VITAMIN C (and its derivatives)
Pure vitamin C (INCI: ascorbic acid) is the second superstar ingredient in cosmetics with efficacy also proven by various clinical studies for percentages between 5 and 20%, it has:
Clinical studies carried out on % between 5 and 10%.
Vitamin C problems:
- Antioxidant properties
- Anti-aging properties
Clinical studies carried out on % between 5 and 10%.
- Anti-stain properties
Vitamin C problems:
- Its stability: vitamin C can oxidize very quickly, which can reduce its effectiveness
- Its penetration: since vitamin C is water-soluble, it has difficulty penetrating into the skin.
- Its irritant nature: to overcome the two problems above, one of the solutions is to lower the pH to a pH of around 3.5, which can be irritating for certain skin types.
- ascorbyl tetraisopalmitate
- ascorbyl glucoside: stable and easy to formulate, in vitro studies show that it can penetrate the skin and is then converted into pure vitamin C. It also exhibits the three anti-aging benefits of pure vitamin C: antioxidant protection, collagen strengthening and reduction of hyperpigmentation which has been tested in vivo. Ascorbyl glucoside is typically used in 2-5% concentrations when the goal is to brighten dull skin and fade the appearance of hyperpigmentation.
- ethyl ascorbic acid: stable and penetrates the skin. According to the supplier, EAC is metabolized in the skin to pure ascorbic acid and they also claim that EAC seems to have both an antioxidant and anti-inflammatory effect, and may be able to stimulate the production of collagen skin. The strong point of the EAC however is the lightening of the skin. In addition to the manufacturer's claims, there is also in vivo clinical data (tested on real people) showing that 2% EAC can improve skin tone.
Sources:
- Stability, transdermal penetration, and cutaneous effects of ascorbic acid and its derivatives, Journal of Cosmetic Dermatology, 2012
- Assessment of penetration of Ascorbyl Tetraisopalmitate into biological membranes by molecular dynamics, Computers in Biology and Medicine, Volume 75, 2016