Vitamin C

Vitamin C (L-ascorbic acid) is a powerful antioxidant that protects the skin from environmental damage, boosts collagen synthesis, inhibits melanin production (brightening), and enhances SPF efficacy when used under sunscreen.

L-ascorbic acid (LAA) is the most bioavailable and effective form. For stability and penetration, look for formulations at pH < 3.5, typically 10–20% concentration. If LAA irritates your skin, consider derivatives like sodium ascorbyl phosphate (SAP) or ascorbyl glucoside (more stable, gentler).

• Apply in the AM on clean, dry skin before moisturiser and sunscreen. • Wait 10–15 minutes for full absorption before applying SPF. • Vitamin C and SPF work synergistically — C neutralises free radicals while SPF blocks UV. • Store in a cool, dark place or in the fridge to prevent oxidation (serum turning yellow/brown).

• Vitamin C + Vitamin E + Ferulic Acid is the gold-standard antioxidant cocktail. • Vitamin C + SPF: proven to increase photoprotection by up to 4x. • Vitamin C + Niacinamide: the old myth of incompatibility has been debunked — they work fine together. • Avoid using Vitamin C with benzoyl peroxide (oxidises Vitamin C).

Vitamin C is suitable for all skin types. It is especially beneficial for those with hyperpigmentation, melasma, dull skin, or premature ageing concerns. Sensitive skin types should start with a lower concentration (10%) or use a derivative.

The biggest challenge with vitamin C is stability. L-ascorbic acid oxidises rapidly when exposed to light, air, and heat — turning the serum yellow, then orange, then brown. An oxidised vitamin C serum is not only ineffective but can potentially cause hyperpigmentation. How to know if your vitamin C has oxidised: the serum changes from colourless/pale yellow to orange or brown. A slight yellow tint is normal but dark orange or brown means discard it. Factors that accelerate oxidation: • Oxygen exposure (always close the cap immediately after use) • UV light (store away from windows) • Heat (bathroom temperatures from showers accelerate degradation) • Metal ions in tap water catalyse oxidation Formulation solutions for stability: • Vitamin C + Vitamin E + Ferulic Acid (ferulic acid drastically increases stability) • Anhydrous (water-free) formulas • Airless pump or opaque packaging • Derivatives like MAP, SAP, ascorbyl glucoside are more stable but slower Best storage: Keep in the refrigerator. A well-formulated serum stored in the fridge can last 3–6 months after opening.

Vitamin C's role in skin health is backed by extensive clinical evidence: Collagen synthesis: A 2001 study in the American Journal of Clinical Nutrition confirmed that vitamin C is a required cofactor for the hydroxylation of proline and lysine — essential steps in stable collagen formation. Without adequate vitamin C, collagen produced is structurally weak. Antioxidant protection: A 2002 study by Lin et al. in the Journal of Investigative Dermatology showed that topical L-ascorbic acid at 15% significantly reduced UV-induced skin damage when applied before UV exposure. Brightening: Vitamin C inhibits tyrosinase — the key enzyme in melanin synthesis — without destroying melanocytes. A 2004 randomised trial showed 5% L-ascorbic acid reduced melanin index in patients with melasma after 16 weeks. Photoprotection synergy: A 1998 study demonstrated that the combination of 15% L-ascorbic acid + 1% alpha-tocopherol + 0.5% ferulic acid provided fourfold protection against UV-induced photodamage compared to either ingredient alone.

L-ascorbic acid delivers the best results but isn't for everyone. Here's when derivatives make sense: Sodium Ascorbyl Phosphate (SAP): A water-soluble, stable derivative that converts to ascorbic acid on the skin. Significantly less irritating. Best for sensitive, acne-prone, or rosacea skin. Also has direct antibacterial activity against C. acnes — making it a useful addition for acne-prone routines even beyond its antioxidant benefits. Ascorbyl Glucoside: Very stable, gentle, water-soluble. Converts to ascorbic acid via skin enzymes. Slower release means slower results but better tolerability for reactive skin types. Magnesium Ascorbyl Phosphate (MAP): Highly stable, hydrating, good for dry skin. Used in concentrations of 3–10%. Ascorbyl Tetraisopalmitate: Oil-soluble vitamin C. Penetrates deeply into the lipid layers of the skin. Excellent for combination with oil-based products or for those who prefer anhydrous formulas. When to upgrade to LAA: If you're using a derivative and see limited results after 3 months, a well-formulated LAA product (10–15%, pH <3.5, ferulic acid stabilised) will provide stronger and faster antioxidant and brightening effects — if your skin can tolerate it.