403 ‒ Peptides: separating scientific promise from marketing hype

KEYPOINTS

• 01

  'Peptides' is a category, not a verdict—each must be judged individually.

  Peter stresses that some of the most important drugs ever made are peptides, including insulin and GLP-1 agonists. His aim is neither to promote nor dismiss them but to give a framework, because the same label covers rigorously proven medicines and essentially untested gray-market products.

• 02

  A five-question framework for anything you put in your body.

  1) Is there a viable mechanism of action? 2) Is there credible human evidence of benefit? 3) Are dose, pharmacokinetics and safety characterized, with a plan for monitoring and intervening? 4) Does the likely benefit justify the risk for this person, compared with doing nothing? 5) Is there a better-characterized alternative, and what do you gain by choosing the less characterized one?

• 03

  Mechanism matters because it makes a claim falsifiable and reveals failure modes.

  Unknown mechanisms exist but are the exception: among FDA-approved drugs, the share with genuinely unclear mechanisms is small. Even among compounds that clear preclinical testing, roughly 30–50% fail in phase 1 to advance, often because they don't behave in humans as predicted.

• 04

  A three-tier evidence system.

  Tier 1: no validated mechanism and little human data. Tier 2: plausible, even demonstrated biology, perhaps working in animals, but little evidence of improved human outcomes. Tier 3: approved drugs with evidence for a specific dose, route, population, indication and endpoint—though that evidence doesn't automatically transfer to other uses or gray-market versions.

• 05

  BPC-157 is Peter's poster child for skepticism.

  Described as a fragment of a 'body protection compound' from gastric juice, its parent protein sequence has never been published—the discoverer reportedly said, 'If you have your own child, you want it to be yours forever.' It doesn't clearly match any known human protein. Proposed mechanisms (VEGF/angiogenesis, nitric oxide, neurotransmitters) aren't established in humans, and 'peptide without a receptor' is not the same as having a mechanism.

• 06

  BPC-157's evidence base is thin and conflicted.

  More than 80% of published work comes from one academic group with IP and commercial ties. After roughly three decades of claims, there are no published peer-reviewed human randomized trials showing faster healing; human pharmacokinetics and bioavailability are unknown, so dosing protocols are guesses; phase 1 safety trials haven't been run. If you believe the angiogenesis mechanism, Peter says, you should worry more about cancer, not less—though that's not proof it causes cancer.

• 07

  Expanding claims signal weakness, not a broad mechanism.

  Legitimate drugs win one indication in rigorous trials and earn more over time. BPC-157's list of uses keeps growing while human trials—which are entirely feasible—aren't happening. A claim that explains away every failure by dose, timing, supplier or stacking isn't scientific.

• 08

  Biological activity isn't clinical benefit: CJC-1295.

  CJC-1295 genuinely raises growth hormone and IGF-1, but almost every drug changes biology. The question is whether it improves outcomes at a known dose with acceptable risk—and stimulating the GH axis may itself be an argument against it. Peter says that case hasn't been made.

• 09

  Testimonials can't establish effectiveness, and placebo effects are large.

  Stories are sincere but confounded: one friend credited peptides while also exercising, changing diet and taking tirzepatide. Pain trials have big placebo responses because pain is shaped by attention, expectation, sleep and mood. In STEP 1, semaglutide beat placebo substantially, but placebo participants also lost weight—showing why controls separate the drug from the drama.

• 10

  Doctors, compounding pharmacies and lab tests reduce some risks but validate nothing.

  A physician can help with screening, technique and monitoring, and third-party testing can check contents, but none proves efficacy, a valid dose, or equivalence to the studied product. Two vials with the same amino-acid sequence aren't necessarily equivalent; trials validate a product, not a sequence in the abstract—relevant to gray-market GLP-1s.

• 11

  Approved molecules sold on the gray market are a different product.

  Tier 3 evidence covers a specific manufactured drug at a studied dose, route and population. A gray-market version of an approved peptide may share a sequence but not purity, concentration, sterility or stability, so the trial evidence doesn't automatically extend to it. Peter asks people to be explicit about what they gain—cost, access, convenience—and what risk they are accepting in exchange.