Thinny Skinnies – Leaky skin: the cause of dermatitis, eczema and skin allergies?
Micki Rose revises her excellent 2009 article looking at recent research and suggesting how you might deal with the problem.
In the past decade, experts have become pretty convinced that people suffering with skin disorders like dermatitis, eczema and psoriasis do so partly because they have thinner, leakier skin, termed ‘epidermal barrier dysfunction.’ This type of skin lets more environmental substances like bacteria, pollens, moulds, chemicals and so on through than it should, which are then thought to set off an allergic reaction as they enter the blood stream. As the immune system weakens over time and the skin gets more porous, food intolerances and asthma are thought to follow. This is called the ‘allergic march’ and it generally starts with atopic dermatitis.
We used to think that the problem was primarily an immunological one in the skin with T-cells over-reacting and causing an inflammatory reaction to allergens - and we thought you would therefore get thinner skin as it all progressed. However, many now think we had that the wrong way round and it is because the skin barrier is not right that it all happens. Therapy to date has therefore been largely immunosuppressive, but barrier repair treatments have been showing great promise.
The Barrier Structure
An average person has about 1.75m2 of skin. At the top of the epidermis is the stratum corneum which is made up of dead skin cells glued together to form a layer of keratin cells and lipids, which give it toughness and moisture. Those lipids are made up roughly of 50% ceramides, 25% cholesterols and 10-20% free fatty acids. This, in effect, is the barrier. It acts as a layer of bricks with the fats in between as the mortar, if you like.
There are fifteen layers of this stratum corneum which constantly move closer to the surface to be shed – a new layer forms every two weeks. Beneficial bacteria live on this part of the skin and form part of the barrier by inhibiting pathogenic organisms. Some of this bacteria is shed with the skin cells and needs to be constantly replaced.
The barrier is dependent on us maintaining the right levels of moisture in the skin, its pH, the content of the lipids between the cells, the bacterial balance and the rate of shedding. The deeper layer under this barrier is the dermis and this is where most of the nutrients are needed to grow a healthy strateum corneum, so we need to nourish that well, too.
Is Leaky Skin Genetic?
There is very likely a genetic component to skin allergies and certainly to barrier weakness. Just two possibilities include issues with the FLG and LCE cluster genes. For example, recent studies suggest up to 60% of people with atopic dermatitis have a fillagrin (FLG) gene defect, leaving them with vulnerable skin barriers. However, not everyone with an FLG defect goes on to develop a skin problem, so it’s unlikely to be the only factor involved. Other studies found that the LCE gene cluster may be implicated, especially in psoriasis, and this genetic variant would likely lead to problems maintaining the skin’s proteins and therefore the barrier. Just because we have a gene SNiP, though, remember it doesn’t mean we will develop the problem – there are myriad other factors and triggers probably involved.
A lack of AMPs and cAMP
Research suggests that eczema sufferers lack what are termed AMPs (anti-microbial peptides), which help specifically to fight off bacteria. These AMPs live in the outer surface of the skin and if you don’t have enough, you are more prone to bacterial attack. If you injure your skin somehow, normally you’d see an increase in AMPs at the site to fight off infection, but this doesn’t happen as effectively in skin sufferers and so bacteria attacks the skin, injures it and prompts a skin flare.
We do know that many eczema sufferers have a lot more staph. aureus bacteria in the upper skin layers than most people and this could be the reason why – they can’t fight it off as well. Of course, then antibiotics are regularly used which damage the skin’s natural bacteria further and have the potential to make the whole problem worse longer-term. Happily, there are now so-called ‘Pro-AMP creams’ being developed using the amino acid L-isoleucine which acts as an AMP-inducer specifically in epithelial cells. Very exciting.
Slightly-confusingly, there is another potential issue involving cAMP, (cyclic adenosine monophosphate), which is an important cell-signalling messenger. Low cAMP essentially leads to higher histamine release and we know that histamine is an important factor in many, especially itchy, skin conditions. Raise the cAMP: lower the histamine, and probably the itching. The Ayurvedic herb Coleus Forskohlii (Forskolin) has been used for years to increase cAMP levels, especially in psoriasis cases. I suspect it will help other histamine-high conditions too.
