The Role of Moisturizers
Moisturizers are important in skin care for several reasons - moisturized skin appears smoother and younger by plumping up cells and reducing the appearance of fine lines and wrinkles. Proper hydration is also important for the health of the skin. Studies show that properly hydrated skin is irritated less easily and recovers more quickly from environmental insults.
Healthy, well moisturized skin requires an intact epidermal barrier, which is responsible for the regulation of transepidermal water loss (TEWL). An increase in TEWL results in xerotic skin changes - dryness, scaling, roughness, and fine fissuring.
The epidermal barrier is composed of 2 functioning components 1) an intertwined and layered grid of keratinocytes ("bricks") with a top layer of thin stratum corneum cells (known as corneocytes) and 2) an intercellular lipid matrix ("mortar"). Proper function and maintenance of both components assures skin integrity, water balance, hydration, and orderly skin cell exfoliation. A disturbance in the function of either of these components results in increased TEWL.
Epidermal barrier lipids are important in the formation of a barrier that is responsible for maintaining intracellular water content. A shortage of these lipids results in increased TEWL, a reduction in skin plasticity, and the adverse consequences related to dry skin.
If, due to external or internal conditions, there is a shortage of these lipids, or, if for some reason, they are not performing properly, it is the role of a moisturizer to temporarily perform the functions of epidermal lipids - regulating and maintaining proper epidermal water content.
It is important to recognize that the term moisturizer does not imply that moisture is being added to the skin; instead a properly designed mosturizer formulation contains occlusive, humectant, and emollient ingredients.
The occlusive ingredients (plant oils, petrolatum, lanolin, silicones, etc) prevent water loss by forming a hydrophobic* (*Repelling, tending not to combine with, or incapable of dissolving in water) film on the skin surface and within the gaps between corneocytes.
Humectants (hyaluronic acid, urea, honey, propylene glycol, etc) attract water from the dermis and bring water into the outer epdiermal layer. In humid climates, where humidity is higher than 70%, humectants can also attract and trap water from the surrounding air.
Emollient ingredients (isopropyl alcohol, cetyl alcohol, octyl stearate, etc) help to fill in the gaps between fragments of dry skin - transforming a rough surface into a smooth and soft surface. This helps improve makeup application, as well as provides an immediate improvement in the appearance of the skin.
Choosing a Basic Moisturizer
When choosing a moisturizer, always take into account your skin type and needs. Is it dry, oily, sensitive, sun damaged?
Dry skin types are better off with cream formulations, formulations that contain more oil than water in the base.
Normal skin types may prefer a lightweight lotion for the day and a cream formula for use at night.
Oily skin can be a little more tricky. During the day, either a moisturizer with shine-control properties or a hydrating gel or serum would probably be ideal. At night, a non-comedogenic lotion could be used if active skin care treatments leave the skin feeling dehydrated.
Extremely dry skin types may need both a cream (or balm) and a hydrating booster. A hydrating booster is a gel or serum filled with humectants, lipids, ceramides, or other barrier-repairing and anti-inflammatory ingredients. When layered underneath a moisturizing cream, it provides long-lasting, extra hydrating results.
Beyond the Basics
If you want to get more out of your moisturizer, then you can up the ante by choosing an advanced formulation with antioxidant, anti-inflammatory, barrier repair, anti aging, or skin lightening capabilities.