The study by researchers at University of Texas Southwestern Medical Center at Dallas says such patients should first check with their doctors to determine the dietary guidelines that work best for them.

The findings published in the December issue of the Journal of Urology say urinary calcium -- the amount of calcium in a person's urine -- is an important contributing factor in the formation of both types of kidney stones.

Earlier studies had downplayed the significance of calcium when compared to the levels of oxalate in urine, and even encouraged kidney stone patients to increase their dietary intake of calcium.

"We often see patients who tell us they have been advised to take more calcium; however, that could be a dangerous recommendation for some individuals," said Dr. Margaret Pearle.