Testing and Clinical Studies

Clinical Studies


Medik8 is a cosmeceutical skincare brand. As such, we use only the best active ingredients in our formulations. We use clinical studies from trusted, ethical sources to validate what we do.

Studies on Retinaldehyde

Study - Retinol and retinal metabolism. Relationship to the state of differentiation of cultured human keratinocytes.
G Siegenthaler et al, Biochemical Journal, 1990, 268(2), pp 371-378

An in vitro study using cultured keratinocytes (epidermal skin cells) to observe how quickly retinol and retinaldehyde metabolised into retinoic acid (the bioactive form of vitamin A). Rate of formation of retinoic acid (pmol/h per mg of protein):
Retinol: 4.49
Retinaldehyde: 51.6 (11x faster)

Key result - Retinaldehyde converts to retinoic acid 11x faster than retinol. Faster conversion = faster results.


Study - Topical retinaldehyde on human skin: biological effects and tolerance
J Saurat et al, Journal of Investigative Dermatology, 1994, 103(6), pp 770-774

An in vivo study on 229 patients on keratome biopsies obtained after 4 day exposure to types of vitamin A in the same vehicle cream. Types used were retinol, retinoic acid and retinaldehyde. The study measured retinoic acid activity using CRABP2 protein induction (a hallmark of retinoic acid activity). Retinaldehyde is found to induce CRABP 2 to a similar extent to retinoic acid, and much more than retinol.

Key results - Retinaldehyde is more biologically active than retinol = better results.


Study - The antibacterial activity of topical retinoids: the case of retinaldehyde.
M Pechere et al, Dermatology, 2002, 205(2), pp 153-158

In vitro study exposing retinaldehyde, retinol and retinoic acid to different strains of bacteria. Retinaldehyde was the only type of vitamin A tested which showed significant, direct antibacterial action against gram-positive bacteria such as P. acnes.

Key result - Retinaldehyde is the only type of vitamin A tested which has direct antibacterial action, making it ideal for use on blemish-prone skins.


Study - Profilometric evaluation of photodamage after topical retinaldehyde and retinoic acid treatment.
P Creidi et al, Journal of American Academy of Dermatology, 1998, 39(6), pp 360-365

In vivo study on 125 patients over the course of 18 weeks. 40 patients used 0.05% retinoic acid, 40 patients used 0.05% retinaldehyde, 45 patients used a placebo cream. Both vitamin A creams produced a significant reduction in wrinkles and roughness, and no statistically significant differences were found between the retinoic acid and retinaldehyde groups. Retinaldehyde was much better tolerated than retinoic acid.

Key result - Retinaldehyde provides the results of retinoic acid, without the irritation.


Study - Repair of UVA-induced elastic fiber and collagen damage by 0.05% retinaldehyde cream in an ex vivo human skin model. S Boisnic et al, Dermatology, 1999, 199(Suppl 1), pp 43-48

An ex vivo study using human skin explants which had been subjected to UVA exposure to stimulate photoaging. 0.05% retinaldehyde cream was then applied for 2 weeks and the results compared to non-treated skin explants. In the retinaldehyde skin explants, collagen and elastin fibers were restored to the level of non-photodamaged skin.

Key result - Retinaldehyde can help to repair collagen and elastin damage induced by UVA exposure.