Does Vitamin C Benefit Skin: A Scientist’s Take

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Vitamin C Science

You are in for a real treat today! One of my esteemed coresidents Dr. Kumar Sukhdeo (bio below) gave an excellent talk to our entire dermatology department about the science behind Vitamin C. It was such a good talk that I asked him afterwards to do a guest post here to share with all of you what he found. These are my favorite type of blogposts, because they combine science with skincare, and help you as a consumer figure out what’s actually worth spending money on and what’s a waste. Please leave questions below!

Here we go!

Vitamin C: the devil is in the details!

Vitamin C has been touted as the ultimate natural and organic anti-aging ingredient, but information about vitamin C in topical products is confusing and often inaccurate. Here, I discuss some of the science, challenges, benefits, and recommendations for including vitamin C in your skin care regimen.

Chemistry beakers

Vitamin C Chemistry

Vitamin C Molecular StructureFirst, let’s take a walk down memory lane to revisit some chemistry. Vitamin C, more specifically referred to as ascorbic acid*, is part of a family of molecules known as antioxidants. What does this mean, exactly? To review the chemistry briefly, antioxidants function by donating electrons (negative charges) to other molecules. In doing so the recipient molecule is reduced while the antioxidant is itself oxidized. This is useful in situations when important molecules, such as DNA and proteins (e.g. collagen), are protected from damage through radical oxygen species created by UV exposure, cigarette smoke, pollutants, and others. One way to think of it is that ascorbic acid neutralizes the damage created by the radical oxygen species that carry an unpaired electron. Oxidized ascorbic acid becomes dehydroascorbic acid, which is then further oxidized into additional byproducts. In theory then, topical vitamin C should be beneficial in protecting collagen in your skin from breaking down, which would keep your skin looking more full and youthful. However, research shows that vitamin C may also work on cells in a number of other ways in addition to its antioxidant function.

 

Ascorbic Acid in Collagen Production

Ascorbic acid gets its name from the Latin “ascorbus” meaning “no scurvy.” Scurvy manifests in many ways including poor wound healing, which was well known to sailors making long voyages without citrus products.   Later, scientists discovered that ascorbic acid is essential for cells to produce a finished collagen filament that helps give skin its strength and elasticity.

Several research groups have looked at the question of whether topical applications of ascorbic acid had any benefit in the skin for collagen production. In both petri dishes and in people, applications of ascorbic acid were able to stimulate production of more collagen. Surprisingly, the cells that make collagen grew faster in response to ascorbic acid. In theory, more collagen producing cells might make more collagen for the skin.

 

Ascorbic Acid in Repairing Sun Damage

Studies of people who applied ascorbic acid with concentration between 3% and 10% (concentrations above 20% actually inhibited absorption) showed a statistically significant reduction in fine lines and wrinkles. These reports are often cited as evidence to support using topical vitamin C in skin care products.

Orange beverageHowever, it is worth noting that many of these studies used 1) freshly prepared ascorbic acid, often kept in the controlled environment of a laboratory, 2) small numbers of patients with photodamaged (sun damaged) skin (not normal, undamaged skin), 3) subjective scoring criteria (think judges for gymnastics), and 4) observational studies. In reviewing these studies, the benefits were usually very modest, and there was often great benefit from just using the moisturizer cream alone. Therefore, like a delicious orange citrus margarita, much of the science behind ascorbic acid should be taken with a grain of salt!

 

Vitamin C in Reducing Pigmentation in the Skin

Ascorbic acid has also been evaluated to fade brown spots in the skin. Most skin pigment comes in the form of melanin, a brownish molecule responsible for skin color. On the molecular level, ascorbic acid is able to reduce the visibility of pigment in two ways. First, ascorbic acid inhibits the enzyme (tyrosinase) responsible for making melanin. Secondly, ascorbic acid donates electrons to brown melanin, which becomes a colorless form (see antioxidant function described above). Some studies have shown benefit of topical ascorbic acid in decreasing visibility of brown spots on the face and body. Thus, topical vitamin C may play a role in diminishing age spots and other skin blemishes that surface with age.

