Vitamin D, sub-inflammation and insulin resistance. A window on a potential role for the interaction between bone and glucose metabolism.
Study Goal
The researchers aimed to investigate the role of Vitamin D in inflammation, insulin resistance, and its potential implications in metabolic syndrome, obesity, and type 2 diabetes.
Results Summary
The study found that Vitamin D influences anti-inflammatory and pro-inflammatory cytokines, potentially improving insulin sensitivity and secretion, but supplementation results were inconsistent, with some studies showing benefits in glucose and lipid metabolism while others showed no significant effects.
Population
Patients at risk of developing diabetes and those with metabolic syndrome or obesity.
Effective Dosage
Not specified
Duration
Not specified
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
Vitamin D | increase | some anti-inflammatory cytokines | - | - | increases the production | #1 |
Vitamin D | decrease | some pro-inflammatory cytokines | - | - | reduces the release | #2 |
Low levels of Vitamin D | increase | TLRs expression | - | - | associated with an up-regulation | #3 |
Low levels of Vitamin D | increase | a pro-inflammatory state | - | - | associated with | #4 |
Vitamin D | increase | insulin sensitivity and secretion | - | - | directly increase | #5 |
Vitamin D concentrations | decrease | pro-inflammatory markers, insulin resistance, glucose intolerance and obesity | - | - | inversely associated with | #6 |
vitamin D status | decrease | incident type 2 diabetes mellitus | - | - | inverse association | #7 |
vitamin D supplementation | increase | insulin sensitivity, glucose and lipid metabolism | humans | - | demonstrating improvements | #8 |
vitamin D supplementation | no change | glycemic control and on inflammation | humans | - | showing no beneficial effect | #9 |
Vitamin D supplementation | neutral | - | patients at risk of developing diabetes | - | Encouraging results have emerged | #10 |
Vitamin D is a key hormone involved in the regulation of calcium/phosphorous balance and recently it has been implicated in the pathogenesis of sub-inflammation, insulin resistance and obesity. The two main forms of vitamin D are cholecalciferol (Vitamin D3) and ergocalciferol (Vitamin D2): the active form (1,25-dihydroxyvitamin D) is the result of two hydroxylations that take place in liver, kidney, pancreas and immune cells. Vitamin D increases the production of some anti-inflammatory cytokines and reduces the release of some pro-inflammatory cytokines. Low levels of Vitamin D are also associated with an up-regulation of TLRs expression and a pro-inflammatory state. Regardless of the effect on inflammation, Vitamin D seems to directly increase insulin sensitivity and secretion, through different mechanisms. Considering the importance of low grade chronic inflammation in metabolic syndrome, obesity and diabetes, many authors hypothesized the involvement of this nutrient/hormone in the pathogenesis of these diseases. Vitamin D status could alter the balance between pro and anti-inflammatory cytokines and thus affect insulin action, lipid metabolism and adipose tissue function and structure. Numerous studies have shown that Vitamin D concentrations are inversely associated with pro-inflammatory markers, insulin resistance, glucose intolerance and obesity. Interestingly, some longitudinal trials suggested also an inverse association between vitamin D status and incident type 2 diabetes mellitus. However, vitamin D supplementation in humans showed controversial effects: with some studies demonstrating improvements in insulin sensitivity, glucose and lipid metabolism while others showing no beneficial effect on glycemic control and on inflammation. In conclusion, although the evidences of a significant role of Vitamin D on inflammation, insulin resistance and insulin secretion in the pathogenesis of obesity, metabolic syndrome and type 2 diabetes, its potential function in treatment and prevention of type 2 diabetes mellitus is unclear. Encouraging results have emerged from Vitamin D supplementation trials on patients at risk of developing diabetes and further studies are needed to fully explore and understand its clinical applications.