Calcium in our diets is good for us, and experts advise us to eat plenty of the nutrient through food, especially as we get older. But there are places in the body where it can spell big trouble —namely, calcium around the heart's arteries such as the aorta, the largest blood vessel in the body.
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The problem is calcification – the buildup of calcium that can lead to the development of plaque deposits in arteries, according to the American Heart Association.
Plaque deposits that can build up and form blockages in blood vessels are made up of fat, cholesterol and calcium, according to the Cleveland Clinic. They develop within arteries, just like gunk lines the inside of water pipes, and they can cause heart attacks or strokes when they block blood flow.
As with high blood pressure and high cholesterol, plaque deposits can be silent killers.
"Calcium buildup generally does not cause symptoms unless levels are so high that there is blockage in an artery," says Michael Miller, MD, a cardiologist and professor of cardiovascular medicine, epidemiology and public health at the University of Maryland School of Medicine in Baltimore. "In such cases, symptoms that include chest tightness or shortness of breath with exertional activity may occur."
Who Should Have a Calcium Scan?
Calcium deposits in blood vessels are measured through screening tests that rely on CT imaging. These tests are known as coronary calcium scans (or CAC tests). Results from these tests are given in the form of a score that can range from 0 to the hundreds. A score of 100 to 300 signals moderate plaque deposits and a high risk for heart disease or a heart attack in the following three to five years, according to the Mayo Clinic. A score higher than 300 is of significant concern.
So, should you get a coronary calcium scan? It depends.
In 2018, the American Heart Association released guidelines that suggest that the scans are appropriate for certain people, such as those 40 to 75 years old who might be appropriate candidates for statins, the cholesterol-lowering drugs, but who want a better idea of their personal risk for future heart disease before starting this drug therapy.
Statins have risks and benefits of their own, and having high cholesterol and high blood pressure isn't always enough reason to start these drugs if your heart disease risk is borderline. A coronary calcium scan can reveal risk factors that don't show up on a blood test.
The American Heart Association notes, however, that these tests can cost hundreds of dollars and may not be covered by insurance. And, according to the Mayo Clinic, the tests generally aren't useful in men younger than 40 and women younger than 50 because of their generally low levels of calcium, and the testing may not add any relevant information for people who are already known to be at high risk.
Preventing or Limiting Plaque Is Key
Coronary calcium buildup isn't reversible, Dr. Miller says, but you can keep it from getting worse by intensively managing your risk factors. "This includes quitting cigarette smoking, lowering LDL cholesterol to less than 70 mg/dL [milligrams per deciliter], treating high blood pressure and elevated glucose and adhering to a diet low in saturated fat," he explains.
Medications such as statins work to prevent more deposits as well as reduce inflammation within a plaque, making it less prone to rupture.
Should You Cut Down on Dairy and Calcium Supplements?
There's controversy over whether the calcium we eat is a culprit in the buildup of calcium in arteries. Calcium is found in food such as dairy products and in calcium supplements that are commonly taken to prevent conditions like osteoporosis.
According to the Mayo Clinic, some evidence suggests that calcium supplements — but not calcium in food — could contribute to the risk for heart attacks. But the jury is still out. As the Mayo Clinic notes, calcium supplements can be important for people with calcium deficiency or bone loss. Talk to your doctor before taking a calcium supplement to make sure it's right for you.
- American Heart Association: “Coronary Calcium Test Could Help Clarify Heart Disease Risk – and Control Cholesterol”
- Cleveland Clinic: “Can Too Much Calcium Raise Your Heart Attack Risk?”
- Mayo Clinic: “Calcium supplements: A risk factor for heart attack?”
- Mayo Clinic: “Heart scan (coronary calcium scan)”
- Michael Miller, MD, cardiologist, professor, cardiovascular medicine, epidemiology and public health, University of Maryland School of Medicine, Baltimore