Only some moisturisers make dry skin better
By Dr Des Fernandes & Jennifer Munro
Some moisturisers make dry skin worse
We all want nice, plumped up moisturised skin, but putting ‘moisturiser’ on is not the right way to achieve it. If we give skin the nutritional ingredients it needs to stay healthy, then it will make its own moisture. In fact, most moisturisers will make the problem worse by discouraging your body from manufacturing its own moisture. HYALURONIC ACID and VITAMIN A are critical to thick, healthy self-moisturising skin.
First, let’s introduce Hyaluronic Acid in a non-scientific way.
Think of it as tiny waterbeds in your skin; plump little homemade cushions that can hold over a thousand times their weight in water and make your skin look younger and healthier. They act as shock absorbers, so that when you lose them, your skin bruises very easily and starts to look wrinkled and discoloured. If you’ve ever used moisture beads or gels in the garden to prevent dehydration, particularly in hanging baskets, you’ll get the picture right away!
And now for a more scientific approach:
Hyaluronic acid (probably better called Hyaluronan, but we will shorten it to HA) is the most common and important molecule of the natural glycosaminoglycans in our skin. Others are dermatan sulphate, chondroitin sulphate and keratin sulphate etc. They attract water and form the gel that surrounds the fibres and cells of the skin.
Hyaluronic Acid is an extremely large molecule inside our skin.
We measure it in units called ‘Daltons’ and normal hyaluronic acid, that healthy young people have in their skin (provided it is not too sun-damaged), is in the order of 3-4 million or more Daltons. The amazing feature of this massive molecule is that it is a simple polymer, a long chain of only two different sugar molecules joined repetitively: glucuronic acid and N-acetylglucosamine, repeated thousands of times. It’s made in the membranes of certain cells by specialised structures called hyalurosomes (1)and extruded into the space between the cells.
Hyaluronic Acid’s great power is its ability to attract and hold water.
HA serves a very important function in the skin because it is normally found in the dermis (lower part of the skin) in between the fibres of collagen and elastin. Its great power is that it attracts water and can hold thousands of times its weight in water and this plumps out the skin and keeps it well hydrated.
Hyaluronic Acid has other powers too
HA is also a free radical scavenger and so it helps to reduce the damage of UV rays.(2) HA also insulates the skin against trauma; unfortunately as we get older we produce less HA and, so not only does the skin become drier, but also more fragile and blood vessels get damaged more easily. That causes the awful bruises that we see on old people’s hands, arms and legs. They actually have developed a state of “dermatoporosis” = weak skin. HA also stimulates the growth of keratinocytes to keep the skin at the ideal thickness.
CD44 receptors for HA ensure normal growth
The little detail that I think is worth remembering, is that there is a special receptor involved in the natural production of HA in the skin. This is the CD44 receptor. If you read about CD44 you might be frightened and think that it’s a dangerous receptor that is involved in cancer development and metastasis. It’s just an example of how multifunctional some systems can be. It has a very benign and comforting role for your skin, because it's a receptor for HA and ensures normal growth of the epidermis and good hydration of the epidermis and dermis. We should remember it, because it is the receptor that will respond to certain shorter chains of HA and then stimulate the production of the really effective long chain HA.
HA is something we make ourselves, using our CD44 receptors
One third of the total HA in the body is in the skin and is found in the dermis and, also in the epidermis. It lies in the narrow spaces between cells so ends up being in a rather high concentration. Keratinocytes in the basal layer have the ability to make HA because they have CD 44 receptors, and fibroblasts in the dermis also have CD44 receptors.(3)
There is more information about this in our book, Vitamin A Skin Science
Sunlight destroys HA very easily
HA has a very large turnover in the body. We break down about a third of our HA every day (4) so we easily can fall into a deficit if we expose out skin too much to the sun. UV rays destroy HA, hyalurosomes and also the CD44 receptor. That causes a thin skin with poor keratinocyte activity. The damage is accumulative and that is why older people can develop Dermatoporosis. Did you notice how this also sounds like vitamin A depletion? You should not be surprised to realise that vitamin A supports the hyalurosomes and CD 44 activity and actually reverses the effects. Vitamin A is one of the most powerful stimulants for HA production. This is why we say that Vitamin A is a moisturiser and the moisture that your own body makes using Vitamin A is so much better than any moisturiser that you put onto it.
How do we fix the loss of HA?
