Egg yolk is the key nutrient in eggs that are needed for a chick embryo to grow up. Since it includes essential parts for embryonic development, such as lipids, protein, vitamin A, B1,  B2, calcium, and so on, it is a complete food, which is why it is a beloved ingredient for foods worldwide. Egg yolk is also popularly used as a successful cosmetic ingredient. Applying an egg yolk mixed with honey or grain powder on the face is well-known home therapy for skincare and pore care. It is an easy mask pack for skincare, removing sebum and fine wrinkles.

Lecithin, one of the main nutrients in egg yolk, has a good emulsification effect, which helps active compounds to be emulsified well on the skin. A study also demonstrated lecithin keeps the water balance on the skin as a skin protector. It can be existed on the skin surface after washing and makes skin smooth and flexible.