Ch.04, Vitamin A
Vitamin A encompasses retinol and other well-known derivatives, collectively known as retinoids.
They are one of the few skincare ingredients that have been tested and proven in countless clinical studies to treat just about everything from acne to hyperpigmentation, and wrinkles. However, adding retinoids to your skincare routine can be a bit confusing and even bring along some unwanted side effects (cough flakiness cough). Don't worry, though! This chapter is dedicated to help you navigate the retinoid maze.
Retinoid Story and Benefits
Retinoids are a family of compounds that look and function similarly to Vitamin A. Originally developed to treat acne, retinoids also became extensively researched and known for their anti-aging properties starting in the 1980s. Since then, retinoids have been among the leading skincare heroes to treat fine lines, wrinkles, acne, and dark spots (1).
So, how do these anti-aging molecules work their magic?
Retinoids work by penetrating deep into your skin, targeting cells called keratinocytes and fibroblasts that are located in the upper layers of the skin. Once inside these cells, they bind to specific receptors, effectively communicating with them to kickstart various cellular processes. These processes include speeding up cell turnover, boosting collagen production, and increasing the deposition of hyaluronic acid, also known as glycosaminoglycan. The result? Smoother, younger-looking skin with fewer fine lines and wrinkles (2, 3).
But that's not all!
For dark spots, retinoids also block the transport of pigment (melanin) to skin cells, resulting in a lighter, more even skin tone.
Retinoids are likewise highly beneficial in the treatment of acne. They prevent pore clogging by promoting proper exfoliation and reducing the accumulation of dead skin cells, sebum, and debris. Additionally, retinoids regulate sebum production, minimizing the ideal conditions for acne-causing bacteria to thrive. Their anti-inflammatory properties help calm redness and inflammation associated with acne breakouts (3).
Types of Retinoids
The family of retinoids is huge and includes variations in strength, side effects, and benefits.
The 4 major ones are retinol esters, retinol, retinaldehyde, and retinoic acid.
Retinoic acid, sold under tradenames like Retin-A or Tretinoin, is the most potent retinoid in the group as it’s the biologically active form of vitamin A that acts directly on skin cells. The other retinoids have to be converted into retinoic acid by enzymes in our skin to have an effect (3). In other words, no matter which retinoid type you choose, the end goal is to get retinoic acid into your skin(4).
It works like this: retinol esters (derivatives) are broken down first into retinol, then into retinaldehyde, and finally into retinoic acid.
While it might seem intuitive to just skip all the conversion steps and use pure retinoic acid, it is so strong that it can cause undesirable side effects. For that reason, it is available by medical prescription only. On the other hand, retinoids that need more conversions are generally less effective but more gentle on the skin. Using coffee as a measure of strength, you can think of retinoic acid as a double espresso and retinol esters as lattes.
Click on below to see the nerdy details about each retinoid type along with their pros and cons 🤓!
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The most active (potent) form of retinoids when applied to the skin with zero conversion steps.
Retinoic acid, when utilized as a topical medication, is commonly referred to as Tretinoin which is sometimes marketed under trade names such as Retin-A®, Renova®, and Avita®, among others.
Conversion Steps: ↪ X 0
Potency: ★★★
Gentleness: ★
Stability: ★★
Level of research: ★★★
At least 8 well-designed studies have demonstrated a significant overall improvement of skin texture, fine lines, hyperpigmentation, and roughness when applying 0.01 – 0.1 % tretinoin. Commonly found in a cream or gel presentation, tretinoin at 0.05% seems to be a safe and effective treatment for skin with photodamaged signs (5).
Pros ✔️ : Most researched and effective type of retinoid since its structure allows it to immediately bind to skin cell receptors to produce an effect. Effective treatment for moderate to severe cases of acne.
Cons ✗ : Available only via prescription. Low penetration on the skin, and since is trapped in the top layer of the skin usually causes retinoid dermatitis (dry skin, flaking, redness, and burning sensation) (2).
