Sunny Days May Help Eczema

Sunlight and Vitamin D

Vitamin D is sometimes called the sunshine vitamin because the body can actually synthesize it from cholesterol when the skin is exposed to certain wavelengths of ultraviolet light found in sunlight and UV lamps.

Although vitamin D is the only vitamin that can be naturally produced in the body, its synthesis is often inadequate to meet the body’s daily needs. Therefore, food sources of the vitamin, as well as dietary supplements, are often recommended to meet the recommended daily intake.

When the skin is exposed to ultraviolet (UVB) light, in the wavelengths between 270 nm and 330 nm, a metabolite of cholesterol known as 7-dehydrocholesterol is converted to vitamin D3 (cholecalciferol).

The production of vitamin D from exposure to sunlight proceeds rapidly even as the synthesized vitamin D degrades quickly. Overall, the body can produce all the vitamin D it needs for a day from a 30-minute, full-body exposure to the right wavelength of sunlight.

This synthesis is controlled by a feedback mechanism that prevents the body from accumulating toxic levels of vitamin D.

However, the synthesis of vitamin D in the skin can be blocked by sunscreen. This is because sunscreens keep out ultraviolet light.

A sunscreen with an SPF (sun protection factor) of 8 can reduce vitamin D synthesis in the skin by 95%.

Eczema and Exposure to Natural Sunlight

The Australian Study

In a recent study published in the Journal of Allergy and Clinical Immunology, a group of researchers investigated the variation in the incidences of food allergy, asthma, and eczema among 7,600 children across the country.

Australia represents an ideal location to investigate the link between natural sunlight, vitamin D and allergic diseases because the northern part of the country sees more sunlight than the southern part.

The results of this Australian study showed that the children from southern Australian with fewer hours of sunlight and lower temperatures than the north were twice as likely to develop eczema.

The researchers rightly concluded that the main reason for this difference was the level of vitamin D production between the 2 climates. The children living in northern Australia saw more hours of natural sunlight and, therefore, had higher vitamin D levels than the children living in the south of the country.

This study provides solid evidence for the direct link between sunlight exposure and the production of vitamin D in the skin as well as the benefits of vitamin D in the treatment of eczema.

Photosensitive Eczema

The higher exposure to sunlight is the reason why eczema improves during the summer months for most people while it worsens during the winter. However, exposure to sunlight should be limited as it can also damage the skin and worsen eczema.

Because sunlight heats the skin directly, it can quickly dry up the skin. By removing moisture from the skin, exposure to sunlight can, therefore, worsen itching in people with eczema.

Furthermore, sunlight exposure should be limited in eczema patients with photosensitive skin.

People with light-sensitive eczema can develop exaggerated skin reactions to sunlight. Unfortunately, some of the drugs prescribed for eczema patients can make the skin even more sensitive to sunlight. Drugs such as topical steroids, antihistamines and antibiotics can leave the skin vulnerable to even a little exposure to ultraviolet light.

Ultimately, moderate exposure to sunlight is recommended for relieving the symptoms of eczema.

To reduce the chances of damage, the exposure should be limited to less than 30 minutes (10 minutes for those with sensitive skin) per day. In addition, sunlight exposure between noon and early afternoon should be avoided since the sun is at its peak during that period.

Lastly, the skin should be properly moisturized before and after exposing it to sunlight. This will help keep it moisturized and prevent itching.

Why Sunlight is Good for Eczema

Vitamin D and Cathelicidins

The chief benefit of moderate sunlight exposure for people with eczema is the increased production of vitamin D.

Multiple studies have demonstrated that vitamin D is indeed useful in the treatment of eczema.

First, the production of vitamin D in the skin directly increases the serum concentration of the vitamin. As the level of vitamin D rises, it promotes the release of a family of antimicrobial proteins known as cathelicidins.

Cathelicidins are naturally produced in the skin. However, skin biopsy examinations show that people with atopic eczema have lower levels of cathelicidins in their skin than the general population.

Therefore, when vitamin D raises the level of cathelicidins, it can help fight skin infections by reducing the population of pathogenic bacteria, fungi, and parasites in the skin. Such actions not only reduces the keratinization and discoloration of the skin, but it also reduces the local inflammation triggered by these microbes.

All of this means that vitamin D can restore the normal skin flora by killing off the microbes destroying the skin.

Vitamin D, Gut Flora, and the Immune System

The antimicrobial effect of vitamin D extends beyond the skin. There are indications that vitamin D can also restore normal gut flora. Basically, vitamin D can help treat leaky gut syndrome too.

Because most of the body’s immune system is directly wired to the gut, vitamin D can also influence immune functions from there. Studies show that vitamin D supplementation can help fight systemic infections just as it fights skin infections.

Therefore, vitamin D can help boost the immune “attack” response to the microbial colonization of the gut and skin while reducing inflammatory response from the immune system.

In summary, moderate sunlight exposure can increase serum levels of vitamin D which in turn can relieve atopic eczema.

Treating Eczema with Phototherapy

Phototherapy is also known as light therapy. It involves exposing a patient to sunlight or ultraviolet light from special lamps.

