The Science Behind Vitamin C: Why Your Serum Needs It at 15%

Excerpt: Not all Vitamin C serums are created equal. The concentration, formulation, and stability of L-ascorbic acid determines whether your serum actually works — or just oxidises in the bottle. Here's what the research says.

Body: Vitamin C is one of the most clinically studied skincare ingredients in existence. But walk into any beauty aisle and you'll find serums ranging from 5% to 30% — so which concentration actually delivers results?

The research is clear: L-ascorbic acid at 15% sits in the sweet spot. Below 10% and the concentration isn't potent enough to trigger meaningful collagen synthesis or melanin inhibition. Above 20% and the risk of irritation outweighs the benefit — especially for darker skin tones prone to post-inflammatory hyperpigmentation. At Lumé we formulate at exactly 15% — stabilised with ferulic acid to prevent oxidation and extend shelf life. The result is a serum that stays active from the first pump to the last. What to look for on a label: — L-ascorbic acid (not ascorbyl glucoside — a weaker derivative) — pH between 2.5 and 3.5 for optimal absorption — Ferulic acid or Vitamin E as stabilisers — Dark or opaque packaging to prevent light degradation