Vitamin C in skincare: form and concentration decide
Not every vitamin C is the same. L-ascorbic acid is the pure, active form - most effective, but also most unstable. Vitamin C derivatives (ascorbyl glucoside, ascorbyl palmitate) are more stable, but first have to be converted in the skin and work more slowly. The best serums use stabilised L-ascorbic acid in a high concentration.
The ZO Skin Health 10% Vitamin C Self-Activating is something special: the active is only activated on application (not beforehand in the bottle), which increases stability. 10% pure ascorbic acid plus vitamin E as a co-antioxidant. The formula is hydroquinone-free and relies on free-radical defence as its mechanism of action.
The iS Clinical GeneXC Serum and the Super Serum Advance+ combine vitamin C with Centella Asiatica and peptides for a multi-target approach: protection plus repair plus depigmentation. The mesoestetic AOX Ferulic relies on the classic CE Ferulic combination (vitamin C, vitamin E, ferulic acid) - clinically proven to be the most effective antioxidant trio.
Dr. med. Niels Freitag explains in our skincare studio in Cologne: vitamin C belongs in the morning routine. In the morning it protects against free radicals from UV, pollution and blue light. In the evening, retinol is the better choice. The combination of both actives (vitamin C in the morning, retinol in the evening) is the gold standard in anti-ageing.
Related categories: Combine vitamin C in the morning with sun protection (strengthens UV protection). Alternate with retinol in the evening. For pigment spots, additionally use niacinamide. Especially with dull skin, vitamin C can visibly revive the complexion.
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Frequently asked questions about vitamin C serums
Which form of vitamin C is most effective?
L-ascorbic acid (pure ascorbic acid) is the best-researched and most effective form. It can be used directly by the skin, without conversion. The downside: it oxidises easily and becomes unstable. The ZO 10% Vitamin C Self-Activating solves the problem by activating only on application.
Use vitamin C in the morning or evening?
In the morning. Vitamin C is an antioxidant that protects against free radicals from UV radiation, air pollution and blue light. This protection is most valuable in the morning. Applied under sun protection, vitamin C additionally strengthens the UV protection factor.
Can vitamin C irritate the skin?
At high concentrations (15-20%), pure L-ascorbic acid can tingle or slightly redden sensitive skin. 10% (as in the ZO Vitamin C Self-Activating) is well tolerated by most skin types. For very sensitive skin, vitamin C derivatives at a lower concentration can be an alternative.
What is the CE Ferulic combination?
Vitamin C, vitamin E and ferulic acid together - clinically proven to be the most effective antioxidant trio. Vitamin E stabilises vitamin C, ferulic acid doubles the protective effect of both. The mesoestetic AOX Ferulic uses exactly this combination.
My vitamin C serum is discolouring - is it still effective?
If a vitamin C serum turns dark yellow or brownish, it has oxidised and lost effectiveness. Store it cool and dark (not in the bathroom). The ZO 10% Vitamin C Self-Activating doesn't have this problem, because the active is only activated on contact with the skin.