Science of Skin

Moisturisers

Moisturisers-generic

Moisturisers help to prevent dryness, improve tone and texture, protect sensitive skin and diminish imperfections. They also act as a temporary barrier to moisture loss, holding moisture to the surface of the skin. Moisturisers contain botanical ingredients such as vitamins, minerals, plant extracts and some contain sunscreens.

To understand the way a moisturiser works, it is important to have a basic idea of how skin functions. There are two main layers of the skin: the dermis and the epidermis. The dermis contains, among other things, collagen and elastin fibers which give the skin its strength and flexibility. As we age these fibers fragment and stiffen, causing loss of elasticity and wrinkles. The epidermis is above the dermis and has multiple layers. The deepest layer of the epidermis is the basal cell layer which sits on top of the dermis. The cells in the basal cell layer are continually dividing to produce millions of plump new skin cells each day. These cells are pushed upwards towards the skins surface by the dividing cells below.

The new skin cells have a strong membrane and hold onto water easily. However, as the skin cells age and move towards the surface of the epidermis (the stratum corneum), the cells flatten and die. As they do, the membrane weakens and the cells release their contents such as water and structural lipids, and they accumulate keratin, the protein found in hair and nails. This slow release of water from the cell is called transepidermal water loss, or TEWL. One good analogy, from dermatologist Howard Murad, M.D., is to think of this process of water loss as heat escaping from a cracked, shabby roof. When the cells reach the stratum corneum they are flat and scale-like and are arranged in overlapping layers that give the skin a tough and waterproof protective barrier. This whole process takes around 28 days.

MoisturiserAs the skin ages, this protective barrier weakens, making water retention more difficult. Free radicals, environmental pollutants and UV damage have a greater effect on the health and appearance of the skin, thus finding the right moisturiser is critical.

There are two basic types of moisturisers, water in oil (W/O) and oil in water (O/W). The water in oil formula is mainly oil with a small amount of water, these moisturisers are thicker, heavier products and are for the drier skin types that produce very little oil. The majority of the oil in water formula is, naturally water, with a small amount of oil. Combination/normal and the oilier skin types, those that need only a very small amount of oil and plenty of water, benefit from this type of moisturiser. Sensitive and mature skins can use either O/W or W/O moisturisers depending on their oil flow.

Moisturisers contain combinations of occlusives, emollients and humectants. Occlusives tend to be thick and greasy in texture and are better suited to dry skins or for use in some body moisturisers. According to Dr. J Kraft and dermatologist C. W. Lynde from The University of Toronto, occlusives reduce TEWL and have the most pronounced effect when applied to slightly dampened skin. Mineral oil is often used because of its favorable texture, but it is not as effective at preventing evaporation of water as many other occlusives. Some commonly used occlusives are: caprylic/capric triglycerides, mineral oil, lanolin, avocado or olive oil, petroleum, petrolatum, silicone, dimethicone, beeswax and cyclomethicone. Their main limitations include odor, potential to cause allergies and the greasy feel.

Emollients lubricate and soften the skin. They improve its appearance by filling in the spaces between rough, dead cells to achieve soft, smooth skin and provide a layer of oil on the skins surface to prevent water loss. They add that smooth, slippery feel to the moisturiser as they mainly consist of lipids (fats) and oils. Common emollients are: shea butter, petrolatum, lanolin, cyclomethicone, dimethicone copolyol, glyceryl stearates and propylene glycol linoleate, silicone, mineral oil, jojoba oil, avocado oil, soybean oil and vitamin E.

A humectant increases a moisturiser’s water holding capacity by attracting water to itself. A humectant requires a minimum of 70% humidity in the air to be effective. If you are in a tropical climate, where there is more moisture in the air than there is in your skin, a humectant will draw this moisture to the skin and increase the hydration considerably. However, if you live in a dry climate, where there is more moisture in your skin than in the air, a humectant will draw the moisture from the dermis to the stratum corneum, where it evaporates, leaving your skin feeling dry and dehydrated. The combination of humectants and emollients helps to reduce this moisture loss. Commonly used humectants are: hyaluronic acid, glycerin, urea, butylene glycol, propylene glycerol, sorbitol, sodium PCA, panthenol and lactic acid.

The best defense against free radicals is to ensure regular consumption of fresh fruit and vegetables high in antioxidants like carrots, tomatoes, sweet potatoes, citrus fruits and whole grains for internal health and topical application of an antioxidant rich moisturiser for external health. While all moisturisers containing antioxidants will show benefit from daytime application, there is some evidence of greater benefits of night time applications.

Antioxidants absorb UV, but they are also damaged or destroyed by it, so using an antioxidant rich moisturiser at night allows the product time to penetrate the skin and neutralize free radicals within the cells. UV rays can cause collagen breakdown and DNA damage, increase premature signs of aging, cause skin and pigmentation disorders and changes the skins’ ability to protect itself against infection. A high sun protection factor (SPF) and broad spectrum sunscreen should be used every day to protect the skin and help to prevent photodamage.

The biggest addition to cosmetics in recent times has been the introduction of over the counter retinoids and alpha-hydroxy acids - AHA’s, these products are known as cosmeceuticals. Retinoids are said to be beneficial for cell renewal, preventing oxidative stress and act as a UV filter to improve the appearance of aging skin and photoaging. AHA’s are water soluble and are better used on thickened, sun-damaged skin where breakouts are not a problem.

These products have been developed to focus on the effects of UV damage and aging. They are of great benefit to mature skins but can be used by all skin type. They should, however, be used only as directed as they can cause irritation and initially increase skin sensitivity to UV.

Know your skin type - Moisturisers

Combination/Normal skin. For Combination/Normal skin types there are hundreds of moisturisers on the market. Use a water-based (O/W) cream or, if you like a light moisturiser, try a lotion.

Dry skin. An occlusive and antioxidant rich cream moisturiser has enormous benefits for dry skins. It nurtures the skin leaving it looking soft and smooth.

Oily skin. Oily skins should use a light O/W moisturiser, an oil-free moisturiser or try a gel ensuring that they are labeled "non-comedogenic," which means it won't clog pores and create blackheads.

Sensitive skin. Sensitive skin should use a moisturiser that doesn’t contain synthetic fragrances or dyes. While the skin is sensitive, avoid using strong vitamin C products and retinoids as these can cause further irritation.

Mature skin. Mature skins will benefit greatly from the use of a glycolic or AHA’s. These products get rid of the dead, dry skin that builds up on stratum corneum, revealing fresh, new, smoother skin lessening the appearance of sun damage and photoaging.

No matter what skin type you are, your skin needs water. If you do not drink enough water the body will redirect the water away from the skin to the vital organs, reducing the amount of water to the skin causes it to form fine lines and become dull in appearance. It is essential to the health of your skin and your body that you drink 2 to 3 liters of water a day. If you commit to increasing your daily water intake, it will take 28 days for the new hydrated cells in the basal layer to reach the stratum corneum. These cells will lose their water content slower than those that have been dehydrated and your skin will look and feel smoother and brighter.

There are thousands of moisturisers on the market for all skin types. Do you research, spend the time looking at different ranges and products online, perhaps talk to a beauty therapist not only about their range but of other product ranges treating similar conditions. It may be worth while to see a dermatologist for some advice on your specific concerns. The cost of appointment may be minimal compared to the hit and miss approach with the hundreds of brands in the pharmacy or department stores.

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