25-hydroxyvitamin D and testosterone levels association through body mass index: A cross-sectional study of young men with obesity

Abstract

BackgroundsVitamin D and testosterone deficiency have been widely related to obesity. However, only a few studies have investigated the effect of vitamin D on testosterone in the context of obesity, in which controversial results have been raised.ObjectivesThe purpose of this study was to determine the relationship between serum 25-hydroxyvitamin D (25(OH)D) and testosterone levels in young men with different grade of obesity.Design and methodsThis cross-sectional study included 269 healthy young men with obesity (body mass index (BMI) ≥ 30 kg/m2). Participants were divided into two groups based on their serum 25(OH)D levels (134 subjects with vitamin D sufficiency and 135 participants with vitamin D deficiency, according to the 50th percentile of 25(OH)D). Serum 25(OH)D and sex hormones have been measured. The relationships between 25(OH)D, sex hormones, and obesity grades were investigated with linear and binary logistic regression analyses, as well as mediation analysis.ResultsCompared to the 25(OH)D sufficiency group, total and free testosterone levels were found to be decreased, whereas serum androstenedione levels were increased in the 25(OH)D deficiency group (p<0.05). Using multivariable lineal regression analyses, 25(OH)D was correlated with the majority of sex hormones (p<0.05). When mediation with BMI was performed, the direct effect between 25(OH)D and sex hormones disappeared, and only the indirect effect via BMI remained (demonstrating the importance of BMI). Furthermore, after controlling for age and smoking status, we discovered that total testosterone and SHBG were both significantly associated with 25(OH)D (p<0.05) in subjects with obesity type III. Using a mediation analysis, we discovered that BMI had a partial effect on the association between 25(OH)D and total testosterone levels in morbidly obese participants, indicating that a direct association between 25(OH)D and total testosterone levels, and that BMI partially mediated this association.ConclusionsSerum 25(OH)D is associated with total testosterone levels in only those subjects with morbid obesity, suggesting a specific benefit in severe cases of obesity. Additional research is needed to elucidate possible common mechanisms.

Seasonal Variation in Vitamin D Status Does Not Interfere with Improvements in Aerobic and Muscular Endurance in Conscripts during Basic Military Training

“…At first glance, this finding contradicts the data of Damas-Fuentes et al [54], Nimptsch et al [55], and Wehr et al [57] and the general conclusion of a large-scale meta-analysis [56]. However, all our participants were healthy young men, whereas Damas-Fuentes et al [54] reported a significant positive association between serum 25(OH)D and testosterone levels only in men with morbid obesity, and Nimptsch et al [55] and Wehr et al [57] observed such an association in middle-aged and elderly men. A meta-analysis by D'Andrea et al [56] included data from eighteen studies involving 20,576 individuals altogether.…”

“…Previous studies [54,55] and a recent large-scale meta-analysis [56] have revealed a positive association between vitamin D status and serum testosterone levels. In addition to a positive association, Wehr et al [57] reported similar seasonal variation in serum 25(OH)D and testosterone concentrations.…”