Thin skin is often dry skin. Dry skin is often itchy. Scratching damages the skin and allows the bacteria and other pollutants in leading to yet more itching and more scratching, and so it goes on. The trick must be, then, to keep the skin well-oiled and that’s the argument behind many barrier creams.
Babies in the womb are covered in a kind of waterproof cream called Vernix caseosa, made up of fats, water and dead skin cells, which forms the skin’s all-important barrier. One team of scientists is trying to make a synthetic version of this for use when the barrier is compromised, as in eczema. Researchers in India applied sunflower oil several times a day to vulnerable premature babies to strengthen their immature skin barrier and found that there was a drop in deaths by a staggering 26%. Simply keeping them well moisturised prevented them absorbing damaging environmental pollutants.
So far, so good, but barrier creams are often toxic and mineral-oil based. Some experts think this compounds the problem, as they don’t allow the skin to breathe and hold petroleum by-products and sweat next to the skin for much longer than normal, possibly contributing more damage. Certainly they are not nourishing the strateum corneum very well, we know that; it’s like sticking cling film on to prevent moisture loss!
We also need to think about how we moisturise our skin internally. We know that the glue holding the barrier together is made of fats, ceramides and cholesterol as we said above. These are used to make phospholipids which form cell and other membranes. So surely, we must make sure we’ve got enough of the right elements to go around.
Lipids in our bodies are dependent upon our consumption of essential fatty acids like omega,3, 6, 7 and 9. Research suggests that eczema sufferers tend to have higher than average levels of linoleic acid and lower amounts of polyunsaturated fats like GLA, EPA and DHA. Even more interesting, one study found that there was a definite correlation between pregnant women who ate more omega 6 rich foods as margarine and vegetable oils in their last four weeks and the number of their children who had developed eczema and other allergies by two years old. Those who ate more fish (Omega 3, DHA/EPA) didn’t.
This may partly be because of the impact of omega 3 fatty acids on strengthening our immunity, forming strong membranes and lowering inflammation levels, but could also be because people have a problem converting linoleic acid into the more beneficial fats. This is dependent on specific nutrients, most importantly zinc, which is needed for the enzyme delta-6-desaturase required for conversion to take place. Zinc is a key skin and immune nutrient, and this could go some way to explaining why zinc often helps in these cases, both as supplements and as zinc oxide cream applied topically. Giving omega 3 oils as fish oil is likely to help people side-step this conversion problem, although vegetarian sources of these such as linseed (flaxseed) may not, as these still need to go through a conversion process.
Since we also know that cholesterol plays a really important part as one of the barrier and cell membrane substances, we must avoid over-zealous reduction of our cholesterol levels. Research suggests that we should be aiming for a healthy total cholesterol level of between 4.9-5.4 and that cholesterol, as well as causing problems when it is too high, can also be problematic when it’s too low. Membrane and barrier strength being compromised is one of the key issues.
One of the key lipids to consider, if you recall, was ceramides and there has been a lot of research on these over the last few years, suggesting that ceramide-dominant creams can actually feed the deeper layers of the skin and truly make it stronger. They are rivalling steroid relief for mild to moderate cases. Some creams (Epiceram/Triceram) now exist which have a 3:1:1 ratio of ceramides, cholesterols and fatty acids respectively and studies are showing they are working especially well in atopic dermatitis. In actual fact, it seems that it is the ratio that works best – you can have three in the ratio of any of the elements; it doesn’t have to be ceramides.
Lastly, we musn’t forget the importance of water. Remember what the babies’ natural ‘cream’ is made of: fats, skin cells, but mostly water. Hydration is key. And fats have a role to play here again too since efficient hydration of the body only happens if you have the correct essential fats in place. If you’re deficient in the right fats, you won’t hydrate effectively no matter how much water you throw down.
We have already touched on the damage chemicals can cause. In hand dermatitis studies, researchers have found that hand washes can alter pH, destroy resident good bacteria and reduce the level of fatty acids. Damage is pretty much immediate even after one wash and is cumulative, with repair taking seventeen days after using a hand wash for a week. We can only guess from the damage a simple handwash does what may result from the concoction of chemical beauty, washing and cleaning products we use on a daily basis!
