What Oxidative Stress Does to Skin
Free radicals — unstable molecules with unpaired electrons — are generated by UV radiation, pollution, cigarette smoke, and normal metabolic processes. They cause oxidative stress by stealing electrons from stable molecules (lipids, proteins, DNA), creating a chain reaction of cellular damage. In skin, this manifests as collagen fragmentation, accelerated photoageing, and impaired barrier function.
Antioxidants are molecules that neutralise free radicals by donating an electron — terminating the chain reaction before cellular damage accumulates.
Vitamin C: L-Ascorbic Acid vs Derivatives
| Form | Stability | Potency | % Range |
|---|---|---|---|
| L-Ascorbic Acid (LAA) | Low (oxidises rapidly) | Highest | 10–20% |
| Ascorbyl Glucoside | High | Moderate | 2–3% |
| Sodium Ascorbyl Phosphate | High | Moderate | 5–10% |
| Tetrahexyldecyl Ascorbate (THD) | Very high | High (oil-soluble) | 10–20% |
| 3-O-Ethyl Ascorbic Acid | High | Moderate-high | 2–3% |
L-Ascorbic Acid at 10–20% (pH 2.5–3.5) remains the gold standard for antioxidant protection and collagen synthesis support — but it requires proper formulation and storage. Derivatives offer more stability at the cost of some potency.
Why Vitamin C Is Essential for Collagen
Beyond antioxidant function, Vitamin C is an irreplaceable cofactor in collagen synthesis. The enzymes prolyl hydroxylase and lysyl hydroxylase require ascorbic acid to hydroxylate proline and lysine residues in procollagen. Without this step, collagen triple helix formation cannot complete — molecules are unstable and degraded. In other words: no Vitamin C = impaired collagen production, regardless of any other intervention.
Niacinamide: Multiple Pathways
Niacinamide (Vitamin B3) is not a classical antioxidant — it works through several mechanisms simultaneously:
- Inhibits melanosome transfer from melanocytes to keratinocytes (→ brightening)
- Upregulates ceramide, fatty acid, and keratin synthesis in keratinocytes (→ barrier repair)
- Inhibits sebum secretion from sebocytes at 5%+ (→ oil control)
- Anti-inflammatory via PPAR-γ activation (→ redness reduction)
- Restores cellular NAD+ levels (→ mitochondrial function support)
Ferulic Acid: The Synergy Multiplier
Ferulic acid itself is a moderate antioxidant (found in rice bran, oats, and wheat). Its critical role in skincare is synergistic: when combined with Vitamin C (15%) + Vitamin E (1%), ferulic acid doubles the antioxidant protection of the combination compared to either ingredient alone. The classic CE Ferulic formulation (Duke University research, Pinnell et al.) remains the most evidence-backed topical antioxidant protocol.
Application timing: Apply antioxidants in the morning, before SPF. UV-generated free radicals are the primary daytime stressor — antioxidants provide a chemical shield that SPF alone cannot.
For how antioxidants interact with collagen, see Collagen & Elastin. For pigmentation-specific Vitamin C use, see Hyperpigmentation.