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This guide teaches you to read the peptide space like a researcher, not a customer. We're Andres and Marko. We read the studies, and we're tired of watching people buy into claims nobody checked.
What's inside: what peptides are, what researchers actually study, how to tell a mouse study from a human one, what "research use only" means, how to read a certificate of analysis, and the red flags that should make you walk away.
Who we are
Marko Milovic is the founder and head coach of BOLD Fitness. He coaches clients in person, online and in hybrid programs on fat loss, building muscle and getting their energy back. He has worked with dozens of clients and learned from some of the best coaches in the game. He keeps this guide honest about what holds up in real life, not just on paper.
Andres Ocampo is a self-proclaimed peptide nerd with a PubMed habit he can't quit. He reads studies past the abstract, follows FDA hearings and compounding rulings the way other guys follow the draft, and tracks every shift in this market so you don't have to. His own approach to health is simple: nail sleep, training and nutrition, measure everything, and never believe a claim until he's seen the study behind it.
Five questions before you believe any claim
- Who was it tested on? Cells, rodents or people.
- How many? A dozen people is a pilot, not proof.
- Can you find the paper? No PMID, no claim.
- Who's telling you? Check what they sell and what they own.
- What does the certificate say? Lot, lab, identity, purity, date.
The rest of this guide explains each one.
What a peptide actually is
A peptide is a short chain of amino acids, usually 2 to 50 of them. String more than about 50 together and you have a protein. That's the whole definition.
Your body makes thousands of them. Oxytocin is 9 amino acids. Insulin, at 51, sits right on the line. Most peptides work as messengers: they bind a receptor on a cell and tell it to do something it already knows how to do.
That's the key difference from the things people lump them in with:
| What it is | How it works | |
|---|---|---|
| Peptide | Short amino acid chain | Binds a receptor and sends a signal |
| Anabolic steroid | Synthetic hormone built on a cholesterol ring | Crosses into the cell and binds a receptor that switches genes on and off |
| Protein supplement | Long chains you eat | Digested back into amino acids for fuel and building blocks |
What researchers are studying
Most of the peptides you hear about online sit in one of five research areas. The column that matters is the last one: where the evidence comes from. For most of these, it's cells and rodents, not people.
| Research area | Compounds people name | What's being studied | Where the evidence mostly comes from |
|---|---|---|---|
| Tissue repair | BPC-157, TB-500 | Tendon, ligament and gut tissue in injury models | Rodent studies; very few small human reports |
| Growth hormone signaling | CJC-1295, ipamorelin, tesamorelin | How the pituitary is signaled to release growth hormone | Mixed; tesamorelin is an approved drug for one narrow condition, the rest are early research |
| Skin and copper peptides | GHK-Cu | Collagen signaling in skin cells | Cell studies plus cosmetic topical research |
| Brain and nervous system | Semax, selank | Nerve growth factors and stress signaling | Mostly Russian clinical literature and rodent work |
| Cell aging and mitochondria | Epitalon, MOTS-c, SS-31 | Telomeres, cell energy, mitochondrial function | Mostly cell and animal studies; SS-31 (elamipretide) became a prescription drug for one ultra-rare genetic condition in 2025 |
A name on this table is not a recommendation. It means researchers are asking a question about it. Most of those questions don't have a human answer yet, and anyone who tells you otherwise is selling something.
How to read the evidence
The fastest way to see through peptide hype is to ask one question: who was this tested on? Evidence comes in tiers, and each step up is harder and rarer.
- In vitro. Cells in a dish. Useful for mechanism, useless for predicting what happens in a whole body.
- Animal. Usually rats or mice. A finding in a rodent often fails to repeat in humans, and doses don't translate one to one.
- Small human studies. A few dozen people, often no control group, sometimes funded by someone with a stake in the result.
- Randomized controlled trials. Hundreds of people, a placebo group, blinded. This is the bar for real confidence, and most research peptides have never cleared it.
When someone cites a study, find it on PubMed. Every paper there has a PMID, an ID number you can paste into pubmed.ncbi.nlm.nih.gov. Then check three things in the abstract:
- The species. "Rats" or "mice" in the methods means stage 2, no matter how the post described it.
- The size. Count the participants. Twelve people is a pilot, not proof.
- The outcome. Did they measure the thing being claimed, or something next to it, like a blood marker?
