We’ve all heard of acids such as glycolic acids, and if you’re acne prone- salicylic acid and the rest. These acids are used in skincare products as chemical exfoliants i.e they help to chemically detach cells in the upper most layer of the skin from one another, yielding a more youthful, smoother, brighter skin.
What are the various types of acids used in skincare ?
How do they work?
Lower strength acids as found in OTC cosmetics (usually <10%) works at the level of the epidermis specifically at the stratum corneum (upper most layer of skin) and causes exfoliation.
Higher strength acids (>20%) are used as in-office procedures by professionals as chemical peels. Higher strength and lower molecular size acids such as glycolic acid can penetrate deep into the skin (upto the dermis) to boost collagen, GAG’s production thereby increasing the thickness of skin, and reversing signs of photoageing such as wrinkles, deep lines, sun spots etc.
Concept behind exfoliation
As we age our skin cell turn over (cells from the lower layer, divide and mature and are eventually shed off) slows down. As a results more cells from the startum corneum accumulate on the surface which gives aged skin a more dull, and rough appearance. Chemical exfoliation using acids helps speed up the process of shedding the upper layers of the skin. Hence, incorporating acids in our skin care are of benefit a we age and and for addressing certain skin concerns. They are un-necessary for younger age groups as their skin can naturally exfoliate at a good rate.
Rough estimate on the average skin cell turnover with various age groups
Acids beyond exfoliation
Uses of acids in skin care products can be more than just for exfoliation. Different acids have a slightly unique properties that help address specific concerns.
How to choose a chemical exfoliant?
Firstly, not everyone needs a chemical exfoliant in their routine. If you do not have any skin concerns, or if you are happy if your existing routine, continue what works for you regardless of whether you have such acids or not in your routine.
Amongst AHAs :
Glycolic acid is most commonly used and widely available in skincare products. However being of smaller molecular size, it can penetrate the deeper layers of the skin and cause irritation for some.
Lactic acid: another common AHA, but has additional properties of being able to retain water thus hydrating the skin. It’s also less irritating as compared to GA
Mandelic acid : a larger molecular weight AHA that is great for people not tolerating other acids or for people with sensitive skin as it is least irritating.
PHA and PBHAs, the newer generation acids. Not only do they provide gentle chemical exfoliation, some PBHAs such as lactonionic acid help hydrate and soothe the skin.
Note: The tolerability of such acids are also dependent on the overall formulations. Some products have a combination of these acids for maximum benefit and least irritation. Most often you only require a single product, and try not to use too many chemical exfoliants in your skin care routine without a professional consultation.
Irritation is the most common side effect of using such products. It can present as redness, burning or itching. It can also be seen as bumps resembling acne. Start by using such products just once-twice a week instead of every night and do not forget your sunscreen.
Some people may be allergic to certain acids, always perform a patch test prior to using such products especially if you have sensitive skin.
Over exfoliation can disrupt your skin barrier, making it sensitive, dry and irritated. In this case, stop using such chemical exfoliants and jut stick to the basics: cleanser, moisturiser and sunscreen.
If you already have a routine for your acne or pigmentation, please consult your dermatologist prior to incorporating such products in your routine.
As part of the series for active ingredients for pigmentation and as a continuation to my blog post on “vitamins and skin”, let’s dive in the details of another vitamin, that is – Vitamin A, also known as Retinoid.
Retinoid was a term first used to describe the active form of vitamin A. It comes in two forms: trans retinoic acid (tretinoin) and cis retinoic acid (isotretinoin), depending on the molecule groups orientation. The prefixes “cis” and “trans” are Latin for: “this side of” and “the other side of”.
Today retinoid is used as an umbrella term to encompass all derivatives of viatmin A such as retinoic acid, retinol, retinal esters, retinaldehyde.
Vitamin A and its derivative
The order of activity of a topical retinoid
The order of activity of a topical retinoid is as follows:
In others words retinoic acid is highly effective while retinol esters are least reactive. The irritant potential however is reverse, retinol esters causes the minimum irritation while retinoic acid causes maximum irritation.
How Vitamin A works on the skin?
Vitamin A derivative found in our skin are retinol and retinyl esters. These are then converted to retinoic acid, the biologically active form, by certain enzymes. Retinoic acid binds to receptors present inside the nucleus (center) of our skin cells to mediate various biological effects.
