Not yet investigated
What we have so far
The only topical class with decades of evidence for photoageing, and it works by making the skin behave younger, not by moisturising it. It is vitamin A, and it is teratogenic.
This star is on the map because the show intends to take the question apart properly — the trials, how it is actually tested, whether the thing sold is the thing studied. That work is not done yet, and nothing here should be read as a conclusion. When the investigation is published it will appear on this page.