| Ingredient | Strength in the studies | How long | Reported |
|---|---|---|---|
| Niacinamide | 2% to 5% | 4 to 12 weeks | Softer look of blotchiness, dark spots, roughness12 |
| Hyaluronic acid | 0.1% creams, various weights | 60 days | More hydration and elasticity than a plain cream4 |
| L-ascorbic acid | 5% to 15% | 3 to 6 months | Improved look of fine lines and roughness89 |
Niacinamide
Niacinamide is vitamin B3. In one set of trials, a 5% niacinamide moisturiser in 18 people and a 2% niacinamide sunscreen in 120 people reduced the look of dark spots after four weeks1. In a study of 27 people with melasma, 4% niacinamide and 4% hydroquinone each improved skin over eight weeks with sunscreen, and the colour difference between them was not significant2. The Cosmetic Ingredient Review panel found no irritation in use tests up to 5%3.
More does not look clearly better. That is why our serum is 5%, which sits at the top of the range studies used, and no higher.
Hyaluronic acid
Hyaluronic acid is a humectant that holds water. In a 76-woman trial, 0.1% hyaluronan creams of five different molecular weights all improved hydration and elasticity over 60 days, and wrinkle depth improved only with the two lower weights4. A lab study on excised skin found low-weight hyaluronic acid passes into the stratum corneum and high-weight does not5. It plumps the look of skin. It does not fill wrinkles.
Vitamin C
Pure vitamin C, L-ascorbic acid, has to be at a pH below 3.5 to get into skin, and absorption in pig skin topped out at 20%6. Adding ferulic acid to a mix of 15% L-ascorbic acid and 1% vitamin E made it more stable and roughly doubled its photoprotection in skin7. Reviews add that it oxidises in light and air, turning yellow to brown, and that stinging is a common minor effect8. It can be used with sunscreens and other antioxidants8.
In a 6-month double-blind trial, a 5% vitamin C cream improved photoaged skin on the neck and arms compared with a plain cream9. Our serum is 10% with ferulic acid and vitamin E. That is below the 15% studied, and we have not run the study on our formula.