 

Challenges of Vitamin C Getting Into the Skin

In an ideal world, we’d be able to put some vitamin C onto our skin or eat enough vitamin C in our diets and reap all the benefits I just wrote about, right? Well, as we will see, it’s not so simple!

Orange vitamin C

The Skin: a Major Barrier for Entry

Applying Skin LotionThe biggest obstacle for ascorbic acid is actually getting into the skin. Melanocyte cells (produce melanin) and fibroblast cells (produce collagen) live below the outermost layer of skin known as the stratum corneum. This is a specialized layer of the epidermis that by design prevents too much water from coming in and too much water from getting out. Herein lies the problem for vitamin C. As a water-soluble vitamin, it must be dissolved in a water (aqueous) base. As such, much of the content in water-based creams are blocked from entering the skin. Still, the absorption of ascorbic acid can be enhanced through pre-treating the skin with laser, chemical, or mechanical (abrasive) means. Complicating matters further is that ascorbic acid is most effective as an antioxidant at an acidity level equivalent to lemon juice (pH <4.0); this can be quite irritating to the skin. To make products more useable for consumers, some manufacturers decrease acidity although this ultimately reduces efficacy too.

Ascorbic acid is most stable in a powder form, but begins to degrade once dissolved in water. Studies have shown that within a month or two at room temperature, more than half the product is lost! The decay of ascorbic acid is further accelerated by heat, higher pH (less acidity), the presence of certain metals (especially copper and iron), and exposure to oxygen in the air.

 

Ascorbic Acid Derivatives Lack Stability and Efficacy

Cosmeceutical companies have been trying to circumvent the above listed issues by introducing several derivatives. Simply put, they come in two major categories: salt-based and non-salt-based derivatives. The former group includes sodium ascrobyl phosphate (SAP) and magnesium ascorbyl phosphate (MAP). Like regular vitamin C, these derivatives are water-soluble. In contrast, SAP and MAP exist as pro-drugs that must be enzymatically converted in the skin to ascorbic acid in order to have an effect. The evidence that this actually happens on a meaningful level in people is not very clear. These molecules have a harder time getting into the skin than ascorbic acid. Moreover, these studies testing SAP and MAP in the skin are less numerous and not as comprehensive as those for ascorbic acid, so its hard to say if they work as well as ascorbic acid.

The non-salt derivatives, such as ascorbyl palmitate (AA-PAL), are found in many products branded as “vitamin C” but don’t fare much better. These derivatives tend to be lipid-soluble rather than water soluble, so they must be delivered in an emulsion (a mix of oil and water akin to mayonnaise). There is limited data showing they are absorbed past the stratum corneum and may be even more unstable than ascorbic acid. Furthermore, the evidence that non-salt derivatives work to increase collagen, prevent sun damage, and decrease melanin is harder to find.

Given the significant modification of derivatives from the original version, it’s hard to call these molecules equivalent to ascorbic acid. If the supplement industry were regulated like the pharmaceutical industry, SAP, MAP, and AA-PAL, among others, would probably be given a different name and not be allow to be marketed as “vitamin C.”

Love Your Skin

So, is it worth it?

In a nutshell, the data behind vitamin C’s anti-aging benefits is suggestive but not conclusive, and the experiments used ideal conditions that we may not be able to realistically replicate in real life.

It is harder to tell if the product on your shelf can achieve the same effect as those shown in experiments. That being said, it is worth your time to read the labels and know what you’re buying – the details behind the product and how it’s made do matter!

