High-dose cholecalciferol supplementation to obese infertile men is sufficient to reach adequate vitamin D status.

Obesity is associated with low vitamin D status and the optimal supplement and dosage of cholecalciferol (vitamin D 3 ) or calcidiol (25OHD) for individuals with obesity has been debated. We aimed to determine the effect of high-dose vitamin D 3 supplementation on achieving adequate vitamin D levels among infertile men with normal weight versus obesity. Here, we present secondary endpoints from a single-center, double-blinded, randomized clinical trial, comprising of 307 infertile men randomized to active or placebo treatment for 150 days. Men in the active group initially received an oral bolus of 300,000 IU vitamin D 3 , followed by daily supplementation with 1,400 IU vitamin D 3 and 500 mg calcium. Baseline body mass index (BMI) was listed as a predefined subgroup. At baseline, serum 25OHD was significantly higher in men with normal weight (BMI < 25 kg/m 2 ) compared with men with overweight (BMI 25-30 kg/m 2 ) and obesity (BMI > 30 kg/m 2 ) (48 nmol/L vs. 45 nmol/L and 39 nmol/L, respectively; p = 0.024). After the intervention, both men with normal weight, overweight and obesity treated with vitamin D 3 had a significantly higher serum 25OHD compared with corresponding placebo-treated men (BMI < 25 kg/m 2 : 92 nmol/L vs. 53 nmol/L, BMI = 25-30 kg/m 2 : 87 nmol/L vs. 49 nmol/L and BMI > 30 kg/m 2 : 85 nmol/L vs. 48 nmol/L; p < 0.001 for all respectively). In conclusion, we show high-dose vitamin D 3 supplementation to infertile men with obesity and low vitamin D status, is sufficient to achieve adequate serum 25OHD levels.