Could More Sun Exposure Improve Your Atopic Eczema?
Doctors believe a variety of factors contribute to atopic dermatitis1 (the most common type of eczema), some environmental, some genetic.
Atopic dermatitis occurs when the immune system steps into high gear over minor triggers and irritants. This leads to an overproduction of immune responses, causing the redness, inflammation and itching common to people with eczema.
Why are atopic dermatitis rates increasing?
Researchers think that our population’s large-scale move from rural to urban settings reduced childhood exposure to germs and bacteria. Called the hygiene hypothesis, doctors have learned that without early exposure to microorganisms and antigens, children may not build a strong immune tolerance, which has led to increased rates of atopic dermatitis and other atopic conditions such as asthma and allergic rhinitis.2
Other potential environmental triggers of atopic dermatitis include tobacco smoking, alcohol consumption, frequent bathing, pre-term birth, use of high pH soaps, low humidity in homes with forced indoor air, and exposure to domesticated furry pets, chemicals and dust mites.2
Now, a team of researchers in Denmark and the U.S. have found that the change from rural to urban living contributes to atopic dermattis in another way: Reduced exposure to sunlight.2
How sunlight may help, not hurt
These doctors found that moderate doses of the UVB irradiation that comes from sun exposure actually has a protective effect on skin. (We’re not talking about sun exposure that leads to burns, which actually has the opposite effect and makes atopic dermatitis symptoms worse and increases the risk of skin cancer.) Moderate, or suberythemal, amounts of UV-B, actually improves the way the skin barrier and its antimicrobial defenses work.
By looking at studies from Australia, China, Denmark, France, Japan, Korea, Spain and the U.S., these researchers found that moderate sun exposure helps children develop a healthy immune system rather than the characteristic Th2-dominant (allergic) inflammation found in most patients with atopic dermatitis.2
Additional study findings:
- Children born in the fall (a low-UVB season) were more likely to develop atopic dermatitis
- Children born further from the equator were more likely to have atopic dermatitis than those born near the equator
- Higher levels of sun exposure were associated with lower rates of atopic dermatitis
- Children whose parents put sunscreen on them and restrict their sun exposure show higher rates of atopic dermatitis
Collectively, these studies also revealed some explanations for why moderate sun exposure may help improve atopic dermatitis symptoms, including:
- Increases Vitamin D production which in turn stimulates creation of antimicrobial peptides in the skin
- Reduces Staphylococcus aureus growth on the skin, which is often found on people with atopic dermatitis
- Moderated immune activity by decreasing production of superantigens
How much sun is enough sun?
To use sun exposure as therapy for symptoms of atopic dermatitis, the researchers recommend going outside between 10 a.m. and 3 p.m. in late spring, summer, and early fall. That’s because UVB rays are strongest during that time. Little UVB reaches us in late fall, winter, and early spring, so you’ll need regular light treatments at your doctor’s office or a home light box during those times of the year.
As for what constitutes ‘moderate’ sun exposure, there’s no easy answer. This study didn’t broach that topic and other medical advice says it depends on your individual skin color and type. Another study recommends 3–15 minutes for those with lighter skin and 15–30 minutes for those with darker skin, when the sun is highest in the sky, with 40% of the skin area exposed.3
After all, the sun hasn’t always been a medical boogie man. Doctors once recommended sun exposure to prevent rickets (bone deformation due to Vitamin D deficiency) in children and to help treat tuberculosis, among other health conditions.3
It is recommended that if you will be outside and have prolonged exposure to sunlight that you do have protection, whether that be in the form of sunscreen, protective clothing or seeking shade.
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