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Vitamin C as L-ascorbic acid (Part 3)

February 26, 2009 Reviewed by admin 24 Comments

L-Ascorbic Acid is - simply - the scientific name for Vitamin C in its purest from. And that's where the simplicity ends...All of the other vitamin C ingredients that you'll find on labels - such as magnesium ascorbyl phosphate, ascorbyl glucosamine, and tetra-isopalmitoyl ascorbic acid - are derivatives of ascorbic acid, and each come with their own set of unique pros and cons that I'll be discussing in a future post (so keep on the look out).

There's a lot of confusion and misinformation out there about L-ascorbic acid specifically, and it's about time somebody clears this up.

In this post I'll be taking you through the what-you-need-to-know details about L-ascorbic acid - from the good and the bad to the facts and the fiction.

The Rap Sheet.

L-Ascorbic Acid (AA) is a, highly unstable, water-soluble antioxidant (available commercially as a dry, white powder) that needs to be at high concentrations and at a low pH in order for it to enter your skin and do good. (See "What it does for your skin" for specifics.)

TIP: Look for formulas with high concentrations (10%+) and a low pH levels (<3.5) for maximum effectiveness.

Typical concentrations of L-ascorbic acid range from 5% to 25%, but there is no definitive answer as to what is optimal. Some say 20% is the best for absorption, while others maintain that concentrations over 18% cannot be absorbed adequately. Another statistic points to a threshold of at least 10% to boost collagen synthesis.

Concentration. Regardless, at any concentration, from the moment it makes contact with the outside environment (through high storage temperatures, light, high pH values, and the presence of dissolved oxygen) it begins to destabilize and lose its effectiveness at a rate of 6% to 16% (when stored for four weeks at 45 degrees Celsius for four weeks, according to one study). What's more, even better-stabilized AA derivatives only last at intended concentrations for about three weeks

pH. Also important to its effectiveness, in terms of stability and permeability, is the formula's pH level: the lower the pH level, the more stable, permeable and effective it is. At higher pH levels, ascorbic acid degrades much more quickly, rendering itself irreversibly into a biologically inactive form. Or worse yet - might actually promote harmful free radical formation.

TIP: One way to tell if your Vitamin C has lost its effectiveness is to check its color. Oxidation reveals itself through a yellowish-brown tint.

Irritation. The downside to all this is that the more effective formulations (with the higher concentration, and the lower the pH) tend to be quite irritating - especially so for men, smokers, individuals with sensitive skin, rosacea, and those in poor general health. (source)

From personal experience, I can attest to this.  The first time I applied a high-concentration serum I nearly wanted to claw my face off -- every inch of skin treated felt itchy and aflame for a good fifteen minutes, although I must say, after the discomfort resided, my skin did look quite nice.

TIP: Another nice-to-know detail is that Vitamin C does not play nice with mineral-rich skin care products or copper peptides. When they get together, bad things happen (such as the visible graying of skin).

The Bright Side.

Because of everything above, many people correctly believe that ascorbic acid cannot be stabilized in aqueous formulations. However, tests reveal that if a formula is prepared and packaged correctly than ascorbic acid actually out-performs nearly all of its better stabilized derivatives.

Tip: Look for topical base creams that contain no water - they will be less irritating since any discomfort is primarily caused by hydrogen ions generated by acid disassociating in water.

In one study, results revealed that topical application (in both lipid and aqueous formulas) of L-ascorbic acid on human skin actually outperformed the derivatives magnesium ascorbyl phosphate (MAP) and ascorbyl tetra-isopalmitate (ATIP) in both antioxidant potential transepidermal water loss values. A similar study (source) revealed that AA was better absorbed by the skin than MAP in gel, gel-cream and cream formulations.

In yet another study comparing the effectiveness of microparticle AA compositions in anhydrous (without water) solutions, research revealed that when applied topically to the skin, MAP and sodium ascorbyl phosphate (SAP) did not increase levels of AA in the skin; had negligible free radical scavenging ability in comparison to AA; and (for SAP) required ten times the concentration of AA to induce equivalent neocollagenesis in cultured fibroblasts.

