Wednesday, March 17, 2010

Dry skin type (D)

If you have dry skin, you know it can be a pain in the bum (or the arm or the face...choose your body part). What contributes to dry skin? The ability of our stratum corneum to maintain skin hydration! Low levels of stratum corneum lipids, natural moisturizing factors, sebum, hyaluronic acid, and aquaporins all contribute to dry skin.

How is dry skin defined? It is when your skin is a dull colour (gray to white) with a rough texture and an elevated number of ridges. When the equilibrium of the stratum corneum is out of whack, the skin's ability to maintain hydration is decreased, and skin is more susceptible to environmental factors because the skin barrier is impaired. Trans-epidermal water loss increases. Desquamation is abnormal, with skin coming off in sheets instead of cell by cell, so your skin looks rough and dry, and you get that white or ashy look.

Dry skin could be genetic, or it could be the result of over exposure to UV radiation, solvents, chlorine, detergents, or excessive amounts of water, all of which can lead to a disturbance in the stratum corneum lipids. This means water can escape faster through your skin, leading to a reduction in hydration. The ceramides in your skin are also messed up, which reduces the barrier properties. The increase in TEWL and the reduction in barrier properties means your skin will get drier and drier until the situation is improved!

If these things weren't bad enough, the reduction in your skin's natural moisturizing factor makes the situation even worse! NMF is derived from filaggrin: The degradation of this protein makes it possible for our outer skin layers to maintain an adequate water supply in dry or arid environments. When we're in a low humidity environment, the NMF production increases. If it doesn't, our skin gets drier. If your skin is already too dry and poorly hydrated, the NMF fails to increase in arid environments, which only increases the level of dryness!

Hyaluronic acid is found in the middle spinous layer of our skin, not in the stratum corneum or stratum granulosum. Its role in skin hydration is not completely known, but it is a very powerful humectant that can bind a thousand times its weight in water and it does help our skin in retaining said water for hydration. Older and dry skin is characterized by lower levels of HA. (And as a note, so far studies are showing that topical application of HA won't penetrate your skin to increase the amount in the stratum spinosum, although it will make your stratum corneum feel nicer.)

And we come to aquaporins. Our epidermis contains aquaglyceroporins (AQP3), which are proteins embedded in our skin's cell membranes that allow for the transport of water and glycerin into our skin. AQP3 is thought to enhance trans-epidermal water permeability to protect the stratum corneum from water evaporating through the skin and/or to spread water throughout the layer of the keratinocytes.

Mice deficient in AQP3 show reduced stratum corneum hydration, impaired skin barrier recovery, delayed wound healing, altered skin elasticity, and reduced glycerol in the stratum corneum due to the impaired glycerol and water transport to the epidermis. In short, an impairment in AQP3 leads to a reduction in the water holding capacity of our skin.

When our skin has been exposed to too much sun, we find decreased water permeability in cells, impaired cell migration (meaning new cells aren't moving to the stratum corneum), and delayed wound healing, all thanks to impairment in the AQP3.

Dry skin also sees an increase in pH, which is not a good thing. Various proteases involved in the desquamation process don't work well when the pH is increased, so we see less turnover of the top layer of cells! As well, our skin is less resistant to chemical and microbial attack.

So how can we treat dry skin with our lovely creations? As always, we need to use mild cleansers with very mild detergents. As much as I love surfactants, they can remove the stratum corneum lipids and reduce the NMF from our skin. Luckily, most surfactants are mild, and there are tons of ways to increase mildness in those types of products.

Because the skin's barrier mechanisms are probably impaired, we want to use a lot of lovely oils with good fatty acids, cholesterol, ceramides or glycerol, those things that make up the stratum corneum lipids. You'll want to apply these lovely lotions two to three times a day and especially after bathing to trap in the moisture.

