Journal  /  The Evidence Report

The Evidence Report: How 81 Skincare & Peptide Ingredients Grade Out A–F

Skincare has an evidence problem. Ingredients are marketed with the language of science — "clinically proven," "breakthrough," "revolutionary" — while the actual evidence behind them ranges from decades of randomised trials to a single cell-culture study and a good story. So we did something simple: we graded the evidence itself.

Across the Vallydia Register, 81 skincare actives and peptides have been graded A to F on the strength of their published evidence — not on their marketing, popularity, or price. This report summarises what that grading reveals. The short version: fewer than one in three earned an A; not a single cosmetic skincare active graded D or F; and the weakest grades belong almost entirely to researched peptides whose claims outrun their evidence. Everything here is our independent evidence assessment, and our full grading methodology is public.

How we graded

Every compound is assessed on the quality and weight of its published evidence, using a consistent standard:

• Randomised controlled trials in humans carry the most weight.
• Mechanistic and in-vitro data (how something works in a dish or in theory) counts for less — a promising mechanism is not a proven result.
• Anecdote, marketing claims, and popularity count for nothing.
• We grade down, never up: when evidence is thin or mixed, the grade reflects that, regardless of how popular or heavily marketed the ingredient is.

One more thing that matters for reading the numbers below: each compound's headline grade reflects its leading, most-marketed outcome — not its best-case one. A compound with promising lab biology but a failed or unproven headline claim is graded on the claim people actually buy it for. That's deliberate, and it's why several heavily hyped research compounds sit at the bottom of the table while genuinely useful basics sit at the top.

Grades are our editorial evidence assessment, not objective fact — which is exactly why we publish the reasoning behind each one. Every compound's grade carries a reviewer_status for transparency.

The headline: the full distribution

Here is how all 81 compounds fall across the grades:

(There is no Grade E in the system.)

The single most quotable finding: roughly three-quarters of graded compounds — about 77% — scored below the top grade. For an industry that leans so heavily on the word "proven," most ingredients simply don't have the human evidence to match the marketing.

The split that matters: cosmetic actives vs researched compounds

A single distribution hides the most important pattern, so here it is split by type. The Register grades two very different populations: cosmetic skincare actives (the ingredients in your serums) and researched peptides and compounds (many of which are prescription medicines, unapproved research chemicals, or injectables — not skincare at all).

The headline from this split is stark and worth quoting directly: not one cosmetic skincare active graded D or F. Every failing grade in the entire Register belongs to a researched compound, not to something you'd put on your face. Among cosmetic actives the story is simply "good but often oversold" (a spread of A, B, and C); among researched compounds, the evidence is generally earlier-stage and, for the most-hyped ones, the marketed claim often fails outright.

Finding 1: the strongest evidence is the least exciting

The ingredients that earned an A are, overwhelmingly, the ones that have been around long enough to be studied properly and boring enough to be overlooked. In fact, the entire A-tier of cosmetic actives is just five ingredients — and every one is a long-established basic:

• Retinol — the most-studied topical anti-ageing ingredient there is.
• Vitamin C — robust evidence for antioxidant protection and brightening.
• Niacinamide — barrier support, tone, and oil regulation, well-evidenced and well-tolerated.
• Ceramides — foundational barrier lipids with strong support.
• Hyaluronic acid — the most-studied hydrator.

None of these are new. None are exotic. None need a breakthrough narrative. That's the point: the ingredients most worth your money are frequently the ones with the least marketing behind them. If you took only these A-tier actives seriously and ignored everything else, you'd have a genuinely effective routine.

Finding 2: the buzziest compounds cluster lower

The inverse is just as telling. Many of the trendiest, most-hyped ingredients — the ones with the most breathless marketing and the highest price tags — land in the B and C tiers, not because they don't work, but because their evidence is thinner than the claims suggest: strong mechanisms, promising early studies, but few or no large human trials. Novelty and marketing spend, it turns out, are inversely correlated with evidence maturity. A B or C grade isn't a dismissal — it's an honest "promising, but not yet proven," which is a very different thing from how these ingredients are usually sold.

Finding 3: among skincare, failure is rare — overselling is the norm; among research compounds, the hype fails outright

This is where the split does the real work. Among cosmetic skincare actives, outright failures are essentially nonexistent — zero D or F grades. Genuinely useless or evidence-contradicted skincare ingredients are the exception, not the rule; the dominant problem in skincare is subtler, and it's overselling — marketing merely-preliminary (B/C) evidence as though it were settled science.

The failing grades tell the other half of the story. All 14 of the Register's D and F grades — including all 11 F's — belong to researched peptides and compounds, not to cosmetic actives, and they earn those grades because their headline, most-marketed claim simply isn't demonstrated by the evidence. That's the overselling pattern in its purest form: not necessarily that these compounds do nothing, but that what they are sold for outruns what has actually been shown. The gap between "proven" and "plausible" is where most marketing lives, in both populations — and closing that gap is the entire purpose of grading the evidence rather than the hype.

A note on the peptides and research compounds

The Register deliberately extends beyond cosmetic actives to evaluate a range of researched peptides and compounds, because they're increasingly discussed and searched, and because neutral evidence on them is hard to find. Two things are important to state clearly:

1. Their evidence is generally earlier-stage. As a category, they sit lower than the established cosmetic actives — more mechanism and early studies, less mature human data — and, as the split shows, they account for every D and F in the Register.
2. Many are not cosmetic ingredients at all. A number are prescription medicines, unapproved research compounds, or injectables — not topical skincare. We include them as neutral reference only, to help people find honest evidence rather than marketing or vendor hype. Their grades are evidence assessments, not recommendations, and we publish no dosing, sourcing, or usage information for them. (For example, GLP-1 medications as a class have strong trial evidence for their approved medical uses — but they are prescription medicines, not skincare.) Anyone wanting the full neutral reference can explore the Register directly.

