Until a few years ago, taking a daily calcium supplement was considered a safe, effective way to protect against the bone loss that comes with aging and to reduce the risk for fractures—especially for women, who are more prone to osteoporosis than men.
Then the standard advice came under fire…big time. Not only was serious doubt raised about calcium’s usefulness in preventing fractures, but some studies suggested that calcium supplements actually cause harm—increasing the risk for heart disease.
Now a large new British study—with more than half a million subjects—appears to show that calcium supplements actually are safe for your heart. Should we believe this study? Are calcium pills suddenly safe again? And even if they are, do we really need them to keep our bones strong?
To get answers, we spoke with Connie Weaver, PhD, distinguished professor and head of the department of nutrition science at Purdue University in West Lafayette, Indiana. She is a world-renowned mineral and bone-health expert.
THE GREAT CALCIUM/HEART DEBATE
A little background: Until 2010, the only serious health concern from taking calcium was thought to be a very small increase in the risk for kidney stones. But that year, in a study published in The BMJ, New Zealand researchers analyzed several studies of people (mostly women over age 70) who took calcium supplements. They found that calcium supplements were associated with a 30% increase in the risk for heart attack and a smaller increase in the risk for stroke. Even calcium supplements that contain vitamin D, which other studies have suggested protects the heart, were associated with a small increased risk for heart attack and stroke, the same team reported in 2012.
Such statistical links can never be proof of causation, however, and from the start some researchers had their doubts about whether this danger would turn out to be real. The New Zealand researchers speculated that taking calcium supplements gives the body a surge in calcium all at once, which then ends up in our arteries and contributes to the formation of plaque, the substance that leads to atherosclerosis (hardening of the arteries). Yet animal studies conducted at Purdue University (and elsewhere) showed no such mechanism, notes Dr. Weaver. When animals were given high levels of calcium as supplements (or as dairy products), “there was no increased calcification of arteries.”
Even the statistical link was an outlier. In a comprehensive review of studies by the US Preventive Services Task Force (USPSTF), a government panel of 16 experts that evaluates health research and makes official health recommendations, none showed any increased cardiovascular risk.
The 2010 and 2012 calcium studies got plenty of press, though, and suddenly people were seriously worried that the calcium they were taking was hurting their hearts…and some stopped taking it.
The new British study, presented in April 2016 at the World Congress of Osteoporosis, Osteoarthritis, and Musculoskeletal Diseases, dealt a strong new blow against the heart-harm hypothesis. More than a half-million participants ages 40 to 69 were followed for seven years. Their use of calcium with or without vitamin D was tracked over the entire period of the study. Then the researchers analyzed their heart-disease–related hospitalizations and deaths, using hospital records.
Result: No link was found between calcium or calcium/vitamin D supplementation and hospital admissions or death related to heart disease.
Bottom line? To Dr. Weaver, this large new study—combined with the fact that nearly all other studies have found no heart risk and that careful animal studies find no plausible mechanism—make a compelling case. Her conclusion? “The new research adds to the now large body of evidence that there is no cardiovascular risk of calcium supplementation.”
BUT DO YOU NEED A CALCIUM SUPPLEMENT?
Just because calcium pills are safe for the heart, though, doesn’t mean you should take them. According to the USPSTF, there simply isn’t enough evidence to recommended a calcium/vitamin D supplement for the prevention of fractures—even in postmenopausal women. It’s true that in postmenopausal women, as well as in older men, calcium plus vitamin D supplements halt bone loss and modestly increase bone density, but there’s no good evidence that any particular supplementation level will actually prevent fractures.
Still, there’s no question that both calcium and vitamin D are important for bone health. For men age 71 and older and women age 51 and older, the Institute of Medicine’s current recommended dietary allowance (RDA) for calcium is 1,200 mg.
To get enough, and to protect your bone health, Dr. Weaver recommends an approach that starts with dietary calcium and vitamin D and looks to supplements only if necessary…
- Eat plenty of calcium-rich foods, especially dairy foods such as milk and yogurt (by far the most calcium-dense foods)—but also nondairy calcium-rich foods such as kale, broccoli and turnip greens. Nuts, especially almonds and hazelnuts, also are good sources of calcium, as are canned sardines and canned salmon (be sure to eat the bones). (For a list of foods rich in calcium, click here.)
- Tip: If you’re a yogurt fan, eat some traditional American-style yogurt, not only Greek-style yogurt—traditional American has twice as much calcium, ounce for ounce.
- Factor in fortified foods. Many foods are fortified with calcium, including orange juice, breakfast cereal and soy foods such as tofu and soymilk. Remember to include these amounts when adding up your daily calcium intake.
- If you’re not getting enough dietary calcium, discuss taking a supplement with your health-care provider. A typical serving of most dairy foods includes about 300 mg of calcium. Nondairy foods contribute, but you would need about three cups of cooked kale to get to that 300 mg. Add in the calcium in fortified foods that you eat daily (check labels), and if you’re still below 1,200 mg, consider a supplement for just what you’re missing.
- For vitamin D, the RDA is 600 IU for people age 70 and younger. For those 71 and older, the RDA is 800 IU. It’s very hard to get this amount without taking a supplement. See Bottom Line’s video “Get the Most from Vitamin D.”
- Eat a wide variety of whole foods. Many nutrients contribute to bone strength and the prevention of osteoporosis, not just calcium and vitamin D but also boron, manganese, silicon, zinc, magnesium and potassium. Eating enough protein is important, as is moderating how much sodium and caffeine you consume and eating plenty of fruits and vegetables. To increase your body’s ability to absorb calcium, especially if you are over age 50, Bottom Line’s medical consultant, naturopathic doctor Andrew Rubman, ND, advises also taking digestive enzyme supplements that include betaine HCL.
To learn more about a bone-healthy lifestyle, including exercise, see Bottom Line’s “Guide to Strong Bones for Life.”