It regulates the cell turnover: As the cells in our skin divide and move from the basal layer to the uppermost layer as dead cells (the stratum corneum) and are shed off, there are various changes that can take place, such as changes in the shape and composition of the cells. This entire process is call “keratinisation” or in simple words “cell turn over” which takes approximately 28-30 days. Retinoids help regulates and makes sure this process is occurring normally. This is particularly useful for acne, where the follicular keratinisation (the cell lining inside of a hair follicle) is abnormal. Check out my previous blog post on to see how acne develops: “How to deal with truncal acne?”.
fig. Layers of the epidermis (superficial most layer of skin)
It also affects the growth and differentiation of cells: it increases the activity of cells responsible for production of collagen, and causes an increase in the thickness of the epidermis.
Retinoids also increase production of extracellular matrix and prevent its degradation by UV rays. Extracellular matrix are carbohydrate molecules present in the dermis which act as a cushion in which blood vessels, collagen and elastin are embedded and is responsible for the suppleness of our skin.
Anti-inflammatory: Thus helps prevent the development of inflammatory (red, painful) acne.
Reduction in pigmentation: Retinoid inhibits tyrosinase – an enzyme required for melanin production (pigment responsible for our skin colour) and due to the increase cell turnover it reduces the transfer of melanin to the keratinocytes.
The expected results with retnoid
The overall clinical effects of topical retinoid are:
It prevents formation of comedones (white heads, black heads), reduces the number of breakouts. Retinoids are the topical medication for choice for non inflammatory comedonal acne.
Helps reduce fine lines, and can reverse changes seen with chronic unprotected sun exposure (photoaging).
Retinoids can help improve the appearance of pores, and provides a smooth texture with a youthful appearance to the skin.
Retinoid in the form of retinoic acid (tretinoin) is used in combination with hydroquinone (depigmenting agent) and mild steroid called “triple combination” to decrease pigmentation and evens out skin tone. This combination has been the standard first line treatment by dermatologists for pigmentary disorders such as melasma, post inflammatory pigmentation (dark spots following conditions such as acne, or various forms of dermatitis). Another combination using 10% retinol + 7% lactic acid has shown to be equally effective to reduce pigmentation.
Therefore, retinoids in various forms are used for the management of acne and as an anti ageing ingredient.
Commercially available retinoids
1. Retinoic acid
The biologically active retinoid, retinoic acid is available as tretinion. It comes in three strengths : 0.025%, 0.05% and 0.1% formulated in a cream base. There is also a microsphere gel base in the strength 0.04% and 0.1%.
Adapalene is a synthetic retinoid similar to all trans retinoic acid tretinoin. It is available as a 0.1% gel, cream or solution and as a 0.3% gel for the treatment of acne. Adapalene (Differein) can be bought at the pharmacy without a prescription. It is now available as a combination with benzoyl peroxide (Deriva BPO gel, Epiduo gel) or with clindamycin (ClearApgel, Deriva CMS gel) as well.
3. Retinaldehyde
Retinaldehyde is the immediate precursor of the active form of Vitamin A-retinoic acid. Retinaldehyde in 0.05% and 0.1% concentration used twice daily for 12 weeks have been shown to be effective in treating photodamaged skin (rough, dry skin with fine or coarse wrinkling) and pigmentation. After application, retinaldehyde needs to be converted in the skin to retinoic acid by certain enzymes. This prevents the over saturation of our skin with retinoic acid and thus is better tolerated with fewer side effects. However the expected results can be slower than with retinoic acid.
3. Retinols
Many over the counter anti ageing, and pigmentation cream contain various concetration of retinols (0.3%, 0.5%, 0.1%) as the active ingredient. As you can see from the above image on vitamin A & its derivative, retinol needs to be converted to retinaldehyde which is in turn converted to retinoic acid. Retinol is 20 times less potent than retinoic acid (tretinoin) but the bears the advantage of less side effects. But retinol is highly unstable and gets degraded easily to inactive forms therefore the choice of the vehicle is of utmost importance for this ingredient. This neutrogena does not mention the concentration of retinol but from what I found online, its probably a lower concentration of 0.025%, which is great if you’re just starting with a retiniod.
Side effects of topical retinoids and how to combat it
Over saturation of our skin with retinoic acid can irritate our skin. Therefore the side effects are mostly seen with topical retinoic acid such as tretinoin. For this reason and because retinoic acid has biological effect when applied on the skin, it is considered a drug and requires a doctor’s prescription. Such regulations are not followed in India, and one can buy almost anything over the counter here, but I strongly discourage using retinoic acid as part of your skin care regimen without a prior dermatological evaluation or without supervision from your prescribing doctor.
During the first few weeks of topical application of a retinoid, redness, flaking of the skin, acne flare, photosensitivity are expected. This can be minimised by starting with the lowest concentration of retinoid, or by limiting the amount and the frequency of application.
