 · Randomized Controlled Trial · n=1,879 · PMID 34170647

    Cited on Tirzepatide

  13. Effects of Testosterone Treatment in Older Men (The Testosterone Trials)

    2016 · Randomized Controlled Trial · PMID 26886521

    Cited on Testosterone (TRT)

  14. Metabolic effects of a growth hormone-releasing factor in patients with HIV

    2007 · Randomized Controlled Trial · n=412 · PMID 18057338

    Cited on Tesamorelin

Eli Lilly investor release · 2 sources

  1. TRIUMPH-1 phase 3 topline results

    2025 · Randomized Controlled Trial · n=2,339

    Cited on Retatrutide

  2. TRIUMPH-4: retatrutide in obesity with knee osteoarthritis

    2025 · Randomized Controlled Trial

    Cited on Retatrutide

International Journal of Obesity · 2 sources

  1. The weight-reducing effect of an orally active growth hormone fragment in obese subjects (12-week trial)

    2004 · Randomized Controlled Trial

    Cited on AOD-9604

  2. The weight-reducing effect of an orally active growth hormone fragment in obese subjects

    2004 · Randomized Controlled Trial

    Cited on AOD-9604

Russian-language clinical literature · 2 sources

  1. Selank clinical use in generalized anxiety disorder

    Randomized Controlled Trial

    Cited on Selank

  2. Semax in post-stroke rehabilitation

    Observational Study · n=110

    Cited on Semax

The Lancet · 2 sources

  1. Tirzepatide for maintenance of bodyweight reduction in people with obesity in the USA (SURMOUNT-MAINTAIN)

    2026 · Randomized Controlled Trial · n=378 · PMID 42119587

    Cited on Tirzepatide

  2. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2)

    2023 · Randomized Controlled Trial · n=938 · PMID 37385275

    Cited on Tirzepatide

US Food and Drug Administration · 2 sources

  1. FDA integrated review, elamipretide (NDA 215244)

    2025

    Cited on SS-31 (Elamipretide)

  2. TAZPOWER trial and FDA integrated review

    2025 · Randomized Controlled Trial · n=12

    Cited on SS-31 (Elamipretide)

