March 2013 Issue

Calcium Supplement Concerns

New studies suggest that you might be better off getting calcium from foods—dairy products, soy foods and green vegetables—instead of supplements.

For years we’ve been advised to consume ample calcium to protect our bones and combat osteoporosis. Not surprisingly, many people turn to calcium supplements. Indeed, 43 percent of the U.S. population, and nearly 70 percent of women over 50, take supplemental calcium. That could change in light of recent troubling reports that calcium supplements may do more harm than good. The conflicting messages have left many wondering if it’s time to toss out the bottle of calcium pills.

Supplemental calcium consequences. Last spring, the press widely covered research published in the journal Heart that linked calcium supplements to increased risk for heart attacks. The news didn’t get better after the U.S. Preventive Services Task Force (USPSTF) draft recommendation against calcium and vitamin D supplements, issued in June 2012, which asserted that they offered no protection against fractures in post-menopausal women, and increased risk of kidney stones.

An editorial published in the same issue of Heart suggested calcium supplements aren’t natural to the body. Diane L. Schneider, M.D., geriatrician and author of “The Complete Book of Bone Health,” says, “It’s a bigger load when you’re taking calcium concentrated as a tablet rather than as food.”

This is because the body may not be equipped to effectively metabolize large amounts of calcium all at once. Calcium supplements are also known to cause gastrointestinal problems, particularly constipation and bloating, in some people. And further, you’re at higher risk of reaching the tolerable upper intake level from supplements (see Meeting Your Calcium Needs) rather than from foods.

High calcium intake also has been linked with an increased risk of prostate cancer, but the jury is still out on this health concern: “The science is not adequate for us to conclusively determine the role of calcium in prostate cancer risk,” says Timothy Wilt, M.D., member of the USPSTF and professor at the University of Minnesota School of Medicine.

Good news for calcium in food. There’s no doubt your body needs the essential mineral calcium. In addition to its importance in bone health, “calcium is involved in the release of hormones, muscle health, activating enzymes, and helping the nervous system transmit messages,” explains Heather Mangieri, registered dietitian and spokesperson for the Academy of Nutrition and Dietetics.

The trick is to take in just enough calcium, without consuming too much. It’s important to note that dietary calcium has not been linked to the negative health risks recently reported. “When it comes to calcium, the recommendation is food first,” says Schneider. “Add up what is in your dietary intake and try to get the recommended amount from diet rather than from supplements.”

How to get your calcium. Ensure you’re meeting your calcium needs in your diet with these tips.

• Know your food sources. “Become familiar with foods that have calcium and that are good sources,” suggests Mangieri. Dairy products like milk, cheese and yogurt are excellent sources; aim for three fat-free or low-fat servings per day, according to the U.S. Department of Agriculture’s Dietary Guidelines.

• Space it out. We absorb calcium best in doses less than 500 mg, so space your intake of calcium sources over the course of the day.

• Non-dairy sources. If you don’t consume dairy products, or can’t seem to reach three servings a day, have no fear. There are plenty of other calcium-containing choices, such as calcium-fortified plant milks, “cheeses” and “yogurts” made from ingredients like soy, almonds, and rice (about 100 mg to 450 mg per serving); calcium-fortified juices, cereals, breads and tofu; kale, collard greens, almonds, broccoli, and molasses.

• Check nutrition facts labels. Similar products can vary in calcium content between brands and even within a brand (see Comparing Calcium in Foods).

• Calculate calcium in foods. The nutrition facts label lists calcium content in a serving of food as a percentage of the Daily Value (DV) instead of milligrams. The DV for calcium is 1,000 mg. To determine the milligrams of calcium, add a zero to the DV figure listed. For example, if the nutrition facts label lists calcium as 30% DV, that food has 300 mg of calcium.

• When to consider a supplement. If you can’t reach your calcium goal from diet alone, consider a supplement to cover the gap. Schneider cautions, “Supplements are only warranted when the food choices cannot supply the need. Remember that supplements are just that—supplements to the diet, not the primary intake.”

• Get enough vitamin D. You need adequate levels of the sunshine vitamin—vitamin D—to promote absorption and utilization of calcium. “Very few foods naturally contain vitamin D and few of us get unprotected sun,” says Schneider, who suggests that you might want to consider taking vitamin D supplements to obtain recommended levels (600 International Units for adults aged 19-70.) 

—Andrea N. Giancoli, M.P.H., R.D.