Vitamin C
Antioxidant active — ascorbic acid and stabilised derivatives
Function in skin biology
Vitamin C (L-ascorbic acid) is a water-soluble antioxidant and a required cofactor for several enzymes involved in skin's structural protein synthesis. In cosmetic formulation, vitamin C is evaluated for its antioxidant capacity — helping to neutralise reactive oxygen species generated by UV and pollution exposure — and for its association with a more even-looking skin tone over consistent use.
Why Ambernay evaluates it
Pure L-ascorbic acid is notoriously unstable — it oxidises on exposure to light, air and water, losing efficacy and potentially destabilising a formula. Because of this, Ambernay evaluates vitamin C derivatives (such as ascorbyl glucoside, sodium ascorbyl phosphate or magnesium ascorbyl phosphate) which offer improved stability, alongside formulation techniques (airless packaging, low pH systems, antioxidant co-formulation) before any vitamin C product is finalised.
Where concentration matters
L-ascorbic acid is typically studied at 5–20% in cosmetic formulas, generally requiring a low pH (below 3.5) to remain stable and absorb effectively — which can increase irritation potential. Stabilised derivatives are effective at different concentration ranges and are generally better tolerated, with a trade-off in potency that formulators weigh against tolerability.
What we do not claim
We do not claim that vitamin C lightens skin in a depigmenting-drug sense, treats melasma or other diagnosed pigmentation conditions, or replaces daily SPF. Vitamin C's antioxidant role is a complement to — not a substitute for — UV protection.
Best paired with
Vitamin C is commonly paired with vitamin E and ferulic acid, which extend its antioxidant stability. It is generally best applied in the morning routine, before SPF, and is formulated separately from retinoids and strong acids where pH incompatibility can affect both actives.
Claim caution / regulatory note
Vitamin C and its derivatives are cosmetic ingredients. Claims must remain within cosmetic function: antioxidant support, visible tone evenness, skin radiance appearance. Claims of treating diagnosed hyperpigmentation conditions require dermatological, not cosmetic, substantiation.