When it comes to eggs, there's no need to separate the benefits -- both yolks and whites hold skin care gifts.
Egg yolks are an important source of vitamin A, which helps your skin repair itself. If you're not getting enough of it from your diet, it will show in your skin. But the vitamin also works from the outside. Vitamin A derivatives like tretinoin (more commonly known by the brand name Retin-A) have been shown to help erase acne as well as wrinkles [source: Borel].
Egg yolks are also a source of biotin, a B-complex vitamin, which is needed for healthy skin and nails. There isn't much evidence to support popular claims that biotin supplements will improve your hair and nails, but it's definitely something you want on your plate [source: University of Maryland Medical Center]. (In an interesting twist, raw egg whites can interfere with the body's absorption of biotin, anti-yolk folks might want to reconsider their stance.) The yolk also contains lecithin, which is an emollient that softens the skin. Try an egg yolk beaten with some olive oil for an inexpensive hair mask.
The white of an egg, the albumen, is composed of 40 different proteins and water. The egg white facial is known as an "instant facelift" because of its temporary tightening effect. But it's those proteins in the white that make it such a great conditioner; the ionic charge of its amino acids helps it bind to hair. It's also possible that one of the proteins can help skin that's irritated from the sun [source: Phoenix Chemical, Inc.].
Next up: Peel some of these for tighter skin.