Peptide is doing a great deal of work on labels at the moment. It is worth knowing that the word means far less than it appears to.
The word does almost no work
A peptide is a relatively short chain of amino acids. Amino acids are the building blocks of proteins, and a protein is a much longer chain of the same things, folded into a particular shape.
So peptide is a description of size and structure. It is not an ingredient class. It is not a category of product. It is not a measure of strength.
Which means two things called peptides can be entirely unrelated.
Both of these are peptides
GHK-Cu, the copper peptide in cosmetic serums, is three amino acids — glycine, histidine and lysine — bound to a copper ion. BPC-157, one of the compounds circulating in the injectable market, is fifteen amino acids and a different molecule with a different origin. Grouping them because both are peptides is like grouping two products because both contain a carbon chain.
What the ambiguity is for
Once you notice it, the pattern is everywhere.
Search for copper peptides and you will find pages that move between face serums and injectable products inside a single article, and comparison guides that set a skincare ingredient directly against an injectable research compound as though they were competing options. There are blends sold as one product that combine the two.
The ambiguity is useful to whoever is selling.
A word that sounds specific but denotes only a shape lets credibility travel between molecules that have nothing to do with each other. Research on one becomes atmosphere around another.
