Smoking is a significant determinant of low serum vitamin D in young and middle-aged healthy males

Abstract

OBJECTIVE: We aimed to determine the prevalence of 25(OH)D (D2 and D3 independently) inadequacy in healthy young/middle-aged men and to investigate its relationship with BMD, bone markers, demographic and lifestyle parameters such as age, BMI, smoking, alcohol consumption and dietary calcium intake. DESIGN: We determined 25(OH)D levels using LC-MS/ MS, a robust method for measurement of both 25(OH)D3 and 25(OH)D2, iPTH, osteocalcin, beta C terminal cross-linked telopeptides of type I collagen (b-CTXs), procollagen type 1 aminoterminal propeptide (PINP), BMD at L2-L4 and proximal femur, smoking habits, daily dietary calcium intake and alcohol consumption in 181 randomly selected healthy men aged 20-50y. RESULTS : The prevalence of vitamin D deficiency (25(OH)D <20ng/ml) was 50.3%. Only 8.8% of the participants had vitamin D sufficiency (25(OH)D ≥30ng/ml). We found a strong correlation between 25(OH)D and smoking in the totality of participants (p<0.001). 25(OH)D level was lower by approximately 4.3 ng/dl (p<0.001) in a smoker compared to a non-smoker among the totality of participants, while this value increased to 9.2ng/ml in the 40-50y subgroup (p=0.003). A multinomial logistic regression model demonstrated that a young smoker (20-29y) had 58% increased likelihood of having vitamin D deficiency compared to a non-smoker of the same age group (p=0.041). CONCLUSIONS: A high prevalence of vitamin D deficiency was identified in a young and middle-aged male population. Smoking is a significant determinant of serum 25(OH)D, while it increases significantly the likelihood of having vitamin D deficiency. In our hands, vitamin D levels are not a determinant of bone turnover and BMD in this population.