Spotlight On: L-Ascorbic Acid

About the author:  John Su is an established skin care expert and aspiring dermatologist.   He also runs a blog, The Triple Helix Liaison, dedicated to providing unbiased, meaningful, and insightful information about skin care. For his full bio, please visit our About page.

Ambersweet oranges, a new cold-resistant orang...

L-ascorbic acid (vitamin C) is the father of all topical treatments, found to do everything from brighten to stimulate/enable collagen production. USDA photo. Image Number K3644-12. (Photo credit: Wikipedia)

I’ve been on such a kick talking about tretinoin recently, that I figured I might as well talk about the other elephant in the room. If tretinoin is the mother of all topical treatments, L-ascorbic acid would undoubtedly be its father. Together, these two ingredients form the cornerstone of modern-day skin care. Though several other classes of ingredients have gained prominence in recent times such as polyphenols, flavonoids, and hydroxy acids; none can rival the combined preventative and corrective effects of these two giants.

This post will be limited to the discussion of just L-ascorbic acid. Its derivatives like magnesium/sodium ascorbyl phosphate and ascorbyl (tetraiso)palmitate/acetate will not be addressed simply because Nicki beat me to the punch [Read more:  Ascorbyl Glucoside, Magnesium Ascorbyl Phosphate, and L-ascorbic acid:  What are the differences between different forms of vitamin C?]

What is L-ascorbic acid, anyway?

Chemical structure of ascorbic acid, (aka vita...

Chemical structure of ascorbic acid, (aka vitamin C) (Photo credit: Wikipedia)

L-ascorbic acid is chemically a hydrophilic monovalent hydroxyl compound; colloquially it is basically a water-loving (or water-soluble) molecule that possesses many singly covalently-bonded hydroxyl groups, which largely determine its function and role, such as those in ionization and various hydrogen bonding scenarios.

Many people know that L-ascorbic acid is beneficial, but don’t know the reason why it enjoys such attention. So I’m going to lay it out for you!

How L-Ascorbic Acid Fights Hyperpigmentation

English: Eumelanine Deutsch: Eumelanine

Structure of eumelanin. Vitamin C limits melanin formation. (Photo credit: Wikipedia)

L-ascorbic acid inhibits melanin production, so it can help with irregular hyperpigmentation such as melasma. Specifically, it reduces o-DOPAquinone back to DOPA, thereby, avoiding melanin formation (1). It however, has not been shown to significantly lighten the skin for example, from NC40 to NC30.

UV Damage: Being an excellent electron donor, L-ascorbic acid acts as a potent antioxidant against reactive oxygen species (ROS) like the superoxides and hydroxyl radical from peroxides because it interferes and “scavenges” the lone electrons that all radicals possess (2).

Collagen Production: Because the L-ascorbic acid ion is a cofactor for the enzymatic activity of prolyl hydroxylase, which binds aspects of procollagen prior to triple helix formation (like my blog name!), it is essential for collagen synthesis (3). The introduction of L-ascorbic acid to fibroblast cultures have been shown to upregulate collagen production because it increases the transcription rate of genes that code for procollagen as well as elevating procollagen mRNA levels (4). In other words, the presence of L-ascorbic acid increases the rate at which genetic information instructing the creation of additional collagen is manufactured while adding additional “messengers” to deliver these instructions, resulting in more finished “product,” or in this case, collagen.

What to look for in “Vitamin C” products

In vitamin C products, look for:
1.) Packaging. Vitamin C is sensitive to light and air, so small, dark bottles and airtight pumps are best.
2.) Low pH. Look for vitamin C in acidic form, as with Skinceuticals CE Ferulic.
3.) Vitamin C with vitamin E or alpha lipoic acid, both of which are found to increase vitamin C’s strength.

L-ascorbic acid is notoriously difficult to stabilize because it is such an excellent antioxidant, and therefore electron donor. It will gladly donate electrons to the oxygen content in air (to form water) and become doubly oxidized, forming dehydro-L-ascorbic acid (DHAA), which contains an aromatic (lactone specifically) ring. If further oxidized, the ring will open and the molecule (now diketogulonic acid) will become completely useless. All of this happens within hours after initial exposure. Therefore, a Vitamin C product needs to be properly packaged. Ideally, tube packaging or an airless pump bottle would be best. The packaging also needs to be opaque since UV radiation such as sunlight will degrade the L-ascorbic acid and any other antioxidants present.

Furthermore, being an acid with a pKa(1) of 4.2, L-ascorbic acid needs to be incorporated into a vehicle that has a low pH (less than about 3.5) in order to function and more effectively penetrate the stratum corneum.

