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The Truth About Calcium

Recent studies have linked calcium supplements to heart disease and kidney stones

By Sheryl Kraft | Grandparents.com | August 20, 2014

(This article previously appeared on Grandparents.com.)

Some things seem to be a given when it comes to your health: fruit and vegetables are linked to healthy aging; a good night's sleep goes a long way to making you happy and productive and calcium is key for healthy bones.

But while there's no arguing with the first two, there's been quite a bit of confusion lately when it comes to calcium. Are calcium supplements dangerous to the heart? Are we getting enough calcium — or too much? And is dairy the best source?

How Much Calcium Do You Need?

Before talking about the risks of calcium supplements, it's important to understand that the amount of calcium you need per day changes over time.

Your body undergoes a continuous bone "remodeling" process by removing small amounts of calcium from your bones and replacing them with new calcium. If you remove more than you replace, your bones slowly become weaker and more prone to fracture. As we age, our body becomes less efficient at absorbing calcium. The Institute of Medicine says that women 50 and over need 1,000 mg per day; for men, it's 800 mg per day. For men and women over 71, the recommendation is 1,200 mg per day.

Keep in mind that this includes the total amount you need from food and supplements.

To determine how much calcium is in a particular food, check the nutrition facts panel of food labels for the daily value (DV) of calcium. The amount listed is based on 1,000 mg of calcium per day. For example: 30 percent DV of calcium equals 300 mg; 20 percent DV of calcium equals 200 mg of calcium and 15 percent DV of calcium equals 150 mg of calcium.

(MORE: Calcium — What Is Needed and Where to Get It)

Food and Supplements

As a rule, in terms of absorption in the body, it's best to get your calcium from food rather than supplements. However, says Dr. Ronald Hoffman, a New York City physician, author and broadcaster, "Most diets provide less calcium than you need, so you'll likely need supplements to fill in the gap."

In fact, about 43 percent of the U.S. population — including almost 70 percent of older women— take dietary supplements containing calcium, according to the National Institutes of Health.

So what's the problem? Some studies have recently shown that calcium supplements can have an impact on health issues such as heart disease:

Calcium and Your Heart

Does calcium really increase the risk of a heart attack?

A recent National Institutes of Health study found that men who took more than 1,000 mg of calcium supplements daily were more likely to have heart disease than those who didn't take the supplements. (Women were shown to have no increased risk, although other studies have shown the opposite.)

However, doctors caution that more research needs to be done on calcium supplements.

"The research is inconclusive," says Dr. David Goltzman, a professor in the Department of Medicine at McGill University in Montreal, Canada. More research is needed before doctors can know the association between calcium supplements and your risk of a heart attack, he says.

"I believe people should feel very comfortable following the recommendations from the Institute of Medicine," adds Goltzman. If you're concerned, talk to your doctor and try to get your daily allowance of calcium from food.

Great sources of calcium, aside from dairy products:

  • Canned sardines or salmon (with bones)
  • Turnip greens
  • Kale
  • Chinese cabbage or bok choi
  • Whole-wheat bread
  • Broccoli
  • Calcium-fortified foods like cereal, orange juice and tofu

(MORE: Fiftysomething Diet — Is It Time to Go Vegan?)

Kidney Stones and Calcium

Research done at Creighton University in Omaha, Neb. found that calcium-vitamin D supplements (calcium supplements often contain vitamin D which helps protect bones and aids in absorption) caused a higher level of calcium in blood and urine, and may cause increased risk of kidney stones.

However, like with heart disease, doctors caution that more research still needs to be done. If you're concerned and take a calcium-vitamin D supplement, talk to your doctor about the amount of calcium you take; he or she may lower the dose.

Drinking Milk and Osteoporosis

We've all been taught that milk helps bones. In fact, most of the calcium in the American diet comes from dairy products. However, some research done over the years has found a link between milk and a higher rate of osteoporosis and bone fractures.

Despite what you may have heard, says Goltzman, drinking milk will not cause calcium to leach from your bones. "That's old school," he says, "based on studies dating back to the late 1970s that found that eating a high-protein diet caused calcium to wind up in your urine. Consuming too much protein may cause calcium to be deposited into the urine, but milk itself is not the culprit, and it's not coming from your bones. High protein from any source may increase calcium absorption and cause calcium to be deposited into the urine," he says.

It is generally believed that the benefits of protein in the diet, outweigh the risks.

Medications & Other Bone Sappers

Steroids, proton pump inhibitors (which reduce gastric acid), SSRI antidepressants and certain diabetes drugs can interfere with the absorption of calcium, according to Goltzman. "Taking steroids for over three months has always been known to increase your risk of osteoporosis and fractures," he says.

What if you stop the medication? In the case of steroid use, studies show you're still at risk for a long time after you stop and it's not clear if you'll ever fully regain normal bone, Goltzman says. So far, no studies have looked at results from the other medications. Doctors stress that it's the long-term use of the medications, not short-term use, that's in question.

Another item you may want to cut down on is soda — specifically cola. Researchers at Tufts University found that women who drank diet or regular cola at least three times a week over a five-year period had lower bone density. The culprit, they believe, is phosphoric acid. It's only in colas. not other carbonated drinks, and is thought to interfere with calcium metabolism.

Alcohol and caffeine do not contain phosphoric acid,but also may decrease calcium absorption and contribute to bone loss, according to the National Osteoporosis Foundation.

Differences Among Calcium Supplements

Walk into a drugstore and you'll likely be confused when you see the varying arrays of calcium supplements on the shelves. There are several kinds of calcium supplements:
  • Calcium supplements that contain calcium citrate. Calcium citrate is a more expensive form of the supplement and is absorbed well on an empty or full stomach. "If you're a person who has low levels of stomach acid (as happens with acid reflux, more common in people over 50), I recommend taking calcium citrate, which will be better absorbed," says Dr. Leila Kahn, an endocrinologist at the Cleveland Clinic.
  • Calcium supplements that contain calcium carbonate. Calcium carbonate is generally inexpensive and is best absorbed when taken with food. The food helps produce stomach acid, which in turn helps your body absorb calcium supplements.
  • Multivitamins that include calcium
  • Calcium supplements that contain other nutrients, such as vitamin D. To absorb calcium, your body needs adequate vitamin D, which also plays an important role in protecting your bones. Without adequate amounts of D, you may lose bone, have lower bone density or be more likely to break a bone as you age, according to the National Osteoporosis Foundation.
  • Calcium included in over-the-counter antacid products such as Tums and Rolaids. Each pill typically contains between 200 and 400 mg of calcium carbonate.

If your doctor has approved a calcium supplement, know that calcium absorption is best when you consume a maximum of 500 mg at one time. Kahn recommends dividing your supplements and taking half in the morning (500 mg) and half in the evening (500 mg) if you require 1,000 mg.

If you're starting a new calcium supplement, start with 200 to 300 mg every day for a week and drink an extra six to eight ounces of water along with it, gradually adding more calcium each week. Slowly acclimating yourself to calcium supplements can help you avoid side effects like gas or constipation.