A Guide to Vitamin C and its Derivatives

Vitamin C is most often known as Ascorbic Acid. However, this form is known to be very unstable during formulation, and not tolerated by all skin types due to its low pH. This is where derivatives come into play. Derivatives of vitamin C are known as inactive forms, or esterified forms. These require conversion in our skin to ascorbic acid, and get activated once applied onto the skin. They also tend to penetrate the skin better, and are more stable than pure Ascorbic Acid. 

When comparing the efficacy of derivatives (and confirming whether they’re worth the skincare splurge), we compare them to the three main benefits of pure vitamin C, which are discussed below. 

Keep reading for a guide to the various vitamin C forms, and which one is best suited for you!

1. L-Ascorbic Acid (L-AA)

She’s pure, 100% authentic, and helps you achieve all your vitamin C dreams - she’s ascorbic acid! This is vitamin C in its purest form - the gold standard of vitamin C. Ascorbic acid is the most biologically active of all the derivatives, making it the strongest and most effective in terms of antioxidant abilities, reducing pigmentation, and boosting collagen production. Because it is active, once applied it does not have to undergo an extra step of conversion and is ready to do its magic. It is the most effective at 8-20%, but also remember that a higher percentage does not mean better results - higher can mean more irritation.

However, this form is currently the most unstable, and can easily oxidize (which is confirmed through its colour - a deep amber colour signifies it has oxidized). This occurs due to high temperatures, light, and exposure to air. Once oxidized, it has lost its antioxidant properties, and is rendered useless. This is why it is often recommended that once you open a serum with L-AA, you try to use it everyday before it reaches its oxidized stage. It is also recommended that you store it in the fridge, to prolong its life.

So who should and shouldn’t turn to ascorbic acid? If your skin tends to be more oily and acne prone, it is best to avoid ascorbic acid, as it can cause purging. If you have sensitive skin, it is best to use less than 10%, as any higher can cause irritation, or utilize a derivative instead!

2. Sodium Ascorbyl Phosphate (SAP)

SAP has been proven to be as beneficial as L-Ascorbic Acid, with regards to antioxidant properties, collagen boosting properties, and evening out skin tone. This derivative is especially best for those with acne prone skin, as it has been proven to fight acne, and suppress the bacteria that causes acne (it's an antimicrobial derivative!). SAP is typically found in serums at 20% concentration.

3. Magnesium Ascorbyl Phosphate (MAP)  

MAP is one of the most stable derivatives of Vitamin C - he’s what your ex couldn’t be for you. While research has proven MAP to boost collagen production and help with pigmentation, its antioxidant capabilities are still questionable, and it is poorly absorbed. However, this doesn’t mean it's without benefits - its poor absorption is what makes it the least irritating derivative, and tolerable by even the most sensitive skin types! Even with sensitive skin, you don’t have to miss out on incorporating vitamin C into your routine - MAP is your saviour! It also does a great job at overall brightening the skin.

4. Ascorbyl Glucoside 

This is the least stable among the derivatives. While its collagen boosting effects are similar to L-AA, more studies are still needed to confirm whether it boasts other similar benefits to Ascorbic Acid, and how effective it is. It converts to sugar and L-AA when applied on the skin.

5. Tetrahexyldecyl Ascorbate (THD)

This derivative is stable, penetrates the skin, AND does all three things that Ascorbic Acid does - photoprotection, reducing pigmentation, and collagen boosting. It’s role in reducing hyperpigmentation and even melasma is especially noteworthy, and may be just as effective as L-AA. However, this derivative is on the irritating side, especially for those with sensitive skin, so it is best to ease it in slowly. THD also tends to be more moisturizing, so it is best for those with dry, or mature skin. 

6. Ethylated L-Ascorbic Acid

This derivative is slightly different than the rest - it does not require conversion into L-AA when applied. The skin recognizes this ethylated form as ascorbic acid, but a far more stable form that is less likely to oxidize, and remains more effective over a longer period of time (as compared to L-AA). Because this derivative is very similar to L-AA (aside from the extra ethyl group that makes it stable), it is still just as strong and provides identical benefits. If your skin can’t tolerate L-AA, this derivative is not recommended!

What’s your favourite derivative? Have you tried a derivative or given up after a skin freak out from pure Ascorbic Acid? L-AA may not have been for you - but that doesn’t mean you need to give up on vitamin C! With multiple derivatives, you are sure to find a formula that suits you and your skins’ needs, because everyone deserves that vitamin C glow.