Some calcium and vitamin D supplements may increase calcium excretion and blood levels in older women, resulting in serious health implications, a new study finds.

Older women are often advised by physicians to take calcium and vitamin D supplements to enjoy good health. However, these supplements may not be as beneficial for all older women, according to the findings of a new study. Researchers from the North American Menopause Society found that such supplements may cause calcium excretion and blood levels to reach exceedingly high levels in some women, resulting in serious health implications.

The study was conducted on 163 white women, aged between 57 and 90. All the women had low vitamin D levels but none of them suffered from hyperparathyroidism, a condition in which the body makes too much calcium-regulating hormone. All women were made to take calcium citrate tablets to meet their recommended intake of 1,200 mg/day. They also took various recommended doses of vitamin D.

At the end of the study, researchers found that 9 percent of the participants developed excess levels of calcium in their blood and 31 percent developed excess levels of calcium in their urine. This development was despite them taking recommended doses of the supplements. Excess calcium in the urine and blood can lead to kidney stones and other serious health issues.

"Even a modest calcium supplementation of 500 mg/day may be too high for some women," the authors said in a press statement. "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."

The silver lining of the study was that the researchers found a way to predict whether a woman is likely to develop excess calcium levels from taking supplements or not. Researchers said that women with a 24-hour urine calcium level above 132 mg were at 15 times higher risk of developing excess urine calcium. This risk increased to 20 times for women with a 24-hour urine calcium level of 180 mg and above. However, every one year increase in age reduced the risk by 10 percent.

Findings of the study were published online in Menopause, the journal of The North American Menopause Society.