In a departure from typical clinical conclusions, researchers at the North American Menopause Society (NAMS) say common supplements could elevate calcium levels too high, putting them at risk for kidney stones, among other health problems.
Women approaching menopause are commonly advised to take supplements containing calcium and Vitamin D to fend off diseases like osteoporosis to which they are particularly prone.
"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.
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In the randomized, placebo-controlled trial, 163 women between the ages of 57 to 90 were examined. Each subject had been told her Vitamin D levels were too low and had been taking calcium citrate tablets of 1,200 mg per day.
All participants took Vitamin D supplements, ranging from 400 to 4,800 IU per day. The dosages of both supplements all fall into the normal range in terms of meeting daily intake requirements. The trial was limited to white women due to differences across ethnicity groups in the rate at which they metabolize Vitamin D.
Collected at three-month intervals during the one-year study, blood and urine indicated that nine percent of the women had an excess of calcium in their blood, and 31% had an excess of calcium in their urine. Researchers were particularly concerned because they claim to have eliminated the possibility of hyperparathyroidism, a hormonal condition that could lead to such results.
They were encouraged, however, when they discovered that a 24-hour urine calcium level above 132 mg indicated the likeliness of subjects developing excessive calcium levels after normal supplement use. For these women, the authors caution that even a modest 500 mg per day calcium citrate supplement may be too much.
The study will be published in the print addition of the journal Menopause in November and an abstract is available online. Although numerous studies recommend supplements of calcium and Vitamin D for everyone and particularly older women, research is beginning to question how much is too much.
A recent example is a 2013 British study cautioning pregnant women against such supplements.