RETINAL
Retinaldehyde, better known as retinal, is a vitamin A derivative (retinoid). Retinoids increase collagen levels in the upper dermis by inhibiting collagen breakdown and stimulating collagen synthesis. Retinal is a natural precursor to retinoic acid, meaning it requires only a single conversion step to be oxidized into its active form. According to recent studies, retinal is considered the most effective over-the-counter retinoid, offering a favorable balance of efficacy and tolerability.(1)
Retinal is a popular active ingredient for treating skin with signs of photoaging and is generally better tolerated than retinoic acid. Photoaging is the premature aging of the skin caused by cumulative exposure to ultraviolet radiation. A randomized, double-blind study investigated the effects of 0.05% and 0.1% retinal on photoaged skin. Both concentrations resulted in an improvement in general signs of photoaging as well as a significant improvement in fine wrinkles and skin roughness. In addition, both concentrations reduced transepidermal water loss and increased the skin’s moisture content. 0.1% retinal also resulted in a significant improvement in skin pigmentation. Both concentrations were well tolerated.(2)
The conversion of retinal to retinoic acid occurs only in keratinocytes at a specific stage of differentiation, which results in a more controlled uptake of retinoic acid. This leads to milder retinoid-related side effects, such as skin irritation or redness, compared to tretinoin and other retinoids, which is why retinal is generally better tolerated.(3)
In another study, a 0.05% retinal solution was shown to significantly increase epidermal thickness and skin elasticity. The retinal treatment also led to an increase in dermal thickness and a reduction in skin stiffness, and was very well tolerated by the patients.(4)
In an ex vivo study, significant repair of elastic fibers and collagen changes caused by UV radiation, as well as increased collagen synthesis, were observed.(5)
Overall, it can be concluded that 0.05–0.1% retinal is effective in reducing signs of skin aging.
Retinal has mild comedolytic properties.(6) In a study examining the antibacterial activity of retinal against C. acnes, daily topical application of 0.05% retinal was also associated with a significant reduction in C. acnes density. This finding suggests direct antibacterial activity.(7)
In another study, 0.05% retinal, when applied topically, exhibited the same activity profile as 0.025% retinoic acid, namely a comedolytic and epidermal-thickening effect. The study’s results support the topical use of retinal in the treatment of acne.(8)
(1) Milosheska, D. & Roškar, R. (2022). Use of Retinoids in Topical Anti-Aging Treatments: A Focused Review of Clinical Evidence for Conventional and Nanoformulations. Advances in Therapy, 39(12), 5351–5375. https://doi.org/10.1007/s12325-022-02319-7
(2) Kwon, H. S., Lee, J. H., Kim, G. M., & Bae, J. M. (2018). Efficacy and safety of 0.1% and 0.05% retinaldehyde creams used to treat photoaged skin: A randomized, double-blind, controlled trial. Journal of Cosmetic Dermatology, 17(3), 471–476. https://doi.org/10.1111/jocd.12551
(3) Mukherjee, S., Date, A., Patravale, V., Korting, H. C., Roeder, A., & Weindl, G. (2006). Retinoids in the treatment of skin aging: an overview of clinical efficacy and safety. Clinical Interventions in Aging, 1(4), 327–348. https://doi.org/10.2147/ciia.2006.1.4.327
(4) Diridollou, S., Vienne, M.P., Alibert, M., Aquilina, C., Briant, A., Dahan, S., Denis, P., Launais, B., Turlier, V., & Dupuy, P. (1999). Efficacy of Topical 0.05% Retinaldehyde in Skin Aging as Assessed by Ultrasound and Rheological Techniques. Dermatology, 199, 37–41.
(5) S. Boisnic, M.-C. Branchet-Gumila, Y. Le Charpentier, C. Segard; Repair of UVA-Induced Elastic Fiber and Collagen Damage by 0.05% Retinaldehyde Cream in an ex vivo Human Skin Model. Dermatology 1 July 1999; 199 (Suppl. 1): 43–48. https://doi.org/10.1159/000051378
(6) Zouboulis, C. C., Katsambas, A. D., & Kligman, A. M. (Eds.). (2014). Pathogenesis and Treatment of Acne and Rosacea (pp. 121–122). Heidelberg, Germany: Springer.
(7) Péchère, M., Pechèreb, J., Siegenthalera, G., Germaniera, L., & Saurat, J. (1999). Antibacterial Activity of Retinaldehyde against Propionibacterium acnes. Dermatology, 199, 29–31. https://doi.org/10.1159/000051375.
(8) Fort-Lacoste, L., Verscheure, Y., Tisne-Versailles, J., & Navarro, R. (1999). Comedolytic effect of topical retinaldehyde in the rhino mouse model. Dermatology (Basel, Switzerland), 199 Suppl. 1, 33–35. https://doi.org/10.1159/000051376