Tip: How a formula is packaged is important to maintaining its efficacy.  Look for tinted bottles that block out light, or go for individualized application packets - both help keep the ascorbic acid from oxidizing too quickly.

What's important about these findings, says Dr. Geoffrey Heber (a lead investigator in one of these studies in an interview with Cosmetic Surgery Times) is that "AA can be stabilized and absorbed percutaneously..." He goes on to say,

"... published studies show these derivatives suffer from disadvantages compared to ascorbic acid. Ascorbyl palmitate is no more stable than ascorbic acid in aqueous solution. Ascorbyl phosphates and glucoside are more polar and would be expected to have lower percutaneous absorption, that of magnesium phosphate having been reported to be less than two percent absorption from a three percent cream 48 hours after application to dermatomed cadaveric human skin. Ascorbyl phosphates contain only approximately 50 percent ascorbate by weight, and ascorbyl tetraisopalmitate contains only 15 percent ascorbate by weight."


* L-ascorbic acid is not the hopeless and hapless cause that many say it is, nor is it any cure-all.
* A good vitamin C serum (in my opinion) would always include L-ascorbic acid in its formula, but with a derivative as well.
* For maximum effectiveness, formulas should be at high concentrations (10%+) and with low pH levels (<3.5).
* It would be free of water, heavy minerals and copper peptides...
* ... and packaged in small, fresh portions.
* Any noticeable coloring should be suspect.

Related posts:

Part 1: What is it? Vitamin C: An Investigation & Discussion

Part 2: What is it? Vitamin C: What it does for your skin

Part 4: What is it? Vitamin C derivatives

Five Best Vitamin C Serums

  • April 28, 2015

    by Alisa

    I have two questions:

    1. Is the powder that I purchased at Whole Foods, Vitamin C (Asorbic Acid) the same as l-asorbic acid?

    2. I am mixing the powder with water and applying to skin. Should I mix with a different ingredient for maximum effectivness?

    Thank you,

  • June 23, 2014

    by Laura Kimberley, RN

    Love your site! I do anti-aging as well, my specialty is more injectables. I found your information to be very helpful! Do you have printer friendly versions of these articles?

  • January 26, 2013

    by rod lake

    see lots of references to skin care use for the l-ascorbic acid, but nothing about oral consumption.
    can it be used to create liposomal vitamin c & ingested?

  • May 6, 2012

    by sonia padilla

    I will like to know the price of the age is 70 but i dont look like 70, every said 58 or 60

  • February 7, 2012

    by christina

    Claire or Jess- what are your thoughts on oxidizes l-ascorbic acid with amino acids (osmosis catalyst)? the vit c is supposed to be oxidized in order to work with the amino aids.....the serum is a dark, dark brown, with an orange tint. anyways, my acne has improved insanely since i have been using it!!

  • January 25, 2012

    by Jess


    This isn't quite an answer to your question, but you might be interested to know that topical preparations of vitamins C + E using ferulic acid as a stabilizer have been shown to have photoprotective effects on their own (i.e. without the use of additional sunscreens). Here's one of several studies that have obtained this result:

    While I can't find any studies directly comparing MAP vs. stabilized L-ascorbic acid as a sunscreen base, this in vitro study found that a combination of vitamins A, C, and E remained effective when mixed with a set of photostable UV filters (octyl methoxycinnamate, benzophenone-3, and octocrylene) but not photounstable UV filters (octyl methoxycinnamate, avobenzone, and 4-methylbenzilidine camphor):

    I can do some digging to find a more direct answer to your question. In the meantime, I hope this is at least somewhat helpful!

  • January 25, 2012

    by jc

    Thank you for your excellent articles regarding vitamin C.

    I have a question which I am having a hard time finding an answer to. Which is more stable (and for longer when exposed to air and sun) -magnesium ascorbyl phosphate or L ascorbic acid? The latter having been stabilized with the addition of vitamin E and ferulic acid.

    This is a question I know many people have. I'm particularly curious because I am deciding between a MAP product by Nufountain or a LAA based serum by Cosmetic Skin Solutions that like Skinceuticals is supposed to be stabilized by the addition of ferulic acid and vitamin E. I cannot find any research comparing MAP to "stabilized" L ascorbic acid with regard to air and sun exposure. My concern is that wearing it as a base to sunscreen may cause free radical damage.

