Dermatologists are generally big proponents of vitamin C, because a lot of research has been done on it and this vitamin always comes out very well.
There is real evidence that vitamin C really, really helps.
This vitamin is an antioxidant and thus protects against damage: sun exposure, pollution and smoking.
Vitamin C is also involved in the production of collagen and therefore helps keep the skin firm.
The best known is L-ascorbic acid, but derivatives are most often used. Because these irritate the skin much less. Examples of derivatives are Sodium Ascorbyl phosphate and Ascorbyl palmitate.
Research shows that a concentration of 1.5% is already effective on age spots on the hands
Unfortunately, even the more stable forms of vitamin C continue to struggle with exposure to oxygen. So also when using cosmetics with a high concentration of these ingredients, choose light-tight packaging with pumps.
TIP: add vitamin E for an even better effect of vitamin C