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Retinaldehyde also referred to as retinal is another well-researched type of retinoid. There is a conversion of retinal to retinoic acid through a 1-step oxidative process so that it can bind to skin cells.
Conversion Steps: ↪ X 1
Potency: ★★
Gentleness: ★★
Stability: ★
Level of research: ★★
Some studies have shown that retinal and retinoic acid at the same concentration (0.05 %) have similar improvements on the skin after 44 weeks of treatment, but retinal was better tolerated (5).
Pros ✔️ : offers benefits for wrinkles and texture improvement while being less irritating compared to retinoic acid. Notably, it exhibits antibacterial properties against acne-causing bacteria. On the other hand, retinoic acid and retinol do not possess antibacterial activity but aid in acne management through other mechanisms, such as accelerating cell turnover (6).
Cons ✗ : Retinaldehyde has shown to be unstable in typical cosmetic formulations.
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Retinol is the most common type of retinoid found in cosmetic products. There is a conversion of retinol to retinoic acid through a 2-step oxidative process before it becomes active.
Conversion Steps: ↪ X 2
Potency: ★★
Gentleness: ★★
Stability: ★
Level of research: ★★★
Retinol, the second most extensively studied retinoid after tretinoin (retinoic acid), has demonstrated remarkable efficacy in improving fine lines and dark spots with minimal side effects. In fact, a study revealed that retinol is associated with less water loss, irritancy, and scaling compared to tretinoin, which caused nearly four times more irritation issues among participants (5).
Pros ✔️: It also improves wrinkles and tone and is better tolerated than retinoic acid. Retinol is as gentle on the skin as retinal.
Cons ✗: Retinol is 20 times less potent than Tretinoin. Although retinol has slightly better stability than retinal, it is still very sensitive to heat, light, and air (7).
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Retinol esters, including retinyl propionate, retinyl palmitate, retinyl acetate, and retinyl linolate, are considered the least effective types of retinoids. They need to undergo three conversions before becoming active in the skin.
Conversion Steps: ↪ X 3
Potency: ★
Gentleness: ★★★
Stability: ★★★
Level of research: ★
In a study, retinyl propionate did not demonstrate significant improvement after 48 weeks of treatment. On the other hand, retinyl palmitate showed a slight increase in collagen, but the study involved its combination with peptides and antioxidants, making it challenging to evaluate the specific activity of retinyl palmitate as the primary anti-aging ingredient (8).
Pros ✔️: Retinol esters are unlikely to irritate the skin, so they can be a good option for first-time retinoid users and people with sensitive or reactive skin.
Cons ✗: There is little to no significant scientific evidence to support the effectiveness of retinol esters as anti-aging agents.
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Hydroxypinacolone retinoate is a retinoic acid ester that was discovered and popularized in recent times. It is commonly referred to by its abbreviation, HPR or by its trade name, Granactive Retinoid. It is marketed as a skincare ingredient that provides the benefits of retinol without the associated drawbacks such as flaking and redness.
Conversion Steps: ↪ X 0
Potency: ★★
Gentleness: ★★★
Stability: ★★★
Level of research: ★
Currently, research on Granactive Retinoid remains limited. A study conducted by a cosmetic company demonstrated that it activates skin cells at a higher rate compared to retinol and retinal, but caution is necessary when interpreting these results due to potential biases. Furthermore, the study employed skin models, which are considered preliminary and may not reflect real-life conditions. Additionally, only two studies have investigated Granactive Retinoid in human participants; however, both of these studies evaluated its effects in combination with retinol, making it challenging to assess the specific activity of Granactive Retinoid (9).
Pros ✔️: Suggested to be more gentle on skin vs other retinoids. One study showed that granactive retinoid has better stability than retinol and retinyl palmitate (7). Because it is an ester of retinoic acid it does not require any conversions.
Cons ✗: There are no studies in human participants demonstrating the efficacy of granactive retinoid as a main ingredient. More research is needed to establish its efficacy as a standalone anti-aging ingredient
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Bakuchiol is an antioxidant compound found in the seeds and leaves of several plants. It is not a retinoid derivative but has been found to exhibit retinol-like effects in some studies.
