2009年7月24日 星期五

Thinny Skinnies –the low-down on leaky skin and allergies

Thinny Skinnies –the low-down on leaky skin and allergies
皮膚薄導致多種皮膚問題
Micki Rose looks at recent research and suggests how you might deal with the problem.In the past few years, scientists have become pretty convinced that people suffering with skin disorders such as dermatitis, eczema and psoriasis do so partly because they have thinner or leakier skin.This type of skin lets more environmental substances (bacteria, pollens, moulds, chemicals etc) through than it should. These are thought to set off an allergic reaction as they enter the bloodstream. As the immune system weakens over time and the skin gets more porous, food intolerances and asthma are thought to follow. If being a ‘thinny skinny’ is at the heart of skin allergy problems, is there anything we can do to prevent it starting or worsening, or are we just sitting ducks with the wrong geneticmake-up? Well, there’s an argument for both, so let’s start by looking at how the skin barrierworks, what the genetic scientists think is going on, consider how we might be making the problem worse for ourselves and end with ways we can limit our leakiness.The barrier 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.This, in effect, is the barrier. It acts as a layer of bricks with the fats in between as the mortar. There are 15 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 bacteria. Some of this bacteria is shed with the skin cells and needs to be constantly replaced as well.The barrier is dependent on us maintaining the right levels of moisture in the skin, its pH, the content of the fats or lipids, between the cells and the rate ofshedding. The deeper layer is the dermis and this is where most of thenutrients are needed to grow healthy skin, which then moves up gradually to form the stratum corneum.It should be pretty obvious, then, that to maintain a good non-leaky skin barrier we need to feed the dermis the right nutrients, keep moisture, fats and pH levels right and avoid doing anything that encourages too fast shedding.

Genetics
Now let’s look at what do geneticists think might be going wrong. Scientists realized a while ago that, in many cases, children with eczema had no antibodies in their blood that would explain an allergic cause of eczema. This set them looking for other reasons.There was no doubt that certain substances kicked off a skin flare, so they assumed the substances were somehow getting through the skin’s naturaldefense barrier – but why?A team at Dundee University discovered that about half the people they tested had a genetic defect in the gene that that controls the production of fillagrin,a protein found on the skin’s surface thought to be involved in maintaining the barrier.
Too little, or no fillagrin explained the leaky skin. But clearly, if they found only half had this problem it can’t be the full story, and the researchers themselvessay it’s unlikely to be the only factor involved.
Thinny Skinnies –the low-down on leaky skin and allergiesMicki Rose looks at recent research and suggests how you might deal with the problem.Interestingly, the team felt that it may, in fact, be a genetic advantage since a mildly leaky skin would allow a small amount of pathogens, such asbacteria, through acting rather like a ‘natural vaccination’ process and leading to a stronger species immunity.
So thinny skinnies may actually be the top of our species tree, which is a nice thought!Other teams found that the LCE gene cluster may also be implicated and, again, this genetic variant would likely lead problems maintaining the skin’s proteins and therefore the barrier.Yet other scientists believe that eczema sufferers lack what are termed AMPs (anti-microbial peptides), more proteins that help specifically to fight offbacteria. 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 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 staphylococcus aureus bacteria in the upper skin layers than most people and this could be the reason why they can’tfight infection off as well.If antibiotics are regularly used they damage the skin’s natural bacteria further and make the whole problem worse longer term, while the skin may also develop resistance to them.So, it appears there may be several genetic mechanisms involved in why we have leaky skin, and there is clearly much more to learn. We need to keep in mind that many illnesses have been found to have a genetic component, but that it is often lifestyle and environmental elements that tip the sufferer over the edge. Think of most cancers: we know genes make us vulnerable but scientists also know that diet and lifestyle are the straws that break the camel’s back.
So, what else could be going on?
Moisture loss
This seems to be the biggest issue. Thin skin is often dry skin. Dry skin is often itchy. Scratching damages the skin and allows in the bacteria and other pollutants 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 vulnerablepremature babies to strengthen their immature skin barrier and found that therewas a drop in deaths by a staggering 26%.
Simply keeping them well moisturised prevented them absorbing damagingenvironmental pollutants.So far, so good, but as I said in my article in the February Foods Matter, 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 to more damage.Therefore it’s important to choose your moisture cream made of fats, ceramides and cholesterol.These are used to make phospholipids which form cell and other membranes. So it much make sense to ensure 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 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 such as margarineand vegetable oils, in their last four weeks and the number of their children whohad developed eczema and other allergies by two years old.
The babies of the mothers who ate more fish (Omega 3, DHA/EPA) didn’tdevelop allergies.
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 conversion is dependent on specific nutrients, most importantly zincs, 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 oils is likely to help people sidestep this conversion problem, although vegetarian sources of these such as linseed may not, as these still need to go through a conversion process.Since cholesterol plays a really important part as one of the barrier and cell membrane substances, we must also 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 and 5.4 and that cholesterol, as well as causing problems when it is too high, can also be problematic when it’s too low.
Compromised membrane and barrier strength is one of the key issues.Lastly, we mustn’t forget the importance of water. Remember what the babies’ natural ‘cream’ is made of: fats and skin cells but mostly water.
Hydration is key. And fats have a role to play here 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.
DamageSo that deals with genetic factors, moisture and fat content of the skin, but what about the pH of the skin and skin shedding?We 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(loosening the glue holding the barrier together).
Damage is pretty much immediate, even after one wash, and is cumulative,with repair taking 17 days after using a hand wash for a week.
Just imagine what you’re using on your whole body, and how long you’ve been using it for, then think about how long that might take to repair!Consider what’s in your water and how many chemicals you are using every day on yourskin in seemingly innocuous toiletries.We can only guess from the damage a simple handwash does what may result from a concoction of chemical beauty, washing and cleaning products slathered onto our bodies on a daily basis.
Put it this way, if you’re predisposed to leaky skin, it’s not going to help.
Skin shedding
Now consider the shedding of the skin cells and 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.Sometimes that’s a good decongestant for dull skin, but not if you have a thin skin and are prone to skin allergies.
A team at University College, London showed that even ripping a piece of cellotape off the skin once was enough to allow allergens through into the blood.They showed that these allergens epidermis, and are then taken to the nearest lymph node to be dealt with, ie an immune response.
Other impacts• Scratching, of course, causes damage, which is why the moisturizing and avoiding it is so important.• Steroid creams have been found to thin the skin and hence could make the problem worse in the long term.• 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 these environmental allergens as well as 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 probably because it had been covered up and therefore not exposed to environmental allergens.
• Ozone. 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 tooxygen, creating free radicals that must then are taken up by Langerhan be quenched by antioxidants.
Think of what happens when your car is scratched. If left exposed it rusts. This iswhat 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. So a lack of antioxidants, especially vitamin E, is going to mean alower ability to repair the oxidative damage.
• Trauma. I know several cases, including my own, where skin problems occur only where there has been a trauma, such as a burn or infection.Highly toxic hair products designed to get my hair to stand on end when I was young (don’t ask!) have left me with a vulnerable scalp and eczema in myears when I’m stressed.
I also wonder whether an episode as a very young child when I fell practically naked into a nettle patch exacerbated an already allergic tendency by damaging my skin barrier.
Who knows, but it’s an interesting concept? As a naturopath, I would also have to consider the link between skin allergies, a leaky gut and respiratory problems such as asthma.To a naturopath, our lungs and bowel are just bags and tubes of the same sort of skin we can see externally. It stands to reason that if we have a tendency for leaky skin on the outside, this may be no different on the inside.
This could explain the established link between skin and bowel issues, wherebythe skin is often simply reflecting what is happening in the bowel.If I see a person with IBS or constipation, for example, they invariably have some form of skin problem too.
And could the leaky gut be at the heart of the later food intolerances and othersensitivities – leaky skin, leaky gut?
And what about the link between early eczema developing into asthma – is this simply a reflection of leaky lung skin?

