By: Marc Sorenson, Sunlight Institute–
According to the Centers for Disease Control in May 2011, “about one in 12 people in the United States now has asthma—a total of 24.6 million people and an increase of 4.3 million since 2001.”[1] This is another of those diseases like diabetes that is increasing out of control and shows no sign of abating.
The Scientific American, on April 14, 2011, published an article entitled Why are Asthma Rates soaring?[2] In that article, they lamented the fact that for the last three decades asthma rates have been surging, and that differing theories have arisen as to the reason for the increase, only to be disproven and discarded. Among those theories was the hypothesis that the world has become so “clean” or sterile, that youngsters are not subjected to infectious organisms and thereby do not develop strong immune systems capable of fighting off pollens, dust, etc. To me, that seemed like a rather lame hypothesis, and the article indicates that the idea is no longer in vogue. Another theory was that those who had allergic reactions to various environmental pollutants had weaknesses that predisposed them to asthma. Both of these ideas have failed the test of truth; neither allergy nor early-life “cleanliness” leads to an increase in asthma. The latest theory to surface is that the pandemic of obesity is to blame, because it causes inflammation throughout the body. However, there are many obese people who are not asthmatics.
Newer research has the answer. In Qatar, researchers measured serum vitamin D levels in asthmatic children and compared those levels to levels of healthy non-asthmatic controls.[3] Deficiency was defined as having levels below 20 ng/ml. Many other possible factors were also measured, such as nutritional practices, and various serum measurements such as calcium, phosphorus, alkaline phosphatase, magnesium, creatinine and Parathyroid hormone.
The results were these: asthmatic children had less exposure to sunlight (67%) and less physical activity (71.3%). Vitamin D deficiency was by far the strongest predictor of asthma; those who had the lowest vitamin D levels were nearly five-times more likely to have asthma.
The Scientific American’s editors must not to know that many scientists other than the aforementioned have suggested that vitamin D deficiency, caused by lack sunlight, leads to asthma. Much of the research was done before they published their article.
Researchers in Boston have hypothesized that the decrease in sunlight exposure and resultant vitamin D deficiency is responsible for the asthma epidemic.[4] Others show the same facts: the increase in asthma has paralleled the decline in sunlight exposure, and asthma risk is 40% lower in children of women who have the highest vitamin D consumption during pregnancy.[5]
A scientific experiment from Australia also demonstrated that when asthmatic mice were exposed to ultraviolet light, before being exposed to an asthma-causing allergen, asthma symptoms were reduced.[6] Finally, another study from Spain showed that children exposed to the most sunlight have much lower risks of asthma.[7] To me, it is amazing that the article in Scientific American never even mentioned the possibility of asthma being caused by deficiency of vitamin D brought on by lack of sunlight. Now that this latest research is in, It is my hope that they will correct the mistake and use their considerable prestige to promulgate the vitamin D/sunlight/asthma connection. It is time to return to the sun.
[1] Vital Signs: Asthma Prevalence, Disease characteristics, and self-Management education—United States, 2001-2009. MMWR 2011;60(17):547-552
[2] http://www.scientificamerican.com/article.cfm?id=why-are-asthma-rates-so…
[3] Bener A, Ehlayel MS, Tulic MK, Hamid Q. Vitamin D deficiency as a strong predictor of asthma in children. Int Arch Allergy Immunol 2012;157(2):168-75.
[4] Devereux, G. et al. Maternal vitamin D intake and early childhood wheezing. Am J Clin Nutr 2007;85:853-59
[5] Camargo, C. et al. Maternal intake of vitamin D during pregnancy and risk of recurrent wheeze in children at 3 y. Am J Clin Nutr 2007;85:788-95.
[6] Hart, P. et al. Sunlight may protect against asthma. Perth (Australia) Telethon institute for child health research. Quoted in Australian AP Oct 24, 2006.
[7] Arnedo-Pena, A et al. Sunny hours and variations in the prevalence of asthma in schoolchildren according to the International Study of Asthma and Allergies (ISAAC) Phase III in Spain. Int J Biometeorol 2011;55:423-434.