We know Vitamin C to be the gold standard ingredient when it comes to antioxidants and skin brightening but L-Ascorbic acid in its true form is a highly unstable ingredient. Sunlight, air and temperature are just some of the things that can set it off and make it unstable. This is why a good vitamin c product should always be packaged well in opaque airless containers. If your Vitamin C serum changes colour e.g. turns brown it’s no longer effective. High concentrations of Vitamin C are also extremely notorious for skin irritation and generally speaking you would also need a high percentage of Vitamin C in order to experience the full benefits of it.
Vitamin C derivatives are different forms of Vitamin C that have been formulated to be more stable but offer the same skin brightening benefits as Ascorbic acid. There is a lot on the market but I will talk about the 3 derivatives I have had the most experience with.
Magnesium Ascorbyl Phosphate (MAP) – this a water-soluble Vitamin C derivative with the same skin brightening properties of Ascorbic acid. Even though it’s not as potent as Ascorbic acid, this derivative is less irritating meaning that most people can tolerate it as high (ish) percentages.
I first came across MAP from The Ordinary’s MAP 10% serum. I really love this product because it’s lightweight and hydrating and it worked well to brighten my skin. MAP is always the Vitamin C I recommend to others when they want a good starting point. My full review is here
Ascorbyl Glucoside– this is another water-soluble Vitamin C derivative and it’s considered one of the best derivatives on the market. This one also offers skin brightening and antioxidant benefits as well as boosting collagen synthesis. This is the type I find quite common in products on the market. You can find Ascorbyl glucoside in Vichy Normaderm Double Correction Daily Care, Avene A-Oxitive Defence Serum and of course The Ordinary Ascorbyl Glucoside 12% which is how I came to know of it and love it. Remember if it’s been formulated with other ingredients, it needs to be listed within the 1st 5 or10 ingredients in order to truly benefit from it
Read my full review of this serum here
THD Ascorbate– this is a fat/lipid-soluble derivative of Vitamin C which allows it to penetrate into the deeper layers of the skin. Again you are getting the best of vitamin C without the irritation. I haven’t used a lot of products with this derivate but there are plenty out there. I first came across THD in the Sunday Riley CEO serum and cream. The CEO serum contains 15% THD however I did not like this serum. Read my full review of it here. This year, I used the Peter Thomas Roth Potent C serum which contains 20% THD along with Vitamin E and Ferulic acid. I’m not sure if it’s the higher THD percentage or the combination of other antioxidants but I really liked it and it helped to brighten my skin. My full review of the PTR serum is here
Summary
Vitamin C is naturally found in the skin but with ageing and environmental damage, production of it slows down. Finding a well-formulated Vitamin C serum can be quite tricky as there are tons on the market. My recommendation will always be to find a well packaged and well-formulated one e.g. in an opaque airless container and preferably a serum/cream that also contains other beneficial ingredients.
I would recommend the Ordinary MAP and Ascorbyl Glucoside as budget-friendly options. If you want the real deal, The Inkey List Vitamin C is another favourite of mine which is pure 30% L ascorbic acid. My full review is here. This serum is in a waterless formula so it’s slightly tricky to add to a routine and you can experience irritation. In my full review, I explain how and why I mix it with another serum. Be sure to also check out the full Vitamin C range from The Ordinary too.
For luxury options, I recommend PTR Potent-C serum or Ole Henriksen Banana Bright serum which is a different derivative of Vitamin C plus PHA. Sunday Riley CEO is another popular choice although it didn’t work for me
I prefer to use my Vitamin C serums in the morning underneath my SPF in order to get the best possible protection against the sun and the environment however you can also use them in the evening or even twice a day. I personally don’t think layering two or 3 different Vitamin C products will give you more results so don’t be tempted to do that.
In short, find a good Vitamin C serum and start using it!
Let me know your favourite Vitamin C serums!
sarah fynn 
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