What it is
Lecithin is a phospholipid (a lipid composed of a phosphate group and fatty acids) that occurs naturally in egg yolk and animal and plant tissue.
What it does
Lecithin is an emollient that has water-binding properties. It reduces flakiness and restores suppleness, thus improving the appearance of dry skin.
It addition, it helps to form emulsions as well as enhancing the penetration of other ingredients into the skin.
When Lecithin is used in products containing nitrosating agents, it could form nitrosamines, which are carcinogenic. Many products, however, are formulated to avoid this risk and even when nitrosamines occur, they’re present in such small quantities, there’s still a debate on whether or not they pose any serious problem for human health.