Vitamin D Is a Prognostic Marker in Heart Failure

Survival rates in heart failure patients with reduced levels of vitamin D are lower than in patients with normal levels, according to a new study.

Researchers at University Medical Center (Groningen, The Netherlands) assessed vitamin D concentration in plasma samples from 548 heart failure patients; the patients were divided into three groups depending on their blood levels of vitamin D. Over the 18 months of follow-up, 165 patients died and 142 were hospitalized again. The researchers found that those patients with the lowest vitamin D levels were 30% more likely to be hospitalized again or die than people with the highest levels. The effect of vitamin D levels held even after accounting for other factors. The researchers also found significant correlations between vitamin D, plasma Renin activity, and C-Reactive Protein (CRP) levels.

According to the researchers, there are several potential reasons for low vitamin D levels in heart failure patients. It might due to the fact that they are often bedridden or house-bound due to their clinical symptoms, leading to a serious deficiency in sunlight. 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. Severe heart failure is also 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.

Vitamin D has also been suggested as a negative regulator of the Renin Angiotensin System (RAS), which is responsible for volume and blood pressure homeostasis and is a pivotal regulatory system in heart failure. Low levels may activate the RAS, which in turn may contribute to the development and progression of heart failure. Several studies have shown that vitamin D also alters the cytokine profile and may therefore contribute to the inflammatory processes in heart failure. The study was presented at the European Society of Cardiology (ECS) annual congress, held during August-September 2010, in Stockholm (Sweden).

"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 lead author and study presenter Licette Liu, B.Sc. "With this new information, we then hope to provide better insight into the pathophysiology of heart failure.”

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. Recent studies, however, have provided novel insight into the vitamin's other functions. It has been shown that most tissues and cells have a vitamin D receptor, and there is strong evidence that it's 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 now, apparently heart failure as well.

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