Finally, several other antioxidants have been shown to work in-tandem or synergistically with Vitamin C, such as vitamin E and alpha lipoic acid. For example, vitamin C can reduce oxidized vitamin E, effectively recycling the latter for further use (5). Therefore, products with more than just L-ascorbic acid as their primary antioxidants are recommended. Chemical penetration enhancers wouldn’t hurt either.

Links/References:

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21 thoughts on “Spotlight On: L-Ascorbic Acid

  1. Pingback: Spotlight On: L-Ascorbic Acid-FutureDerm Post! v 0.12 « TheTripleHelixLiaison

  2. jeff says:

    Philosphy has a vitamin C powder that you mix with any serum or cream? But what about the PH of the serum or cream your using? dos tham matter?

  3. Nicki says:

    @Jeff – Thanks for the great question! We talk a lot about what delivery systems are “best” or “optimal” for products. Yes, the vitamin C powder from philosophy will work at any pH, but it will work best if it is added to a solution that is at an acidic pH (less than 3.5). Hope this helps!

  4. Karen K says:

    Is there any ingredient we should avoid when using vitamin c products? A few sources say we need to avoid sodium benzoate. The reason why I’m asking is because I like to layer products and I would like to avoid layering on ingredients that would make vitamin c ineffective.

  5. John Su says:

    @Karen K

    If the vitamin C form is present as L-ascorbic acid, the pH needs to be less than 3.5 to allow it to penetrate, protonate, and exfoliate the skin. So you’ll want to avoid ingredients that either change the pH or do not work optimally at low pH environments. For example, retinol.

    As for your questions about sodium benzoate, the reason to avoid using that with L-ascrobic acid, is not because it will make the latter ineffective. Rather, and more importantly, it’s to avoid forming a known carcinogenic compound. When you mix the two compounds together, they form benzene, which is highly carcinogenic. However, please note that the amounts formed are significantly lower than the amount necessary to deem something as “toxic.” This has been ruled by the FDA, so I’m sure most manufacturers will know not to use these two compounds together. Here’s the link for the interaction (which was shown in beverages).

    http://www.fda.gov/Food/FoodSafety/FoodContaminantsAdulteration/ChemicalContaminants/Benzene/ucm055815.htm

    I hope that helped!

  6. John Su says:

    @Soi Dog

    Sure! Because the copper is bound and not present as a free ion, it won’t have any significant deleterious effect on the L-ascorbic acid content that eventually forms from the ascorbyl glucoside. And its high affinity for copper may even reduce the overall environmental levels of free copper ions.

  7. Kitty says:

    Regarding vitamin C serums oxidising – we know they use potency that way, but could they do your skin any harm? I’ve read on various beauty blogs that oxidised vitamin C can “create free radicals”. I’ve been searching and searching and I can’t find any scientific back up for this, is it just a myth?

    Another thing I was wondering was, how long does it take vitamin C to fully oxidise and become dehydroascorbic acid? Because in all my googling I came across people asking how they could make their own DHA, and the answers were a lot more complicated than just “leave vitamin C lying around getting air to it”!

    Also, am I right in thinking that it’s best to use distilled water for the mix because that has less oxygen in it than plain old tap water, or is there a other reason? I’ve also been told that mixing it with a metal spoon oxidises it…?

  8. John Su says:

    @Kitty

    Of course all antioxidants have the potential to act as pro-oxidants! See, antioxidants have the capacity to donate electrons to reactive oxygen species (ROS). But after they do so, they themselves can become pro-oxidant via intermediate radical phases. Therefore, they either have to be regenerated (such as how vitamin E regenerates vitamin C) or they will decay. The effects of that decay is dependent in-part by the oxidized antioxidant’s pathway of decay: is it destructive or degradative? This means is it more likely to interact with surrounding structures or with itself? For example, after donating electrons, alpha lipoic acid tends to interact with surrounding tissues, while L-ascorbic acid is less reactive and tends to bind to itself. Check out this post for more info: http://thetriplehelixian.com/2013/02/11/spotlight-on-thioctic-acid-or-alpha-lipoic-acid/ So no, it’s not a myth.

    As for how long it takes vitamin C to oxidize to DHAA, I can’t give an accurate number, but it happens within hours of exposure to air. Keep in mind that DHAA is not the final oxidized endproduct of L-ascorbic acid. LAA bcomes DHAA after it donates two electrons. At this point, it can be regenerated. But if it donates more electrons (or more are taken away), the lactone ring will open and DHAA will become diketogulonic acid, which cannot be regenerated and is physiologically inactive. Therefore, you wouldn’t want to make DHAA products anyways… Why would you want an oxidized antioxidant that has to be regenerated, and is one electron away from becoming inactive?

