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06 September 2010

Vitamin D Is a Prognostic Marker in Heart Failure, Study Finds

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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, according to a presentation at the European Society of Cardiology's Congress 2010 in Stockholm
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 altered cytokine profile.

Vitamin D is produced by the skin when it is exposed to the natural Ultra Violet-B (UV-B) radiation from the sun. Low levels have long been known as the underlying mechanism of rickets however, in recent years, new studies have provided novel insight into the multiple vitamin's functions. It has been proved that most tissues and cells have a vitamin D receptor, and there is strong evidence that its presence plays a part in reducing the risk factor profiles of several chronic illnesses, such as common cancers, autoimmune diseases, kidney diseases, chronic infectious diseases, hypertension and apparently also heart failure.

"By showing that vitamin D is an independent predictor, we hoped to prove that it is a contributory factor to, rather than peripheral to, the development and prognosis of heart failure," said Ms. Licette Liu of the University Medical Center, Groningen. "With this new information, we then hope to provide better insight into the pathophysiology of heart failure."

Experiments with mice lacking the vitamin D receptor have shown typical signs of heart failure, while small-scale clinical studies have shown that low levels are a consistent factor amongst human heart failure patients. "There are several potential reasons for low vitamin D levels in heart failure patients, including the fact that they are often bedridden or house-bound due to their clinical symptoms" Ms. Liu explains. "This would lead to a serious deficiency, because 80-90 percent of vitamin D is obtained by UV-B radiation. Another factor is that the capacity of the skin to produce vitamin D declines with age, and as heart failure has a high incidence among elderly people, it is not entirely surprising to measure low levels. Furthermore, severe heart failure is associated with impaired renal function due to decreased blood supply. This may be responsible for a reduced synthesis of the active form of vitamin D, since the final step of conversion takes place in the kidneys. All of these factors may add to vitamin D deficiency in heart failure patients."


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