How Can You Get the Calcium You Need?

Getting enough calcium is vital for healthy teeth and bones. But some Harvard experts question whether the recommended amount of calcium set by the Institute of Medicine is too high, especially for men. For women, there doesn't seem to be any disadvantage to getting 1,000 to 1,300 milligrams (mg) of calcium a day. But some studies have found a connection between calcium and prostate cancer. The Health Professionals Follow-Up Study found that men who drank two or more glasses of milk a day were almost twice as likely to develop advanced prostate cancer as those who didn't drink milk at all. Men who took calcium supplements were also at higher risk.

The controversy doesn't end there. Another question is whether it's best to obtain the calcium you need from food or supplements. Traditionally, dairy products have been touted as excellent sources of calcium, because they deliver hefty amounts of it in every serving. For example, a cup of 1 percent milk provides 300 mg of calcium. But not every expert recommends pouring your daily requirement of calcium from a milk bottle or getting it from other dairy products. One concern is that protein in dairy products might actually leach some calcium from bones. There are also questions about whether this form of dietary calcium protects against fractures. A 12-year study reporting on more than 77,000 women, ages 34–59, actually found somewhat more hip and forearm fractures among women who drank two or more glasses of milk per day compared with those who drank one glass or less per week.

So are calcium supplements helpful? Again, studies have reached different conclusions. One small study found that people who took calcium and vitamin D supplements daily lost significantly less bone over the course of three years than their counterparts who did not take supplements. Yet a much larger clinical trial involving more than 36,000 healthy postmenopausal women, ages 50–79, conducted as part of the Women's Health Initiative, found that taking calcium and 400 international units of vitamin D supplements resulted in only a 12 percent reduction in hip fractures overall—statistically a modest benefit. Yet when researchers analyzed the impact on particular subsets of women, they found significant benefits for two groups. Women of any age in the study who consistently took the supplements (as opposed to those who tended to miss doses) had a 29 percent reduction in hip fractures, while women older than 60 had a 21 percent reduction— in both cases, statistically significant.

Clearly, more research is needed. In the meantime, women may want to opt to get most of their calcium from calcium supplements and other nondairy sources. These include calcium-fortified juices, dark green vegetables such as kale and broccoli, and antacid pills. But no matter what its source, calcium can't build strong teeth and bones by itself. It works best when teamed with other vitamins and minerals, and when combined with weight-bearing exercise.

Source: Vitamins and Minerals: What You Need to Know. Copyright © by Harvard University. All rights reserved.