Effect of vitamin D3 supplementation on serum 25(OH)D, lipids and markers of insulin resistance in obese adolescents: a prospective, randomized, placebo-controlled pilot trial.

To determine the effect of vitamin D3 supplementation on 25-hydroxyvitamin D [25(OH)D], lipid profile and markers of insulin resistance in obese adolescents. In this double-blind, randomized, placebo-controlled trial, 58 obese adolescents (n = 58; 12-18 years of age) received either vitamin D3 (2,000 IU/day) or placebo for 12 weeks. Total 25(OH)D, fasting plasma glucose, insulin and lipid profile were measured at baseline and following supplementation. The trial was completed by 44/58 enrolled participants. At the end of the 12 weeks, total serum 25(OH)D concentrations increased to a modest degree (median 6 ng/ml) in the vitamin D-supplemented group (p < 0.001). Supplementation showed no detectable changes in fasting plasma glucose, insulin, homeostatic model of assessment index (HOMA-IR), lipids and highly sensitive C-reactive protein. 12 weeks of vitamin D3 supplementation in obese adolescents with 2,000 IU once daily resulted in a modest increase in 25(OH)D concentration in obese adolescents, but did not affect the lipid profile and markers of insulin resistance and inflammation. Further studies with higher doses of vitamin D3 and/or longer duration of supplementation are needed to understand if vitamin D3 supplementation can impact lipid profiles and markers of insulin resistance and inflammation in obese children.

Nader NS ，Aguirre Castaneda R ，Wallace J ，Singh R ，Weaver A ，Kumar S ... -  《-》

Cholecalciferol supplementation does not influence β-cell function and insulin action in obese adolescents: a prospective double-blind randomized trial.

There is increasing interest in the extraskeletal effects of vitamin D, particularly in the obese state with regard to the development of insulin resistance and diabetes. The objective of the study was to determine the effect of 2 doses of cholecalciferol (vitamin D3) supplementation on insulin action (Si) and pancreatic β-cell function in obese adolescents. We performed a 12-wk double-blind, randomized comparison of the effect of vitamin D3 supplementation on Si and β-cell function in obese Caucasian adolescents (body mass index > 95(th) percentile). The subjects were randomly assigned to receive either 400 IU/d (n = 25) or 2000 IU/d (n = 26) of vitamin D3. Each subject underwent a 7-sample 75 g oral glucose tolerance test, with glucose, insulin, and C-peptide measurements, to calculate Si and β-cell function as assessed by the disposition index (DI), with use of the oral minimal model before and after supplementation. A total of 51 subjects aged 15.0 ± 1.9 y were enrolled. Included for analysis at follow-up were a total of 46 subjects (20 male and 26 female adolescents), 23 in each group. Initial serum 25-hydroxyvitamin D [25(OH)D] was 24.0 ± 8.1 μg/L. There was no correlation between 25(OH)D concentrations and Si or DI. There was a modest but significant increase in 25(OH)D concentration in the 2000 IU/d group (3.1 ± 6.5 μg/L, P = 0.04) but not in the 400 IU/d group (P = 0.39). There was no change in Si or DI following vitamin D3 supplementation in either of the treatment groups (all P > 0.10). The current study shows no effect from vitamin D3 supplementation, irrespective of its dose, on β-cell function or insulin action in obese nondiabetic adolescents with relatively good vitamin D status. Whether obese adolescents with vitamin D deficiency and impaired glucose metabolism would respond differently to vitamin D3 supplementation remains unclear and warrants further studies. This trial was registered at clinicaltrials.gov as NCT00858247.

Javed A ，Vella A ，Balagopal PB ，Fischer PR ，Weaver AL ，Piccinini F ，Dalla Man C ，Cobelli C ，Giesler PD ，Laugen JM ，Kumar S ... -  《-》

Calcium plus vitamin D supplementation affects glucose metabolism and lipid concentrations in overweight and obese vitamin D deficient women with polycystic ovary syndrome.

Few studies have examined the effects of calcium plus vitamin D supplementation on glucose metabolism and lipid concentrations in overweight and obese vitamin D deficient women with polycystic ovary syndrome (PCOS). This study was conducted to determine the effects of calcium plus vitamin D supplementation on glucose metabolism and lipid concentrations among overweight and obese vitamin D deficient women with PCOS. This randomized double-blind placebo-controlled clinical trial was conducted among 104 overweight and obese vitamin D deficient women diagnosed with PCOS. Participants were randomly assigned into four groups to receive: 1) 1000 mg/d calcium + vitamin D placebo (n = 26); 2) 50,000 IU/wk vitamin D + calcium placebo (n = 26); 3) 1000 mg calcium/d + 50,000 IU/wk vitamin D (n = 26) and 4) calcium placebo + vitamin D placebo (n = 26) for 8 weeks. Fasting blood samples were taken at baseline and after 8 weeks' intervention to measure glucose metabolism and lipid concentrations. Calcium-vitamin D co-supplementation resulted in higher levels of serum calcium (P = 0.002) and vitamin D (P < 0.001) compared with other groups. Co-supplementation, compared with other groups, led to decreased serum insulin levels (P = 0.03), homeostasis model of assessment-insulin resistance (HOMA-IR) score (P = 0.04) and a significant rise in quantitative insulin sensitivity check index (QUICKI) (P = 0.001). Furthermore, a significant decrease in serum triglycerides (P = 0.02) and VLDL-cholesterol levels (P = 0.02) was seen following the administration of calcium plus vitamin D supplements compared with the other groups. Co-supplementation with calcium and vitamin D had no significant effects on FPG, total-, LDL-, HDL-, and non-HDL-cholesterol levels. In conclusion, calcium plus vitamin D supplementation for eight weeks among vitamin D deficient women with PCOS had beneficial effects on serum insulin levels, HOMA-IR, QUICKI, serum triglycerides and VLDL-cholesterol levels, but it did not affect FPG and other lipid profiles. Clinical registration numberwww.irct.ir: IRCT201309275623N10.

Asemi Z ，Foroozanfard F ，Hashemi T ，Bahmani F ，Jamilian M ，Esmaillzadeh A ... -  《-》

Correcting vitamin D insufficiency improves insulin sensitivity in obese adolescents: a randomized controlled trial.

Belenchia AM ，Tosh AK ，Hillman LS ，Peterson CA ... -  《-》

A double-blind, randomized, placebo-controlled trial of the short-term effect of vitamin D3 supplementation on insulin sensitivity in apparently healthy, middle-aged, centrally obese men.

Nagpal J ，Pande JN ，Bhartia A 《-》