Phototherapy is commonly used to treat skin diseases especially psoriasis but also acne, eczema, and jaundice in infants. Other conditions commonly treated with phototherapy include sleep disorder, SAD (seasonally affective disorder, a form of depression) and psychiatric disorders.

Like natural sunlight, phototherapy uses ultraviolet light in the wavelengths known to promote vitamin D synthesis in the skin. Therefore, phototherapy can increase the serum level of vitamin D and relieve atopic eczema through all the mechanisms described in the previous section.

Both types of ultraviolet light (UVA and UVB) are used in phototherapy. Sometimes, oral and topical pigmenting drugs such as psoralen are also added to help repigment the skin.

In the treatment of eczema, the type of phototherapy commonly used are

• ultraviolet B (UVB) in the wavelengths 280 – 315 nm
• ultraviolet A (UVA) in the wavelengths 315 – 400 nm
• combined UVA and UVB exposure

Sometimes, high doses of the specific wavelength bands of ultraviolet light are used.

For example, UVA1 light in the range 340 – 400 nm as well as narrow-band UVB (NB-UVB) in the wavelength 311 nm are commonly used to treat atopic eczema.

Studies on Ultraviolet Light and Eczema

Changes in Sunlight Exposure and Severity of Eczema

A 1991 study published in the journal, Archives of Diseases in Childhood, provides a very clear picture of the effect of sunlight exposure on the severity of eczema.

For the study, the researchers collected data over a period of 3 years from 126 British children with severe atopic eczema regarding the state of their condition during and after holidays spent away from home in a different climate.

The results of the study are summarized below.

This simple study shows that increased exposure to sunlight can improve eczema. Therefore, an excellent way to determine the eczema patients who will benefit the most from increased sunlight exposure is to visit a sunnier location and see if their eczema improves.

A 2006 study published in the journal, Allergy, also reached the same conclusions.

While the designs of both studies were similar, this study provided more direct observation of the effect of climate change on eczema. Here, the researchers recruited 56 children aged 4 – 13 with severe atopic eczema.

Thirty of these children were moved down south to the sunnier Gran Canary while the rest stayed home in Norway for the 4-week duration of the study.

Then during a follow-up period of 3 months, both groups were monitored for signs of improvement or deterioration in their eczema.

The results of the study showed that

• the severity of eczema significantly reduced in the group that moved to the sunnier locale than in the control group
• the improvement in eczema promoted by the move to subtropical climate was not completely lost even 3 months after moving back to the temperate region
• the dermatological index of quality of life improved in the first group and not in the control group
• bacterial (Staphylococcus aureus) colonization of the skin decreased in the first group during the study and 3 months after it
• the children in the first group were able to reduce their use of topical steroids while those in the control group still needed the same doses of those steroids

Combined vs. Single UV Phototherapy

A 2001 study published in the journal, Lancet, compared the effectiveness of narrow-band ultraviolet B, broad-band ultraviolet A and visible light phototherapies in the treatment of moderate to severe atopic eczema.

The researchers randomly assigned 26 eczema patients to narrow-band UVB, 24 patients to broad-band UVA and 23 patients to visible fluorescent light.

Each of these participants received 2 sessions of phototherapy per week for 12 weeks.

The results of the study showed that narrow-band UVB was more effective than broad-band UVA and visible light.

A 1996 study published in the Journal of Investigative Dermatology showed that IgE-associated eczema responded better to high-dose ultraviolet A1 phototherapy than combined UVA/UVB phototherapy.

The researchers compared the population of certain immune cells and certain immune markers in the skin of eczema patients exposed to either UVA1 or UVA/UVB light. They found that only UVA1 lowered the number of IgE (immunoglobulin E)-bearing Langerhans cells in the epidermis.

This study shows that IgE-binding skin cells are involved in the development of atopic eczema and that high-dose, narrow-band UVA1 light is the right phototherapy for this kind of eczema.

A 2009 study published in the journal, Medical Hypotheses, also confirmed this conclusion.

However, in the 2009 study, the researcher concluded that UVA1 was effective in the treatment of eczema because it induced the destruction of immune T cells.

With Psoralen

A 1978 study published in the British Journal of Dermatology determined the benefits of adding the oral pigmenting agent, psoralen, to phototherapy in the treatment of atopic eczema.

The researchers demonstrated that oral psoralen along with ultraviolet phototherapy produced better results than conventional ultraviolet phototherapy. However, the researchers identified that regular treatment with psoralen and phototherapy was required to keep eczema in remission.

A 2004 study published in the Archives of Dermatology built on these results. It compared the effectiveness of using oral psoralen and portable UVA tanning unit at home to psoralen bath and UVA phototherapy in the hospital.

The researchers recruited 158 patients with moderate to severe hand eczema and randomly assigned them to either treatment for 10 weeks before allowing an 8-week follow-up period.

The study showed that both treatments significantly improved the patients’ eczema and this improvement was maintained throughout the follow-up period.

The researchers concluded that eczema patients can safely and effectively use psoralen and phototherapy to treat their condition at home and save the cost and time required for weekly phototherapy sessions in hospitals.