    Thank you very much for your time, JC

  • November 9, 2009

    by marta

    The <a href="" rel="nofollow">link</a> is fixed and here it is:

  • November 9, 2009


    Hi Claire,

    Great post!
    However, I was unable to locate "Part 2: What is it? Vitamin C: What it does for your skin." as the link connected to it redirects to TIA home. Any suggestions on its location would be greatly appreciated.


  • October 14, 2009

    by marta

    Hi Nicki, You could try looking at some of these <a href="" rel="nofollow">C & E creams</a>.

  • October 14, 2009

    by nicki brooks

    Hey Claire, I am fairly new to doing my own research on facial products etc.,but I am loosing hope of finding anything on my supermarket shelf that actually works well on wrinkles!I recently heard about vitamin c with l-ascorbic acid and would love to read what your 5 best cremes are.Please write to me if you can and let me know,I can't seem to find your post about it.Thanks so much, nicki brooks

  • May 29, 2009

    by marta

    Please check back in on Saturday June 6th - we'll have the recipe and some ascorbic acid giveaways.

  • May 28, 2009

    by Donna Izen

    Hi Claire,

    I was researching the correct form of Ascorbic Acid to make my own Vitamin “C”
    many different opinions.. I see you were coming out with your recipe, I cannot find it, would you be kind enough to email it to me.. I have spent hours trying to get the right ingredients and suppliers, being as I am from Canada, it is challenging

    Thanks really appreciate it


  • March 23, 2009

    by Junko

    Marta or Claire,

    I've had my ciruit serum since Nov 08, in the medicine chest. Been using it off and on. If i remember correctly it was always a bit orange in color. So I'm not sure if i can assess it potency based on the color at this point.

    What's the shelf life of these C serums? I'm wondering if mine is bad now? Should we keep it in the refrigerator rather than at room temp? In post, 4 weeks at 45 celcius is 113 F (my bathroom has to be about 70 F or less most days).

    Doesn't seem to be itching my face to put it on.

    Any advice or thoughts on this would be highly appreciated!

  • March 19, 2009

    by marta

    I haven't yet found anything other than off-the-cuff comments saying you can't use vitamin C with copper peptides. One web site said that ascorbic acid detaches the copper from the peptides - but that doesn't make much sense to me. Au contraire, I've seen plenty of references to taking a vit C supplement while using CPs.

    Anyway, if you want to play it safe, 12 hours apart seems to be the rule of thumb.

  • March 18, 2009

    by Keli

    Hello, and thanks for a very informative site! I am wondering if copper peptides can be used in the morning and vitamin c at night, or vice versa? In other words, will they only have a negative effect on the skin if used simultaneously in the same product? Thanks!

  • March 14, 2009

    by Karen

    What do you think about pure ascorbic acid in green tea as a facial application?

  • March 12, 2009

    by claire

    Thanks, Leslie. I'm going to check that one out.

  • March 7, 2009

    by Leslie Wayne

    I have been using a high concentrate (25%) Vitamin C serum made by Alaur Skin Solutions called Clock-Stopping C with Antioxidants, which I love, and does not irritate. My skin improved a lot when I started using it, and continues to look great.

  • March 5, 2009

    by claire

    MAP is my favorite vit c derivative, studies showing that it does better than ATIP at free radical quenching. AND, it is a better hydrator than L-AA for the deeper layers of the skin.

  • February 27, 2009

    by tarala

    great post, per usual claire. any thoughts/information on all the vitamin c MAP?

  • February 27, 2009

    by Julie

    great post!

  • February 27, 2009

    by claire

    Hey Beata, I'm working on a Five Best Vit C post that will be coming out next week. But perhaps more exciting, I've been playing mad scientist and have come up with my own recipe, which I will be posting the week after (along with a video of me making the stuff). Look for my next post on Vit C derivatives early next week!

  • February 26, 2009

    by Beata

    Can you suggest serum that meets all the criteria that you mentioned in conclusion above?

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