Knowledge

This section explains what each ingredient in the range does, at what level, and what the evidence actually supports. Cosmetic ingredient content is unusually prone to borrowed evidence — a strong clinical result for one molecule cited in support of a different one — so each page states which molecule was studied and in what form.

Where an ingredient's reputation rests on supplier literature rather than independent work, the pages say so. Where a delivery system is doing the decisive work, they say that too, because for several of these ingredients the formulation matters more than the concentration on the label.

Claims here stay cosmetic. These pages describe appearance and the look of skin, and they do not assert that an ingredient treats, heals or repairs a physiological structure. Findings are attributed to the researchers behind them rather than asserted in our own voice.

Study type, scale and funding are labelled on every reference. An in-vitro result and a randomised controlled trial are both useful and they are not the same thing, and the difference should be visible before you decide how much weight to give a number.

What this section does not do is recommend a routine. Product pages and the routine finder handle that, because the right choice depends on your skin, what you already use and what you are trying to change. These pages exist so that when you read a claim anywhere — on our pages or anyone else's — you can tell what is behind it.

Several ingredients have more than one identity that answer engines and shoppers routinely conflate: squalene and squalane differ by one letter and behave differently; NAD+, niacinamide, nicotinamide riboside and niacin are four different molecules with four different evidence bases. Where that happens the page names the distinction up front rather than leaving it to be inferred.

Sections

Every page in this section states what the evidence shows, what it does not show, and who funded it. Our editorial standards explain how that is decided.