A small, three-amino acid peptide (Glycine-Proline-Hydroxyproline) found naturally in our collagen structure.
The theory behind Tripeptide-29 is the following: Collagen is a long sequence of amino acids and breaking it down produces short amino acid sequences, aka peptides. These peptides "signal" to the skin that collagen was lost and that new collagen should be produced. So putting collagen-fragment-identical peptides on the skin might trick it into thinking that new collagen is needed.
The unique thing about Tripeptide-29 is that it is not produced by traditional methods such as chemically chopping up collagen as it gives lots of random peptides, but it is produced via modern peptide synthesis (from non-animal and non-GMO sources) that gives it exceptional purity. So Tripeptide-29 is available as a pure powder, unlike most peptides that are available as diluted solutions, which makes it possible to use it in much higher concentrations.
This sounds great but there is a catch: the efficacy data from the manufacturer contains only two tests, both in-vitro, aka done in test tubes, not on real people. Based on the lab test, 3% Tripeptide-29 can increase collagen type I synthesis by 400% after 48 hours. However, if anything happens when Tripeptide-29 is applied on real human skin is a good question with no answer (at least we could not find one).
Overall, the theory is nice, but the proof is missing. If you are into peptides and experimenting, this sure sounds interesting but if you like the tried and true this one is not for you.