Study: Calcium Pills Raise Heart Attack Risk by 86 Percent
Wednesday, May 23, 2012 6:23 PM
By Sylvia Booth Hubbard
Americans have been told for years to take calcium supplements for healthy bones, but increasing your calcium intake may come at the expense of your heart.
Shocking new research published in the journal Heart found that calcium supplements might increase the risk of having a heart attack by 86 percent, and experts warn they should be should be "taken with caution."
In addition, the research found that boosting overall calcium intake from dietary sources confers no significant advantage in terms of staving off heart disease and stroke.
Previous research has linked higher calcium intake with a lowered risk of high blood pressure, obesity, and Type 2 diabetes, all of which are risk factors for heart disease and stroke. And calcium supplements are routinely recommended to premenopausal women and the elderly to help avoid bone loss and prevent osteoporosis.
The new research is based on a German study
- involving 24,000 people who were
- 35 to 64 years old when they joined the study between the years of 1995 and 1998.
- They filled out food frequency questionnaires assessing their diet for the previous 12 months, and were asked whether or not they took vitamin or mineral supplements.
- The participants were tracked for 12 years,
The researchers found that people whose diets included about 820 milligrams of calcium daily from all sources, including supplements, had a 31 percent lower risk of having a heart attack than those whose calcium intake was in the bottom 25 percent.
(The recommended daily allowance (RDA) for calcium in the United States is 1,000 mg for ages 19 to 50 and 1,200 mg for those 51 and older.)
In regard to a daily calcium intake above 820 milligrams, those people whose intake totaled more than 1,100 mg daily did not significantly lower their risk.
When the relationship between calcium intake and stroke was evaluated, overall there was no evidence that any amount of calcium either protected against or increased the risk of stroke.
But when the researchers looked closely at vitamin and mineral supplements, they discovered that people who took calcium supplements on a regular basis increased their risk of having a heart attack by 86 percent when compared to those who didn't use supplements.
The risk was even higher when the subjects took only calcium supplements: They were more than twice as likely to have a heart attack than those who didn't take supplements.
The authors concluded: "This study suggests that increasing calcium intake from diet might not confer significant cardiovascular benefits, while calcium supplements, which might raise [heart attack] risk, should be taken with caution."
Previous research has shown
- a link between calcium supplements and kidney stones,
- as well as gut and abdominal symptoms.
Professors Ian Reid and Mark Bolland from the Faculty of Medical and Health Science at the University of Auckland in New Zealand noted in an editorial that accompanied the study's publication, that the safety of calcium supplements "is now coming under increasing scrutiny."
Reid and Bolland also noted that the overall protective effect of calcium supplements taken to prevent osteoporosis lowers risk only about 10 percent.
They explain the fact that dietary calcium is helpful while supplements are not is because dietary calcium is ingested in small amounts throughout the day and is absorbed more slowly than supplements.
Supplements, they say, cause calcium levels in the blood to soar above the normal range, and it is this flooding effect which might ultimately be harmful.
"Calcium supplements have been widely embraced by doctors and the public, on the grounds that they are a natural and therefore safe way of preventing osteoporotic fractures," they write.
"It is now becoming clear that taking this micronutrient in one or two daily [doses] is not natural, in that it does not reproduce the same metabolic effects as calcium in food," they say.
Since studies have shown that calcium supplements are neither safe nor effective, taking calcium supplements should be discouraged, they say.
The German study isn't the first to suggest that calcium supplements raise the risk of heart attacks. Last year, a meta-analysis of 11 studies published in the British Medical Journal found that people who took calcium supplements increased their risk of heart attack by 30 percent. Those researchers also speculated that the surges in blood calcium levels caused by supplements are responsible.
"We should return to seeing calcium as an important component of a balanced diet, and not as a low cost panacea to the universal problem of postmenopausal bone loss," Reid and Bolland wrote.