5 Important Ingredients in Face Moisturizers for Women

Pronounced "dye-METH-i-kone", this ingredient may be found in many skin care, makeup and hair care products. Manufacturers use it in moisturizers, primers and foundations because it helps fill in uneven texture and fine lines, creating a smooth, flawless look. "Dimethicone is the main ingredient in most oil-free moisturizers," says Joshua Zeichner, M.D., director of cosmetic and clinical research at Mount Sinai Medical Center in New York City. "It's a light emollient that forms a protective layer over the skin's surface, helping to hydrate and keep moisture in." Emollients, like petrolatum, lanolin, and mineral oil, soften and moisturize the skin and can also decrease flaking [Source: WebMD]. They do this by creating an oily layer on top of the skin that traps water.

If you've ever used Vaseline, you're probably familiar with petrolatum (aka, petroleum jelly). Derived from petroleum (the same kind used for gasoline and other products such as deodorant), petroleum jelly is a staple in many people's medicine cabinets—and for good reason. It's great for smoothing and protecting rough skin. "Petrolatum is an occlusive ingredient that prevents water loss and an emollient that hydrates the rough dead cells on the skin's surface," says Zeichner. If you have dry skin, be sure to look for petrolatum on a product's ingredients list. Folks with normal to oily skin may want to skip petrolatum, though, as it may exacerbate greasy skin.

Hyaluronic acid has been getting a lot of buzz in the beauty world lately. Because of its ability to plump and soften skin, it's been showing up in moisturizers and serums over the last few years. Unlike some other skin care ingredients, hyaluronic acid is actually already present in the human body [Source: WebMD]. A viscous, gooey substance, it helps lubricate joints and is even found in the fluid of eyeballs to help maintain their shape [Source: WebMD]. However, like many substances in our bodies, it naturally depletes as we age—which is why beauty product manufacturers have begun adding it to products. "Hyaluronic acid is a humectant that hydrates by drawing water in to the outer layers from deep within the skin," says Zeichner. In fact, it is said to hold up to 1,000 times its weight in water. As a result, it makes skin appear plumper and feel softer and smoother. That may be why it's often used as a lip filler in plastic surgery!

Also known as glycerol, glycerin is a humectant that works similarly to hyaluronic acid, says Zeichner. Composed of fats and sugars, it's a sweet-tasting lipid that's actually found in all fats, whether they are from animals or vegetables [Source: Paula's Choice]. Because glycerin is a humectant, it readily absorbs and retains water, keeping skin sooth and hydrated. It attracts water from the environment and from the lower layers of skin (aka, the dermis) adding moisture to the surface layers of skin (the epidermis). In general, it helps maintain the skin's outer barrier, which helps prevent dryness and flaking. One recent study found that after 10 days of treatment with a cream that was 20 percent glycerin, volunteers saw an increase in corneometer values, a measurement used to measure the hydration levels of your skin [International Journal of Cosmetic Science].

Ceramides are fats naturally found in the skin's outer layer, and they make up a major component of skin structure. For this reason, they are crucial for maintaining the skin's natural moisture barrier. "Just like a house is composed of bricks, your skin is made up of cells," says Zeichner. "Ceramides serve as the mortar between the skin cell 'bricks' holding it all together." In fact, studies have linked dry, damaged skin to low ceramide levels [Source: Journal of Investigative Dermatology]. In addition to causing dry, scaly skin, a lack of ceramides makes the skin more susceptible to environmental factors like dirt, pollution and other irritants.