What is it
Eczema is a term used for a number of skin conditions, but usually it refers to the medical condition atopic dermatitis. It causes skin to become itchy, red and swollen. Dryness, flaking, cracking and bleeding also commonly occur with temporary skin discolouration in some areas.
All areas of skin can be affected, but most typically the following areas:
- Hands and feet.
- Skin creases such as ankles, wrists, back of knees and inside of elbows (flexural pattern).
- Discoid (coin shaped) patches anywhere.
- Patches associated with hair follicles (follicular pattern).
Repeated scratching of eczema patches can lead to thickening of the skin, called “lichenification”.
Ageing and eczema
Eczema is a chronic condition that can last a lifetime, however most children grow out of it.
Different parts of the body get affected, with infants often getting their most persistent eczema on the face. In older children most persistent eczema is at the back of the knees and front of the elbows, while in teenagers and adults it is the hands and feet predominantly. Other parts of the body typically get temporary patches, but not so persistently.
Eczema rates are thought to have trebled in the last 30 years. In the US it is now estimated to affect more than 10% of children at any one time. As the rates of childhood eczema go up, adult eczema rates can be expected to follow in the future as these kids grow up. Eczema affects both sexes, with some data suggesting that women and people of Asian and African origin get it more often than others.
There is one third of a chance that a child affected by eczema will also later on be affected by food allergy, asthma and/or hay fever. These are known as atopic diseases and the cases where a child develops all or several of them in order is known as the “atopic march”.
It is also the case that if either asthma, hay fever or eczema run in a family then children are more likely to get it. The tendency is for each type of atopic condition to run true to type in a family, and so if eczema is in your family, but not hayfever or asthma, then you are more likely to develop eczema than the other conditions.
Eczema is most likely caused by an environmental agent or agents stimulating a allergic type response from the immune system. However your genetics plays a key role in determining how likely you are to suffer from it.
The proteins in skin
Some 5% of people have 2 mutations that affect the production of the protein, filaggrin. This protein keeps the skin moisturised by keeping water in the stratum corneum (the outermost layer of the skin consisting of corneocytes). It also helps keep the skin surface slightly acidic. People affected by these mutations will often have dry skin all over their body making eczema far more likely, as well as dry epithelial surfaces in their lungs, predisposing to hay fever and/or asthma. About half of people with moderate or severe eczema will have these filaggrin mutations.
The lipids in skin
Another common problem with the skin of people with eczema is lack of lipids called ceramides. The outer layer of skin consists of cells called corneocytes in a sea of lipid, made up of cholesterol, ceramides and free fatty acids. The ceramide/cholesterol ratio can be lower than normal in people with eczema(1). This ratio can be improved if the deeper layers of skin change pH to become more acidic. An acidic skin allows the enzymes that produce certain types of ceramides that help with lipid structure to operate more effectively, whereas the enzymes that create cholesterol require a more alkaline pH.
Ceramide type also influences eczema, with those types of ceramide with longer chain lengths being associated with less water loss from the skin surface. Ceramides include a fatty acid portion and the fatty acids from oily fish are the longest suggesting a reason why omega 3 supplementation can help with eczema.
There are also at least 12 different types of ceramide and type 1 has been established as particularly important for eczema sufferers as it helps with the organisation of lipids on the skin surface(2).
The immune system
Eczema and other atopic conditions are characterized by an imbalance of immune T-helper cells (Th1 & Th2). Th2 cells (anti-inflammatory, allergy related) were found to predominate over Th1 cells (pro-inflammatory, autoimmunity related). This was especially the case in children with reduced microbial exposure in early childhood and led to the formulation of the hygiene hypothesis (see below). However people with chronic long lasting eczema sometimes show up with Th1 cells predominating. It has also been found that overall numbers of both Th1 and Th2 cells are reduced in people with eczema.
More recently the hygiene hypothesis has been modified as it has been realised that Treg (regulatory) cells also play an important role in determining who is most susceptable to developing atopic conditions.
Some genes produce bacteria sensing proteins that live inside cells on our body surfaces. In particular genes called NOD1 and NOD2 can in some people produce proteins that affect the development of Treg cells in the thymus. This could have knock on effects on the lining of the lungs as well as the skin(3).
There is good evidence that exposure to dogs, parasitic worms and unpasteurised milk help reduce likelihood of eczema while excess hygiene and exposure to dust mites seem to contribute towards the condition. This is explained as being due to a lack of T regulatory immune cells caused by a Western lifestyle.