We can’t simply rub HA on our skin. It is such a large molecule that it cannot enter the skin if it is applied to the surface. It just remains as a wasted and expensive ingredient on the surface. Of course, from my point of view, we can get such a large molecule into the skin if we prepare the skin with the Cosmetic Roll-CIT. Even though the holes are very tiny and shallow, the only barrier is the Stratum Corneum (the Horny Layer) and even 0.1 mm needles easily penetrate the Stratum Corneum and most of the HA can then penetrate.
Research has shown that if we snip HA into shorter fragments then we can make the molecule small enough to penetrate the Stratum Corneum. However, there are problems! Very small fragments imitate the small fragments found after injury and they seem to stimulate inflammation, but may also improve the natural defence of the skin to infection.(5)There are fragments that we call medium chain HA that can be absorbed through the skin but for the best absorption we can enhance the penetration by cosmetic needling or Low Frequency sonophoresis. Obviously the larger the molecule, the more difficult it is to get through the skin. These medium chain HA have been found to be valuable in treating people with Dermatoporosis because they stimulate the CD44 receptor to make more HA and also, they stimulate the keratinocytes to grow better and make a thicker epidermis to reverse the Dermatoporosis.
Young people don’t need HA unless they are sun damaged.
Interestingly enough, research shows that if you apply medium chain HA to young people’s skin, there is no change in the thickness of the skin and minimal evidence of HA production. It seems that the CD44 receptors were well supplied with natural HA and did not respond to the applied medium chain HA. That tells us that younger people should not waste money on applying HA products.
HA application is essential as we age.
As we get older we all run into a little deficit of HA that will benefit from applying medium chain HA… Some companies will tell you that they have the best most absorbable HA and some companies even use very short HA which can be absorbed, but they do not stimulate the CD44. Only HA fragments from about 50,000 to 150,000 (HAF1) to 400,000 Dalton will stimulate the CD 44. The best are in the HAF1. Companies may use variants of these medium chain HA fragments. The bigger they are, the more difficult it is to get them into the skin. But there is another, more natural, way to stimulate the production of HA : Vitamin A has long been known to stimulate the production of HA through the stimulation and protection of the CD44(6-8). Hyalurosomes are also protected by vitamin A. Remember that vitamin A is naturally found in the epidermis, and it acts as a sunscreen, which further protects the HA. The combination of vitamin A and HA (medium chain) in more mature skin makes for an excellent skin care regime, especially with the addition of collagen and elastin forming peptides.
1. Kaya G. New therapeutic targets in dermatoporosis. The journal of nutrition, health & aging. 2012;16(4):285-8.
2. Trabucchi E, Pallotta S, Morini M, Corsi F, Franceschini R, Casiraghi A, et al. Low molecular weight hyaluronic acid prevents oxygen free radical damage to granulation tissue during wound healing. International Journal of Tissue Reactions. 2002;24(2):65-71.
3. Kaya G, Tran C, Sorg O, Hotz R, Grand D, Carraux P, et al. Hyaluronate fragments reverse skin atrophy by a CD44-dependent mechanism. PLoS Med. 2006;3(12):e493.
4.Kaya G, Augsburger E, Stamenkovic I, Saurat JH. Decrease in epidermal CD44 expression as a potential mechanism for abnormal hyaluronate accumulation in superficial dermis in lichen sclerosus et atrophicus. J Invest Dermatol. 2000;115(6):1054-8.
5. Gariboldi S, Palazzo M, Zanobbio L, Selleri S, Sommariva M, Sfondrini L, et al. Low molecular weight hyaluronic acid increases the self-defense of skin epithelium by induction of beta-defensin 2 via TLR2 and TLR4. Journal of Immunology. 2008;181(3):2103-10.
6.Kaya G, Grand D, Hotz R, Augsburger E, Carraux P, Didierjean L, et al. Upregulation of CD44 and hyaluronate synthases by topical retinoids in mouse skin. Journal of Investigative Dermatology. 2005;124(1):284-7.
7.Calikoglu E, Sorg O, Tran C, Grand D, Carraux P, Saurat JH, et al. UVA and UVB decrease the expression of CD44 and hyaluronate in mouse epidermis, which is counteracted by topical retinoids. Photochemistry and Photobiology. 2006;82(5):1342-7.
8.Barnes L, Tran C, Sorg O, Hotz R, Grand D, Carraux P, et al. Synergistic effect of hyaluronate fragments in retinaldehyde-induced skin hyperplasia which is a Cd44-dependent phenomenon. PloS one. 2010;5(12):e14372.