What are peptides used for?

The clusters

• Metabolic and weight — the incretin family, where the evidence is deepest because these compounds went through commercial drug development.
• Tissue repair and recovery — largely animal literature, often extensive, with human trials scarce.
• Growth-hormone signalling — secretagogues that raise endogenous GH rather than supplying it, with older clinical work behind several of them.
• Cognition and mood — a cluster where much of the human data was generated outside Western regulatory systems and is harder to appraise.
• Pigmentation and skin — a small group where the mechanism is well characterised and the safety literature is thin.

What “studied for” is doing in that sentence

A compound being studied for something is not evidence that it achieves it. Trials fail, and a large share of the literature behind these compounds is preclinical — cells and animals, where a mechanism can be real and still not translate. Each profile states the evidence stage rather than flattening everything into “research shows.”

The gap between the studied use and the marketed use is where most confusion on this subject originates. A peptide investigated in a rat tendon model becomes, three retellings later, a recovery product. The intermediate steps — does it work in humans, at what exposure, with what safety — are exactly the ones missing.

For how the evidence behind each compound is weighed and labelled, see the methodology.

Why the per-compound page is the real answer

Grouping by research area is useful for orientation and misleading past that point. Two compounds in the same cluster can differ by decades of evidence: within the metabolic group, one has completed Phase 3 trials with published outcomes and another has never been given to a human. The cluster tells you what question was being asked, not what answer came back.