How we research

Published research available in the public domain. We search the medical literature databases including the dermatology and cosmetic science journals, the trial registries (ClinicalTrials.gov, Australia's ANZCTR, and the World Health Organization portal that pulls registries together), and conference abstracts. We search ingredient by ingredient, and by manufacturer too, since product trials can get registered under the parent company rather than the brand.

Well-run research studies in humans carry the most weight, lab findings carry less, theory on its own carries least. We also look at whether more than one group found the same result, whether the concentrations studied resemble what is actually in products, how long the study ran, who paid for it, and whether the outcome was objectively measured or subjectively reported.

Consistency beats drama. An ingredient with several modest study results that keep showing up stands on firmer ground than another ingredient with a spectacular finding in one study that nobody else has reproduced.

Strong. Multiple well-run human trials point the same way. Retinol for the appearance of fine lines is the classic example: decades of controlled studies, consistent results, well-understood dosing. When we say strong, we mean the kind of evidence that would satisfy a sceptic.

Moderate. Real human studies exist and are promising, but there are fewer of them, they are smaller, or they used the ingredient in combinations that make it hard to isolate the effect. Worth using with realistic expectations.

Limited. Some evidence exists, but it is thin: a small number of studies, lab or cell research that has not been well confirmed on real skin, or results that depend heavily on formulation. Limited does not mean useless. It means nobody can honestly promise you results yet, so it should not command a premium price.

Early. Mostly laboratory findings, tradition, or manufacturer data. Interesting, unproven on skin like yours.

Alpha arbutin is sold widely for evening skin tone, and we grade it Limited. There are plausible mechanisms and some supportive studies, but the independent human evidence is modest, and results vary with formulation. So Stratum Skin describes it as a gentle, low-risk option worth trying with patience over 8 to 12 weeks, not a guaranteed fix. No brand page will tell you that. We will, because the grade is the product.

Compare niacinamide, which we grade higher: repeated independent human trials, effects on the look of tone and texture at known concentrations, and good tolerability data. Two brightening ingredients, two very different levels of certainty, and you deserve to know which is which before you spend money.

That is where the answerable evidence sits. Research gets done on ingredients: what one does, at what concentration, over how long. Testing on a finished product is usually done privately by the company selling it. We work from an individual ingredient's evidence base, so we are clear about what that does and doesn't cover.

We don't have access to most product testing reports. Only drug and device trials have to be registered publicly; cosmetic testing doesn't. Australian law requires a company to hold evidence for its claims, but not to publish it, so when a product says "clinically proven", the study behind it usually stays with the company.

This means an unpublished study might be well-designed, or might be small, brief, and not able to answer the question convincingly. So when we say the evidence for something is thin, we mean the public evidence is thin. The claim might well be true but from outside the company, we cannot verify it. This is why our reviews rest on ingredient evidence, which is public and checkable, rather than on product claims we have no way to test.

In short, it's expensive and there is little commercial reason to do it. Nobody is required to run a proper trial to sell you a moisturiser, and since most ingredients aren't exclusive to one brand, good research funded by one company benefits every competitor using the same ingredient.

A careful read of the public evidence gives you some evidence, honestly labelled. Not knowing everything is different from knowing nothing. The alternative is trusting the hype and the pretty wrapping.

No. No brand, manufacturer or retailer pays us, supplies us, or sees a review before you do.

Yes, in both directions. We recheck against the latest meaningful research on a regular basis. A category can move up when better evidence appears, or down if what looked promising doesn't hold up.

We are telling you what the evidence supports and where it stops. Stratum Skin does not diagnose or manage skin conditions and is not a substitute for seeing a doctor. Think of it as a compatibility check and a personal log to track your skin behaviour over time.