Prevention, protectionand repair
So what can be done to limit the damage and repair it? Obviously, we can’t do much about our genetic predisposition, but just because you have a genetic issue, it doesn’t mean the problem will develop, and we can do plenty to prevent it doing so through lifestyle choices.
Here are my top tips:1. If you’re pregnant, take good quality fish oils in the last trimester especially.
2. Keep babies’ skin covered up lightly with clothes and oil to avoid environmental pollutants affecting the immature barrier.
3. If your skin is dry, make sure you have plenty of fatty acids in your diet, keep nicely hydrated and check out your thyroid – underactivity is a common cause.
4. Moisturise well daily with a non-toxic, no perfume, no-mineral products, oil based lotion.Vitamin E, vitamin C and green tea extracts have been found the best to offset free radical damage.
Use oil in the bath to coat skin and dry naturally.

5. Fit a whole house dechlorinator so any water that comes into contact with your skin is as chemical-free as you can get.And whilst you’re at it a reverse osmosis filter on your drinking water wouldn’t go amiss either – remember your internal skin.
6. Make sure you eat plenty of foods rich in essential fats such as fish, seeds and nuts, and, to make sure, take a good quality fish oil supplement daily.
7. Avoid any form of harsh chemicals such as toiletries and cleaning products. Wear gloves as a protective barrier.
Avoid over zealous skin cleaning.
8. Choose organic cotton, nonscratchy clothes, towels and bedding wherever possible.
Cotton is one of the most toxic, pesticide-ridden fabrics there isand you need to avoid chemical ingestion.

9. Get your environment right. Invest in a HEPA air filter and clear the rooms you use most, especially your bedroom and lounge, of pollens, moulds, mites, dander etc. Use a HEPAfitted vacuum cleaner for your house, bed and upholstered furniture to get rid of dust mites and other allergens. Keep temperaturecontrolled: neither too hot, nor too cold.
10. Avoid physically damagingyour skin with exfoliation, waxing or biological washing powders.
11. Cover your skin lightly to limit environmental and ozone ingestion.
12. Eat plenty of organic fruit and vegetables to keep antioxidant levels high.
To make sure, invest in a good broad-spectrum antioxidant supplement that includes plenty of zinc and take it daily.
You could even have an oxidative stress test done to check your internal levels of antioxidants and show which ones you need specifically.

13. Avoid steroid and antibiotic use as much as possible.
Choose creams containing licorice extracts (glycyrrhetinic acid), which have been shown to have a similar effect to steroid creams.
DGL, a form of licorice, is used often to heal internal skin wounds such as ulcers so it makes sense it would help external skin too.
Creams containing probiotics, such as acidophilus, will boost your natural levels of good bacteria to fight the baddies more effectively.
Take a probiotic daily for your inside skin.
14. Do not lower your total cholesterol levels too far.
Instead, aim to achieve a high level of protective HDL cholesterol and less of the harmful LDL cholesterol with a good diet and lifestyle.(Source: FoodsMatter)

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