Vitamin C Serum: Anti-Aging Guide
Why Vitamin C for Anti-Aging
Vitamin C is a potent antioxidant that neutralizes free radicals, boosts collagen synthesis, and inhibits melanin production. It's the #2 anti-aging ingredient after retinol.
Types of Vitamin C in Skincare
- L-Ascorbic Acid (L-AA): Most potent, most researched. Unstable, oxidizes quickly. pH 3.5 required.
- Sodium Ascorbyl Phosphate (SAP): Stable, gentler, good for acne-prone skin
- Tetrahexyldecyl Ascorbate (THD): Oil-soluble, penetrates deeply, very stable
- Ethylated Ascorbic Acid: Fast-absorbing, converts to L-AA in skin
Choosing the Right One
- Beginners/sensitive: SAP or THD at 5-10%
- Experienced/normal: L-AA at 15-20%
- Oily skin: Water-based L-AA serum
- Dry skin: Oil-based THD serum
Storage and Shelf Life
- L-AA: Dark glass bottle, refrigerate, use within 3 months of opening
- Derivatives: Room temperature OK, 6-12 month shelf life
- If serum turns brown/orange, it's oxidized — discard
Application Order
Cleanse → Vitamin C → Hydrating serum → Moisturizer → SPF. Use in the morning for photoprotection synergy with sunscreen.