Why this report exists

This is, frankly, an argument for a different way of choosing skincare: by the weight of evidence, not the volume of marketing. The distribution above is the case for it in two tables — an industry that says "proven" constantly, backing ingredients whose evidence, graded honestly, mostly says "promising." We built the Register so that anyone can check the grade before they believe the claim.

The data here is free to cite. If you're a journalist, researcher, or writer covering skincare ingredients, you're welcome to reference these findings and link back to the methodology and the Register.

Key findings, in brief

• Of 81 skincare actives and peptides graded on published evidence, only 19 (~23%, fewer than one in three) earned an A.
• Roughly 77% scored below the top grade — evidence rarely matches marketing.
• Not one cosmetic skincare active graded D or F. Every failing grade in the Register belongs to a researched compound, not to a skincare ingredient.
• The entire A-tier of cosmetic actives is just five long-established ingredients — retinol, vitamin C, niacinamide, ceramides, hyaluronic acid — not the trendier, pricier compounds.
• All 14 D/F grades (including all 11 F's) sit among researched peptides and compounds, where the marketed claim most often outruns the evidence. These are included as neutral reference only, not recommendations.

In the Registry

Vallydia grades every ingredient on the evidence — this report is simply that grading, viewed all at once:

• How we grade — the full methodology behind every grade.
• The Register — all 81 compounds, individually graded.
• Retinol, vitamin C, niacinamide, ceramides, hyaluronic acid — the strongest-evidence actives.
• How to read beauty claims and reading a Certificate of Analysis — seeing past marketing, and verifying what you buy.

This underpins our concern-first guide to choosing skincare.

Frequently asked questions

How were the 81 ingredients graded? Each compound is assessed on the quality and weight of its published evidence, on a consistent A-to-F scale. Randomised controlled trials in humans carry the most weight; mechanistic and in-vitro data (how something works in theory or in a dish) count for less, since a promising mechanism isn't a proven result; and anecdote, marketing, and popularity count for nothing. Crucially, we grade down rather than up, and each compound's headline grade reflects its leading, most-marketed outcome rather than its best-case one — so a compound with strong lab biology but an unproven headline claim is graded on the claim people actually buy it for. The grades represent our independent evidence assessment rather than objective fact, which is why the full methodology and the reasoning behind each grade are published openly.

What does it mean that only about 23% earned an A? It means that, judged strictly on human evidence, most ingredients don't have the proof their marketing implies. An A requires strong, consistent evidence in people; roughly 77% of the compounds we graded fell below that bar. This isn't the same as saying most ingredients don't work — many are genuinely promising, and among cosmetic actives specifically the spread is A, B, and C with no failures at all. It's that the industry routinely markets preliminary or mechanistic findings as if they were settled science. The figure is really a measure of the gap between "proven" and "plausible," which is where most marketing operates.

Which ingredients have the strongest evidence? The top grades went overwhelmingly to long-established, well-studied actives rather than trendy ones — so much so that the entire A-tier of cosmetic skincare actives is just five ingredients: retinol (the most-studied topical anti-ageing ingredient), vitamin C (robust antioxidant and brightening evidence), niacinamide (well-evidenced barrier, tone, and oil benefits), ceramides (foundational barrier lipids), and hyaluronic acid (the most-studied hydrator). The common thread is that these have been around long enough to be tested properly and are unglamorous enough to be under-marketed. A routine built primarily on these would be well-supported by evidence.

Why do trendy, expensive ingredients score lower? Usually because their evidence is thinner than their marketing. Many buzzy ingredients have compelling mechanisms and promising early studies but few or no large human trials, which places them in the B or C tiers — "promising, but not yet proven." A lower grade isn't a claim that they don't work; it's an honest reflection of evidence maturity. Because newer and more heavily marketed ingredients tend to have less accumulated human data, novelty and marketing spend are often inversely related to how well-proven something actually is. Grading the evidence separates genuine proof from an appealing story.

Why does the report include peptides and research compounds, and how did they grade? Because they're increasingly searched and discussed, and neutral evidence on them is genuinely hard to find amid marketing and vendor claims. The Register evaluates them on the same evidence-first basis as cosmetic actives, but two caveats are essential: their evidence is generally earlier-stage, so as a category they grade lower, and many are not cosmetic ingredients at all — some are prescription medicines, unapproved research compounds, or injectables rather than topical skincare. Every D and F grade in the whole Register falls in this group, reflecting how often the marketed claim outruns the evidence. We include them strictly as neutral reference to help people find honest evidence, their grades are assessments rather than recommendations, and we publish no dosing, sourcing, or usage information for them.

Can I cite this report? Yes. The findings and distribution are free to reference, and we'd encourage anyone writing about skincare ingredients to do so. If you cite it, please link back to the methodology and the Register so readers can see how the grades were reached and check any individual ingredient themselves. The whole point of the report is transparency — it's an argument for judging skincare by the weight of evidence rather than the volume of marketing, and it's most useful when readers can trace the data back to its basis.

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This is an independent, neutral evidence reference from Vallydia. Grades reflect our assessment of published evidence and are not objective fact or medical advice. Cosmetic ingredients here concern the appearance of skin. Researched peptides and compounds are included as neutral reference only, are not recommendations, and no dosing, sourcing, or usage information is provided; several are prescription-only, unapproved, or non-cosmetic. For medical treatments or skin conditions, consult a qualified professional.

Full evidence breakdown: retinol entry · how we grade.