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The latest reason to get calcium from food, not pills
Food sources of calcium, including milk, cheese, ricotta, yoghurt, sardines, kale, broccoli, spinach, soy beans, kidney beans, lentils and figs (as per USDA nutrient databank). - photo by Jennifer Graham
If you take a calcium supplement to stave off osteoporosis, you might want to consider eating more yogurt and spinach instead. A new study out of Sweden found that women who take calcium have a higher risk of dementia, and that the effect is seven times higher in women who have had a stroke.

Researchers analyzed the health records of 700 women between the ages of 70 and 92, and examined their memory and reasoning at the start of the study and five years later, Lisa Rapaport of Reuters News Service reported.

Overall, women who took calcium supplements were twice as likely to develop dementia as their peers who didnt, the study found. But the increased risk appeared limited to people who had had a stroke or other signs of existing cerebrovascular disease, Rapaport wrote.

While the study, published Aug. 17 in the journal Neurology, suggests calcium supplements are associated with a higher risk of dementia, it cant prove theyre the cause, the lead researcher, Dr. Silke Kern, a neuropsychiatric researcher at the University of Gothenburg, said.

But this is not the first study to suggest that calcium supplements can cause health problems. Previous studies found an elevated risk of heart attacks and strokes among people who take them. Others have found no connection.

The conflicting results may be bewildering to millions of women who take calcium in hopes of avoiding osteoporosis, the thinning of bones that affects 1 out of 2 women in their senior years. Although most of the bone mass is built before age 30, health experts recommend 1,000 to 1,200 milligrams of calcium a day for women over the age of 65.

It appears to be calcium supplements, not calcium in food, that pose a risk, Kern said. Researchers arent sure why but suspect that high levels of calcium may contribute to the death of neurons or affect blood vessels in the brain.

But because other nutrients impact calcium absorption, Dr. Neelum Aggarwal told Reuters that more research is needed before doctors stop prescribing calcium supplements. Cognitive function is affected by multiple nutrients, including phosphorus and magnesium, said Aggarwal, research director for the Rush Heart Center for Women at Rush University Medical Center in Chicago.

To say that only one nutrient increases the risk of dementia is premature, and more studies need to look at a combination of nutrients, she said.

A spokesman for the trade group that represents dietary supplements also noted that researchers did not have information on how much calcium the women who developed dementia were consuming, through supplements and diet.

Most health professionals agree, however, that when it comes to supplements, you can have too much.

"Its important not to overdo it on the calcium," wrote Jennifer Adaeze Okwerekwu for STAT News earlier this year, reporting on another study.

"Until more robust studies demonstrate that supplementation is safe, experts say its healthier to increase dietary calcium rather than relying on pills," she wrote.

The best sources of calcium, according to the Mayo Clinic, are dairy products, dark green leafy vegetables, and fish with edible soft bones. But the body can only absorb 500 to 600 milligrams of calcium at a time, so intake should be broken up over the course of the day.

And don't forget about vitamin D. Without it, calcium can't be properly absorbed. We need about 600 international units each day from sun or food, the Mayo Clinic says.