L-Ascorbic Acid (LAA)
Pure Vitamin C
Pure Vitamin C
Stability
3/10
Poor
Irritation Risk
High
for most skin types
Bioavailability
10/10
skin absorption
pH Needed
Below 3.5
for efficacy
What Is It?
The gold standard of Vitamin C. L-Ascorbic Acid is the most researched and bioavailable form, but also the most unstable. It requires a low pH (below 3.5) to penetrate the skin and work effectively. Best stored in dark, cool conditions and used within 3 months of opening.
🔬 The Science
LAA acts as the active cofactor for collagen-synthesizing enzymes prolyl and lysyl hydroxylase. It also inhibits tyrosinase — the enzyme responsible for melanin production — making it effective for both anti-aging and brightening.
⚗️ Stability Note
Oxidizes to dehydroascorbic acid (DHAA) and then to diketogulonic acid (DKA). An orange/brown tint indicates oxidation.
Optimal Concentration
Available Range
5%–20%
Our Recommendation
10%–20%
Best For
- Hyperpigmentation
- Photoaging
- Collagen Synthesis
Avoid If
- Sensitive Skin
- First-time Vitamin C users
- Rosacea
Brands Using LAA
Top-Rated LAA-Based Serums
Eternal Bright
Eternal Bright Vitamin C Serum 20%
Excellent
Pure Vit C (LAA)
The Derma Co
The Derma Co 20% Vitamin C Serum
Very Good
Pure Vit C (LAA)
WOW Skin Science
WOW Skin Science Vitamin C Face Serum
Good
Pure Vit C (LAA)