What are the alternatives to retinol?

Retinol is primarily known for its effect on wrinkles and skin sagging. This is due to its ability to stimulate dermal production of collagen and elastin, two essential proteins for maintaining skin firmness and elasticity. By binding to nuclear receptors RAR, retinol regulates the expression of genes involved in the synthesis of type I and III collagen, thus promoting better skin support. In addition, it inhibits the action of matrix metalloproteinases, enzymes responsible for the degradation of collagen fibers. It should be noted that the action of retinol is progressive and takes about three months to be noticeable. Several active ingredients, also acting on skin aging, could be used to replace retinol.

• Bakuchiol.

  Often presented as the natural alternative to retinol, bakuchiol is also involved in the activation of fibroblasts and the synthesis of collagen and elastin. Like retinol, bakuchiol inhibits matrix metalloproteinases and has a protective effect on collagen fibers. It also has antioxidant properties, which are beneficial in preventing oxidative stress in cells, one of the causes of skin sagging.

  A study aimed to compare the effectiveness of a 0.5% bakuchiol cream to a 0.5% retinol cream on the wrinkles of 44 patients. For 12 weeks, the volunteers applied one or the other of these formulations. Although a significantly greater reduction in wrinkles was observed in the "retinol" group, bakuchiol was still effective and was approximately twice as well tolerated, in terms of redness, tingling, and flaking.

• Vitamin C.

  Primarily known for its antioxidant role, the Vitamin C is also capable of stimulating collagen synthesis. Indeed, Vitamin C acts as a cofactor for prolyl and lysyl hydroxylases enzymes, which are essential for the stabilization and cross-linking of collagen fibers. Some research also reports that this molecule inhibits the expression of certain matrix metalloproteinases. Vitamin C thus appears to be a comprehensive active ingredient for delaying skin sagging.

  Several studies have highlighted the benefits of vitamin C for mature skin, including a 2020 study involving 50 volunteers. These individuals applied a cream containing 20% vitamin C, vitamin E, and raspberry extract to one half of their face daily for two months. After eight weeks, an average reduction of 15.8% in wrinkle visibility was measured on the side where the cream was used, while no change was observed on the other side. However, 50% of the participants experienced a tingling sensation when applying the cream, likely due to the high concentration of vitamin C.

To avoid irritations associated with the use of pure vitamin C, most skincare products today utilize vitamin C derivatives.

• Glycolic acid.

  The glycolic acid is a molecule belonging to the family of alpha-hydroxy acids, known for its action on wrinkles. Its effectiveness is based on several biological mechanisms. Firstly, due to its small molecular size, it easily penetrates the epidermis and stimulates cellular renewal, which helps improve the skin's appearance and reduce wrinkles. Glycolic acid also has direct effects on stimulating the components of the dermal connective tissue, such as collagen and elastin. This active ingredient can also induce a slight controlled inflammatory response, which activates tissue repair processes and promotes dermal remodeling. Finally, glycolic acid increases levels of hyaluronic acid, thus promoting a more plump skin and a reduction in dehydration fine lines.

• Peptides.

  Peptides are powerful allies in combating wrinkles. Composed of amino acid chains, they play a crucial role in cellular communication by mimicking natural signals that regulate the production of the skin's structural proteins. Some peptides stimulate fibroblasts to increase the synthesis of collagen, elastin, and glycosaminoglycans, while others act as messengers to activate tissue repair pathways, thus promoting dermal renewal. There are also so-called enzyme inhibitor peptides, capable of limiting the activity of matrix metalloproteinases.

  A study was conducted on the effects of a moisturizing cream containing 3 ppm of the peptide Pal-KTTKS on the signs of aging in 93 volunteers. Divided into two groups, they applied the cream containing Pal-KTTKS or an equivalent without the active ingredient daily. A more significant reduction in wrinkles (13.5% versus 11.6%) was observed in individuals who received the cream with the peptide. Although small, the difference between these reductions was deemed significant by the authors.

Retinol does more than just address signs of aging: it can also target hyperpigmentation. This effect is largely due to its ability to accelerate the cellular renewal of the epidermis, leading to a rapid loss of melanin pigment through epidermopoiesis. Another theory is that retinol can cause a uniform dispersion of melanin granules within keratinocytes. It could also directly affect melanogenesis by inhibiting the expression of the enzyme tyrosinase, which is essential for melanin production. Retinol is not the only molecule capable of reducing brown spots, the active ingredients presented below can also fulfill this role.

• Glycolic acid.

