By Marc Sorenson, EdD, Sunlight Institute…
Asthma is a disorder characterized by inflammation of the air passages, which cause narrowing of the airways that transport air from the nose and mouth to the lungs.[i] The mechanism by which sunlight may reduce asthma and its symptoms could be the anti-inflammatory properties of the vitamin D production that it stimulates in the skin. Inflammation is often caused by proteins called cytokines that are either pro-inflammatory or anti-inflammatory elements of the immune system.[ii] Vitamin D has the ability to inhibit pro-inflammatory cytokine production while stimulating the production of anti-inflammatory cytokines.[iii] However, there are likely other attributes of sunlight, beyond stimulating vitamin D production in the skin, that have beneficial affects.
One of the most recent studies on factors that contribute to asthma showed that living in a room without windows was associated with an increased the risk of asthma of 930%, and living in an area without adequate sunlight was associated with an increased the risk of 220%.[iv] Considering that windows filter out the UVB light that stimulates the production of vitamin D, having windows could not have reduced asthma by vitamin D production—it had to be some other factor—something that entered the room through that window glass protected the people with windows from the remarkable increase in asthma they would have otherwise had. We know that UVA light, which does pass through windows, stimulates the production of nitric oxide, which is a potent vasodilator. Could it also be a bronchodilator? This explanation, of course, is theory.
Other research that indicates a direct influence of sunlight on asthma, is one by Hart and her colleagues, which showed that controlled exposure to ultraviolet light (UVR) in mice markedly limited the development, incidence and severity of asthma symptoms such as inflamed airways and lungs.[v] These researchers exposed mice to allergens that generally brought on asthma attacks and then exposed them to sun lamps for 30 minutes. After the exposure, the allergens caused no attacks. The researchers also stated that sunlamp exposure produced a cell type in mice, that when transferred into other mice, suppressed the immune reactions and halted symptoms. This is another indication that sunlight has a healthful effect on asthma beyond vitamin D production.
Dr. Litonjua and Dr. Weiss, noting that the prevalence of asthma and allergic diseases began to increase worldwide in 1960, hypothesized that since people have increasingly spent more time indoors, there has been less exposure to sunlight, which has led to decreased cutaneous vitamin D production.[vi] This could have further led to vitamin D deficiency in pregnant women, resulting in more asthma in their offspring. But was vitamin D deficiency the cause or was it simply sunlight deficiency? Or could it have been both?
At the health resort owned by the Sorensons, we often noticed that asthmatics ceased using their inhalers after a week or two of hiking in the sunshine. One of them decreased the dosage from 6 inhalers per day to zero in about a week. Could it have been sunlight? We believe that the combination of mostly plant-based nutrition, combined with sunlight, made the difference, and the aforementioned research provides reasonable support for that opinion.
[i] Asthma and Allergy Foundation of America: Asthma Facts and Figures. Accessed 3-6-2010 http://www.aafa.org/display.cfm?id=8&sub=42
[ii] Kurtzke J. On the fine structure of the distribution of multiple sclerosis 1,25-Dihydroxyvitamin D3 inhibits cytokine production by human blood monocytes at the post-transcriptional level. Cytokine 1992;4:506-12.
[iii] Canning MO, Grotenhuis K, de Wit H, Ruwhof C, Drexhage HA. I-alpha,25-Dihydroxyvitamin D3 (l,25(OH)(2)D(3)) hampers the maturation of fully active immature dendritic cells from monocytes. Eur J Endocrinol 2001;145:351-57.
[iv] Kamran A, Hanif S, Murtaza G. Risk factors of childhood asthma in children attending Lyari General Hospital. J Pak Med Assoc 2015 Jun;65(6):647-50.
[v] Hart, P. Exposure to sunlight could reduce asthma. Newsletter of the Telethon Institute for Child Health Research 2006;3:2
[vi] Litonjua AA, Weiss ST. Is vitamin D deficiency to blame for the asthma epidemic? J Allergy Clin Immunol 2007;120:1031-35.
By Marc Sorenson, EdD, Sunlight Institute
Although several of my posts on the Sunlight Institute have discussed sunlight and MS, this post will provide the results of the most recent paper that I am aware of, and it reviews some of the most important investigations showing that sunlight exposure is absolutely essential for preventing or mitigating the disease.
MS is a disease in which the myelin sheaths (nerve coverings and insulators) are destroyed, leaving nerves bare and susceptible to “short circuiting.” This process is known as demyelination. New research, which should surprise no one, demonstrates that teenagers who have the greatest exposure to sunlight have a delayed onset of MS as adults. The study involved 1,161 Danish patients with MS who were given questionnaires regarding their sun-exposure habits and body-mass index (BMI) as teenagers. BMI is a measure of obesity (or the lack thereof). Besides sunlight, other vitamin-D predicting measures were also used to determine the probable cause of MS.
Interestingly, only sunlight exposure and lower BMI were associated with later age at the onset of the disease; other serum vitamin D predictors such as fish consumption did not show any association with MS. The authors still seemed to feel that vitamin D was the reason for the extended time before disease onset; however, that is unlikely, since other predictors of higher vitamin D levels showed no association. And, it has been shown that sunlight exposure has profoundly protective effects against MS, independently of vitamin D. Researchers determined to find the mechanism by which sunlight exposure suppressed the disease and found that UV light selectively inhibits spinal cord inflammation and demyelination. In that study, they performed an investigation in which ultraviolet radiation (UVR)—the same radiation that is found in sunlight and tanning beds—was administered to animals who suffered from experimental autoimmune encephalomyelitis (EAE). EAE is MS that has been deliberately induced in animals in a laboratory setting. The researchers found that the UVR treatments stopped inflammation and demyelination of the spinal cord by inhibiting a chemical known as a chemokine, also known as a cytokine. Chemokines are the cause of the inflammation and autoimmune attacks that result in MS. The MS-ameliorating effects in the study were directly initiated by UVR, independent of vitamin D.
Stunningly, another study by some of these same investigators determined that vitamin D was actually necessary for EAE to take place! Mice that lacked the vitamin D receptor, which causes vitamin D deficiency, had a markedly lower risk of developing EAE. In those mice that had receptors but were simply vitamin D deficient, the development of EAE was also partially suppressed. I do not look on this research as proving that vitamin D sufficiency leads to MS, but it certainly indicates that sunlight exposure, independent of vitamin D, is absolutely critical to prevent and ameliorate this frightening disease.
The bottom line? Be sure to get plenty of non-burning sun exposure!
 Julie Hejgaard Laursen, MD, PhD, Helle Bach Søndergaard, MSc, PhD, Per Soelberg Sørensen, MD, DMSc, Finn Sellebjerg, MD, PhD and Annette Bang Oturai, MD, PhD. Association between age at onset of multiple sclerosis and vitamin D level–related factors. Neurology 2015, Published online before print October 7, 2015.
 Becklund BR, Severson KS, Vang SV, DeLuca HF. UV radiation suppresses experimental autoimmune encephalomyelitis independent of vitamin D production. Proc Natl Acad Sci U S A. 2010;107:6418-23.
 Wang Y, Marling SJ, Beaver EF, Severson KS, Deluca HF. UV light selectively inhibits spinal cord inflammation and demyelination in experimental autoimmune encephalomyelitis. Arch Biochem Biophys. 2015 Feb 1;567:75-82.
 Wang Y, Marling SJ, Zhu JG, Severson KS, DeLuca HF. Development of experimental autoimmune encephalomyelitis (EAE) in mice requires vitamin D and the vitamin D receptor. Proc Natl Acad Sci U S A. 2012 May 29;109(22):8501-4.