Also, think about how often you do something that removes a top layer of skin – exfoliation techniques like scrubs, loofahs, skin brushing, peel masks, microdermabrasion, waxing etc, even simple rubbing with a hard towel will encourage a layer of skin to come off. A team at the University College London showed that even ripping a piece of sellotape off the skin once was enough to allow allergens through into the blood. They tracked the allergens, which were taken up by the Langerhan immune cells in the epidermis and shunted to the nearest lymph node to be dealt with ie. a full-blown immune response just from sellotape!
Dust mites are also an important consideration. An enzyme released in their faeces is thought to be able to harm the skin barrier so it’s vital to take steps to avoid them. In fact, some experts believe that it is environmental allergens such as these, pollens, moulds, fumes and animal dander that are the first allergens to enter a leaky skin. This precedes the development of food allergies, intolerance and other allergies such as asthma as the immune system becomes weaker and the skin allows more and more in. An interesting study showed that in some babies, the bum was the only part of the body not affected by eczema and they believed this was because it had been covered up and therefore not exposed to environmental allergens.
One of the major environmental pathogens is air, or the ozone in it anyway. We know that part of the body’s ageing process involves exposure to oxygen creating free radicals which must then be quenched by antioxidants. Think of when your car has a scratch and rusts after being left exposed for a while and you get close to what happens to our skin. This oxidative damage occurs in the stratum corneum all the time. This layer is particularly rich in Vitamin E, a powerful fat-soluble antioxidant. A lack of antioxidants, especially Vitamin E, then is going to mean a reduced ability to repair the oxidative damage.
Finally, we have to consider trauma to the skin. I know several cases, including myself, where skin problems occur only in the places where the person has had some form of trauma, such as a burn or infection.
The Gut Connection
Studies show that many people with IBDs such as coeliac disease, ulcerative colitis and Crohn’s are more prone to skin disorders or have skin involvement in their condition somehow: think dermatitis herpetiformis in coeliacs, for example. In fact, we know that coeliac disease sufferers are about three times more likely to get a skin disorder and skin issues occur twice as frequently in their relatives, so there is probably a genetic tendency too. This might explain why going on a gluten free diet helps many.
We also know that gluten-sensitives suffer a leaky gut in many cases as zonulin levels in the barrier ‘wall’ are affected, so why not leaky skin or leaky lungs or leaky blood-brain barrier too? Many NCGS (non coeliac gluten sensitivity) sufferers get neurological and skin issues rather than or as well as gut, depending on which autoimmune transglutaminases are affected. Sadly, we only tend to look for tTg2, the transglutaminase linked to coeliac disease, but those with a tTg3 and tTg6 are more prone to skin and neurological problems than gut, although not exclusively. I look for all three every time in case.
We mentioned earlier the importance of maintaining bacteria levels on the skin – and this goes for the gut too, obviously. Probiotic and gut therapy, especially for conditions such as SIBO (small intestinal bacterial overgrowth) and the use of fermented foods both on the skin and consumed are known to help. We need the bacteria and the right pH to produce those AMPs!
Finally, a slightly more difficult concept to grasp, but one I think holds great promise: some of the bacteria in the gut release a neuropeptide called Substance P and the more Substance P we have in our system – usually expressed in the nervous system, gut and skin - the more reactive we become to life and allergens.
I’ve been doing a lot of work in the last couple of years on CSS (Central Sensitivity Syndrome) illnesses like ME, fibromyalgia and hyper-sensitivity to foods and chemicals and Substance P seems to be quite a big part of why people’s sensitivity dials are too-turned up. Maybe that is why probiotic therapy works in some; it lowers the Substance P and therefore the reactivity levels. It may also help explain why stress makes the skin worse since we know one way to reduce Substance P is to increase GABA, the anti-anxiety neurotransmitter. That’s a whole other story I will be writing about soon!
Prevention, Protection & Repair Tips
March 2009, revised and updated March 2017