The Science: Ingredient Research Hub

What it is. PDRN, or polydeoxyribonucleotide, is a purified fragment of DNA taken from salmon. Polynucleotides, or PN, are the closely related longer chains used in clinic skin boosters. Both are prized in Korea for being gentle and skin compatible.

In Korean skincare, PDRN and PN are loved for a hydrated, plumped, smoother looking finish and a healthy looking glow. Laboratory work has also looked at how PDRN behaves around pigment cells.

Our honest read. Most of the deeper research on PDRN and PN comes from professional and laboratory settings, not from skincare applied to the skin. We stock cosmetics that feature salmon DNA, so we share this to explain the ingredient, not to borrow those results as claims about our serums. The brightening idea is promising but still at the laboratory stage.

What it is. NAD+ is a molecule every cell uses for energy and repair. Its levels fall as we age, which is why it has become such a talking point in skin science.

Research explores how NAD+ underpins skin cell energy and DNA repair, and whether feeding that pathway can support healthier looking skin over time.

Our honest read. The biology is real and well described, but NAD+ applied directly to the skin is still at the laboratory stage. The practical, human proven way to support the NAD+ pathway on your face is niacinamide, the vitamin your cells convert into NAD+. See the niacinamide section for the strong human evidence.

What it is. Collagen is the protein that gives skin its firmness and bounce. Collagen peptides are small, broken down pieces that the body can absorb, used in supplements and in some skincare.

Research explores whether oral collagen peptides improve skin elasticity and hydration, and whether smaller peptides applied to the skin can soften the look of lines.

Our honest read. The strongest, most repeated evidence is for oral collagen supplements taken as a drink or capsule. Peptides applied to the skin have smaller cosmetic studies. Oral and applied are different things, so we keep them separate here.

What it is. Exosomes are tiny messenger packages that cells use to send signals to one another. In skincare they are being explored as a way to carry rejuvenating signals to the skin.

Research explores exosomes for the look of ageing, for calming, for skin recovery and for hair, from many different sources including stem cells and plants.

Our honest read. This is an exciting but early field. Most of the strong data is still from the laboratory or animal studies, and human work is small and often done alongside a clinic procedure. Manufacturing is not yet standardised for cosmetics, so we describe exosomes as emerging, not proven.

What it is. Cica exosomes are exosome like nanovesicles drawn from Centella asiatica, the soothing herb known as cica. They pair the messenger idea of exosomes with the calming reputation of centella.

Research explores whether centella derived vesicles can calm the skin, protect against sun stress and support a smoother, more hydrated look.

Our honest read. This is the newest and thinnest area on the whole page. The laboratory and animal signals are interesting, and the one human study is a preprint, meaning it has not yet been checked by other scientists. Treat this as one to watch, not settled proof.

What it is. Centella asiatica, known as cica, is a herb used for centuries to calm and comfort skin. Its active parts include madecassoside, asiaticoside and asiatic acid.

Research explores centella for soothing, for supporting the skin barrier, for the look of firmness and for helping skin recover.

Our honest read. Centella has a solid soothing tradition and some good human studies. A few of the strongest results come from formulas that combine centella with other actives, so we avoid crediting centella alone for every benefit.

What it is. Adenosine is a small molecule your cells make naturally for energy signalling. In skincare it is a well known smoothing ingredient, and it is an approved anti wrinkle functional ingredient in Korea.

Research explores adenosine applied to the skin for the look of fine lines, roughness, firmness and hydration.

Our honest read. This one has good human studies for skincare applied to the face. Many use a specific formula, so effects are best described for adenosine containing products rather than adenosine on its own.

What it is. Amino acids are the building blocks of proteins, and they make up much of the skin's own natural moisturising factor, the built in system that holds water in the outer skin.

Research explores how amino acids support hydration and a healthy skin barrier, and how the skin's amino acid supply changes with age.

Our honest read. Amino acids are genuinely central to how skin stays hydrated and comfortable, and the human evidence supports their use for moisture and barrier support.

What it is. Niacinamide is a form of vitamin B3 and one of the best studied ingredients in all of skincare. It is also the vitamin your cells turn into NAD+.

Research explores niacinamide applied to the skin for even tone, the look of fine lines, barrier comfort and oil control.

Our honest read. This is as solid as skincare evidence gets, with several independent human trials. We are comfortable calling niacinamide well proven for even tone, smoothness and barrier support.

What it is. Glutathione is an antioxidant your body makes. It is popular for skin tone, and it comes in oral, applied to skin and injected forms.

Research explores whether glutathione can gently even skin tone and reduce pigment when taken by mouth or applied to the skin.

Our honest read. The evidence is mixed. Small trials suggest a modest effect on pigment, but studies are short and results are inconsistent, so we frame it as limited and emerging. Injected glutathione is a separate matter, covered in the caution below.