Skin Permeability 


Introduction    (

"Allergy prevention is literally skin deep. The skin is the largest organ of the body and one of the first lines of defense against external pathogens, such as chemicals and poisons, and one of the key pathways in eliminating toxins from the body.

For all the emphasis Americans place on the appearance of skin - using cosmetics to cover up blemishes, topical ointments to combat pimples, and collagen and botox injections to fight wrinkles - they generally do a poor job of protecting their skin. In fact, many skin-care products actually damage the skin barrier and clog detoxification pores, leading to a host of allergic conditions and other skin problems. Other factors, including essential fatty acid deficiency, humidity, radiation, and stress, impair cutaneous integrity.

Anatomy of the Skin Barrier

The skin is made up of two distinct layers, the epidermis and beneath it, the dermis. The outermost level of the epidermis, called the stratum corneum (SC), is important for allergy and sensitivity. The SC is a network of cells on the surface of the skin that provides immediate protection from the outside world and helps restrict the loss of water.

The SC requires three main types of lipids (fats) to form a healthy cutaneous barrier - ceramides (such as alpha-hydroxy and omega-hydroxy acids), cholesterol, and polyunsaturated fatty acids (essential fatty acids). When the lipids are tightly packed into the spaces between the SC cells, potentially harmful substances that touch the skin are unable to squeeze their way through the skin surface and enter the body. On the other hand, when there are disruptions in the number and compactness of the intercellular lipids, the skin barrier becomes permeable.

Skin Permiability and Allergic Skin Conditions

Does increased skin permeability cause allergic skin conditions? In the case of allergic contact dermatitis, the answer is obviously yes. When you brush up against poison ivy, oak, or sumac, the urushiol oil released by the plant leaves touches your skin. If your skin barrier function is impaired, the toxin seeps through the gaps between the SC cells, enters the blood vessels in the dermis and subcutaneous fatty tissue, and sparks an antibody-mediated reaction. This explains why some people do not suffer with allergic contact dermatitis when exposed to poisonous plants - their skin barriers are intact and able to effectively protect the body from the toxin.

Atopic dermatitis can also be sparked by numerous allergens - inhaled, ingested, and contactant substances. Various studies have shown that foods (especially eggs) or inhalants (dust mites and cat dander are most common). Other studies have determined that atopic eczema is not always accompanied by skin permeability, but it appears that skin barrier default is the primary culprit in initial sensitization.

The fact that individuals with eczema develop allergies to substances that enter the body via the gut or respiratory tract suggests that these people become more susceptible to other allergies once the skin barrier has been disrupted.

Causes of Skin Barrier Damage

In general, two mechanisms increase skin permeability: removing/depleting surface lipids and altering the cells in lower levels of the epidermis. Essential fatty acid deficiency or abnormal metabolism of essential fatty acids, skin-care and cleaning products, ultraviolet radiation, climate changes, hormonal changes, and even psychological stress can lead to skin permeability and increase the risk of sensitization.

Usually most Americans have adequate supplies of cholesterol or ceramides for the skin, both from dietary sources and internal metabolism, but they may not get enough polyunsaturated fatty acids (essential fatty acids, EFAs) that are only available through diet. The skin barrier requires an abundance of omega-6 essential fatty acids.

There are two primary types of omega-6 EFAs, linoleic acid and arachidonic acid, both of which are only found in foods. Linoleic acid is found in the oils of safflower, sunflower, corn, soy, and sesame. An enzyme is responsible for converting linoleic acid into gamma-linolenic acid (GLA), a fatty acid that is needed to complete the skin surface lipid structure. GLA is found naturally in evening primrose oil, black currant oil, and borage oil.

Exposure to humidity changes seems to cause an increase turnover rate of skin cells, which exhausts the oils in the skin barrier and exacerbates inflammatory skin conditions such as atopic dermatitis and psoriasis.

