Last week, OneSkin introduced a new segment that delves deeper into individual anti-aging ingredients; and for our first post in this segment, we figured that no ingredient would be more fitting to start with than retinol/retinoic acid. After all, if I were a gambling girl I would easily bet that this ingredient can be found on the back of at least a few of your favorite anti-aging skincare products that you use right now. So let's take a closer look at the benefits and drawbacks of this incredibly common ingredient.
We'll start by getting everyone on the same page by discussing what exactly retinol is. Retinol belongs to the retinoid family, which includes Vitamin A and its natural derivatives, such as retinoic acid (1). The tricky thing about Vitamin A is that it does not naturally occur in the body. Therefore, you must attain it from outside sources in order to reap its benefits, namely the promotion of natural processes such as cell reproduction, proliferation, and regulating cell death (1). Like all other vitamins, food can be a great place to incorporate such nutrients, and getting your daily dose of Vitamin A is pretty straight forward. The primary dietary sources of Vitamin A include sweet potatoes and carrots... basically any plant that contains red, yellow, and orange hues since those colors come from carotenoid pigments which contain Vitamin A. But, when your bright fruits and veggies game is lacking a little, it's always nice to have some scientifically proven products in your back pocket that can give your skin an extra boost (2).
Curiously, even though retinoic acid is one of the main ingredients in the anti-aging market, the first indication of retinoic acid in the skincare industry was to treat acne, rosacea, psoriasis, and more. Nevertheless, soon after people started to use retinoic acid, scientists and consumers observed that it also visibly improved skin appearance, and by 1984, Kligman et al took the anti-aging industry by storm by investigating retinoids' effects on common signs of skin aging. These initial studies demonstrated retinoids' positive effects on skin thickening, increased collagen, elastin, and fibrillin production, and increased angiogenesis... effects that manifest in the skin as less wrinkles and better elasticity (2). So yes, it's common ground that retinoic acid does promote benefits to skin appearance.
Slowing the process of aging, particularly in the skin, is no new goal within the cosmetic industry, therefore later on, retinoic acid was approved by the FDA to treat other conditions, including photoaging (premature aging induced by UV exposure), and was considered a successful anti-aging ingredient for decades.
In the following years, though, we gradually learned more about retinoic acid's side effects, and also that beautiful skin is not necessarily young skin. Therefore, recently the vision of retinoic acid as the gold standard for skin anti-aging has started to change.
As far as skin goes, retinoids can be very harsh, with most people initially observing what is known as the 'retinoid reaction', characterized by redness, a burning sensation, and peeling at the site of exposure (1). More closely related to OneSkin's mission, it has also been shown that retinoids induce cellular senescence by upregulating two critical regulators of senescence: p16 and p21 1. As you might recall from one of our previous posts, cellular senescence is responsible for many indirect effects of organismal and, of course, skin aging. So, even though retinoic acid may contribute to a beautiful and renewed skin in the short-term, it may be doing so at the cost of skin youth! This means that, whenever you stop stimulating your cells to produce collagen and to replicate, your skin will likely be molecularly older than if you had never used retinoic acid. Retinoids properties of inducing cellular differentiation and senescence have even resulted in the application of them as a treatment alternative for cancer. Actually, back in 1995, the FDA approved the use of all-trans retinoic acid for acute promyelocytic leukemia treatment. In the case of cancer cells, treatment with retinoids in specific concentrations was shown to induce cancer cell differentiation into normal cells (3) and also cellular senescence1, contributing to cancer control.
OneSkin has corroborated part of such findings and observed that retinoic acid treatment in human skin promotes a significant increase in cellular senescence (figure), as well as aging markers p16 and p21. Furthermore, we detected that IL-8 production was high in retinoic acid-treated skins, indicating that the treatment elicits inflammatory response. As explained in another of our previous posts, inflammation induces aging and age-related conditions, so it should also be avoided by using more gentle compounds in your skin, whenever possible.
Figure: Skin structure is shown in the left panel, revealing epidermal and dermal sections. Using a special labeling technique, called senescence associated beta-galactosidase staining, senescent cells were painted blue (central and right panels). While non-treated skin tissue has an average amount of senescent cells, retinoic acid-treated counterparts show a significantly higher amount of blue cells.
So, we agree that retinoic acid may be great at making your skin beautiful if used in low doses, but wouldn't it be awesome if new ingredients could be developed to make your skin more beautiful and also decrease cellular senescence, to really make your skin beautiful AND younger in the long run? If you think this is a great idea, you have another reason to stay tuned and to leave your email in the subscription box in the upright corner of this page! See you in the next post!