Not all skincare ingredients are created equal

Vitamin C is amazing for brightening the skin, supporting collagen, and protecting against environmental stress. But the form of vitamin C you use matters so much more than the percentage on the bottle. The two most common forms are L ascorbic acid and THD ascorbate, and they behave very differently on the skin.

L ascorbic acid

This is the classic vitamin C everyone talks about. It is heavily researched, but it is also extremely unstable... It breaks down quickly when exposed to air, light, or heat. It only works at a low pH of around 3-3.5,  which can sting or irritate sensitive or acne prone skin (our skins natural ph is around 5.5). Even if it is formulated well you will still have to use it religiously and store it correctly. It’s never my first choice.  

THD ascorbate

THD is the version I tend to love for most people. It is much more stable and gentle. Because it is lipid soluble, it moves through the skin barrier more easily and penetrates deeper into the dermis. THD converts into active vitamin C once it is inside the skin (similar to the ester form of vitamin a) so you still get all the brightening and collagen benefits without the irritation that can happen with L ascorbic acid. It is a great option for sensitive, reactive, or acne prone skin.

My recommendation

If your skin is resilient and you love a stronger, faster brightening effect, L ascorbic acid can work well as long as it is in proper packaging(likely it will not be). If you are sensitive, breaking out, dealing with barrier damage, or simply want something gentler, THD ascorbate is usually the better choice. Both forms work. The key is choosing the one that your skin can actually tolerate and benefit from.

Sources

    1.    Telang PS. Vitamin C in dermatology. Indian Dermatology Online Journal.

    2.    Pinnell SR. Regulation of collagen biosynthesis by ascorbic acid. Journal of the American Academy of Dermatology.

    3.    Farris PK. Topical vitamin C in aging. Dermatologic Surgery.

    4.    Burke KE. The role of lipid soluble vitamin C derivatives.