Obesity is associated with low vitamin D status, and the optimal supplement and dosage of cholecalciferol (vitamin D3) or calcidiol (25OHD) for individuals with obesity have been debated. We aimed to determine the effect of high-dose vitamin D3 supplementation on achieving adequate vitamin D levels among infertile men with normal weight v. obesity. Here, we present secondary end points from a single-centre, double-blinded, randomised clinical trial, comprising 307 infertile men randomised to active or placebo treatment for 150 days. Men in the active group initially received an oral bolus of 300 000 mg of vitamin D3, followed by daily supplementation with 1400 mg of vitamin D3 and 500 mg of calcium. Baseline BMI was listed as a predefined subgroup. At baseline, serum 25OHD was significantly higher in men with normal weight (BMI < 25 kg/m2) compared with men with overweight (BMI 25–30 kg/m2) and obesity (BMI > 30 kg/m2) (48 nmol/l v. 45 nmol/l and 39 nmol/l, respectively; P = 0·024). After the intervention, men with normal weight, overweight and obesity treated with vitamin D3 had a significantly higher serum 25OHD compared with corresponding placebo-treated men (BMI < 25 kg/m2: 92 nmol/l v. 53 nmol/l, BMI = 25–30 kg/m2: 87 nmol/l v. 49 nmol/l and BMI > 30 kg/m2: 85 nmol/l v. 48 nmol/l; P < 0·001 for all, respectively). In conclusion, we show that high-dose vitamin D3 supplementation to infertile men with obesity and low vitamin D status is sufficient to achieve adequate serum 25OHD levels.

The global prevalence of vitamin D deficiency is high. Poor vitamin D status, especially in women, has been reported in several countries in the Middle East despite adequate year-round sunlight for vitamin D synthesis. However, data on vitamin D status in Palestine are scarce. The aim of this cross-sectional study was to evaluate vitamin D status based on serum concentrations of 25-hydroxycholecalciferol [25-(OH)D] among young healthy Palestinian students (18–27 years) and to assess associations between 25-(OH)D concentrations and several predictors. The mean 25-(OH)D concentration of women (n 151) was 27⋅2 ± 14⋅5 nmol/l, with the majority having insufficient (31⋅1 %) or deficient (<60 %) 25-(OH)D status. Only 7 % of women achieved sufficient or optimal 25-(OH)D status. In contrast, men (n 52) had a mean 25-(OH)D concentration of 58⋅3 ± 14⋅5 nmol/l, with none classified as deficient, and most obtaining sufficient (55⋅8 %) or even optimal 25-(OH)D status (11⋅5 %). Among women, 98 % wore a hijab and 74 % regularly used sunscreen. Daily dietary vitamin D intake (3-d 24-h recalls) was 45⋅1 ± 36⋅1 IU in the total group (no sex differences). After adjustment, multiple linear regression models showed significant associations between 25-(OH)D concentrations and the use of supplements (B = 0⋅069; P = 0⋅020) and dietary vitamin D (B = 0⋅001; P = 0⋅028). In gender-stratified analysis, the association between supplement use and 25-(OH)D concentrations was significant in women (B = 0⋅076; P = 0⋅040). The vitamin D status of women in the present cohort is critical and appears to be mainly due to wearing a hijab, regular use of sunscreen and low dietary vitamin D intake. The vitamin D status of the women should be improved by taking vitamin D containing supplements or fortified foods.