If you are suffering from dry skin thanks to too much sun exposure (current or past), you likely have an impaired skin barrier, lower NMF, and lower hyaluronic acid levels. Unfortunately, adding HA to your creations isn't going to change this as it won't penetrate to the stratum spinosum level, which is where you really need it. There have been a few studies indicating that oral glucosamine supplements might help reduce the possible wrinkling, but not the hydration levels of your skin. Avoid the sun - that just seems obvious! - and use sunscreen to avoid further photo-damage.

Remember glycerin is your friend, as are the lower molecular weight hydrolyzed proteins, like silk or Phytokeratin, that penetrate your skin. Both of these ingredients will offer tons of moisturizing without oils.

When you are formulating mineral make-up for dry skin, make sure to include humectants like allantoin or silk powder to ensure you have a moisturizing ingredient, even in powdery formulas. Magnesium myristate treated sericite mica will offer moisturizing - it's a better choice than untreated sericite mica.

Join me tomorrow for more about skin types - the oily skin type!


junaid india said...

hey susan i am junaid 21 years old boy from problem is that i suffer from very dry skin,,,,n dthis dry skin is an internal problem,,u must be aware o fthe university of dundee study which state sthat some ppl are genetically predisposed to dry skin due to deformities in the fillagrin gene!!!from childhood i have suffered a lott due to my dry skin, no topical treatment works..i read ur article about essential fatty acids,,,,i started taking two fish oil capsules containing 360mg epa nd 240 mg dha and 2 Vitamin E 400 IU capsules,,,,after doing this for 20 days i found a welcome change ,,my skin became so hydrated nd plumped up like never before my hand peeeling stopped all this at the time wen the atmospheric humidity was very low,,btw i also take one multivitamin and eat awell balanced diet..but my 15 days of blessing ended,,and my normal dull deeply dry skin and hair returned!!!since a month i am taking 2 fish oil capsules +2 evening primrose oil caspsules per day ,,,but no rsults!!! can u help me out please?????i am really depressed by my skin cause its very irritating to hav d ry skin all around on scalp ,dry hair ,,etd

geri said...

A very useful article! I have one question - is oral use of HA effective ?

Erika Macaw said...


I'm having a heck of a time with a facial butter. My formula is as follows (this is a request of my mom, I make lotions (usually successfully lol) and such for sale but I haven't ever played with cosmecueticals and specialty ingredients)

100g total
water phase

30g h2o
20g aloe juice
10g lavender hydrosol
1g hyaluronic acid (I've never used this before, I dissolved it in 15g of the water portion for several hours and then added to water phase)
2g hydrolyzed wheat protein

oil phase

5g c12-15 alkyl benzoate
7.5g BTMS
3g pomegranate oil
5g rosehip oil
4g shea butter
3g cupacu butter
3g cetyl alcohol

I've yet to reach the cool down phase as I can't get a homogenous lotion with the first two phases.

cool down phase
.5g chamomile extract
.5 ginko extract
1g EO
.5g liquid germall plus
2g panthanol
2g dimethicone

I can't get an emulsified product with this formula. What am I doing wrong? I usually formulate fairly simple and easy to work with ingredients, but I'm trying to make things out of my comfort zone now.

Susan Barclay-Nichols said...

Hi Erika. I have no idea. Sorry. I think you need to do a few experiments. Make it with only water as the water phase. Make it without the HA. Make it with one oil type. And so on. There's nothing in the recipe that is out of whack...

How are you processing it? Are you heating and holding at 70˚C for 20 minutes in separate containers? How are you mixing it? Make sure you're following all the good manufacturing processes as well. (If you're selling, I'm sure you're doing all of this, but I have to put the reminders out there!)

melian1 said...

i'm wondering about the ultra low weight version of the h.a. ( ) less than 5,000 daltons, as compared to the regular h.a. at about 100,000 daltons.

does this penetrate far enough in to do some actual good? does it carry other stuff in the cream or lotion deeply into our skin that might not be as good for it?