Calcium and Vitamin D Supplements Lead to High Levels of Blood and Urine Calcium in Some Older Women

Every year a majority of the aging American population spends billions of dollars on vitamin and mineral supplements. A study found that these supplements elevate the levels of calcium excretion as well blood levels in some women.

The randomized study including placebo controls was done on 163 white women in the age group of 57 to 90 with extremely low levels of vitamin D.  The women took vitamin D and calcium supplements to meet the minimum recommended levels,  which is 1,200 mg/day for calcium,  and varies for vitamin D.

The researchers say that different people react differently to the supplements. In this study they observed that 9 percent of the participants had excess calcium levels in blood, which is called hypercalcemia and nearly 31 percent of them had developed excess levels of calcium in their urine called hypercalciuria. These increased levels occurred even though the women took normal doses of the supplements and did not have hyperparathyroidism, in which the body produces excess calcium controlling hormones. 

"Even a modest calcium supplementation of 500 mg/day may be too high for some women," note the authors. It is recommend measuring blood and urine calcium levels before women start using the supplements and again within three months.

Due to excess levels of calcium in both blood and urine, the risk of women suffering from kidney stones or other problem also increases.

Researchers identified a way to pinpoint which women suffered the risk of developing these excess levels. Women who started with a 24 hour urine calcium level of more than 132 mg were 15 times more susceptible to developing excess urine calcium than women with lower levels. The women who started with 180 mg or more had 20 times increased risk of developing high calcium levels in urine.  But one-year increase in age lowered the risk by nearly 10 percent.

"I would recommend that women determine how much calcium they typically get through their food sources before taking a hefty calcium supplement. They may not need as much as they think," says NAMS Executive Director Margery Gass, MD.

The study was funded by the National Institute on Aging and the Office of Dietary Supplements and is documented in Menopause.