Every peptide, explained.
Most peptides work by restoring a signal your body already uses. Each entry covers what the peptide is, the signal it works through, and what the research actually shows, with every claim referenced to the primary literature. How entries are graded
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Immune defense
Sermorelin
A small peptide that copies the first 29 amino acids of growth-hormone-releasing hormone, the signal your brain sends to tell the pituitary to make growth hormone.
Human-testedSemaglutide
A longer-lasting version of GLP-1, a hormone your gut releases when you eat.
EstablishedBPC-157
A 15-amino-acid piece of a protective protein found in stomach juice, made synthetically.
Early researchTirzepatide
A weekly peptide that acts like two gut hormones at once, GLP-1 and GIP.
EstablishedIpamorelin
A small five-amino-acid peptide that mimics ghrelin, one of the signals that triggers growth hormone release.
Human-testedCJC-1295
A modified version of growth-hormone-releasing hormone engineered to last days instead of minutes.
Human-testedPT-141 (Bremelanotide)
A seven-amino-acid peptide that works on the brain circuits involved in sexual desire.
EstablishedTB-500 (Thymosin Beta-4)
A synthetic version of thymosin beta-4, a 43-amino-acid protein found in almost every cell, concentrated where the body is repairing itself. Products sold as TB-500 are the full peptide or a short active fragment of it.
Early researchGHK-Cu
A three-amino-acid peptide bound to copper, found naturally in your blood, saliva, and wound fluid.
Early researchRetatrutide
An experimental weekly peptide that acts on three metabolic hormone receptors at once: GLP-1, GIP, and glucagon.
Human-testedTesamorelin
A stabilized version of growth-hormone-releasing hormone, engineered to resist breakdown so it lasts longer than the natural signal.
EstablishedGlutathione
A three-amino-acid peptide your cells make themselves, and the body's main antioxidant.
Human-testedAOD-9604
A synthetic copy of the tail end of the growth hormone molecule (amino acids 177-191), the region tied to fat metabolism.
Early researchMOTS-c
A 16-amino-acid peptide encoded not in your chromosomes but in your mitochondria, the energy factories inside cells.
Early researchEpithalon
A four-amino-acid peptide modeled on epithalamin, a substance produced by the pineal gland, the small brain structure that runs your sleep-wake hormones.
Human-testedThymosin Alpha-1
A 28-amino-acid peptide originally isolated from the thymus, the gland where immune T-cells learn their job.
Human-testedSelank
A seven-amino-acid peptide developed in Russia from tuftsin, a natural immune fragment, taken as a nasal spray.
Human-testedSemax
A seven-amino-acid peptide built from a fragment of ACTH, a brain signaling hormone, with the hormonal activity removed. Also a nasal spray, also Russian.
Human-testedKisspeptin
The body's master switch for the reproductive hormone system, a peptide discovered surprisingly recently, in the 1990s.
Human-testedOxytocin
A nine-amino-acid hormone your brain makes, tied to labor, bonding, and social connection.
EstablishedThe Atlas is growing. New entries are added in reviewed batches, ordered by what people ask about most.