When it comes to hygiene one of the worst culprits seems to be antibiotic use. The change in the gut flora brought about by a course of antibiotics (or several courses of antibiotics) is thought to activate certain immune cells to attack skin cells, much like the scenario with psoriasis.
It should also be remembered that the skin is (or should be) covered by bacteria, fungi, viruses and even mites. Having the right bacteria in residence makes a big difference to the condition of the skin by making it more acidic, or helping it retain water.
Staphylococcus and proteobacteria are pretty normal residents with Staph epidermidis being able to reduce skin inflammation and produce a more acidic environment(4).
Propionibacterium acnes is associated with the oily sebaceous glands that lubricate human body hair. They make the skin more acidic by breaking down fatty acids from the triglycerides stored in sebum. This makes it less likely that other bacteria will cause infection for someone with eczema.
Skin is an unstable environment for residents as it is formed from cells called corneocytes, that are continuously shed. These cells are embedded in a lipid bi-layer made of cholesterol, ceramides and free fatty acids.
Because the gut is one of the key areas that determines how the immune system responds to environmental agents, the make up of bacterial species there is critical. The greater the variety of bacterial species the better, especially in the early months of life(5). Modern lifestyle factors that reduce the number of species in the gut include antibiotic use on pregnant mothers, neonates and C-section deliveries.
Other related conditions
Because eczema results from the activity of certain parts of the immune system, it is associated with other conditions that also result from the activity of the same parts of the immune system. In particular, asthma and hay fever.
There is also an association with both celiac disease and non-celiac gluten sensitivity, suggesting that leaky guts caused by gluten could be a contributory factor.
Causes of flare ups
There are a number of environmental factors that can make flare ups more likely. These include:
- Heat – any temperature above 21C is probably too much depending on how you are dressed.
- Dust including dust mites which are found in soft furnishings and carpets. Allergen proof covers for mattresses, duvets and pillows are available.
- Dryness – so adequate humidity in a house >50% normally helps.
- Soap and detergents, which should be kept to a minimum. Swimming pool chlorine can also make matters worse, but this depends on the exact chemicals used and how you wash after swimming.
- Woollen clothing can cause irritation and cotton clothing is a better choice.
- Skin coverings or anything that does not allow the skin to breathe can make matters worse by making the skin more alkaline and encouraging the wrong sort of bacteria (Staph aureus and Strep pyogenes) to thrive(4).
- Infections and being unwell often make eczema generally worse. This would include infection with the common cold.
- More problematic infections include a) the bacteria staphylococcus, which can make skin yellow and crusty and b) the herpes simplex virus (causes cold sores), which can cause painful flares with weeping sores.
- Teething in babies.
- Long nails in babies which will scratch when they can.
- Changes in hormone levels, especially for women.
- Stress, especially in adults.
- Allergic reactions to food.
Treating the symptoms
Because eczema dries out the skin, this allows the body underneath the skin to come into contact with more irritants such as bacteria, chemicals and other potential allergens. The way to reduce the problems this causes is to moisturise the affected areas.
Conventional medicine treats the symptoms by a range of methods. These include:
- Moisturisers are often used to prevent the skin drying out and cracking. This reduces the likelihood of bleeding. The more greasy a moisturiser, the more effective it is likely to be. However the more greasy moisturisers may be less comfortable. Also “aqueous creams” are not advisable for use with eczema as they cause irritation. It is thought by some that this is due to the presence of sodium lauryl sulphate in most aqueous creams(6).
- Steroids, such a hydrocortisone, can be quite effective over the medium term, but they don’t remove the root cause. Regular use of steroid creams can thin the skin and cause stretch marks. In general you should allow the skin to breath as much as possible when such creams have been applied as coverings such as skin dressings enhance absorption. Also apply such creams only to the affected areas. The greater the area covered, the greater the strength, and the longer duration of use all affect the level of side effects.
- Calcineurin inhibitors are sometimes used if the above treatments don’t work. These drugs dampen the immune response by inhibiting T-cells. Two of these are Protopic ointment tacrolimus (a protein phosphatase 3 inhibitor) and Elidel cream pimecrolimus. These products don’t thin the skin and therefore may be more appropriate for use on the face. However long term or regular usage is generally avoided as they are associated with skin cancer and lymphoma.