    If you must make you own Vitamin C serum, it is best to distilled water because the minerals in tap water will reduce the antioxidant potential of vitamin C, since it will chelate the free metal ions and thereby become inactive. But you don’t have to worry about not using a metal spoon because the amount of free metal ions formed is irrelevant.

    Finally, keep in mind that unless you have sophisticated equipment, technique and/or you make a new batch everyday, I wouldn’t personally recommend making a DIY vitamin C serum.

    Does that all make sense?

  9. charu alwani says:

    when should I use l ascorbic acid? in the morning or night ? according to dr.neal schutz if we use in the daytime these antioxidants will function as a sunscreen while if we use it at night it will function properly as an antioxidant. Specifically this is what I read:
    “I recommend antioxidants as part of an anti-aging regimen because they have been shown to effectively destroy harmful energy from being released within and damaging your skin’s cells, DNA, etc. In order for them to do this, they need to be properly absorbed into your skin. If they are applied during the day, while they will effectively absorb and destroy the harmful UV rays of the sun, they will also be destroyed in the process even before having a chance to be absorbed into the skin’s cells. So, instead of functioning as an antioxidant product, if antioxidants are applied during the day, they’ll just function as a sunscreen (and you can just buy a sunscreen if you want a sunscreen, especially considering that they are much less expensive than antioxidants). If, on the other hand, they’re applied at night, they have a much better chance to be absorbed into your skin’s cells and properly protect it from damaging energy within your skin“. What is your opinion?

    And if i were to use l ascorbic acid how can i combine this with the melaglow cream (with niacinamide, tetrahydrocurcumin, soy isoflavones and kojic acid)and tretinoin cream i use at night?From what I read on futurederm posts retinoids and lascorbic acids cannot be combine, nor can niacinamide and l ascorbic acid . However Dr.Schultz states ” The relative incompatibility between retinoids and acids is directly proportional to the strength of the acid; the stronger the acid, the more injurious it is to the fragile Retin A molecule. Ascorbic acid is such a weak acid that it probably can not damage Retin A (as opposed to most Alpha Hydroxy and Beta Hydroxy acids, eg. glycol, salicylic, etc.) which are much stronger and will inactivate the Retin A. So in fact you can use products with ascorbic acid with Retin A.”

    all in all I am confused please suggest what to do and which l ascorbic acid product you would recommend , which doesnt have a dropper packaging !Thanks !:-)

    also which l ascorbic acid products would you recommend?

  10. John Su says:

    @charu alwani

    Well, you should use antioxidants morning and night. And no, using it during the daytime won’t be “bad” because you’re wearing a sunscreen over it. So some of the antioxidants will absorb the UV light and become “deactivated.” That being said however, UV light is responsible for the overwhelming majority of damage to the skin. So what’s wrong with using antioxidants as “shields” for the skin?

    What would you rather have? Use antioxidants during the day, so they act as a second barrier against the sun? Or would you rather let more UV light hit your skin during the day, and then go back and try to repair the damage afterwards at nighttime with antioxidants working via non-absorption mechanisms? It makes no sense. I do not agree with Dr. Schultz. What he’s saying is true, but it’s irrelevant.

    Also, L-ascorbic acid is not weak at all. Try using 10-15% L-AA on your skin for the first time in an appropriately low pH, and you’ll see that it’s quite irritating! Chemically speaking, glycolic acid and L-AA are both considered “weak” acids. They also have similar pKas, as well.

    I hope that helps!

  11. nelson says:

    hello john! it’s been ages since i participated here! anyway i took interest in philosophy’s turbo booster c powder and i remembered this episode of dermtv which addresses the issue of such DIY vit c serums:

    http://www.youtube.com/watch?v=xlqkAjBqbMQ

    and im no vit c fanatic and/or expert like a few of the participants on this site, so here are my questions (mostly based on what he said):

    1. since he said ascorbic acid (which is the type of vit c used in the powder formula) is not lipid soluble, and would not be able to be readily penetrated into the skin, would mixing it with a low pH BHA product be able to help with the penetration?
    2. because of the way ascorbic acid is less stable, i was thinking that it would definitely be better to mix batch by batch before usage and application. but is the ascorbic acid in the powder form prone to degeneration by air and light? if indeed the powder ascorbic acid is prone to degeneration, then wouldnt consumers be wasting BOTH the powder (when exposed to air upon initial opening) and stably packaged and/or bottled serums (i’m assuming that they would have to open the pump and pour in the powder, and those in tubes would prolly have to transfer the product into a jar and/or another receptacle)?

    i hope i make sense @.@ and as usual, thanks in advance for the lengthy reply to come =P

  12. John Su says:

    @nelson

    Haha you don’t have to come on here to post a question. The blog or Facebook *ahem* are perfectly fine avenues of communication.

