Too Much Calcium Could Cause Kidney, Heart Problems, Researchers Say

When it comes to a healthy diet — especially for women, and especially after menopause — nutritionists, doctors, everybody it seems, will tell you: calcium, calcium, calcium.

Federal health officials recommend that women and men younger than 50 consume 1,000 milligrams of calcium per day. The recommendation goes up to 1,200 milligrams after age 70 for men and after menopause for women, when a major drop in estrogen causes bone loss.

So, in a culture that often considers "more" to be "better," one might ask, if 1,200 milligrams of calcium is good, is 2,000 mg of calcium better?

No, says Dr. Ethel C. Siris, director of the Toni Stabile Osteoporosis Center at Columbia University Medical Center in New York. "You need enough; you don't need extra," she says.

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"Extra calcium does you no good, and there is a small risk that if you take too much you might get a kidney stone," says Dr. Siris. That's because the body can only handle 600 milligrams of calcium at once. Extra calcium can build up in the bloodstream and, when excreted through kidneys in urine, it can cause a kidney stone.

That's been known for a while. But recently, a few studies raised concern that excess calcium may also calcify coronary arteries in susceptible individuals and even precipitate heart attack.

Robert Eckel, a cardiologist and endocrinologist at the University of Colorado, is a past president of the American Heart Association. While these studies are far from conclusive, and far more research needs to be done, he says they do raise the question about whether there's potentially some danger in over-the-counter calcium supplements that go beyond our usual dietary intake of calcium.

"At this point in time, there's a bit of a signal" that should raise caution but remains highly controversial. "I don't think anyone has stepped up to say calcium supplements should be abandoned," says Eckel.

That's particularly because calcium is so critical for bone health. The best plan of action, says Siris: Eat more calcium-rich foods.

"If you're somebody who has a glass of milk with breakfast, that's 300 milligrams of calcium; a container of yogurt will give you another 200 to 300 milligrams; a couple of ounces of cheese will give you 200 to 300 milligrams," she says. For most healthy adults younger than 50, that's about all you need for bone health.

If you don't eat dairy, Siris says there are plenty of other foods that also contain calcium. These include vegetables (like broccoli, bok choy and turnip greens), oranges, figs, salmon and sardines. Cereals and soy milk often have added calcium, along with added vitamin D, which is essential to help the body absorb calcium.

So, estimate your daily intake of calcium from food, says Siris, and then calculate whether you need to take an extra supplement. You may just need 300 or 600 milligrams of calcium extra, and you may not even need that every day.

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