Results from a new study published in the Journal of Allergy and Clinical Immunology suggest that cigarette smoke is related to lower vitamin D levels and a reduced ability to activate vitamin D in nasal cells.
Cigarette smoke is a known carcinogen and is associated with an increased risk for inflammation in the respiratory system. Previous research has shown that vitamin D may play a role in respiratory health and helps to reduce inflammation.
Despite the role that cigarette smoke and vitamin D play in causing and reducing inflammation, respectively, there hasn’t been much research that has looked at how cigarette smoke might affect vitamin D status and its ability to function in the respiratory system.
Recently, researchers from the Medical University of South Carolina conducted a study to determine if cigarette smoke might be related to lower vitamin D levels and how that relationship might affect inflammation in the nasal sinuses.
The research team recruited 85 patients with chronic rhinosinusitis (CRS) and 21 patients who were about to undergo surgery to serve as a control group.
CRS is a condition that is characterized by inflammation in the sinuses and a swollen nasal passage. There are two types of CRS, CRS without nasal polyps (CRSsNP) and CRS with nasal polyps (CRSwNP). CRSwNP is the more severe form of CRS and is more difficult to treat. Past research suggests that cigarette smoke can increase the risk for CRS.
The researchers collected blood samples to determine the vitamin D levels of all patients. They also collected sinonasal endothelial cell samples from the lining of nasal sinus tissue from all patients to determine any mechanisms for cigarette smoke on vitamin D. Finally, the researchers asked all of the patients to report their smoking habits.
The patients were than separated into two groups based on whether they smoked cigarettes or not. There were 12 participants in the control group and 44 patients with CRS (14 with CRSsNP and 30 with CRSwNP) who did not smoke cigarettes. There were 9 participants in the control group and 41 patients with CRS (26 with CRSsNP and 15 with CRSwNP) who did smoke cigarettes.
The researchers wanted to see if cigarette smoke related to decreased vitamin D levels, and if there was a mechanism leading to this decrease.
Here is what they found:
- All patients who smoked cigarettes had significantly lower vitamin D levels compared to those who did not smoke cigarettes.
- Cigarette smoke was related to the down regulation of the gene responsible for converting inactive vitamin D to the activated form. This effect was strongest in patients with CRSwNP who smoked cigarettes.
- Cigarette smoke was related to a reduced ability for the nasal cells to convert inactive vitamin D to the activated form.
- Activated vitamin D administered to these cells led to a reduction in inflammation in these cells.
The researchers concluded,
“Here we determined that cigarette smoke exposure exacerbates local and systemic [vitamin D] deficiencies in patients with CRSwNP. These effects were not limited to patients with CRSwNP because control subjects and patients with CRSsNP who were cigarette smoke exposed had reduced [vitamin D] levels systemically and locally as well.”
The research team noted that different methods to collect and study the cells could have led to different results in their cell study. Furthermore, the observational design of the study means we cannot know for sure if cigarette smoke decreases vitamin D levels.
Further research is needed to explore if increased vitamin D intake can improve the conversion ability and if it can help reduce inflammation caused by cigarette smoke.