Retinoids are part of the Vitamin A family. They're well-known for their incredible benefits to our skin, making them a powerful tool in fighting aging, acne, and hyperpigmentation.
Did you know that retinoids also play a crucial role in many of our body's essential functions? From maintaining healthy vision to supporting embryonic development, retinoids truly are remarkable.
When taken orally, tretinoin, a type of retinoid, has been shown to be effective in treating leukemia. This is due to retinoids' remarkable ability to regulate cell growth cycles. So, not only do retinoids work wonders on our skin, but they're also vital for our overall health.
When it comes to skincare, tretinoin was the first retinoid to be approved by the FDA in 1971 for treating acne. You might know it by its brand name, Retin-A.
Here's an interesting tidbit: when people started using topical tretinoin for their acne, they began to notice improvements in their overall skin condition. This led to further research, and in 1995, the FDA approved tretinoin for treating sun-damaged, prematurely-aged skin.
Some other popular topical skincare retinoids you might be familiar with include retinol and retinaldehyde, often called retinal with an "A."
For those of you dealing with acne, you may have come across isotretinoin, also known as Accutane, adapalene (aka Differin), and tazarotene (aka Tazorac).
In this discussion, we'll be focusing on the popular anti-aging and anti-acne topical retinoids, specifically retinol, retinal, and tretinoin. Keep in mind that the terms retinoic acid and tretinoin can be used interchangeably.
WHAT CAN RETINOIDS DO FOR MY SKIN? AND HOW DO THEY WORK EXACTLY?
Retinoids have been proven to help keep your skin healthier, which is why dermatologists are such big fans of them. Now, let's dive deeper into how retinoids work, step by step.
When applied and absorbed into the skin, retinol and retinal need to be converted into retinoic acid. Retinol first gets converted into retinal, and then retinal gets converted into retinoic acid. So, retinol is two steps removed from retinoic acid, while retinal is just one step away. Enzymes drive both of these conversion processes.
Enzymes play a crucial role in determining whether a retinoid is actually beneficial for the skin. For instance, when ingested, beta-carotene (in carrots for example) is converted into retinal by enzymes present in the cells of the gut lining. However, these enzymes that can convert beta-carotene into retinal are not present in skin cells. That's why you can't just rub carrot juice on your skin and expect any benefits.
Once retinol or retinal is converted into retinoic acid, it activates skin cells to power the regeneration cycle. Here's the sequence:
- Retinol or retinal is applied to the skin's surface.
- Retinol or retinal penetrates skin cells through the cell membranes. Retinoids are lipophilic, or fat-soluble, which allows them to diffuse through cell membranes made of lipids.
- When retinol or retinal gets inside a skin cell, enzymes help convert retinol into retinal, and then retinal into retinoic acid, which is the same thing as tretinoin.
- Retinoic acid gets on board a "transporter protein" called cellular retinoic acid binding protein (CRABP). This protein's main task is to carry retinoic acid into the cell nucleus. Once retinoic acid enters the cell nucleus, it binds to special receptors known as RARs and RXRs, which stand for retinoic acid receptors and retinoid-X-receptors.
- Picture these receptors in the cell nucleus like USB ports on your computer or phone. When you plug in the right device, it unlocks a whole array of functions and activities.
- By activating RAR and RXR receptors, a chain of biological events is set in motion, ultimately leading to healthier, more radiant skin (Babamiri and Nassab 2010, Beckenbach et al. 2015, Mukherjee et al. 2006).
Retinoids can plump up the skin by empowering skin cell regeneration. Here’s how:
Retinoids work to plump up the skin by boosting the c-Jun transcription factor, which is essential for the proper division and proliferation of cells. By upregulating the c-Jun transcription factor, retinoids directly stimulate an increase in the number of epidermal skin cells, which results in a thicker epidermis layer (Saurat et al. 1994, Kafi et al. 2007, Kong et al. 2015, Shao et al. 2017).
In simpler terms, cell proliferation means the division of a cell into two new cells. It's a fancy way of describing the creation of more cells. Transcription factors are proteins that activate specific parts of your DNA to produce more of certain proteins. They can set off a chain of signals leading to increased cell proliferation.