Unfortunately, there are no consumer agencies that test the stability of ascorbic acid and its derivatives under real-world conditions. To extrapolate from the studies I reviewed, freshly prepared ascorbic acid keeps its integrity roughly as long as an orange in your kitchen (half-life of ~3-4 weeks). If ascorbic acid is kept in a jar (repeated openings to room air with oxygen) and on a bathroom counter (exposed to light; heated with each hot shower) then a consumer might be inadvertently destroying the vitamin C inside!

If you’re concerned about the stability of your product, I’d recommend wrapping any glass bottle in aluminum foil, storing it in the fridge, and limiting the amount of time you keep the lid open.

Given the quick breakdown of vitamin C, it would be worth considering the addition of expiration dates. Could you imagine the sale of eggs or milk without this label?! By the time it is purchased, who knows how long it took to get there, how long it sat on the shelf, and what kind of heat/light conditions it was exposed to during shipment! For this reason, and the evidence cited above, I am cautious about recommending these products and make sure to inform my patients about what they are getting. In my research, there were several formulations of ascorbic acid that were at least prepared under more ideal conditions. These include SkinCeuticals C E Ferulic, SkinCeuticals Phloretin CF, and Cosmetic Skin Solutions C+E sera as well as La Roche Posay Active C10 serum.

I hope this article will help arm you with the information to make informed choices about what you buy for your skin and how to use them to achieve the greatest benefit!

Products mentioned in this post:

* Natural vitamin C (ascorbic acid) exists in two forms that are mirror images of each other (think right hand and left hand): L-ascorbic acid and D-ascorbic acid. Only L-ascorbic acid is biologically active whereas D-ascorbic acid does nothing in the skin. In this article, Vitamin C and ascorbic acid are used interchangeably, and refer to L-ascorbic acid.

Recommended Resources:

Stamford et al. (2012) Journal of Cosmetic Dermatology – Stability, transdermal penetration, and cutaneous effects of ascorbic acid and its derivatives

MyAwesomeBeauty.com – Ultimate Guide to Vitamin C Serums

Oregon State Micronutrient Information Center – Vitamin C and Skin Health

Dr. Kumar SukhdeoKumar Sukhdeo MD, PhD is a resident physician-scientist at the Ronald O. Perelman New York University Department of Dermatology. His interests are in evidence-based dermatology, stem cell biology, and hair/nail disorders. All opinions expressed in this article are his own. Hear more from Dr. Sukhdeo via Twitter (@DrKumarSukhdeo). Feel free to post your questions below!

29 Comments on Does Vitamin C Benefit Skin: A Scientist’s Take

  1. Ana
    March 7, 2017 at 11:04 am (9 months ago)

    Love this article. I really appreciate you taking the time to explain how Vitamin C actually functions in the body.

    Reply
    • Joyce
      March 7, 2017 at 8:49 pm (9 months ago)

      Thanks Ana! Dr. Sukhdeo one of my brilliant MD PhD colleagues wrote this piece for the blog and I personally learned SO much. Glad you enjoyed it too!

      Reply
  2. Prakruti
    March 8, 2017 at 7:33 am (9 months ago)

    Thank you very much for giving your expertise insight . I wanted to purchase vitamin c infused product , but was extremely confused between eating oranges vs putting on my skin . Now , I have an answer .haha! Truly appreciate you bringing the knowledge about vitamin C.

    Reply
    • Joyce
      March 12, 2017 at 5:46 pm (9 months ago)

      Glad we could help!

      Reply
  3. Melody
    March 8, 2017 at 2:02 pm (9 months ago)

    Thanks for sharing, this is so so good :) Love learning more about skincare based on scientific facts from experts!

    Reply
    • Joyce
      March 12, 2017 at 5:46 pm (9 months ago)

      Awesome Melody! :)

      Reply
  4. Kumar Sukhdeo
    March 8, 2017 at 10:18 pm (9 months ago)

    Glad you found it helpful!

    Reply
  5. Betsy
    March 9, 2017 at 10:21 pm (9 months ago)

    This was great! I have had positive results using Vitamin C on my skin (40s, fair-skinned) as a part of my daily regimen but this post was really helpful. The more you know! Thanks!