It is advised to start with either twice in a week application, or alternate days application once at night for the entire face and never in the morning. The frequency and strength can be increase according to our skin’s tolerance to the product. Moisturisers and sunscreens are a must while using a retinoid.
Retinaldehyde and retinols have fewer chances of causing this irritation and are the best bet if one wants to start using a retinoid in their skin care and for someone with sensitive skin.
Retinoic acid such as tretinoin being more irritant should be avoided for someone with dry, sensitive skin or someone with skin conditions such as Rosacea.
Retinoids should not be used during pregnancy.
Interested in a vegan option?
Retinol, retinaldeyde and retinoic acid are animal derived forms of vitamin A while beta carotene is derived from plant and fruits. Beta carotene can be converted to retinal esters and retinaldehyde in our body which are then converted to the active form retinoic acid.
However a carrot can only provide a maximum of 6 mg of beta carotene. So if you want to duplicate the results of this study, you’ll need at least 6 large carrots a day.
Since long term study on the effect of vitamin A supplementation on our body as a whole has not been carried out, the potentials dangers that may result from toxicity of vitamin A has not been ruled out yet. Till we know more about the the benefits and risks of oral intake of vitamin A (beta carotene supplements), its best to avoid oral supplementation and stick to what we know, which is topical sunscreens and topical retinoids to fight signs of ageing and pigmentation.
It is important to note that, scientific research on the role of an active ingredient for pigmentation or ageing are performed over weeks with a minimum of 12 weeks before any conclusion can be drawn from the studies.
Therefore, always use a product for at least 12 weeks before you decide to conclude that the product is not working and move on to the next best thing.
When I first read the chapter on “Nutrition in Dermatology” during my course of residency, I came across this quote before the start of the section on Vitamins which grabbed my attention “If less is good, is more better?”
As we all know, vitamins are micronutrients (they are required in small amounts for the normal bodily functioning). With this knowledge, misconceptions of vitamin supplementations sprang up for various health benefits most of which are vague and commercialised for improvement of our general “well being”. The only indication medically for vitamin supplementation is for proven deficiencies of a certain vitamin.
In dermatology, only Vitamin A (retinoid) and Vitamin D are approved by the Food and Drug Administration (FDA) for specific diseases; Vitamin A for acne, psoriasis, cutaneous T cell lymphomas and Vitamin D for psoriasis. I will get into the details of these in later posts.
Let’s go back to the subject at hand: Vitamin C is a water soluble vitamin derived from our diet. Bell peppers, broccoli, spinach, tomatoes, citrus fruits such as oranges, lemons are its richest source. Vitamin C deficiency can cause a condition called “Scurvy” which presents with bleeding gums, fragile skin and hair abnormalities. This use to be a common disease for sailors around the fifteen century, since there were no refrigerators to keep fruits and vegetables fresh during long journey at sea at that time. The famous Portuguese explorer Vasco da Gama, the first European who opened the sea route to India reportedly lost hundreds of his sailors to scurvy.
Can you see any oranges? Neither did the sailors on board this ship.
The recommended daily allowance (RDA) of vitamin C is around 60mg per day and if you’re wondering how much that actually means think of the weight of a single grain of wheat. This can be obtained from both vegetable and fruit we consume daily. So unless you’re not eating your vegetables or fruits you’re unlikely to be deficient in vitamin C.
What research says about the role of Vitamin C in our skin?
From the observation that Vitamin C deficiency can cause fragile skin which would bruise easily with minor trauma and poor wound healing, it was obvious it has a definite role in the normal functioning of the skin.
Vitamin C plays an important part in formation of collagen which is the main structural component of the dermis responsible for the tensile strength of our skin (the ability of the skin to resists breakage under tension). Studies have shown that Vitamin C actively accumulates in the superficial layer of the skin (epidermis) however the level of Vitamin C in the skin does not increase beyond the maximum level reached in the blood; which means supplementing oral vitamin C is unlikely to have any additional effect on the skin.
Vitamin C is an anti oxidant. It helps removes the reactive oxidative species (ROS) from the epidermis (superficial most layer of the skin). These ROS are produced by various biological reactions that occurs in the skin from environmental exposure to Ultra Violet (UV) radiation, pollutants or smoking. ROS are thought to be responsible for accelerating the ageing process evident on the skin as dry, wrinkled skin with loss of elasticity. It has been shown in some studies that the concentration of Vitamin C is lower in ageing skin. The anti oxidant property of Vitamin C has been extensively researched, which led to the emergence of the use of this vitamin as an anti ageing ingredients in your skin care products.