A useful habit: when a claim sounds huge, look for the tier. The bigger the promise, the more likely it rests on a mouse.
What "research use only" means
Most peptides sold online are not approved drugs and not dietary supplements. They're sold as research materials: compounds for laboratory work, labeled "for research use only, not for human or veterinary use." That label is a legal category, not a wink.
Three categories are worth knowing:
| Category | What it means | Example |
|---|---|---|
| Approved drug | Passed FDA review for one specific condition | Tesamorelin; elamipretide (SS-31) |
| Compounding flagged | The FDA's "Category 2" list names bulk substances with significant safety concerns, which compounding pharmacies can't use | Check the FDA list itself; it changes |
| Research material | Sold for lab research only; no approval for any human use | Most of what you see advertised online |
Status changes, sometimes fast. BPC-157 is the example: the FDA put it in Category 2 in 2023 and took it off on April 15, 2026. That did not make it approved. It still isn't cleared for compounding and has no FDA approval for any human use. Check the FDA's current list before you trust anything written about a specific compound, including this page.
How to read a certificate of analysis
A certificate of analysis (COA) is a lab report on one specific batch. It's the only thing that tells you what's actually in the vial, and most people never read past the green checkmark.
not a real report
Read it in this order:
- Lot number. It has to match the lot printed on the product. A COA for a different batch proves nothing about yours.
- Who tested it. A named, independent lab you can look up beats the seller's own "in-house" report.
- Identity (LC-MS or MS). Mass spectrometry confirms the molecule is the one on the label. No identity test means no proof it's the right compound.
- Purity (HPLC-UV). The percentage of the sample that is the target peptide. The rest is something else.
- Net content. How much peptide is actually in the vial, versus the number on the label.
- Date. An old report on a new batch is a copy-paste, not a test.
- What wasn't tested. Identity and purity tell you nothing about sterility, endotoxins or heavy metals. Those are separate tests, and a COA that doesn't list them didn't run them.
Full disclosure: we own Vitro Labs
Andres and Marko own Vitro Labs, a research materials company. We want that on the table before you read anything we say about testing.
We built Vitro to the standard this guide describes. Every batch is tested by Freedom Diagnostics, an ISO-certified independent lab, for identity by LC-MS, purity by HPLC-UV and net content. Every batch ships with a batch-specific certificate of analysis. What we don't test, we say plainly: Vitro does not run sterility, endotoxin or heavy-metal testing. Hold our reports to the checklist above, the same as anyone's.
Vitro Labs materials are for laboratory research use only, not for human or veterinary use.
See Vitro Labs certificatesvitrolabs.store · batch-verified COAs
Seven red flags
If you see any of these, the seller is telling you who they are.
- No COA, or one COA for every batch. Real testing is per lot.
- Human-use language on a research product. "Dosing guide," "results in 4 weeks," before-and-after photos. That's a seller crossing the line the whole category depends on.
- Purity claims with no method. "99% pure" means nothing without HPLC data and a lab name behind it.
- Influencer codes attached to health promises. Someone earns a cut every time you believe them.
- "Studies show" with no PMID. If they can't name the paper, assume it doesn't say what they claim.
- Undisclosed ownership. A creator praising a "trusted source" they secretly own. We told you ours on this page for exactly this reason.
- No lot number on the label. Without it, no certificate can be tied to the product in front of you.
Glossary
| Term | Plain meaning |
|---|---|
| Amino acid | One building block of a peptide or protein |
| Receptor | A lock on a cell surface; a peptide is the key |
| Secretagogue | Something that signals a gland to release a hormone |
| In vitro | In a dish, outside a living body |
| In vivo | Inside a living organism, usually an animal in early research |
| PMID | PubMed's ID number for a published paper |
| HPLC-UV | Lab method that measures purity |
| LC-MS | Lab method that confirms a molecule's identity by its mass |
| COA | Certificate of analysis: the lab report for one batch |
| Lot number | The batch ID that ties a product to its COA |
Sources
Last reviewed September 25, 2026.
- FDA: bulk drug substances that may present significant safety risks (Category 2)
- Holt Law: BPC-157's regulatory status in 2026 (secondary source for the April 2026 date; the FDA page above lists BPC-157 as withdrawn from Category 2)
- FDA: accelerated approval of elamipretide (Forzinity) for Barth syndrome
- PubMed, for looking up any PMID