Aging · 1 source

  1. The mitochondrial derived peptide humanin is a regulator of lifespan and healthspan

    2020 · Animal Study · PMID 32575074

    Cited on Humanin

Alternative Therapies in Health and Medicine · 1 source

  1. Intra-Articular Injection of BPC-157 for Multiple Types of Knee Pain

    2021 · Case Series · n=16

    Cited on BPC-157

American Federation for Aging Research · 1 source

  1. TAME Trial Design

    2024

    Cited on Metformin

American Journal of Physiology / Gastroenterology · 1 source

  1. KPV inhibits inflammatory signaling in intestinal epithelial and immune cells

    2008 · In-Vitro

    Cited on KPV

BioImpacts · 1 source

  1. Topically applied GHK as an anti-wrinkle peptide: advantages, problems and prospective

    2025 · Systematic Review · PMID 39963574

    Cited on GHK-Cu

Bulletin of Experimental Biology and Medicine · 1 source

  1. Epithalon peptide induces telomerase activity and telomere elongation in human somatic cells

    2003 · In-Vitro · PMID 12937682

    Cited on Epithalon

Clinical Ophthalmology · 1 source

  1. Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial

    2015 · Randomized Controlled Trial · n=72 · PMID 26056426

    Cited on TB-500

Company-reported phase 2 results · 1 source

  1. RegeneRx phase 2 programmes in pressure ulcers and venous stasis ulcers

    Randomized Controlled Trial · n=143

    Cited on TB-500

Current Reviews in Musculoskeletal Medicine · 1 source

  1. Regeneration or Risk? A Narrative Review of BPC-157 for Musculoskeletal Healing

    2025 · Systematic Review · PMID 40789979

    Cited on BPC-157

Eli Lilly press release · 1 source

  1. FDA approves Foundayo (orforglipron)

    2026

    Cited on Orforglipron

FDA advisory committee proceedings · 1 source

  1. FDA Pharmacy Compounding Advisory Committee meeting, July 23-24, 2026

    2026

    Cited on KPV, Semax, DSIP, Epithalon, MOTS-c

FDA Orange Book, via the Federal Register determination · 1 source

  1. Geref (sermorelin acetate) approval history

    1997

    Cited on Sermorelin

FEBS Letters · 1 source

  1. Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex

    1988 · In-Vitro · PMID 3169264

    Cited on GHK-Cu

Food Frontiers (Wiley) · 1 source

  1. NMN and NR Comparison Review

    2025

    Cited on NMN / NR

Frontiers in Bioengineering and Biotechnology · 1 source

  1. Senolytic peptide FOXO4-DRI selectively removes senescent cells from expanded human chondrocytes

    2021 · In-Vitro

    Cited on FOXO4-DRI

Frontiers in Endocrinology · 1 source

  1. Critical Review of Metformin as Anti-Aging Drug

    2021

    Cited on Metformin

GeroScience / medRxiv · 1 source

  1. PEARL Trial: 48-Week Safety and Efficacy

    2025

    Cited on Rapamycin

HSS Journal · 1 source

  1. Emerging Use of BPC-157 in Orthopaedic Sports Medicine: A Systematic Review

    2025 · Systematic Review · PMID 40756949

    Cited on BPC-157

International Journal of Colorectal Disease · 1 source

  1. Ipamorelin phase 2b trial for postoperative ileus

    2014 · Randomized Controlled Trial · PMID 25331030

    Cited on CJC-1295 / Ipamorelin

International Journal of Molecular Sciences · 1 source

  1. Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data

    2018 · Mechanism · PMID 29986520

    Cited on GHK-Cu

JAMA · 1 source

  1. Continued Treatment With Tirzepatide for Maintenance of Weight Reduction (SURMOUNT-4)

    2024 · Randomized Controlled Trial · n=670 · PMID 38078870

    Cited on Tirzepatide

Journal of Medicinal Chemistry / Biochemical Pharmacology · 1 source

  1. Selective and membrane-permeable small molecule inhibitors of nicotinamide N-methyltransferase reverse high fat diet-induced obesity in mice

    2018 · Animal Study

    Cited on 5-Amino-1MQ

Multiple in-vitro studies · 1 source

  1. LL-37 antimicrobial and biofilm activity

    In-Vitro

    Cited on LL-37

Multiple randomized controlled trials · 1 source

  1. Thymosin alpha-1 in chronic hepatitis B

    1998 · Randomized Controlled Trial

    Cited on Thymosin Alpha-1

Nature Medicine · 1 source

  1. Two-year effects of semaglutide in adults with overweight or obesity (STEP 5)

    2022 · Randomized Controlled Trial · n=304 · PMID 36216945

    Cited on Semaglutide

Obstetrics and Gynecology · 1 source

  1. Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials (RECONNECT)

    2019 · Randomized Controlled Trial · n=1,267 · PMID 31599840

    Cited on PT-141 (Bremelanotide)

Original discovery, Schoenenberger and Monnier · 1 source

  1. Isolation of delta sleep-inducing peptide

    1977 · Animal Study

    Cited on DSIP

Preclinical and mechanistic studies · 1 source

  1. Selank effects on gene expression and BDNF

    Animal Study

    Cited on Selank

Preclinical studies · 1 source

  1. Semax effects on BDNF expression

    Animal Study

    Cited on Semax

Presented at the American Academy of Dermatology annual meeting · 1 source

  1. Leyden et al., 12-week facial and eye cream study in 71 women with photoaged skin

    2002 · Randomized Controlled Trial · n=71

    Cited on GHK-Cu

Proceedings of the National Academy of Sciences · 1 source

  1. A rescue factor abolishing neuronal cell death by a wide spectrum of familial Alzheimer's disease genes and Abeta

    2001 · In-Vitro · PMID 11371646

    Cited on Humanin

Randomized double-blind placebo-controlled crossover trial · 1 source

  1. TAZPOWER: elamipretide in Barth syndrome

    Randomized Controlled Trial · n=12

    Cited on SS-31 (Elamipretide)

Signal Transduction and Targeted Therapy (Nature) · 1 source

  1. Metformin decelerates aging clock in male monkeys

    2024

    Cited on Metformin

Various small trials · 1 source

  1. Human DSIP sleep studies

    Randomized Controlled Trial

    Cited on DSIP

Other primary sources · 13 sources

  1. Bremelanotide clinical development program

    2019 · Randomized Controlled Trial

    Cited on PT-141 (Bremelanotide)

  2. Selective NNMT inhibitors reverse high fat diet-induced obesity in mice

    2018 · Animal Study

    Cited on 5-Amino-1MQ

  3. NNMT inhibition and NAD+ salvage

    2018 · In-Vitro

    Cited on 5-Amino-1MQ

  4. KPV in DSS and TNBS-induced colitis models

    2013 · Animal Study

    Cited on KPV

  5. Anti-inflammatory activity of alpha-MSH C-terminal tripeptide

    2008 · In-Vitro

    Cited on KPV

  6. Phase 2b obesity trial (Metabolic Pharmaceuticals)

    2007 · Randomized Controlled Trial · n=536

    Cited on AOD-9604

  7. Randomized trials of thymosin alpha-1 in chronic hepatitis B

    1998 · Randomized Controlled Trial

    Cited on Thymosin Alpha-1

  8. LL-37 antimicrobial and antibiofilm activity in vitro

    In-Vitro

    Cited on LL-37

  9. Russian clinical studies of Selank in anxiety

    Randomized Controlled Trial

    Cited on Selank

  10. Selank effects on BDNF and neurotransmitter gene expression

    Animal Study

    Cited on Selank

  11. Semax effects on BDNF expression in rat hippocampus

    Animal Study

    Cited on Semax

  12. Russian cohort studies of Epithalamin and epithalon in elderly subjects

    Observational Study

    Cited on Epithalon

  13. Elamipretide in aged animal models

    Animal Study

    Cited on SS-31 (Elamipretide)

How we grade this evidence

The rubric that turns these sources into a certainty rating on each claim.

See the ratings

Every graded claim across every peptide, sorted by how strong the evidence is.