Role of Vitamin D and Its Analogues in Diabetic Nephropathy: A Meta-analysis.

BACKGROUND: Diabetic nephropathy remains one of the most common causes of chronic kidney disease in the United States and is associated with significant morbidity and mortality. Recently, there have been emerging data highlighting the role of vitamin D and its analogue in chronic kidney disease especially diabetic nephropathy independent of its effect on bone metabolism. METHODS: This study aimed to evaluate effect of supplementing vitamin D and its analogues on halting or slowing progression of diabetic nephropathy. Electronic databases (PubMed, Scopus, Google scholar) were searched and randomized controlled trials (RCTs) that investigated the use of vitamin D and its analogs for diabetic nephropathy were studied. This meta-analysis of RCTs performed in accordance with Preferred Reporting Items for Systematic review and Meta-analysis statement. RESULTS: This meta-analysis included 9 RCTs and suggested a favorable trend with respect to an effect of vitamin D and its analogues on albuminuria though this did not reach statistical significance (MD, -0.17; 95% CI, -0.34-0.01; P = 0.06]. Serum calcium was unaffected suggesting safe use of these agents. CONCLUSIONS: Use of vitamin D and its analogues may have potential as an adjuvant therapy for reducing albuminuria and slowing progression of diabetic nephropathy but further studies are needed.

Serum Vitamin D Concentrations in Baboons (Papio spp.) during Pregnancy and Obesity.

Obesity is associated with vitamin D deficiency, which can lead to serious problems during pregnancy. However, the mechanisms of the deficiency and guidelines for vitamin D supplementation during pregnancy are not established yet, and variations in environmental exposures combined with the difficulties of performing research in pregnant women are obstacles in the evaluation of vitamin D metabolism. Baboons (Papio spp.) are an excellent, well-established model for reproductive research and represent a unique opportunity to study vitamin D metabolism in a controlled environment. This study used secondary data and specimen analysis as well as a novel experimental design to evaluate pregnant and nonpregnant baboons that were or were not exposed to sunlight while they were obese and after weight reduction. Daily D3 intake was 71% higher in nonpregnant obese baboons than in their nonobese counterparts, but serum vitamin D concentrations did not differ between these populations. In addition, serum 25-hydroxyvitamin D concentrations correlated negatively with the obesity index. This report is the first to show the effect of obesity and pregnancy on vitamin D concentrations in a NHP population. These data underline the importance of adequate vitamin D supplementation in obese animals.