Aim: The aim of this study is to investigate the possible effects of chronic smoking on serum vitamin D and some inflammation markers.

Materials and Methods: The smoking history of a total of 110 volunteer adults, 76 females and 34 males, for whom 25 (OH) vitamin D (VD), C-reactive protein (CRP) and complete blood count were requested were questioned. Laboratory data were taken from the Hospital Information Management System. Age, body mass index (BMI), outdoor time, leukocyte and its subgroups, platelet, mean platelet volume (MPV), neutrophil lymphocyte ratio (NLR), platelet lymphocyte ratio (PLR), CRP and VD levels were compared in smoking and non-smoking groups and in female and male subgroups. Correlations of VD levels and these parameters, comparison of demographic and laboratory data at categorized VD levels, and their distribution by gender were investigated. Statistical significance was evaluated at the p <0.05 (two-tailed) level.

Results: The smoking period of smokers was 16.4±12.7 (1-50) years. No significant difference was found between the age, BMI, outdoor time, CRP and VD levels of the smoking (n=40) and non-smoker (n=70) groups. Leukocyte and neutrophil counts were significantly higher in the smoker group than the non-smoker group (both of them p=0.001). Neutrophil counts, percentage and NLR in females were significantly higher in smokers (n=22) than non-smokers (n=54) (p=0.011; p=0.005; p=0.017 respectively); lymphocyte percentage was found to be significantly lower (p=0.031). In men; Leukocyte, neutrophil and lymphocyte counts were significantly higher in smokers (n=18) compared to nonsmokers (n=16) (p=0.013; p=0.031; p=0.022, respectively). VD levels of non-smoking men were significantly higher than non-smoking women (p=0.003). MPV value did not differ in any group. In the non-smoking group, a significant correlation was found between VD levels and the duration of staying outdoors (rs=0.249; p=0.038). There was a weak positive correlation between VD levels and lymphocyte percentage values in all smokers group (rs=0.322; p=0.043). There was a weak negative correlation with the percentage of neutrophils (rs= -0.313, p=0.049). A significant negative correlation was found between VD levels and leukocyte counts in the smoking men group (rs= -0.564; p=0.015). The frequency of women with VD levels <20 ng/mL was significantly higher than that of men (p=0.011). Outdoor time was statistically significantly shorter in the group with VD level <20 ng/mL compared to the group with 20-29 ng/mL, and significantly shorter than the group with ≥30 ng/mL, although not statistically significant.

Conclusion: While chronic smoking did not cause a change in serum VD and CRP levels, it affects the number of leukocytes and neutrophils in the blood in total smokers and additionally the lymphocyte count in male smokers. The reason for this increase may be that the immunomodulatory chemicals and gases contained in cigarette smoke cause an inflammatory reaction and the resulting cellular defense mechanism. The fact that serum VD levels of non-smoking men are significantly higher than that of non-smoking women can be associated with participation in working life. Although there is a significant positive correlation between the time spent in the open air and VD levels in nonsmokers, the absence of smokers suggests that smoking negatively affects cutaneous VD synthesis. The fact that 73.6% of the cases had a VD level below 30 ng/mL showed that external VD supplementation is required in our region.