Think of your skin as having two primary layers: the epidermis and the dermis. The epidermis is the outer layer that protects your body.
The epidermis also contains melanocytes that produce melanin, which in turn protects you from UV rays. Additionally, it houses immune cells called Langerhans cells that help guard against infection.
So, consider the epidermis as your first line of defense against the environment. As you age, the epidermis thins, becoming fragile and more prone to damage which means the defenses weaken.
Here's a figure from a 2015 study by Kong and colleagues that illustrates the effects of retinoids on the skin.
When a topical retinoid, even a relatively mild 0.1% retinol, is applied, you can see a noticeable increase in epidermal skin thickness, represented by the blue staining. Thicker epidermis is good! This means you have a stronger defense against environmental factors like allergens, bacteria, microbes, as well as UV damage.
Additionally, you can observe an increase in procollagen, a precursor to collagen, shown as red staining in the layer underneath the epidermis.
This is the dermis which is the inner layer that contains blood vessels providing nutrients for the skin, as well as sweat and oil glands and hair follicle roots.
Crucially, the dermis also contains proteins like collagen and elastin which provide structure and support to your skin, giving it a youthful bounce.
In general, more procollagen means more collagen. We will get back to collagen later but first, let’s talk about the blood vessels in the dermis.
Retinoids can improve blood flow to the skin. Here’s how:
Another positive result of retinoid-driven skin rejuvenation is the increased proliferation of endothelial cells. These cells form the lining of blood vessels, helping to support healthy skin.
In this figure, taken from a study by Shao and colleagues, you can observe that applying a topical retinoid for just a week resulted in the proliferation of endothelial cells in the dermis, as shown by the red staining. Enhanced blood flow to the skin leads to better nutrient delivery, as well as improved skin color and tone.
Retinoids boost collagen and elastin in the skin.
Now let’s get back to collagen. Retinoids work wonders for boosting collagen and other essential structural proteins, like elastin, in the dermis. Think of collagen as the scaffolding that supports your skin, preventing it from sagging. Elastin, on the other hand, is like the lycra in your leggings, giving your skin bounce and elasticity.
By the way, we have a whole article on Deep Guide to Collagen. The link is here
By enhancing the collagen and elastin content in your skin, retinoids can help reduce wrinkles in both aged and sun-damaged skin. A study by Shao and colleagues revealed that applying a topical retinoid for just a week could significantly increase procollagen production—by three times compared to a placebo.
The same study also found that retinoid application led to a fourfold increase in elastin, as shown by the red stain. These increases in collagen and elastin directly contribute to smoother, less wrinkled and more bouncy skin.
And these increases in collagen and elastin will directly lead to less wrinkled and more bouncy skin.
RETINOIDS CAN TREAT ACNE. SPECIFICALLY, RETINAL HAS A UNIQUE ANTIBACTERIAL POWER.
Retinoids tackle acne through two main approaches.
First, retinoids help keep your pores clear by regulating the shedding of skin cells, a process known as desquamation, within the pores that have oil-producing glands. This helps prevent the formation of clogged pores, which can lead to acne.
Second, retinoids decrease the activity of enzymes involved in sebum production. This is why some people without acne issues might find retinoids drying (Beckenbach et al. 2015, Leydon et al. 2017, Zasada and Budzisz 2019).
Interestingly, retinaldehyde, or retinal with an "A," possesses antibacterial properties, which is a unique feature among the retinoid family. Retinal's special chemical structure makes it highly reactive, providing it with potent antibacterial properties. For those who enjoy technical details, retinal's reactivity is due to the presence of an aldehyde group in the isoprenoic lateral chain of its molecular structure.
A study by Pechere and colleagues provides evidence that retinal is effective against acne. The researchers compared the performance of 0.05% retinal and 0.05% retinoic acid in combating bacteria, offering a head-to-head analysis of their antibacterial capabilities.
And the study showed that 0.05% retinal treatment for 2 weeks led to a decrease in the density of acne-causing bacteria (called P. acnes).
But on the contrary, 0.05% tretinoin had no effect on reducing P. acnes density.
