Ingredient Deep Dive Vitamin C

Ingredient Deep Dive: Vitamin C

By Safina Ali
20/06/2023 | Read time: 5m

This week’s focus ingredient is on vitamin C, one of the most talked about ingredients in both Western and Asian skincare. So first things first…

What is vitamin C?

Vitamin C, also known as ascorbic acid, is a water-soluble vitamin that plays several important roles in the body.

You might have heard of it referred to as an antioxidant. Essentially, it helps protect cells from damage caused by harmful molecules called free radicals that are produced by UV rays – the rays we all know are responsible for premature ageing and skin cancer. It also plays a crucial role in the synthesis of collagen, a protein that is an essential component of skin and connective tissue.

How does vitamin C work in Korean skincare?

We already discussed briefly how vitamin C protects against UV rays and oxidative stress from the environment to reduce signs of ageing and promote an even skin texture. But there are many other benefits to incorporating a vitamin C product into your skincare routine. Some of the other benefits include:

Collagen Synthesis

Vitamin C plays a crucial role in collagen synthesis, which is a protein responsible for maintaining the skin’s structure, elasticity, and firmness, helping to promote an overall youthful complexion.

Skin Brightening and Hyperpigmentation

Vitamin C has skin-brightening properties and can help reduce the appearance of hyperpigmentation and dark spots. It does this by inhibiting the production of melanin, the pigment responsible for skin colour and so promotes an even skin texture.


Did you know that vitamin C can actually be photoprotective against UV rays through limiting oxidative stress? It’s no replacement for sunscreen, but it can help maximise its effects, which is why you’ll often see it as an ingredient in popular sunscreens.

What are the downsides?

Unfortunately, with all skincare products, there will always be someone who won’t be able to use something, usually because of breakouts or irritation. Vitamin C Korean serums are usually formulated at a lower pH and because of this, many feel they are prone to more irritation, redness and itching. Thankfully, it is only a minority. So if you’re thinking of using vitamin C, it might be a good idea to patch test beforehand!

The other main downside to vitamin C is the short shelf life. Typically, active vitamin C – or L-ascorbic acid – tends to oxidise very quickly when exposed to light or air, hence why you might see it in dark brown airtight bottles. The packaging isn’t always foolproof though, and many people who use pure ascorbic acid tend to find that bottles only last a few months due to its limited stability.

What types of vitamin C are there? Are there any that are stable?

Yes! We’ve come so far in terms of skincare exploration and experimentation that we have so many forms of vitamin C to choose from. Of the types of vitamin C available in skincare, there is:

  1. L-Ascorbic Acid: This is the most studied and potent form of vitamin C used in skincare. It is the biologically active form of vitamin C and has been shown to have various benefits for the skin, including antioxidant protection, collagen synthesis, and brightening effects. However, it is also the most unstable form and can easily degrade when exposed to air, light, or heat.
  2. Ascorbyl Palmitate: This is a fat-soluble form of vitamin C that is more stable than L-ascorbic acid but less stable than other types. It is a combination of ascorbic acid and palmitic acid, which allows it to penetrate the lipid-rich outer layers of the skin more effectively. However, it may not be as effective as L-ascorbic acid.
  3. Sodium Ascorbyl Phosphate: A stable form of vitamin C that is converted into ascorbic acid once it is absorbed by the skin and is less likely to cause irritation.
  4. Magnesium Ascorbyl Phosphate: This is another stable derivative of vitamin C that is converted into ascorbic acid when applied to the skin. It is often used in skincare products targeting acne-prone or sensitive skin. It tends to be a lot weaker than L-Ascorbic acid and tends to be paired with other skin boosting ingredients in formulations.
  5. Tetrahexyldecyl Ascorbate: This is a lipid-soluble form of vitamin C that can penetrate the skin’s lipid barrier allegedly 3x more easily than L-ascorbic acid. It is considered stable and is generally well-tolerated by most skin types, including sensitive skin as it is less likely to cause irritation.

These are just some of the many derivatives of vitamin C available for your skin, some more gentle than others, so you’re sure to find something effective for your skin type!

What Korean products are there out there with Vitamin C?

The list of products are endless! Some personal favourites of mine include the DR. CEURACLE Royal Vita Propolis 33 ampoule. This is formulated with 3-o-ethyl Ascorbic Acid, a research-backed form of vitamin C proven to protect against free radicals. It’s also packed with beneficial anti-inflammatory, antimicrobial ingredients like propolis and niacinamide, as well as centella asiatica. This serum packs a punch!

Another product I really like is the COSRX Refresh AHA BHA Vitamin C Booster Serum. This is formulated with Ascorbyl Glucoside, a superstar Korean vitamin C derivative. Together with glycolic acid and alpha arbutin, this serum promises to deliver brighter, more youthful looking skin.

But not to worry if you feel like your skin can’t handle vitamin C. There are so many ingredients out there that work as fantastic antioxidants. The MARY & MAY Blackberry Complex Serum is one of my personal favourites. It uses blackberry extract instead of vitamin C as its star ingredient, and it really does give a nice instant glow. Over time though, you’ll definitely see its effects on giving you brighter, even skin.

In summary…

As you can see, the benefits of incorporating vitamin C into your routine are numerous! If you haven’t already, definitely trial it out in your morning skin routine for a couple of months and see the difference in makes in brightening and evening out your skin. And of course as always, don’t forget your SPF!