    But anyways, let’s answer your questions:

    1. It doesn’t have to be lipid-soluble. As long as a L-AA molecule is uncharged–achieved by having a sufficiently low pH, it can still pass through the stratum corneum and the viable layers of skin underneath because it’s suspended in some sort of lipid-soluble carrier. Mixing with a low pH SA product can help, but not much due to their buffering regions and the fact that they are both weak acids, which react slowly with each other.

    2. Yes, that’s the main pitfall of making your own L-AA serum. Because it’s so quickly degraded, you’d have to make a fresh batch everyday. And at such small portions, it’s difficult to measure out the proper amounts of each necessary ingredient in order to make consistently well-performing batches. As for the powder form, you should definitely keep it away from the sun. But it’s a lot more stable in its powder form, so it will resist oxidation from atmospheric oxygen–within reason of course.

    As for the manufacturing process, it does come down to trust because there are ways to circumvent this oxidation problem. For example, manufacturers could make the product in low-oxygen atmospheres, or add some type of chemical reaction that will protect the L-AA content until the final product is properly packaged in and sealed–in proper packaging of course. But yeah, we (the consumers) can’t REALLY know if a L-AA product is stable; it does come down to trust. Manufactures have these options, but not all of them use them, But, since options like having a low-oxygen environments are more pricey to maintain, it’s probably better to buy from a larger, more-established company. I’m not saying that smaller companies can’t have good L-AA products, nor that all L-AA products from larger companies are good. It’s just a guideline that would be wise to keep in mind.

    Does that all make sense?

  13. nelson says:

    well, i chose to post here and your blog for specific subject matters (mostly and especially those are related to that that have been addressed) so that other readers and/or participants can benefit from it as well =D

    and yes, it does make sense! would you personally recommend this vit c powder though? i’m thinking bcuz it is in powder form, it’s prolly more stable than most vit c serums packaged in bottled dropper serums. i also guess it’s cheaper per ounce? or maybe not? >.<

  14. John Su says:

    @nelson

    Yeah I get that. Good point.

    And sure you can buy the Philosophy powder. However, you really don’t have to pay that much if you’d like to go the DIY route. You can go to a farmer’s market and just buy L-AA powder in bulk. Here’s a website that sells it (along with a lot of other ingredients): http://www.lotioncrafter.com/ascorbic-acid-ultrafine.html for cheap. You’ll certainly get some efficacy when you put some of the powder into an already prepared low-pH product.

    But since the efficacy of L-AA, as an antioxidant, is largely preventative (though is does have notable “treating” characteristics), sometimes you can’t really know if the product you’re using is effective. Again it comes down to trust and skill/time. I personally stay away from the DIY route because I have better things to do, and other ways to compensate for the money I spend. I mean, I see a $90 L-AA product that’s used up in 3 months as basically spending $1/day. For me, that’s an acceptable trade-off. I’ll just eat out a few times less, which is probably good for my health, too haha!

  15. John Su says:

    @nelson

    Haha don’t seem so down. If you really want to, you can try the powder route. I mean, the Lotion Crafter one is like $5 for a pound or something. Couldn’t hurt.

  16. nelson says:

    do i seem down? LOLOLOL the reason i thought about the philosophy vit C powder was because of packaging and stability issues of most vit c serums in dropper bottles. before this, i didnt even know “cosmetic-grade” vit c powder are so easily available for sale! and most of the DIY vit c serums are those mentioned by dermTV (prolly on bcuz the ones that i saw were from popular beauty gurus from youtube and their blogs XD). in fact, now, being more aware of the issues and weaknesses with dropper bottles also changed my mind about a lot of serums from estee lauder, clinique, murad, and PTR which i used to spend TONS of money on. now, the products which i would accept in dropper bottles are prolly only cleansing products, hydroxy acids w/o AOXs, and liquid foundations (like the armani fluid maestro, how nice and convenient would that be if estee lauder’s double wear and revlon’s colorstay would incorporate droppers too XD i would so purchase them!)

  17. Pingback: Product Review: ORANGEDAILY 10% Vitamin C Serum | FutureDerm - Skin Care - Retinol - Beauty Blog

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