    Reply
    • Joyce
      March 10, 2017 at 5:15 pm (9 months ago)

      Thank you Betsy! Glad that it was useful :)

      Reply
  6. Forever Confused
    March 17, 2017 at 8:36 pm (9 months ago)

    Hi Joyce, I’m kind of disappointed now haha. So vitamin c isn’t that effective in normal conditions? If I eat citrus fruits will that be more effective than topically applying? And those products recommended, do they actually work well enough because I thought vitamin c couldnt penetrate the skin as mentioned.

    Reply
    • Joyce
      March 20, 2017 at 8:39 am (9 months ago)

      Hi, vitamin C is super hard to get into the skin, so you have to look at the conditions the product was made made in and the formulation of the product. The ones Dr. Sukhdeo and I mentioned in the post are ones that were produced in a way that preserves the product and helps it penetrate the skin because of how it’s formulated. Eating the vitamin C is not going to necessarily get it to your skin since it gets absorbed through the gut and doesn’t get directed to the skin specifically.

      Reply
  7. Rachelle Ramilo
    March 18, 2017 at 11:59 pm (9 months ago)

    This is such an informative and helpful article. Thanks for sharing! :)

    Reply
    • Joyce
      March 20, 2017 at 8:33 am (9 months ago)

      Thanks Rachelle!

      Reply
  8. Cyrine
    April 3, 2017 at 11:06 am (9 months ago)

    Hi joyce? could vit c reduce acne scars ?? Because i have a lot ?

    Reply
    • Joyce
      April 3, 2017 at 12:38 pm (9 months ago)

      Hi Cyrine, I don’t think there is good evidence for topical vitamin C as a sole monotherapy for the treatment of acne or acne scars, but it can be useful as an adjunct therapy along with other treatments for acne or scarring, such as microneedling or laser. It also depends on the type of acne scars you have; is it more brown marks or are there dents in the skin from the scars? You will need to see a dermatologist who can assess the type of scarring you have and then suggest a good regimen for you. Good luck!

      Reply
  9. Audrey
    April 5, 2017 at 4:15 am (8 months ago)

    Hi Joyce,

    I would love to hear more about your opinion on MAP. Should we use it, then?

    Reply
    • Kumar Sukhdeo MD PhD
      April 20, 2017 at 6:13 pm (8 months ago)

      Hi Audrey,
      Thanks for your question. By MAP, I’m assuming you are referring to Magnesium Ascorbyl Phosphate (MAP). From my research, I couldn’t find any particular reason to use MAP over the other formulations of ascorbic acid (regular vitamin C). MAP was created to be a more stable version of ascorbic acid, but from what I can tell, there is not much evidence to support it being better than L-ascorbic acid in terms of penetration and improving the skin. There might be benefit, but the studies just have yet to be done. As a general recommendation though, I would stick with products that contain L-ascorbic acid, as listed above, as the ones to use for your skin.

      Let me know if you have more questions, keep them coming!

      Reply
      • Joyce
        April 20, 2017 at 6:44 pm (8 months ago)

        Thanks Dr. Sukhdeo! Audrey, I just posted a review of the SkinCeutical’s Phloretin CF, which is a Vitamin C serum that is formulated in such a way that the product is stabilized. Check it out on the home page!

        Reply
        • Audrey
          April 21, 2017 at 7:39 am (8 months ago)

          Salut Joyce,

          Thank you so much for replying to my message. I will definitely read your new article. Keep up the amazing blog, Joyce! I love how educating your blogs are for skincare junkies like me.

          Reply
          • Joyce
            April 21, 2017 at 7:53 am (8 months ago)

            Thanks for your comment!