So, if addressing acne is a key concern, then using retinal is a no brainer.
RETINOIDS CAN ALSO HELP WITH HYPERPIGMENTATION
Hold on, we're not done yet. Retinoids have even more benefits for your skin. They can help improve hyperpigmentation through several different mechanisms. We'll briefly go over these mechanisms now, and we'll create a separate video on hyperpigmentation for a more in-depth discussion later.
First, retinoids can treat hyperpigmentation by slowing down the spread of melanin from melanocytes, the cells responsible for producing melanin. By inhibiting this melanin transfer, retinoids can reduce the appearance of dark spots.
Second, retinoids can decrease the production of tyrosinase, an enzyme that fuels melanin production. This results in less melanin being produced, helping to lighten dark spots and improve hyperpigmentation.
Third, retinoids speed up cell turnover, meaning that pigmented cells shed more quickly. This can also help to lighten dark spots over time. Treating hyperpigmentation is generally more effective when retinoids are used in combination with other ingredients, as different ingredients can work together in various and complementary ways. (Leydon et al. 2017, Zasada and Budzisz 2019)
Combining retinoids with hydroquinone can diminish hyperpigmentation even more effectively, as can retinoid-glycolic acid, retinoid-arbutin, and retinoid-vitamin C combinations (Mukherjee et al. 2006, Boswell 2006) . Check out more details in our Deep Guide to Hyperpigmentation here.
So to summarize, retinoids are one of the best and most effective anti-aging ingredients that additionally can help fight acne and hyperpigmentation.
One thing we want to mention is that all retinoids should be avoided during pregnancy and lactation. Check out our newsletters on pregnancy and skincare for more information on that.
And always wear sunscreen when using retinoids, particularly in the first few weeks, as this is when retinoids increase sun sensitivity.
Babamiri K and Nassab R (2010). “Cosmeceuticals: The Evidence Behind the Retinoids.” Aesthetic Surgery Journal. 30(1) 74–77
Beckenbach L, Baron JM, Merk HF, Loffler H, Amann PM (2015). “Retinoid treatment of skin diseases.” European Journal of Dermatology. 25(5): 384-391.
Boswell CS (2006). “Skincare Science: Update on topical retinoids.” Aesthetic Surgery Journal (Oxford Academic) 26: 233-239.
Kafi R, Kwak HSR, Schumacher WE, Cho S, Hanft VN, Hamilton TA, King AL, Neal JD, Varani J, Fisher GJ, Voorhees JJ, Kang S (2007). “Improvement of Naturally Aged Skin with Vitamin A (Retinol)” Archives of Dermatology 143: 606-612.
Kong R, Cui Y, Fisher GJ, Wang X, Chen Y, Schneider LM, Majmudar G (2015). “A comparative study of the effects of retinol and retinoic acid on histological, molecular, and clinical properties of human skin.” Journal of Cosmetic Dermatology. 15: 49-57.
Leydon J, Stein-Gold L, Weiss J (2017). “Why topical retinoids are mainstay of therapy for acne.” Dermatology Therapy (Heidelb) 7: 293-304.
Mukherjee S, Date A, Patravale V, Korting HC, 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.
Pechere M, Pechere JC, Siegenthaler G, Germanier L, Saurat JH (1999). “Antibacterial activity of retinaldehyde against Propionibacterium acnes.” Dermatology. 199(suppl1): 29-31.
Saurat JH, Didierjean L, Masgrau E, Piletta PA, Jaconi S, Chatellard-Gruaz D, Gumowski D, Masouye I, Salomon D, Siegenthaler G (1994). “Topical Retinaldehyde on Human Skin: Biologic Effects and Tolerance.” Journal of Investigative Dermatology 103:770-774.
Shao Y, He T, Fisher GJ, Voorhees JJ, Quan T (2017). “Molecular basis of retinol anti-aging properties in naturally aged human skin in vivo.” International Journal of Cosmetic Science. 39(1): 56-65.
Zasada M and Budzisz E (2019). “Retinoids: active molecules influencing skin structure formation in cosmetic and dermatological treatments.” Advances in Dermatology and Allergology. XXXVI(4): 392-397.