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Ascorbyl Glucoside, Magnesium Ascorbyl Phosphate, L-Ascorbic Acid: What are the Differences Between Various Forms of Vitamin C?

Orange fruit and cross section It's like comparing oranges and...well, oranges.
Vitamin C is a big topic on this blog, and for good reason!  It has been proven in numerous studies to: However, it seems everyone and their brother nowadays is premiering a "new" form of vitamin C.  It's impossible to know the differences without studying products all day long - but, thankfully, we've been doing just that for years now! One major thing we're looking for?  Fat - not water - solubility.  According to studies, “the most stable vitamin C preparations remain anhydrous or completely water-free.” (Cosmetic Dermatology2010). So, here they are:

Ascorbyl palmitate

chemical structure of ascorbyl palmitate Ascorbyl palmitate is not our favorite vitamin C derivative: Proven not as stable as sodium ascorbyl palmitate, magnesium ascorbyl palmitate, or ascorbyl glucoside. Not cool.
Benefits:  More stable than L-ascorbic acid in the presence of light and air; non-water soluble Detriments:  Less stable than magnesium ascorbyl glucoside and ascorbyl glucoside; Don't know the concentration of ascorbyl palmitate needed to achieve maximal efficacy, and concentrations are not listed on the bottle(s). Ascorbyl palmitate is a fat-soluble ester of L-ascorbic acid; it is L-ascorbic acid combined with palmitic acid, a fatty acid. According to a 1997 study, ascorbyl palmitate is more stable than L-ascorbic acid. A 2001 study in the International Journal of Pharmaceutics found that the stability of ascorbyl palmitate was increased further when ascorbyl palmitate was used in high concentrations (1-2%), or placed in water-in-oil emulsions rather than oil-in-water emulsions, due to the relocation of the unstable cyclic ring to the internal aqueous phase in the water-in-oil emulsions. Given that ascorbyl palmitate concentrations are generally 0.05-1%, unless a higher concentration of ascorbyl palmitate is established for a product, sodium ascorbyl palmitate or magnesium ascorbyl palmitate have been found to be more stable in solutions (see below).

Sodium ascorbyl phosphate

[367.glass.730.1460] Salt can make all the difference: Sodium ascorbyl palmitate is more stable than ascorbyl palmitate. BUT, it's still water-soluble, which crosses it off our "favorites" list. (Photo credit: zion fiction)
Benefits:  More stable than L-ascorbic acid or ascorbyl palmitate in the presence of light and air Detriments:  Water-soluble (fat soluble is more stable); Don't know the concentration needed to achieve maximal efficacy, and concentrations are not listed on the bottle(s). Sodium ascorbyl phosphate is a water-soluble form of L-ascorbic acid; it is L-ascorbic acid combined with palmitic acid, a fatty acid, and – you’ll never guess – sodium. :-) According to a 2001 study in the International Journal of Pharmaceutics, sodium ascorbyl phosphate has greater long-term stability than ascorbyl palmitate when each is used in similar concentrations. Unlike ascorbyl palmitate, sodium ascorbyl phosphate is stable in water-in-oil emulsions and oil-in-water emulsions.

Magnesium ascorbyl phosphate

Magnesium Magnesium ascorbyl palmitate is more stable than ascorbyl palmitate, but is water-soluble.
Benefits:  More stable than L-ascorbic acid or ascorbyl palmitate in the presence of light and air Detriments:  Water-soluble; don't know the concentration needed to achieve maximal efficacy, and concentrations are not listed on the bottle(s). Magnesium ascorbyl phosphate is a water-soluble form of L-ascorbic acid. According to a 1997 study in the Journal of Pharmaceutical and Biomedical Analysis, magnesium ascorbyl palmitate has greater stability than both L-ascorbic acid and ascorbyl palmitate, like sodium ascorbyl phosphate. (As far as I know, no peer-reviewed published studies have compared the efficacy and stability of magnesium ascorbyl and sodium ascorbyl palmitate.)

Ascorbyl glucoside

English: Macro photograph of a pile of sugar (... Ascorbyl glucoside contains L-ascorbic acid and glucose. It is fat-soluble and breaks down in the skin into L-ascorbic acid and glucose- pretty stellar, in our opinion.
Benefits:  More stable than L-ascorbic acid, fat-soluble Detriments:  Don't know the concentration needed to achieve maximal efficacy, and concentrations are not listed on the bottle(s). Ascorbyl glucoside has a structure in which the C2-hydroxyl group of L-ascorbic acid is masked with glucose. According to the manufacturer, Hayashibara International, once ascorbyl glucoside is selectively permeated through the skin, it is broken down into L-ascorbic acid and glucose by the enzyme alpha-glucosidase. Essentially, because ascorbyl glucoside is broken down into L-ascorbic acid, it has the same functions as L-ascorbic acid! In addition, ascorbyl glucoside has been found to have greater stability in the presence of air, heat, light, and pH changes than L-ascorbic acid.

Ascorbyl glucosamine

Structure of D-glucosamine-6-phosphate (GlcN-6P) Ascorbyl glucosamine is a "pass by," not a "buy": Studies show 5% ascorbyl glucosamine is not as effective as 20% azelaic acid in lightening spots. And when you consider the major benefit of glucosamine is skin-brightening, not stability, why bother with this in the first place?
Benefits:  Combines two skin brighteners: vitamin C and glucosamine Detriments:  Found 5% ascorbyl glucosamine not to be as effective as 20% azelaic acid in lightening spots; don't know the concentration needed to achieve maximal efficacy, and concentrations are not listed on the bottle(s). Ascorbyl glucosamine is L-ascorbic acid combined with (yes, this is obvious) glucosamine. Although the combination of N-acetyl glucosamine (NAG) and niacinamide was shown to reduce facial hyperpigmentation in Japanese and Caucasian subjects with facial hyperpigmentation in two double-blind, vehicle-controlled, split-face, left-right randomized clinical studies, use of a formulation with 5% ascorbyl glucosamine was shown to be less effective in reducing hyperpigmentation than 20% azelaic acid (source: Dermatology).

Bottom Line

Based upon the above, we prefer the following:
  • L-ascorbic acid
  • Magnesium/sodium ascorbyl phosphate
  • Ascorbyl glucoside
What form of vitamin C do you currently use?
Date: June 26 2012 at 7:26 AM
Q&A, Skin Care

Comments (4)

  1. Lisa
    June 26 2012 at 4:10 PM

    Thanks for this, I really appreciate it! I prefer making informed purchase decisions. Which products contain these forms of vitamin C?

  2. Pedro
    June 26 2012 at 5:55 PM

    I want to try a product with two forms (ascorbic acid + ascorbyl glucoside): Innisfree Eco Science Vitamin C Powder Ampoule. This powder contains 60% of ascorbic acid + 17.6% of ascorbyl glucoside - you can mix it with your regular moisturizer. Innisfree is a popular South Korean brand owned by Amore Pacific. Full ingredients list: Ascorbic acid, ascorbyl glucoside, mannitol, trehalose, titanium dioxide, orange peel extract, green tea extract, eriobotrya Japonica leaf extract, dipotassium glycyrrhizate, cysteine HCL, xanthan gum, polysorbate-20.

  3. Rae
    June 28 2012 at 7:42 AM

    Mine says "calcium ascorbate", does that even work?

  4. Sânziene si Mătrăgună
    October 27 2012 at 10:46 PM

    What about Tetrahexyldecyl ascorbate? Also oil soluble and damn expensive for someone preparing its serums at home, like me :-))

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