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By David Blyweiss, M.D.
A few weeks ago, a study blanketed the Internet linking calcium supplements to an increased risk of heart attack. Since then, many of my postmenopausal patients have come to me wondering if they should stop taking calcium. The short answer is no—but there’s more to the story than you might think.
In this particular review, researchers from the University of Auckland in New Zealand combined the results from 11 randomized controlled trials of calcium supplements that involved about 12,000 patients—most of whom were postmenopausal women. They were particularly interested in this demographic since calcium supplements are frequently prescribed to postmenopausal women in an effort to preserve bone health.
One of the studies they analyzed followed 1,471 healthy postmenopausal women over age 55. All of the women got a daily dose of about 860 mg. of calcium from their diet but half of the women got an addition 1,000 mg. via a calcium supplement, boosting their total daily intake to 1,860 mg. Over the next five years, those taking supplemental calcium showed a slightly higher risk of heart attack than the women who got their calcium from food alone. But, when the New Zealand scientists combined this study with prior studies, they found an over 30 percent greater risk of heart attack among those who supplemented with calcium.
So how could calcium supplements alone possibly affect heart attack risk? Here’s the current theory proposed by the Auckland team: When you take calcium supplements, the amount of calcium in your blood goes up significantly over the following four to six hours. That doesn't happen when you eat calcium-rich foods because dietary calcium is absorbed very slowly. This means that blood calcium levels don’t experience a spike like they do when supplements are taken. Higher blood calcium may lead to the formation of plaques in blood vessels, which can lead to heart attack, stroke and other cardiovascular diseases.
But not everyone agrees with this theory. As the Council for Responsible Nutrition points out, seven of the 15 trials they evaluated didn’t mention heart attack at all. In fact, only five of the 15 studies cited any link to cardiovascular problems whatsoever. That certainly isn’t enough evidence to cast doubt on the value of calcium supplementation. What’s more, this review didn’t examine the effects of calcium taken with magnesium. Many experts argue that this could drastically affect the results.
Indeed, large doses of calcium coupled with magnesium deficiency is a dangerous combination that can lead to calcium deposits, muscle spasms, kidney stones, fatigue and even hardening of the arteries. Without magnesium, calcium is not properly dissolved and absorbed. A magnesium deficiency not only compromises calcium metabolism, it also hinders the body’s production of vitamin D, further weakening bones. But magnesium isn’t just important for bone health. It also plays a key role in a healthy heart thanks to its ability to block the entry of calcium into vascular smooth-muscle cells and heart muscle cells. As a result, magnesium supplementation can help reduce vascular resistance, lower blood pressure, and lead to more efficient heart function.
Conservative estimates indicate that 60 to 75 percent of North Americans do not meet the minimum recommended daily amount of magnesium, which is 400 mg. per day. Fortunately, it’s easy to correct this shortfall. The best dietary sources of magnesium include green leafy vegetables, nuts, peas, beans, and cereal grains in which the germ or outer layers have not been removed.
Taking supplemental magnesium is also important. For stronger bones and better heart health, I recommend taking a 1:1 ratio of calcium and magnesium. The type of calcium and magnesium you take matters too. The ideal dosage for most people is 600 mg. of calcium citrate and 600 mg. of magnesium citrate daily. It’s also important to add 1,000 mg. of supplemental vitamin D, too. Vitamin D plays an important role in promoting calcium absorption. It’s also involved in bone growth and bone remodeling. Plus, vitamin D enhances immune function and reduces inflammation. Both of these actions promote cardiovascular health.
You should never have to choose between a healthy heart and healthy bones! Combining a nutrient-rich diet with this trio of supplements can safely and effectively protect both.
References:
Bolland MJ. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. British Medical Journal. 2010;341:c3691.
Spiegel DM. Long-term effects of magnesium carbonate on coronary artery calcification and bone mineral density in hemodialysis patients: a pilot study. Hemodialysis International. 2009;13:453-459.
Wei MY. Vitamin D and multiple health outcomes in the Harvard cohorts. Molecular Nutrition & Food Research. 2010 May 19. [Epub ahead of print] |
