With previous studies linking a deficiency in vitamin D to an increased risk of respiratory infections, researchers are now looking at this essential vitamin and its possible role in bronchiectasis. It is very important for healthy bones, muscles, nerves, and the immune system.
Vitamin D is a nutrient that’s not found naturally in very many foods — fish such as salmon, tuna, and mackerel are among the best sources — but fortified foods and vitamin supplements provide the best source of this vitamin in American diets. It is also produced by the body when the skin is directly exposed to the sun.
How does vitamin D work in respiratory tract infections?
The role of vitamin D in helping the body absorb calcium is well established. People who don’t get enough of this vitamin may develop soft, thin and brittle bones.
Recently, vitamin D receptors (VDR) were discovered in nearly every tissue of the body, especially in cells of the immune system. These receptors can process the active form of vitamin D, which suggests a strong involvement in the immune system.
A protein called cathelicidin has antimicrobial activity against bacteria and viruses. Vitamin D receptors present in the lung cells convert inactive vitamin D into its active form, which will stimulate the production of cathelicidin, helping to fight infection. It may also influence small signaling molecules called cytokines in communicating with the immune system.
Studies of vitamin D in bronchiectasis
In a study of 402 patients with bronchiectasis in Edinburgh, Scotland, participants were assessed for vitamin D levels and classified as vitamin D deficient, insufficent, or sufficent.
Half the patients (50%) were found to have a deficiency (less than 25 nmol/l), compared to 12% of controls; 43% had insufficient levels (25-75 nmol/l); and only 7% had sufficient levels.
When compared to insufficient or sufficient levels, participants with bronchiectasis who had deficiency were more likely to be chronically colonized with bacteria and to have increased airway inflammation. They also suffered more frequent flares, were more likely to be hospitalized due to a severe flare in a 12-month period, and had worse symptoms and poorer health-related quality of life.
A Phase 4 clinical trial (NCT02507843) at the Shanghai Pulmonary Hospital in China is assessing vitamin D as an adjunctive treatment in people with non-cystic fibrosis bronchiectasis. The primary objective of this study is the time to the first acute flare. Secondary objectives are the percentage of participants with one or more flare per year, the severity of the disease, the need for antibiotics use, and changes in quality of life. The estimated completion date for this study is June 2017.
The most natural way to get this vitamin is by exposing your skin to sunlight to get ultraviolet B (UVB), but people must be cautious about sun exposure due to the risk of skin cancer. There is no need to tan or burn the skin to get sufficient vitamin D.
However, if someone has skin problems or can’t get enough sunlight, vitamin D supplements are inexpensive and safe.
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