Are Calcium Supplements Safe? What You Need to Know Now
By Jordan Lite
Could the calcium supplements you take to strengthen your skeleton be doing you more harm than good?
That's the conclusion of controversial new research linking the supplements to increased risk of heart disease, a finding that has many of the 61 percent of older women who regularly take them worried. Calcium supplement use has more than doubled over the last two decades, according to the latest government data. Their popularity has grown along with awareness of osteoporosis, which affects 10 million Americans, 80 percent of them women, according to the National Osteoporosis Foundation.
But before you bag the bone-building pills, here's what top doctors think.
Can Calcium Harm Your Heart?
Women who took calcium supplements - at any dose - had a 13 to 22 percent greater risk of heart attack and stroke than those who didn't take the tablets, according to a new look at one of the Women's Health Initiative (WHI) trials, the government studies that tracked the health of thousands of menopausal women. According to the analysis, published in BMJ, for every 1,000 women who took calcium supplements to ward off osteoporosis, there were six extra heart attacks or strokes and three fewer fractures over five years.
More alarming, when the data was combined with results from eight other studies, there was a 25 to 30 percent greater risk of heart attack and a 15 to 20 percent higher risk of stroke with calcium supplement use.
"Calcium supplements may well cause more heart attacks and strokes than it prevents fractures, so therefore the use of calcium as a preventative and as part of a treatment regimen for osteoporosis should be markedly scrutinized," said Ian Reid, MD, professor of medicine and endocrinology at the University of Auckland in New Zealand and the study's lead author.
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But other experts are quick to point out a few caveats. When the WHI data was initially studied, it found no effect - good or bad - of calcium supplements on the heart. And neither the WHI nor the other studies Reid reviewed directly tested a link between calcium supplements and heart problems; instead, they were designed to look at the relationship between bone health and calcium, and collected additional information about their participants, including their heart health. That makes it difficult to prove a cause-and-effect relationship between calcium supplements and heart problems, said Michael McClung, MD, founding director of the Oregon Osteoporosis Center.
It's unknown why calcium supplements may pose a heart risk. Because they're a concentrated form of the mineral, they may cause a spike in calcium levels in the blood that contributes to hardening of the arteries, Reid said. Or the calcium spike may increase clotting that could lead to stroke.
The risks of calcium supplements seem to be higher the older a woman is, according to Reid. But that may be because old age itself ups cardiovascular risks.
Are You Getting Enough Calcium from Your Diet?
Food sources of calcium - in milk, yogurt, cheese, dark green vegetables and sardines, to name a few - aren't associated with heart problems, possibly because the mineral is absorbed gradually, says Nieca Goldberg, MD medical director of the women's heart program at NYU Langone Medical Center. She recommends that women get as much of their calcium from food as possible.
Women 51 and older should get 1,200 milligrams a day; 50 and younger need 1,000 daily milligrams. A few servings of dairy and veggies a day can get you there:
Plain, low-fat yogurt (8 ounces): 415 mg
Non-fat milk (8 ounces): 300 mg
Cheddar cheese (1.5 ounces: 300 mg
Fortified orange juice (6 ounces): 200-260 mg
Salmon (canned, 3 ounces): 180 mg
Spinach (0.5 cup): 120 mg
Kale (1 cup): 90 mg
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Before you pop supplements, first tally how much calcium you get from your typical diet, and then use supplements to make up the difference of what you're missing from food, McClung says. So, for example, if you have about two dairy servings a day (300 mg of calcium each), you only need to take one 600-milligram calcium supplement instead of two.
Taking too much calcium from supplements can also upset your stomach, causing constipation, gas, and nausea, he says.
It's also important to get enough vitamin D (a minimum of 600 international units, or IUs, daily) along with your calcium because the vitamin helps you absorb it. If you take calcium supplements, look for pills that also contain vitamin D. Top food sources of vitamin D include fish, such as salmon (450 IUs per three-ounce serving) and fortified milk (about 120 IU per cup).
"There's nothing magic about calcium supplements," McClung said. "You should only take them if you don't get enough from your diet."
The Bottom Line for Your Bone and Heart Health
First, determine much calcium and vitamin D you get from your diet before you shell out money for supplements.
If you have a history of heart disease, stroke, or diabetes or risk factors such as high cholesterol and high blood pressure, talk to you doctor about whether calcium supplements are a good idea, says Goldberg.
Depending on your age, family history, and other factors, your doctor may recommend that you get a bone density and other tests to evaluate your risk of fractures to decide whether to increase your calcium/D consumption or take prescription bone-building drugs.
Don't forget about these other healthy bone-boosting habits: weight-bearing exercise (like walking or jogging), not smoking, and avoiding alcohol.
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