The surface skin is thicker than the interior tissues of the body. Circulation comes to the base of the skin, and the water has to seep upwards through all the strata of the skin to reach the outer layer. The exposed surface of the skin is also constantly losing water due to environmental factors such as sun, wind, and chemicals, to name a few. When the body itself is dehydrated, circulation to the base of the outer skin may be shut down as an emergency measure so that water is not lost through evaporation from the skinís surface. Chronic dehydration shows in the face with wrinkles, lines and furrows. It's best to drink filtered water. There are many quality filtration systems on the market.

We know that both types of UV rays, UVA and UVB, can lead to skin cancer and eye problems if we donít protect ourselves from the harsh radiation. What most people donít realize is that UV radiation also increases skin permeability and can be a significant factor in sensitization. Studies have shown that skin lipid synthesis significantly declines 72 hours after UVB exposure but recovered after 96 hours, suggesting that UVB-induced barrier damage may not be permanent.

Skin-Care Products

Most people are aware that abrasives and chemical agents such as bleach can irritate the skin. Research has shown that these, indeed, damage the skin barrier and those with eczema and psoriasis are affected more severely. However, numerous skin-care products also contain ingredients that have been clinically proven to damage the skin barrier.

Nutritional Therapies that Support the Skin

Alternative therapies for the skin focus on repairing barrier function and stimulating detoxification mechanisms. While all allergy and sensitivity sufferers will benefit from these remedies, they are especially important for people suffering from skin allergies. To order the following products, go to the products page and follow the directions.

1.        Essential fatty acids are crucial to skin barrier repair. Both topical and oral administration of essential fatty acids improves skin barrier function. The lipids found in topical creams are absorbed into the stratum corneum and appear to actually fill the intercellular spaces in the skin surface. Oral supplements of omega-6 EFAs, especially GLA, boost skin cohesion and lipids and prevent transepidermal water loss. Since patients with atopic eczema often have low levels or metabolic blocks of the enzyme that converts linoleic acid to GLA, GLA supplements are highly recommended. It is important to avoid fats high in arachidonic acids (such as dairy and meat) because these acids exacerbate allergic reactions. Furthermore, do not overuse omega-6 EFAs, especially if you are suffering from arthritis, since these fats can contribute to an arthritic flare. Omega-6 EFAs need to be balanced with omega-3 fats in a ratio of approximately 1:2 for health.

2.        Evening primrose oil is naturally high in GLAs (9-10%) and is effective as both a topical and oral supplement. It is widely used throughout Europe, Especially Germany and England, for eczema. The typical recommended oral dosage of evening primrose oil is 500 mg to 2,000 mg daily for at least 12 weeks. Severe cases may require up to 6,000 mg daily. There are a few side effects attributed to this oil, including headache, mild nausea, or soft stools. Talk to your doctor if youíre on prescription medications before taking evening primrose oil, because certain drugs may increase its effects. If youíre on anticoagulants, evening primrose oil can enhance blood clotting.

3.        Borage seed oil and black currant seed oil are other sources of GLA. Borage oil contains twice as much GLA (up to 24%) as evening primrose oil and black current oil is at 18%. However, neither oil has proven to be as effective as evening primrose oil. Borage oil is not recommended for people with epilepsy or for those taking phenothiazine drugs, without medical supervision. Standard dosage is three to four 300 mg capsules taken orally, daily.

4.        Moisturizers containing urea, alpha-hydroxy acids (gluconolactone and tartaric acids) and glycerol are recommended. Glycerin (the synthetic version of glycerol), a common ingredient in skin-care products, can be detrimental to the skin barrier because it tends to draw water from the skin layers to moisturize the skin surface leading to chronic dehydration. However, research has shown that glycerol actually promotes skin barrier recovery. Rose Hip seed oil may also help repair damaged skin. This oil contains traces of retinal, a natural retinol (vitamin A). Unlike retinol products, rose hip seed oil is bound in a natural balanced formula and doesnít cause the skin permeability, peeling, and photosensitivity of the synthetic forms. This oil also contains a small amount of vitamin C and omega 3 and 6 EFAs. " (" The information on this page is from the website of  Andrews Chiropractic, 558 Grand Canyon Drive, Madison, WI 53719


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