Calcium and Vitamin D findings show that caring for your bones can be complicated


Calcium is important for bone health, but it’s unclear whether supplements or nutrient-rich foods are better. (Bebeto Matthews/Associated Press)
March 4, 2013

When a 2012 study in the journal Heart found that calcium supplements might raise your risk of a heart attack, I was more than a little alarmed. Might the over-the-counter supplements I’d been taking to strengthen my bones be damaging my heart?

The answer: Maybe.

“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.

The K vitamins — particularly K2, found in organ meats, eggs and certain fermented foods — has also drawn attention for its potential benefits to bone health, says integrative medicine physician Ariane Cometa, founder of the Cometa Wellness Center in Cockeysville, Md.

Heart disease runs in Cometa’s family, so she takes seriously the risks of using calcium supplements. She says that led her to explore alternative approaches to bone health.

Studies have shown that Vitamin K2 may sustain bone density and protect against heart disease, and these have been enough to turn Cometa into a K2 convert. She now recommends K2 supplements to her patients and takes them herself.

But because most Vitamin K2 studies have been relatively small, many physicians don’t yet feel the case for the nutrient is strong enough, Cosman says.

“It looks like people with high Vitamin K intakes have better bones,” she says. “There is some evidence, but it’s not enough for us to go out and recommend it for bone health.”

It’s worth noting that Vitamin K can be tricky if you take blood thinners, because it promotes blood clotting. So if you are on anticoagulants, check with your doctor before increasing your intake of Vitamin K through food or supplements.

Caring for your bones can be complicated. The Preventive Services Task Force recommends testing your bone density if you’re a woman over age 65, earlier if you’re at higher risk for osteoporosis because of family history or other factors. Many physicians, including Cosman, go further, recommending screenings after menopause for women and after age 50 for men.

If you do have osteoporosis or osteopenia (a less severe form of low bone density), your doctor can perform tests to determine if you need more calcium, more Vitamin D, a change in medication or treatment for an underlying condition. Physicians can also prescribe other medications to prevent further bone loss or stimulate new bone formation.

For Cosman and all the other experts I spoke with, the most basic tips for bone health still count the most: Avoid smoking, eat a healthful diet rich in calcium and get plenty of weight-bearing exercise. And keep a healthy, not-too-low weight, since being underweight increases your risk of bone loss.

Behavior is key, Cosman says. “It’s the same general principle as for cancer or heart disease prevention. You can’t distill it down to a single pill.”

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