Conversion Steps: ↪ X 0
Potency: ★★
Gentleness: ★★★
Stability: ★★★
Level of research: ★
Few studies conducted on skin cell models and human participants suggest that bakuchiol is comparable to retinol in its ability to improve photoaging. However, due to the limited availability of scientific evidence, bakuchiol remains a promising but unproven anti-aging ingredient. Further research is necessary to solidify its effectiveness.
Pros ✔️: May exhibit retinol-like effects without the associated drawbacks. There it can be a good alternative for sensitive skin that struggle with retinol and retinal side effects. It’s also more stable than retinol and safe to use during pregnancy.
Cons ✗: Bakuchiol doesn’t seem to act via the retinoic acid receptors, and thus may have a weaker effect than retinoids. More research is needed to support its effectiveness as an anti-aging ingredient.
| Retinoid Type | Potency | Research | Stability | Gentleness |
|---|---|---|---|---|
| Retinoic Acid | ★★★ | ★★★ | ★★ | ★ |
| Retinaldehyde | ★★ | ★★ | ★ | ★★ |
| Retinol | ★★ | ★★★ | ★ | ★★ |
| Retinol Esters | ★ | ★ | ★★★ | ★★★ |
| H. Retinoate | ★★ | ★ | ★★★ | ★★★ |
| Bakuchiol | ★★ | ★ | ★★★ | ★★★ |
Retinoid formulation: what to look for
Whether or not you have decided on which retinoid you want to get, here are general guidelines to consider. Keep in mind that specific considerations may vary depending on the retinoid type.
Stable retinoid
Retinoids are notoriously unstable, breaking down easily when exposed to light, heat, and air. A study testing 12 popular retinoid formulations found that up to 80% of the retinoid degraded within 6 months at room temperature.
Shockingly, the average shelf life for these products, with at least 90% of the retinoid remaining active, was merely 2 months. In some cases, the shelf life was less than 1 month, despite products claiming a 6-12 months shelf life after opening.
To address this issue, seek out smart packaging options that are airtight or allow you to mix the retinoid upon usage separately. Another effective approach is to choose formulas with retinoids encapsulated in liposomes. Studies have demonstrated that when retinoids are encapsulated and airtight packaged, they remain much more stable, with up to 40% of the retinoid retaining stability in the formula after a year.
Lastly, ensure proper storage by keeping any retinoid product in cool, dark places away from direct sunlight (7,11).
0.1-1% concentration
For retinoid beginners or those with sensitive skin, opt for retinol or retinal in low to medium concentrations (up to 0.5%). As your skin acclimates, gradually increase the concentration (up to 1%) for stronger effects. If dealing with acne or seeking more potent solutions, consult a doctor to explore prescription retinoid options.
5-6 pH values
Retinoid formulations should ideally have a pH value between 5 and 6. This range is close to the skin’s natural acidity (5.5) which promotes better absorption and reduce likelihood of irritation. It is also considered optimal for retinoids' stability and effectiveness, as it helps maintain their molecular integrity.
Retinoids: how to use
Lets assume that you finally selected your favorite retinoid product! Now that you're prepared to begin using it, here are some valuable tips and tricks to optimize your skincare routine.
Start slowly
If you are new to retinoids, begin by using them every 2 or 3 days a week until your skin adapts. Gradually increase usage to daily or every other night over a few weeks as your skin becomes accustomed to the product. Remember, apply retinoids only at night since they degrade quickly when exposed to light. Consistency and patience is key as it can take several months to see results with retinoids.
Buffer if needed
If you are new to retinoids or have sensitive skin you can buffer with a moisturizer. The concept of buffering involves applying a thin layer of moisturizer before and after the retinoid application. This barrier slows down the absorption of the retinoid into the skin, reducing the risk of potential irritation.