  Not only beneficial for wrinkles, glycolic acid is also an ally in reducing the visibility of hyperpigmentation spots. As previously mentioned, this active ingredient has a significant exfoliating action. By breaking the bonds between the corneocytes, the dead cells of the horny layer, it promotes their elimination and thus reduces the accumulation of melanin on the surface of the epidermis.

  A relatively recent study examined the effects of a cream containing 0.05% tretinoin, 2% hydroquinone, and 1% hydrocortisone, used alone or in combination with a series of 20% glycolic acid peels (one peel every three weeks, for a total of six sessions). For this purpose, 30 individuals with a dark phototype and presenting hyperpigmentation were recruited and divided into two equal groups. The Hyperpigmentation Area and Severity Index (HASI) score was calculated before and after the study. The results, compiled in the table below, show a significantly greater improvement in hyperpigmentation for the participants who received the glycolic acid peels.

• Tranexamic acid.

  The tranexamic acid is another well-known active ingredient for its effects on hyperpigmentation. Generally found in concentrations between 1 and 5% in skincare products, it works on several levels to reduce melanogenesis. Tranexamic acid notably inhibits the release of inflammatory mediators, such as arachidonic acid and prostaglandins, involved in triggering melanogenesis. Furthermore, it blocks interactions between melanocytes and keratinocytes, thus preventing the cells of the epidermis from pigmentation. Finally, the chemical structure of tranexamic acid allows it to prevent tyrosine from binding to its active site through competitive inhibition.

  A study involving 42 women with hyperpigmentation examined the effects of a cream containing 2% tranexamic acid and 2% niacinamide. The participants were divided into two groups, with one group applying this cream daily and the other applying the same formula without the active ingredients for eight weeks. A significant decrease in the melanin index was observed in the first group. Thus, the combination of tranexamic acid and niacinamide presents an interesting alternative to retinol, even though tranexamic acid alone has also demonstrated its depigmenting potential.

Finally, retinol is a molecule of interest for acne-prone skin. Indeed, due to its keratolytic action, it accelerates cell renewal, which prevents the accumulation of dead cells on the skin's surface, one of the factors contributing to the formation of comedones. In doing so, retinol also promotes an aerobic environment that is inhospitable for Cutibacterium acnes, the primary bacteria involved in acne. However, retinol is not the only one capable of combating skin imperfections.

• Salicylic acid.

  The salicylic acid possesses keratolytic, antibacterial, and anti-inflammatory properties that are beneficial for skin imperfections. In addition to its inhibitory effect on the synthesis of prostaglandins E2, it curbs the production of sebum lipids by activating AMPK enzymes and SREBP-1 proteins. Furthermore, salicylic acid stands out for its liposoluble properties, allowing it to reach clogged pores and eliminate accumulated impurities. According to studies evaluating the effectiveness of an exfoliant containing 30% salicylic acid on 35 individuals, the average number of facial lesions decreased from 68.2 to 39 in 12 weeks. This study is far from being an isolated case, as others have highlighted the anti-imperfection virtues of this active ingredient.

• Succinic acid.

  Gentler than salicylic acid, succinic acid is another relevant option for reducing blemishes. Its mechanism of action is quite similar, except that it cannot be considered a liposoluble active. Succinic acid can interfere with the activity of the sebaceous glands, thus limiting sebum production and preventing pore clogging. It also has antibacterial properties that allow it to target Cutibacterium acnes, as well as an exfoliating action.

  Recent studies have highlighted the potential of succinic acid in combating skin imperfections. For this purpose, 43 volunteers with acne were recruited and used a daily lotion containing 4% niacinamide, 2% succinic acid, and extracts of tea and Morinda citrifolia. After 56 days, researchers observed a decrease in the abundance of C. acnes, along with a reduction of 52.12% in the number of inflammatory lesions and 18.33% in erythema. Furthermore, the lotion was well tolerated by all participants. Despite being relatively unknown, succinic acid deserves more attention for the care of acne-prone skin.

• Fruit acids.

  Fruit acids, also known as AHAs (alpha-hydroxy acids), are particularly beneficial for skin prone to blemishes due to their exfoliating action. By weakening the bonds between dead cells in the stratum corneum, they promote their removal and accelerate cell renewal, thus helping to unclog pores and reduce the formation of comedones. One of the most well-known AHAs is glycolic acid, but there are others, such as the lactic acid, which is appreciated for its gentleness and the hydration it provides to the skin, or the mandelic acid. The latter also has antibacterial and anti-inflammatory properties, making it a comprehensive active ingredient to reduce blemishes.

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• MAIPRASERT M. & al. Anti-aging and brightening effects of a topical treatment containing vitamin C, vitamin E, and raspberry leaf cell culture extract: A split-face, randomized controlled trial. Journal of Cosmetic Dermatology (2020).