“Over the last five years, there have been some studies to suggest that taking a calcium supplement raises blood calcium levels and could precipitate into the arteries,” says Felicia Cosman, senior clinical director of the National Osteoporosis Foundation and author of “What Your Doctor May Not Tell You About Osteoporosis.” “But this whole line of evidence is very controversial, and I think the jury is still out.”
What isn’t controversial is calcium’s important role in overall health: Your body needs it to maintain heart and nerve function and to build and keep strong bones. The Institute of Medicine recommends that most adults get 1,000 to 1,200 milligrams a day.
But as for meeting your daily requirement in whole or in part by taking supplements, there’s a lot of conflicting evidence. The 2012 Heart study and an earlier study in the journal BMJ both suggested links between calcium intake and heart attacks, but the latter study also found that getting too little calcium can contribute to heart disease.
The same ambiguity goes for kidney stones, another side effect of calcium supplements. A large 2006 study in the New England Journal of Medicine found that women taking a 1,000-milligram calcium supplement were more likely to develop kidney stones than women taking a placebo. But an even larger study in 2004 found that overall dietary calcium intake actually reduced kidney-stone risk.
It’s confusing, even for doctors. But there’s a common thread: None of the heart or kidney risks were associated with calcium from food. That has changed how many physicians advise their patients, Cosman says, and it has brought their focus back to what their patients eat.
“We want people to concentrate on modifying diet wherever possible,” Cosman says. “Most of the data show that dietary calcium is better for you and your bone integrity, so if you can get the calcium you need through your diet, you shouldn’t take a calcium supplement.”
Considering the abundance of calcium-rich and calcium-fortified foods out there, getting enough calcium from diet alone isn’t hard. Some breakfast cereals offer as much as 1,000 milligrams of calcium in a single serving. Unless you have a medical condition (such as celiac disease) that impairs your ability to absorb nutrients, eating a varied, healthful diet that includes calcium-rich foods such as milk and yogurt should do the trick, Cosman says — no calcium supplements required.
But what about other supplements for bone health? Vitamins D and K have also gained favor lately.
Vitamin D is crucial to bone health; without it, you wouldn’t be able to absorb or use the calcium you consume. But again, there’s some controversy. Experts disagree about how much you need and how well it prevents osteoporosis or bone fractures. Although the U.S. Preventive Services Task Force — an independent group of national experts that issues recommendations on preventive care — last week reported insufficient evidence that taking 400 international units daily does anything to prevent bone fractures, studies of higher Vitamin D doses have shown a reduced risk of fractures.