Retinoids’ friends
To combat the potential drying effects of retinoids, pair them with hydrating and skin barrier-supporting ingredients like hyaluronic acid, niacinamide, glycerin, ceramides, and calming extracts (e.g., panthenol, centella asiatica, oat extract).
Always wear sunscreen during the day when using retinoids, as they can increase skin sensitivity to the sun. Choose a broad-spectrum sunscreen with at least SPF 30.
Retinoids’ enemies
Avoid combining retinoids with exfoliating acids like glycolic acid, lactic acid, and salicylic acid to prevent skin irritation. Likewise, use Vitamin C (L-ascorbic acid) separately from retinoids due to potential destabilization from differences in pH values when combined. To maximize the benefits of both ingredients without compromising efficacy, use vitamin C products in the morning and retinoids at night.
| Retinoid type | Concentration | pH Value | Frequency |
|---|---|---|---|
| Retinoic Acid | 0.01-0.1% | 5-6 | daily |
| Retinaldehyde | 0.05-1% | 5-6 | daily |
| Retinol | 0.1-1% | 5-6 | daily |
| Retinol Esters | 0.1-1% | 5-6 | daily |
| H. Retinoate | 0.1-1% | 5-6 | daily |
| Bakuchiol | 0.5-1.5% | n/a | daily |
CHEAT SHEET
Retinoids are a family of compounds that look and function similarly to Vitamin A and most notably, include the variants retinol, retinaldehyde and retinoic acid.
Retinoids regulate skin cell turnover and are considered gold-standard ingredients for stimulating collagen production and treating fine lines, acne, and dark spots.
Retinoic acid (available via prescription only) and retinol are the most researched and effective types of retinoids. Hydroxypinacolone Retinoate (also known as granactive retinoid) and bakuchiol seem to have a retinol-like effect but more research is needed.
Start by using retinoids at low concentrations (below 0.5 %) and at a frequency of of 2-3 nights per week to avoid irritating your skin.
Retinoids are delicate molecules and break down easily when exposed to heat, air or light. To address this issue, apply retinoids at night and look for products with airtight packaging, encapsulated retinoids, or individually sealed options.
Remember to wear sunscreen during the day, as retinoids heighten sun sensitivity.
Questions & Answers
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Results from using retinoids can vary among individuals. Some may notice improvements in their skin within a few weeks of consistent use, while others may take several weeks to a few months to see visible changes. Notably, one study demonstrated enhanced collagen synthesis after just 7 days of using 1% retinol. It's advisable to use retinoids consistently for at least 2-3 months to gauge their effectiveness (4).
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A common side effect of using retinoids is retinization, a period of adjustment (typically between 2 to 6 weeks) during which your skin adapts to the retinoid. You may experience discomfort, irritation, and dryness during this phase. If you encounter retinization, consider taking a break from your treatment for a few nights until your skin feels better. During this time, use nourishing moisturizers and anti-inflammatory serums. Be sure to follow our safety tips mentioned above for incorporating retinoids into your skincare routine.
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Similar to Vitamin C, Retinoids are sensitive to heat, light, and air, which can degrade their potency over time. To maintain the stability and effectiveness of retinoids, it is important to store them in a cool, dark place and use them within their recommended shelf life. Additionally, products with airtight packaging or encapsulated retinoids can help protect them from degradation.
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Both retinoids and exfoliating acids enhance skin cell turnover, which can lead to skin sensitivity and irritation, especially when used together. Avoiding the simultaneous use of these products can help prevent excessive irritation and potential skin damage.
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Yes, retinoids can sometimes cause purging. As retinoids increase cell turnover, they can bring underlying blemishes to the surface more quickly, leading to a temporary worsening of the skin's appearance. This purging phase typically subsides as the skin adjusts to the retinoids, resulting in overall improvement in the long run.
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Using retinoids near the eyes should be approached with caution. The skin around the eyes is thin and delicate, making it more sensitive to potential irritation. Opt for specially formulated eye creams with lower retinoid concentrations for a safer and gentler option.
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