One number counts peaks. The other weighs molecules. Confusing them is the most common misreading of a peptide certificate.
Featured investigation
Every major peptide benefit claim, sorted by how strong the human evidence actually is.
Research
Purity and identity are chemistry. Endotoxin and sterility are biology, and they are measured by completely different tests that most peptide certificates of analysis never ran.
Peptides break down through a small set of well-characterised chemical reactions. Here is what deamidation, oxidation, hydrolysis and aggregation actually are, why temperature and moisture drive them, and what a real stability study measures.
Synthetic peptides are sold by gross weight, but part of that weight is salt and water, not peptide. Here is what net peptide content means, why HPLC purity does not measure it, and how the gap is actually quantified.
One target, two targets, three targets: semaglutide, tirzepatide and retatrutide represent three generations of the same drug idea. Here is what their landmark trials actually reported, what can and cannot be compared across them, and where each stands with regulators.
NAD+ is sold as drips, shots and supplements for energy and aging. Precursor pills really do raise NAD+ in blood - but the benefit trials are mostly small and mixed, and direct NAD+ infusions have almost no published human data. Here is the honest picture.
'Peptide therapy' is a marketing umbrella, not one treatment. Some peptides under it are FDA-approved and highly effective; others are unproven research chemicals. Here is how to tell the benefits apart.
Explore by peptide
Synthetic gastric-derived pentadecapeptide
A synthetic 15-amino-acid peptide with a large animal literature on tendon, muscle and gut healing, almost no controlled human data, and no FDA approval.
Growth hormone-releasing hormone (GHRH) analogue
A synthetic GHRH analogue that raises growth hormone and IGF-1 in short human pharmacology studies. Development was discontinued; no outcome trials exist and it is not FDA-approved.
Dietary protein hydrolysate (mixture of collagen-derived di-, tri- and oligopeptides)
Food-grade hydrolysed collagen taken orally, with multiple randomised trials for skin hydration, joint discomfort and body composition — modest effects, mostly industry-funded, and no drug approval needed.
Naturally occurring copper-binding tripeptide
A naturally occurring copper-binding tripeptide with small human trials in topical skin care and wound healing, extensive gene-expression studies, and no drug approval.
Growth hormone secretagogue (ghrelin/GHS-R1a agonist), pentapeptide
A selective ghrelin-receptor agonist that stimulates growth hormone release. Early human studies exist; a post-operative ileus programme was discontinued for lack of efficacy. Not FDA-approved.
Melanocortin receptor agonist (cyclic heptapeptide, melanotan II metabolite)
Bremelanotide, marketed as Vyleesi, is an FDA-approved melanocortin agonist for hypoactive sexual desire disorder in premenopausal women. Its use in men and for erectile dysfunction is not approved.
GLP-1 receptor agonist (incretin mimetic), 31-amino-acid modified peptide
An FDA-approved GLP-1 receptor agonist with large randomised trials for type 2 diabetes, chronic weight management and cardiovascular risk reduction — the strongest evidence base of any peptide in this publication.
Synthetic fragment of thymosin beta-4 (actin-sequestering peptide)
A synthetic fragment marketed as thymosin beta-4. The full-length natural peptide has early human trials in wound healing and eye disease; the fragment sold as TB-500 has none.
Growth hormone-releasing hormone (GHRH) analogue
An FDA-approved GHRH analogue that reduces visceral abdominal fat in HIV-associated lipodystrophy. Widely discussed off-label for body composition and cognition, where evidence is much thinner.
Dual GIP/GLP-1 receptor agonist, 39-amino-acid modified peptide
An FDA-approved dual GIP and GLP-1 receptor agonist with large randomised trials showing the greatest weight loss of any approved incretin therapy, plus approvals for type 2 diabetes and obstructive sleep apnoea.
Explore by research area
Fat loss and lean mass claims are the most common reason people search for peptides. The evidence ranges from large approved-drug trials to zero human data, depending on the peptide.
Cognitive claims for peptides — focus, memory, neuroprotection — are almost entirely preclinical. GLP-1 drugs are the exception, with large Alzheimer's trials now reporting.
"Longevity" claims for peptides rest on animal lifespan studies and hormone-level surrogates. No peptide has human evidence of extending lifespan or healthspan.
A reader's guide to peptide research: study types, what animal models can and cannot tell you, common statistical traps, and how marketing misuses real papers.
Thymic peptides have a long, mixed history in immunology; the popular "immune-boosting" peptides sold online have little or no human evidence for immune outcomes.
GLP-1 and dual-incretin peptides have transformed metabolic medicine with large trials and FDA approvals; almost every other "metabolic" peptide claim rests on far weaker evidence.
What is known about the safety of approved peptides from their trials and labels, and why "no reported side effects" for unapproved peptides usually means "no one has looked".
What peptide research actually shows for tendon, ligament, muscle, gut and wound healing — mostly animal data, with a few small human studies and one approved topical use.
How the FDA classifies peptides — approved drugs, investigational agents, compounding-eligible substances, and "research use only" products — and why the categories matter for evidence and safety.
Bremelanotide (PT-141) is FDA-approved for hypoactive sexual desire disorder in premenopausal women; its use in men and for erectile dysfunction is not approved and rests on older, smaller studies.
Topical copper peptides and oral collagen peptides have small human trials for skin; hair-growth claims for peptides rest almost entirely on animal and cell studies.
Evidence system
Every page carries both labels. The matrix on the right plots each profiled peptide on both axes for its most-discussed use — and shows how often they disagree.
| Evidence ↓ / Regulatory → | FDA-approved for this use | Not FDA-approved |
|---|---|---|
| Established | ||
| Promising | ||
| Preliminary | ||
| Preclinical |
Comparison
BPC-157 vs TB-500
Comparison
CJC-1295 vs ipamorelin vs tesamorelin
Comparison
Semaglutide vs tirzepatide
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