About 20 to 30 percent of habitual smokers develop chronic obstructive pulmonary disease (COPD). After smoking cessation, inflammation continues to plague the lungs. These observations suggest an autoimmune component. Researchers in Ireland studied the disease mechanism and concluded that therapeutic strategies should focus on the immune response.
So far, expensive immune modulating drugs have provided disappointing results in clinical trials. Researchers in Belgium recommend another look at older treatments, especially vitamin D. There are several motivating observations:
1. In the NHANES (National Health And Nutrition Examination Survey) III study, a strong relationship was noted between blood levels of vitamin D and pulmonary function.
2. African American smokers develop severe airflow obstruction faster than Caucasians. Because significant amounts of vitamin D are produced in skin exposed to sunlight, and dark pigment shields the skin from excessive sunlight, African Americans are presumed to have lower overall vitamin D levels.
3. Exacerbations of COPD as well as more conventionally recognized autoimmune diseases peak in winter and early spring.
4. Airflow obstruction is associated with reduced bone mineral density. Vitamin D deficiency is recognized as a factor in osteoporosis, osteopenia, and rickets.
5. Approximately 3 percent of the human genome is regulated by the vitamin D pathway.
Historically, vitamin D deficiency was first recognized as the cause of rickets. This disabling disease is now almost fully eradicated, so health care professionals may have assumed all too often that everyone has sufficient vitamin D. That assumption is now being questioned. Reference 2 suggested important roles for this vitamin in regulating the immune system, to optimize infection fighting and minimize autoimmune damage. Beneficial effects are reported as:
1. Increased intestinal absorption of calcium
2. Increased bone mineralization
3. Decreased tumor cell proliferation and angiogenesis
4. Decreased dendritic-T cell interaction and CD4 cell activation (important for immune modulation)