      • Audrey
        April 21, 2017 at 7:37 am (8 months ago)

        Bonjour dr Sukhdeo,

        Thank you so much for taking your time to answer my question about MAP. I’m trying to find a vitamin C product that doesn’t irritate my rosacea and atopic dermatitis skin. I even used Avene vit C products (the Sensitive White line) and it still irritated my skin, although not as badly as products from other brands.
        Would you recommend people with sensitive skin to use vitamin C products at all? If so, do you think L-ascorbic acid will be well tolerated by very sensitive skin like mine?

        Reply
        • Kumar Sukhdeo MD PhD
          April 21, 2017 at 5:44 pm (8 months ago)

          Hi,
          It’s hard to say what I would recommend because I’d need to see you in clinic to better assess your skin type and any skin conditions. Every patient is different and needs to be treated individually. Your best bet is getting in touch with a reputable local dermatologist that is knowledgeable in this area and can help you select products that work for you. It might take some shopping around to find one that you like, but I think it is good to establish a relationship so that they know how you react and can suggest products they are familiar with. Of course, you can always keep sending questions to TeaWithMD as she is a fountain of knowledge!

          Reply
  10. Todd
    May 7, 2017 at 12:40 pm (7 months ago)

    Glad to find you site Joyce. I just had a facial and the esthetician used Vitamin C on me. She put it on after a microderm. Seems like that might be help with better chance of absorption. I will look for products with L-ascorbic acid. Question: Are there better(effective) brands for Vitamin C? Looks like Natura bisse has quite a big line of Vitamin C products but I’m sure their expensive.

    Reply
    • Joyce
      May 8, 2017 at 10:06 pm (7 months ago)

      Hi Todd, because Vitamin C is so hard to stabilize, there are some brands that are better than others when it comes to actually keeping Vitamin C’s efficacy in the product. As I mentioned in the post and in a later post here, SkinCeuticals holds a patent for the way they formulate their Vitamin C, so that their products actually deliver the full benefits of a stabilized Vitamin C serum rather than a degraded less effective form. Others are linked in the post above as well.

      Reply
  11. Sheela
    May 11, 2017 at 11:39 am (7 months ago)

    Thank you, Joyce and Kumar! This is super helpful, and I especially appreciate the evidence-based explanations. If Kumar is still answering questions, I’d like to ask for his thoughts on the Paula’s Choice RESIST C15 Super Booster. It’s a 15% ascorbic acid formula that sounds similar to the SkinCeuticals C E Ferulic, but is much more affordable. Based on Joyce’s last comment (about SkinCeuticals’ patented formula), I assume the formulations will be different, but I would love to hear your thoughts. Thank you in advance!

    Reply
    • Joyce
      May 16, 2017 at 3:58 pm (7 months ago)

      Hi Sheela, I took a look on Paula’s Choice website and it says the following, “A blend of 15% stabilized vitamin C (l-ascorbic acid) at a pH of 3.0, potent antioxidants including vitamin E and ferulic acid, and skin-smoothing peptides helps diminish visible signs of aging for smoother, brighter, and firmer-feeling skin.” That sounds like a good formulation with percentage of vitamin C between 10-20% and formulation at low pH of between 2.5-3.5. Since SkinCeuticals owns the patent on this formulation I’m not quite sure how Paula’s Choice formulates their vitamin C; perhaps there are small differences that are not listed on the website? I’ll let Dr. Sukhdeo chime in on this. Thanks for sharing!

      Reply
    • Kumar Sukhdeo MD PhD
      May 17, 2017 at 7:32 am (7 months ago)

      Hi Sheela, Thanks for your question. Based on the listed ingredients, this seems like a good option. Let us know how it works for you!

      Reply
      • Sheela
        May 25, 2017 at 12:06 pm (7 months ago)

        Thanks very much for taking the time to respond! I appreciate it. I’ll go ahead with the purchase and will be sure to report back!

        Reply
        • Joyce
          May 25, 2017 at 5:49 pm (7 months ago)

          Yes please let us know!

          Reply

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