“Calcium supplements could increase risk of heart disease, new study finds,” said a Washington Post headline in October. “Calcium supplements could give you a heart attack,” wrote the New York Daily News.
Don’t panic. Relax. It’s not true.
The Post and the Daily News and other media outlets evidently read the press release about this confusing new study and not the study itself. Nor did they put the new research into perspective.
Here’s what the scary-sounding study actually found.
Researchers at Johns Hopkins and other universities analyzed data from the Multi-Ethnic Study of Atherosclerosis Study, which was conducted from 2000 to 2012. The 5,458 study participants came from Baltimore, Chicago, New York City, Los Angeles, Minnesota, and North Carolina.
At the start of the study, the calcium content of their diets and of their dietary supplements and the amount of calcification in their coronary arteries (a measure of atherosclerosis) was recorded. Ten years later, the coronary calcification of the 2,742 remaining participants was again measured.
The results? For those who had some calcification to start with, how much calcium they consumed, whether from food or supplements, didn’t matter one way or the other for how much calcification remained in their hearts after 10 years. For them, calcium supplements clearly did not increase their risk of heart disease.
Among the participants who had no calcification at the beginning of the study, those who consumed the most calcium from food and supplements – an average of about 2,150 mg — significantly lowered their risk of developing calcification by 27 percent. That means their risk of heart disease was lower, not higher.
Then the results got murky.
Among the participants who began the study with no calcification, those who consumed the least amount of calcium from supplements—an average of 90 mg a day — had the highest risk of developing calcification. And those who consumed more calcium from supplements than that — an average of 165 mg to 1,125 mg — had no greater risk of developing calcification.
Somehow this got translated by the media into “calcium supplements could give you a heart attack.” Go figure.
Two weeks after this study appeared, reason prevailed. The American Society for Preventive Cardiology and the National Osteoporosis Foundation assured the public that calcium supplements have no impact on heart attacks, stroke, or other cardiovascular disease.
The two organizations based this advice on a new review of 31 studies — four clinical trials and 27 observational studies — by an expert panel which found no increased risk of cardiovascular disease in people who consumed up to 2,000 to 2,500 milligrams of calcium in supplements a day.
What to do:
If you don’t get the Recommended Dietary Allowance for calcium (1,000 to 1,200 mg a day) from food, it’s safe to take a supplement. Odds are, you only need about 500 mg (or less), since each serving of milk, yogurt, cheese, or most fortified foods has 150 to 300 mg, and most people get 250 mg from the rest of their diet. And now many multivitamins have 200 to 500 mg.
Sources: J. Am. Heart Assoc. 2016. doi: 10.1161 /JAHA.116.003815; Ann. Intern. Med. 2016. doi:10.7326/M16-1165 & doi:10.7326/M16-2193 & doi:10.7326/M16-1743.
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