Surely we know the sun supplies us with an ample supply of vitamin D, the sunshine vitamin. So is it possible lack of sun exposure may cause asthma? We shall investigate the evidence.
John Grever, in his post "Vitamin D Deficiency Linked to Asthma Severity," at Medpage Today reports that most researchers agree that we get little vitamin D from our diets, so we rely on the sun for our vitamin D supply.
However, poor diet can also result in low levels of vitamin D, as the vitamin can be obtained by the intake of dairy products such as cheese and milk, fatty fish, fish oils, and fortified foods like cereal.
Sciencedaily.com, "Vitamin D Levels Linked to Asthma Severity," reports that 90 percent of our vitamin D "is produced by the body in resonse to sun exposure." This is why it's called the sunshine vitamin.
Yet while lack of sun exposure may result in low vitamin D levels, the article notes the following as other possible causes:
- Lack of exposure to the sun
- Sunscreen use
- Inadequate dietary intake
- Increased time spent indoors (a modern dilemma)
Clifford Basset in his Fox News report, "Can Vitamin D Improve Lung Function, in Asthma?" reports that researchers evaluating five decades of studies learned that as many as a third of all children and adolescents in the U.S have low vitamin D levels, and this deficiency is more common in western nations like the U.S. and Europe.
The Journal of Allergy and Clinical Immunology, "Is vitamin D deficiency to blame for the asthma epidemic?" (November 2007, 120, 5, page 1031), reports on one study that links low vitamin D levels in pregnant mothers with a 40 percent greater risk of their children developing asthma.
Researches surmise that vitamin D is essential for adequate development of the immune system. Since asthma is a condition caused by an overactive immuney system, the link is evident.
The Daily News and Analysis, "Lack of Vitamin D linked to airway changes in children with asthma," reports on a study that shows a link between low vitamin D and worsening lung function and the need for an increased need for systemic steroids.
The theory here is that lack of vitamin D causes the muscles lining the air passages of the lungs (bronchioles) to become enlarged or inflammed.
Healthsout reporter Steven Reinberg, in his post "Too Little Vitamin D May Worsen Asthma," reports on a study that shows low levels of vitamin D nearly doubled the inflammatory response. This resulted in worse asthma and asthma less responsive to steroids in people with insufficient vitamin D levels.
He writes that researchers evaluating the report surmise that low levels of vitamin D increases "production of the pro-inflammatory cytokine, TNF-alpha. This raises the possibility that low low vitamin D levels are tied to increased inflammation of the airways."
The American Journal of Respiratory and Critical Care Medicine, "Serum Vitamin D Levels and markers of Severity of Childhood Asthma in Costa Rica," (2009, vol. 179, pages 765-771) reports on a study that linked vitamin D insufficiency with severe or worsening asthma.