Another benefit of Vitamin C is its ability to decrease melanin (brown/black pigment) production by inhibiting the enzyme called tyrosinase required for melanin synthesis. Therefore it has been marketed in skin care products as an “anti blemish” , “glow enhancer”, “glow boosting” must have product for that clear, pigmentation free skin.
With such juicy beneficial effects of vitamin C on the skin, boomed the common practice of applying self made home remedies consisting of various concoctions of lemon or tomato juice in the name of science. This however is the biggest mistakes people make. And yes I was one of those people who would try all sorts of home remedies for my skin. It took me almost 9 years and two degrees to open my eyes to such nonsense. But I did learn from my mistakes. I’m hoping you guys would learn earlier from such posts.
Not only are these home made remedies ineffective, they also have potential side effects. Just because they are obtained naturally and are “chemical free” does not mean it is without any risks. These home made or do it yourself (diy) concoction contains various other components apart from vitamin C. And for some individuals, these may lead to allergic or irritant dermatitis. I’ve seen a patient during my residency walk in to the clinic with red inflamed cheeks after topical application of tomato paste to her face as a “diy face mask”.
Do commercially available Vitamin C products work?
For vitamin C to be able to perform all the above function in the skin, Vitamin C in skin care products has to be carefully and accurately formulated to deliver the active and stable form of Vitamin C at a pH of <3.5 which enables the molecule to be absorbed through the layers of the epidermis (superficial most layer of the skin). The efficacy of a vitamin C product also depends on the concentration, with higher concentration being more effective, the minimum concentration being 8% with a maximum of 20%. Concentration >20% are not more effective and are likely to cause more irritation instead. The entire process can be tricky. Vitamin C is highly unstable and gets easily oxidised on exposure to air which is indicated by the yellow brown discolouration of the product when its completely oxidised. The product will be ineffective at this point. Also as Vitamin C works synergistically with Vitamin E to perform the same function as an antioxidant, most research has been focussed on this combination.
Therefore with such strict parameters to put in mind, the development of Vitamin C for topical use is not an easy or cheap process and not all companies are able to deliver this in their skin care products.
Vitamin C is available commercially as creams, serums, scrubs. Creams contain various other components called vehicle in which the active ingredient and in this case vitamin C is suspended. Vehicles are usually preservatives, and other ingredients which helps in moisturising. The problem with this type of formulation is that the release of the active form of vitamin C that can be absorbed into the skin is uncertain. Also creams, scrubs so not contain adequate concentration of vitamin C. Research has shown that a concentration of at least 8% is required for topical vitamin C to work. Such a concentration are available as serums which are the newest form of skin care product that contain large and adequate amount of the active ingredients with very minimal additional components.
When and how to incorporate Vitamin C to your skin care regimen
Lets recap the benefits of Vitamin C for our skin. First, it protects against UV (UVA and UVB) induced sun damage. Secondly, it acts as an antioxidant and helps in collagen formation which will help reduce signs of ageing. And lastly, it can be use as a depigmenting agent hence beneficial for post acne pigmentation, sunspots, melasma and other pigmentary disorders.
So if you’re looking for something that can perform the above function for your skin, Vitamin C is worth a try. Years of research on topical Vitamin C serum shows that long term daily use of a topical vitamin C serum, does provide great results such as decrease in the number of fine lines, a more even skin tone with decrease in pigmentation.
So when buying a Vitamin C containing product remember that not every product available in the market actually does what it claims.
Do not jump at the sight of “Vitamin C” label, check for the concentration of Vitamin C, preferably go for the one with at least 10% concentration. Always opt for a serum instead of a cream. Research about the company, read the reviews before buying because a legit Vitamin C serum will burn a hole in your pocket.
Vitamin C serums are to be applied daily once in the morning after cleansing your face followed by a moisturiser 5 mins later. The amount will depend on the company’s instruction, usually 3-4 drops is the recommended. But I would advise to start slow, with a lower concentration or fewer drops and work up to the number of drops recommended as it can cause some mild irritation and dryness initially.
Conclusion
Vitamin C like other vitamins are vital for life and are required in very small concentration. Our body receives the perfect amount of vitamins from our diet. So when it comes to vitamins
“Less is definitely good, but more does not equate to better. In fact, more is unnecessary.”
Vitamin C can be beneficial for your skin when applied topically with a correctly formulated products that delivers the right type and amount of Vitamin C and for indications like anti-ageing, photoaged skin where levels of vitamin C in the skin has been shown to be lower than younger skin. Oral Vitamin C supplementation is not indicated except for the treatment of Scurvy (Vitamin C deficiency disorder). And homemade Vitamin C remedies does not deliver the same effect as one expects when reading about the benefits of vitamin C on the skin.
Dr Naphisabet Wanniang 