Pro-Oxidant? What is it?
Vitamin C is one of the most potent antioxidants in skincare and is essential in any skincare routine. It is especially good when used in combination with sunscreens. Vitamin C can boost the sunscreen’s UV protection levels by neutralizing any free radicals caused by UV damage.
Vitamin C is need to produce collagen and is integral in helping proline and lysine to convert into hydroxyproline and hydroxylysine. It will help in transporting the fresh collagen molecule out of the fibroblast cell and into the extracellular matrix.
Vitamin C can act as an antioxidant as we mentioned earlier, but the blocking of free radicals may prevent the transfer of the melanin cells to the surface that cause hyperpigmentation.
Which types of vitamin C products will help your skin
Any good product (serum or cream) should give the vitamin C an environment that preserves its structure. Otherwise, an oxidized vitamin C will work against your skin! How? Oxidized ascorbic acid is a pro-oxidant. Just as ascorbic acid can donate electrons to your skin, oxidized ascorbic acid will be hungry for its missing electrons.
Some people use ascorbic acid as an acid, more precisely, as an alpha hydroxy acid (AHA) because an acid will work as an exfoliant to brighten. In this case, you need a concentrated and acidic ascorbic acid solution. And this exfoliant should not be neutralized. So if you are looking for an exfoliant, make sure there is no base (alkali) like (potassium hydroxide or sodium hydroxide, because you would be cheated and instead of using a AHA (alpha hydroxy acid) you are using a salt solution! For this, you can use the Vitamin C serum from Sorella Apothecary. This is not the type of product that you should use if you have sensitive skin or if you are using retinoids, because retinoids promote skin renewal by themselves. And remember: exfoliation removes the skin barrier and makes it easier for the skin to be damaged by oxidants or by UV. If you exfoliate, don’t forget your sunscreen!
How Vitamin C works
Every human needs Vitamin C. Our body needs it and we can’t make it ourselves, that’s why it is a vitamin! We need to ingest it as food. Why does the skin, in particular, need vitamin C? Because ascorbic acid is essential for the “finishing touches” on collagen. If collagen does not get those biochemical finishing touches, it can’t work. Many organs in the body need vitamin C, this is why we make sure we get it in our food in oranges or any food that contains it.
Why use vitamin C topically? As we age, our skin may not get enough vitamin C even if we ingest it. I like to have some vitamin C in my skin care. However, please note that vitamins are required in very small amounts, and this is true for the role that ascorbic acid plays in collagen synthesis.
Vitamin C has another function, as antioxidant, so it does not hurt to use higher concentrations because, especially in a polluted city, we need more antioxidants on our skin.
Commonly Used Forms of Vitamin C
Structure: Pure vitamin C in the form in which your body receives it.
Function: Exfoliation + stimulation of Collagen, suppresses mutated hyperpigmented cells.
Solubility: Ascorbic acid is water-soluble, so is usually delivered in water-based serums.
Stability: Highly unstable and subjective to oxidative change + potency loss.
Structure: Ascorbic acid with a glucose molecule attached onto the C2-OH group. This blocks a reactive part of the molecule and allows ascorbyl glucoside to be very stable.
Mechanism: The enzyme alpha-glucosidase breaks ascorbyl glucoside into glucose and ascorbic acid, where it can then work as ascorbic acid does.
Solubility: Water-soluble, usually delivered in water-based serums or creams.
Penetration into skin: Able to penetrate skin.
Evidence level: Low-Medium.
Collagen: It has been found in vitro to stimulate synthesis, but to a lesser extent than ascorbic acid.
Warning! Oxidized (brownish) vitamin C will not work as an antioxidant BUT as a PRO-oxidant! Don’t put oxidized ascorbic acid on your skin.
Vitamin C as a Pro-Oxidant
Because ascorbic acid is such a great antioxidant, it can reduce free metal ions which it can find around the skin. Here, iron is reduced from its +3-oxidation state to its +2-oxidation state. Iron in its +2-oxidation state can react with hydrogen peroxide which is present in skin cells, producing highly reactive hydroxyl free radicals.
This is exactly the reactive molecules which we were trying to protect the skin from when we applied vitamin C as an antioxidant. In this way, unstabilized vitamin C can act as a prooxidant – it can cause the free radical damage which it initially sought to protect the skin from. Hence the importance of only using “stabilized” forms of Vitamin c.
Irritation Factor of C
Whether your ascorbic acid serum irritates your skin or not is very often down to its pH level. Your skin sits at a happy, slightly-acidic pH of 4.5-5.5. Applying anything on your skin which is significantly more acidic (much lower in pH), or significantly more alkaline (much higher in pH), will usually cause irritation and may impair the skin’s natural barrier and functions.
Ascorbic acid is best delivered in a formula which is a pH of less than 3.5. This acidic pH, which is quite a bit lower than the skin’s natural pH, can often irritate more sensitive skins. This is trial and error and will affect different skins in different ways.
While an ascorbic acid formula of less than pH 3.5 is the most powerful way to get vitamin C into the skin, for those who are struggling with irritation or the annoyance of stability issues, we turn to the next best thing; vitamin C derivatives in stabilized forms.
What to look for in a vitamin C skin care product?
Rather than talking about brands I would like to comment on which ingredients to look for.
For vitamin C as a vitamin, look for a serum or cream that contains a stable form of the vitamin, like Tetrahexyldecyl Ascorbate (THD Ascorbate). This way you don’t have to worry about stability. This vitamin C derivative is stable as has vitamin C (it will form ascorbic acid once it is in your skin). It will also work as antioxidant and you don’t have to worry about it working against you as a pro-oxidant. A cream or serum with ascorbic acid will start oxidizing as soon as it is mixed, unless you find a good chemist to make it.
Both highly stable and oil-soluble, THD Ascorbate rapidly absorbs into the skin for visible anti-aging benefits, including visual improvement in loss of firmness, the appearance of lines and wrinkles, and dark spots and dullness.
What Skincare Products Have THD?
Both of these Sorella Products have THD as the second ingredient in a 20% blend of vitamin A, C (BV-OSC) and E. Fight daily pollution and complexion-dulling irritants with a dose of antioxidants and vitamins that’s ideal for all skin types. This hydrating serum rejuvenates dry and tired skin while minimizing visible effects of stress and fatigue.
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Fitzpatrick, R. E., & Rostan, E. F. (2002). Double-blind, half-face study comparing topical vitamin C and vehicle for rejuvenation of photodamage. Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.], 28(3), 231–236. https://doi.org/10.1046/j.1524-4725.2002.01129.x
Telang P. S. (2013). Vitamin C in dermatology. Indian dermatology online journal, 4(2), 143–146. https://doi.org/10.4103/2229-5178.110593