IL6 and congestive heart failure: Low 25(OH)D concentrations are associated with elevated tumor necrosis factor-alpha (TNF-α) concentrations [4], and randomized controlled studies among critically ill patients and those with congestive heart failure report that vitamin D supplementation leads to significant reductions in interleukin 6 ( IL-6) and C-reactive protein (CRP) concentrations [5], and resulted in lower tumor necrosis factor-alpha (TNF-α) and increased anti-inflammatory IL-10 concentrations [6].