As of Thursday, May 16, 2013
DEAR DOCTOR K: I’m a man in my 60s. I’ve been taking a calcium supplement to protect my bones, but I recently read that men shouldn’t take calcium supplements. Why not?
DEAR READER: I wish I could give you a clear answer. Several recent studies have raised a question about whether regular use of calcium supplements might be bad for the heart. The bottom line: It’s too early to know if this risk is real.
There’s no doubt that we need calcium. It helps muscles to contract, blood to clot and nerves to communicate. And it plays an important role in building strong teeth and bones. As a result, many people take calcium supplements for bone health.
One new study followed the health of nearly 400,000 men and women. The study was published in the medical journal JAMA Internal Medicine. At the study’s start, the participants reported how much supplemental calcium they took. From diet surveys, the researchers estimated how much calcium the study participants were getting from food.
During 12 years of follow-up, men who took more than 1,000 milligrams (mg) of supplemental calcium per day were 20 percent more likely to succumb to heart disease than those who didn’t take calcium supplements. But there was no connection between calcium supplements and heart disease in women, and there was no connection with calcium from food.
Another recent study that followed more than 61,000 women in Sweden was published in the medical journal BMJ. Among women who took more than 1,400 milligrams per day of calcium supplements, the risk of premature death was more than doubled — particularly death from heart disease.
Both of these studies, and others that have pointed in a similar direction, involve large numbers of people and were carefully conducted. Yet they are observational studies, and you can’t make judgments about cause and effect from such studies. They clearly showed that men and women who took relatively high doses of calcium supplements had higher risks. But that doesn’t prove that the calcium supplements were the cause of higher rates of heart problems and death.
Surely, these studies don’t mean that you should forsake all calcium. Everyone needs calcium to keep bones strong, taken in conjunction with the bone-building vitamin, vitamin D. Losing calcium weakens bones and leaves them more prone to breaking. (I’ve put a table listing the daily recommended intakes of calcium and vitamin D on my website, AskDoctorK.com.)
With the safety of calcium supplements in question, try to get as much calcium as possible from food. Good calcium sources include:
— Low-fat milk and cheese;
— Calcium-fortified orange juice or soy milk;
— Breakfast cereals (which are also fortified);
— Leafy greens, particularly, kale, turnip greens and Swiss chard. (Go easy on spinach. It is high in iron, which tends to block calcium absorption.)
— Sardines and other canned fish with bones included.
I’m sure there will be more research studies on this important question. I’ll keep you posted.
Dr. Anthony L. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.