- Monoclonal antibody treatments are likely to be used in future on severely affected patients. Examples include dupilumab which has been successful in trials on adults. It blocks the response to the cytokines IL-4 and IL-13 which are produced by T-helper (Th2) cells. Omalizumab is another example which blocks IgE antibody function, but is not normally used in children under 12 years of age.
- Phosphodiesterase 4 inhibitors were also in the pipeline in 2015. These are powerful systemic drugs that have been used in many other diseases such as chronic pulmonary obstructive disease (COPD). They reduce levels of phosphodiesterase 4, which are often raised in people with eczema. It is basically yet another drug in the arsenal to be used against moderate and sever eczema. It is not however a cure.
Many people report an improvement in symptoms when their skin is more moisturised as occurs in more humid environments. As such wet and warm weather generally favour better skin condition. Other natural treatments that are best tried before resorting to drugs include the following:
- Sunlight Vitamin D and ultra violet light have been associated with an improvement in symptoms and so getting exposure to sunlight without getting burnt is almost certainly beneficial.
- Probiotic treatments have shown some promise as have synbiotics (combinations of pro and pre-biotics). A typical probiotic that can be used with infants up to 2 years of age is Klaire Labs “Ther-biotic”. This contains 5 species of Lactobacillus and 5 species of Bifidobacterium. Some studies have shown that probiotics are more effective at prevention rather than treatment, while others using Lactobacillus fermentum have shown treatment benefits as well (7)(8).
- Fermented foods are also associated with improvements in symptoms. Natto, sauerkraut and kefir are examples. For instance consumption of natto (a Japanese fermented soybean dish), by pregnant women has been associated with reduced levels of eczema in their offspring(9). The advantage of fermented foods is normally that a much larger variety of microbial strains are present. Many studies have found that the greater the variety of bacterial strains in the gut, the fewer the cases of atopic (e.g. eczema) and autoimmune disease.
- Omega 3 oils have been found to reduce cases of infant eczema when the mother takes supplements during pregnancy(10). In addition DHA, the longest chain omega 3 oil has been associated with “significant clinical improvement” in another study(11).
- Problem foods may cause an individual to have symptoms. Milk is one which some people have eliminated and then found their eczema to have been cleared up.
- Treating the immune system. Naltrexone is a pharmaceutical drug that is normally used to treat heroin addiction by blocking opioid receptors in the brain. In this context 50mg doses are used. Low dose naltrexone - LDN on the other hand makes use of minor blockage of opioid receptors in the brain. People with eczema often have low levels of their own opiates, and with LDN treatment these endogenous opiates are stimulated. Opiates are known to reduce pain, but itching has also been found to be reduced in trials(12). The dose used in LDN treatment varies from 1-5mg.
Some people are genetically more prone to eczema than others. However, most people with eczema can in theory cure themselves by adopting a certain type of lifestyle that avoids environmental triggers.
- Get in the sun regularly.
- Eat a diet including high strength probiotics containing a large variety of strains.
- Introduce fermented foods such as sauerkraut and kefir or natto into your diet.
- Consume oily fish or a cod liver oil supplement 2-3 times per week.
- Keep the skin well moisturised with lipid based creams.
- Avoid potential flare ups by reducing stress and avoiding excess heat, dryness and soaps and detergents.
- http://onlinelibrary.wiley.com/doi/10.1111/cod.12073/epdf Ceramides in the outer layer of skin.
- http://www.ncbi.nlm.nih.gov/pubmed/9469597 Ceramide 1 useful in lipid organisation.
- http://www.jacionline.org/article/S0091-6749(05)00522-1/fulltext NOD1 Proteins associated with atopy.
- http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3535073/ Bacteria that acidify the skin.
- http://www.ncbi.nlm.nih.gov/pubmed/22153774 Eczema and bacterial diversity in the gut.
- http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2133.2010.09954.x/full Aqueous cream causing epidermal water loss.
- https://nationaleczema.org/search-bacterial-balance/ Article on probiotic treatment and prevention of eczema.
- http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1720555/ L.fermentum a useful probiotic treatment.
- http://www.sciencedirect.com/science/article/pii/S132389301530040X Fermented food natto associated with reduced incidence.
- http://www.ncbi.nlm.nih.gov/pubmed/26970335 Study on pregnant mums supplemented with omega 3.
- http://www.ncbi.nlm.nih.gov/pubmed/18241260 DHA associated with significant clinical improvement.
- http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3762292/pdf/ooomb4-20-506.pdf Naltrexone found to reduce itching.