High vitamin D level improves survival rate in heart failure patients: Study Survival rates in heart failure patients with reduced levels of vitamin D are lower than in patients with normal levels. This is the finding of a major study carried out at University Medical Center, Groningen, Netherlands. Results also suggest that low levels of vitamin D are associated with activation of the Renin Angiotensin System (RAS - a pivotal regulatory system in heart failure) and an ... [News Source]