CHICAGO (Reuters) - Kidney disease patients who took a prescription form of Vitamin D were 26 percent less likely to die over a two-year span than those not taking the vitamin, U.S. researchers said on Wednesday.

Vitamin D helps the body absorb calcium and is important for bone health, but several recent studies suggest that this vitamin may have other benefits, such as protecting against heart disease.

Dr. Bryan Kestenbaum of the University of Washington in Seattle conducted a two-year study to see what impact the drug would have on improving the health of kidney disease patients with severely reduced renal function.

People with advanced kidney disease often take a form of Vitamin D to bring down high levels of a hormone secreted by the parathyroid glands in the neck that controls calcium metabolism. Too much of the hormone can weaken bones.

Kestenbaum's team studied 1,418 patients who had moderate to severe chronic kidney disease. All patients also had high parathyroid hormone levels, which is often caused by kidney failure.

One group was being treated with the drug calcitriol, a synthetic form of Vitamin D, to lower their parathyroid hormone levels. Another group was not taking the drug.

After two years, the researchers compared death rates, adjusting for differences in age, kidney function, parathyroid hormone levels and other illnesses.

They found patients taking the drug had a 26 percent lower risk of death compared to people not taking the drug. They also were less likely to develop end-stage kidney disease.

"Recently, there has been an increased focus on the effects of vitamin D beyond those on bone health," Kestenbaum, whose study appears in the Journal of the American Society of Nephrology, said in a statement.

Other studies have found that people undergoing kidney dialysis who are treated with an intravenous form of Vitamin D lived longer than those who are not treated with the drug.

Kestenbaum said more study is needed to see if the use of prescription forms of Vitamin D might reduce the risk of heart disease. He also thinks researchers should test cheaper, non-prescription versions of the vitamin.

In adults, vitamin D deficiency can lead to osteoporosis, and it can lead to rickets in children.

The body makes vitamin D when skin is exposed to sunlight. It is found in fatty fish such as salmon and milk commonly is fortified with it.

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