April 8, 2019
THE NUTRITIONAL STUDIES
THE DO
Vitamin D
Why is Vitamin D so important for Asthma and allergies?
Vitamin D along with vitamin A and commensal gut bacteria promote the maturation of the immune system's police called T regulator cells via the gene FOXP3.
Vitamin D is arguably the most important micronutrient for human health and asthma. It is one of the four fat soluble vitamins and has the added benefit of being naturally synthesized by our skin via exposure to the sun's UVB rays and stored for months in fat.
The big issue surrounding vitamin D and asthma is that humans are avoiding the sun and spending too much time indoor. We are not synthesizing adequate amounts of natural vitamin D in our skin and this is putting downward pressure on our immune system in a negative way. The T regulator cells are critical for dampening inflammation and immune activity post pathogen killing. Unchecked or excess inflammation becomes the main driver of asthmatic disease decline.
In the most recent published literature, vitamin D appears to reduce the number and severity of exacerbations requiring oral steroid use and emergency room visits for asthma and infectious diseases. (Jolliffe et. al. 2017)(Riverin et. al.2015)(Pojsupap et. al. 2015)(Bergman et. al. 2013)(Martineau et. al. 2016)(many more studies...)
Read to the end for a nice high end summary from Dr. Pfeffer. I am in the middle of a deep dive into the field of immunology and all of the posited mechanisms for the beneficial effects of vitamin D in human disease, especially asthma, make me wish everyone could and would get tested for D insufficiency.
The current general health recommendations are to avoid the sun because of skin cancer risks. These recommendations are unhelpful. The goal of skin cancer prevention should be to avoid sunburns which are a noted risk factor for cancer. Exposure to 15 to 30 minutes of direct sun a day without sunscreen has never been shown in any way to be dangerous, however, the beneficial effects on Vitamin D levels are well known during this brief exposure at peak day sun. (Nair et. al. 2012)
Aside from sun exposure, where can we get vitamin D? Food and supplements. Food sources of Vitamin D are dairy, fish, eggs, mushrooms and fortified foods like orange juice and cereals. A diet that includes oily fish like roughly 3 ounces of salmon will provide 400IU of Vitamin D.
Some other caveats are to remember that your skin color dictates how fast you can make D. Darker skin = more time to generate adequate D and lighter skin is the converse. Between the months of November and April, it is quite difficult for most individuals to generate adequate D from the sun in the mid to northern United States. Dark skin color is an advantage for preventing skin cancer, but a disadvantage for developing vitamin D.
From a supplement perspective, I do not recommend taking higher doses of vitamin D without blood level monitoring. Over consumption of vitamin D can be toxic as it is fat soluble and can accumulate in our fat cells. Symptoms and findings of toxicity include hypercalcemia, bone pain, kidney stones, calcium deposits in the body. Diseases that could increase the risk of toxicity include: sarcoidosis, hyperparathyroidism, tuberculosis, lymphoma and other cancers. There is only one way to be sure that you are not in the toxic range and that is to test 25 OH vitamin D blood levels.
Children that are at increased risk for insufficiency or deficiency of vitamin D have: sun avoidance behavior, issues with intestinal fat malabsorption (vitamin D is a fat soluble vitamin like D/E/K), intestinal dysbiosis, inflammatory bowel disease, eating disorders, celiac disease and disorders of bile production or pancreatic enzyme production, chronic kidney disease and magnesium deficiency.
The story continues next week,
Dr. M
Julia Nature Reviews Immunology Article
Jolliffe Lancet Respiratory Medicine Article
Riverin PLOSone Article
Pojsupap Journal of Asthma Article
Bergman PLOSOne Article
Martineau Cochrane Review Article
Pfeffer Chest Article
Nair Journal of Pharmacologic Pharmacotherapy Article
Linus Pauling Institute Vitamin D
"There is increasing interest in the therapeutic utility of vitamin D in asthma, which is supported by a significant body of evidence on epidemiologic associations between vitamin D insufficiency and worse asthma control. In support of a causal relationship, vitamin D beneficially modulates diverse immunologic pathways in heterogeneous asthma endotypes, regulating the actions of
lymphocytes, mast cells, antigen-presenting cells, and structural cells to dampen excessive inflammatory responses. Allergic asthma is characterized by a failure of immune tolerance and the development of pathologic responses to inhaled aeroallergens, and vitamin D has been extensively shown to support immune regulation. Alarmin cytokines are increasingly implicated in nonallergic eosinophilic inflammation, which vitamin D also regulates.
Steroid resistance and pathologic interleukin (IL)-17 responses are features of severe asthma, and vitamin D beneficially enhances the response to steroids in these individuals. Additionally, vitamin D enhances antimicrobialpathways, which is of relevance to infection-precipitated asthma exacerbations. These mechanisms support a role for vitamin D as secondary prevention to reduce exacerbations and inflammation in asthma. Similar mechanisms, and effects on fetal lung development, likely underlie a primary prevention therapeutic role in pregnancy for vitamin D to reduce the development of asthma in children." (Pfeffer et. al. 2018)
